RCA General Catalog - American Radio History

RCA General Catalog - American Radio History
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www.americanradiohistory.com
BROADCAST
AUDIO
Page
EQUIPMENT
CATALOG
Microphones
Consolettes
Custom Audio
Amplifiers
Rack Equipment
(Fourth Edition)
PRICE
$1.00
Turntables
Disc Recording
Speakers
Test Equipment
Index
RADIO CORPORATION
Broadcast and Television Equipment
OF
AMERICA
Camden, N. J.
C01 0ri :ht 1959. Radio Corporation of America, Broadcast 8 Teles ision Equipment Department,
Cunden.
www.americanradiohistory.com
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®
ABOUT
This Catalog
is
THIS
CATALOG
devoted solely to information on RCA audio broadcast
equipment designed especially for broadcast station use. Other RCA Broadcast Equipment Catalogs contain similar information on AM, FM and TV
transmitters, TV cameras, film and terminal equipment, antennas, transmission line equipment and accessories and test equipment.
The information contained in this catalog is intended to serve as a buying
guide for the users of this type equipment. In the belief that broadcast
engineers want facts, rather than generalities, the content has purposely
been kept brief and factual.
desire more information or
individual bulletins on particular equipment items are invited to write to
Readers who
the RCA Broadcast Representative in the RCA Regional Office nearest them
(see opposite page).
OTHER RCA TECHNICAL PRODUCTS
The RCA equipment described in this catalog
is
specifically designed for
broadcast station and closed circuit use. RCA also manufactures many other
electronic products including: two -way radio and microwave radio communication equipment; optical and magnetic film recording equipment;
sound systems of all types; 16mm projectors and magnetic recorders; indus-
trial inspection and automation equipment; scientific instruments, such as
the electron microscope; industrial television systems; intercoms; and many
types of custom -built equipment for industry, the military, educational and
medical services. Information describing these products may be obtained
from RCA Regional Offices.
www.americanradiohistory.com
HOW TO ORDER
The RCA Broadcast Audio Equipment shown in this cata-
log is sold directly through RCA Broadcast Representatives,
who are familiar with broadcast equipment and related
problems. One or more of these RCA Representatives are
located in each of the RCA Regional Offices listed below.
Orders for equipment shown in this catalog, or requests
for additional information, should be directed to the
nearest one of these offices.
PRICES
The prices of the various equipment units shown in this
catalog are given in a separate price list. Prices are listed
in the order in which they are shown in the catalog. To
determine the price of any equipment first note the page
on which it is shown in the catalog, then consult the price
list in accordance with this page number. Equipments are
identified by type and MI (Master Item) numbers which are
used to identify apparatus on invoices and packing slips.
YOU CAN LOCATE YOUR NEAREST RCA REPRESENTATIVE FROM THIS LIST
REGIONAL OFFICES
200 Berkeley Street
Front and Cooper Streets
CAMDEN 2, NEW JERSEY
Woodlawn 3 -8000
BOSTON 16, MASSACHUSETTS
36 West 49th Street
NEW YORK 20, NEW YORK
Judson 6 -3800
1121 Rhodes -Haverty Building
134 Peachtree Street, N.W.
ATLANTA 3, GEORGIA
Jackson 4 -7703
7901 Empire Freeway
DALLAS 35, TEXAS
Fleetwood 2 -3911
1600 Keith Building
CLEVELAND 15, OHIO
Cherry
1
-3450
Hubbard 2 -1700
1006 Grand Avenue
KANSAS CITY 6, MISSOURI
Harrison 1 -6480
1560 North Vine Street
HOLLYWOOD 28, CALIFORNIA
Hollywood 9 -2154
www.americanradiohistory.com
420 Taylor Street
SAN FRANCISCO 2, CALIFORNIA
Ordway
3 -8027
1186 Merchandise Mart Plaza
CHICAGO 54, ILLINOIS
Delaware 7 -0700
1625 K Street, N.W.
WASHINGTON 6, D.
District 7 -1260
C.
2250 1st Avenue, South
SEATTLE 4, WASHINGTON
Main
2 -8350
-
www.americanradiohistory.com
MICROPHONES
RCA
MICROPHONES
General Information
150 Ohms vs. 250 Ohms
The excellence of RCA microphones is the result of continued effort on the part of Engineering and Production
personnel to produce a superior product. Out of this work
When microphones are connected to unloaded input transformers, impedance matching is not a consideration and
the effects of connecting micrcophones with an output impedance of 150 ohms to a microphone amplifier designed
to operate from a 250 ohm source and vice versa will
usually be of small consequence. The effect on the level is
shown in the tabulation below.
have come the several types of broadcast microphones
listed in the catalog. There is considerable overlap in the
applications of the various types, but each does possess
certain attributes which make it particularly well suited to
some specific applications. These have been noted for each
microphone in the catalog in order to assist in the selection
of the microphone best suited for the intended application.
Mk. Output
Level Change
Impedance
db
250
1
High Quality Broadcast and
Television Microphones
150
Broadcast -type microphones such as the Types BK -lA,
BK -5A, BK -6B, BK -10A and 77 -DX all have certain common
performance criteria which make them especially suited
to this application. They have smooth response- frequency
characteristics over the audio range, low distortion, high
output levels, well -shielded output transformers to prevent hum pickup, and where necessary, are shock mounted
to reduce the pickup of low frequency building rumble.
Performance features which are unique to each particular type are listed and the applications discussed in
the catalog.
Public Address Microphones for Broadcast Use
Amp. Input
Designation
o
250
150
In addition there will be some change in the overall response- frequency characteristic of the system below 100
cycles and above 5000 cycles, the magnitude depending
on the connection and the design of both the microphone
and the amplifier input transformer. Variations in response
with the usual broadcast quality microphone amplifiers will
in most cases not exceed ±2 db.
When microphones are connected to a resistance load the
following changes in level will result when the output is
referred to a matched condition.
Public Address Microphones have been designed as economy microphones. In general, frequency range and sensitivity have been sacrified to some extent in order to gain
ruggedness and lower cost. The response limitations should
be borne in mind when these microphones are used in
Broadcast applications.
Level Change
Mic. Output
Impedance
1
db
-2.5
250
0
150
2.0
o
250
150
Load
Impedance
Unloaded Transformer Input
RCA Broadcast Microphones are designed to work into a
microphone preamplifier whose input transformer is un-
+2.2
0
-2.2
Microphones Shipped Less Plug
loaded. Under this condition of operation the voltage
appearing at the grid of the first tube results in a gain in
signal -to -noise ratio of between 3 and 6 db as compared
with a matched resistance load. The exact value will depend on whether the major source of thermal noise is in
the microphone amplifier or in the microphone.
RCA microphones are supplied less the plug for connection to the wall outlet or amplifier system. This is done to
allow the user to select any desired plug. As a convenience four types of Cannon plugs are catalogued and
they may be ordered as an accessory if wanted.*
Microphone Resistance Loading
Microphone Mounting
Microphones in which the moving system is highly damped
will in general have their frequency response characteristics little changed by electrical loading. The BK -1A and
77 -DX (in the pressure position) are examples of this.
RCA has standardized on the rugged 1/2" pipe thread for
broadcast microphone mounting. This size thread makes it
Microphones which show output impedance variations with
respect to frequency will have their response characteristics adversely affected by resistance loading. The Type
BK -5A, and 77 -DX (in the bi- directional and uni- directional
positions) are examples of this. Resistance loading of these
microphones will generally result in a loss in low frequency response.
easy to add microphone stand extensions, booms, etc., for
they may be easily made up locally from standard 1/2"
pipe and fittings. Most of the stands listed may also be
used with microphones having a 5/9 -27 thread by removing
an adapter which is supplied as a part of the stand.
Various adapters are available for microphones should the
use of the 1/2" pipe thread prove inconvenient.
*
Microphones are shipped connected for 250 ohms since in normal
usage an improved signal to noise ratio results when connected to
a 150 ohm preamplifier input.
www.americanradiohistory.com
MICROPHONES
Effective Output Level
square of the undisturbed sound field pressure in a plane
progressive wave at the microphone position. Expressed
When a microphone
is connected to an unloaded input
transformer its power output cannot be expressed in dbm
because no appreciable power is delivered by the microphone. The logical approach to the problem is to arrive
at some level figure which, when combined with the conventionally measured amplifier gain, will give the correct
output level for the combination. This figure is listed in
the catalog for each microphone and is called the Effective
Output Level. It differs from the EIA standard rating G,1
in the value of sound pressure and source impedance.
The EIA rating computation is based on a source impedance of 150 ohms for all microphones having output
impedances between 75 and 300 ohms, and on a sound
pressure of 0.0002 dynes per square centimeter.
While this may look complex the application is simple.
For all practical purposes the output level of the microphone is obtained by adding to Gm, the sound pressure
level relative to 0.0002 dynes per square centimeter. The
sound pressure level of the program material can be measured with any of the several available sound level meters.
The Effective Output Level calculation is based on the nom-
Hum Pickup Level
inal microphone impedance and on a sound pressure of
10 dynes/cm .
An arbitrary standard 60 cycle a -c field of 10_3 gauss
has been established as a reference. It is fairly representative of fields measured at typical microphone locations in broadcast studios. The hum level is referred to
.001 watt and is calculated in the same fashion as the
Effective Output Level, using as the output voltage the
voltage produced by the standard field.
mathematically:
Gm
-
(20 Ioglo
where
E
P
Rita
=
=
=
-
F
loglo Rmit)
10
Electrical reference level
Sound pressure
The EIA standard defines the system rating (G,1) of a
microphone as the ratio in decibels relative to 0.001 watt
per 0.0002 dynes per square centimeter of the maximum electric power available from the microphone to the
-
50 db.
the open circuit voltage of the microphone
the undisturbed sound field pressure
the microphone rating impedance
-
-
.001 watt
.0002 dynes/sq. cm.
Chart Showing Microphone Applications, Chief Characteristics and Recommended Mounts
Type No.
Used
Directional
Characteristic
77 -DX
Program
Announce
Poly- directional
-lA
Program
Announce
Non -directional
BK-5A
Program
Announce
Uni- directional
"Off- Mike"
Semi -directional
BK
BK -68
Speech
BK -10A
Specialized
Program
Ultra- directional
SK -35
Sports
Announce
Bi-directional
Close Up
Non -directional
SK -39
SK -45B
SK -46
Announce
Intercom
& Talkback
Radio & TV
Announce
Effective
-53
Gm
Bi- directional
Frequency
Hum
Response
Pick-up
cps
Level'
dbm
db
30/150
50-15,000
-128
dbm
Satin Chrome
dbm
30/150
60- 10,000
-109
dbm
Satin Chrome
& TV Gray
Desk, Floor
50- 15,000
-128
dbm
TV Gray
Boom, Desk,
Floor
80- 12,000
-112
dbm
TV Gray
Clip & Microphone Lanyard
80.15,000
-127
dbm
50-10,000
-113
dbm
-147
-53
Get
-145 db
-56
Get
dbm
db
30/150
dbm
40/200
-147 db
250
-158
-58
Get
dbm
db
-150
-55
4S0
250
200/15,000
dbm
250
70 -9000
-95
dbm
db
200 /15,000
80 -8,000
-109
dbm
dbm
-150 db
200/15,000
50- 10,000
-113
dbm
dbm
-56
-56149
-58
Reference level 0.001 watt, sound pressure 10 dynes per square centimeter. This corresponds to a rating by the proposed EIA system at
a sound pressure level of 94 db.
2 Level referred to a hum field of 10 -3 gauss.
1
Stand
Finish
Boom, Desk,
Floor
& TV Gray
Black & Low
Gloss Gray
Boom
Satin Chrome
Hand, Desk,
Floor
& TV Gray
-150 db
Gm
G
G >t
250
30/150
-55
G
250
dbm
db
-150
-67
Get
GN1
Non -directional
Output
Impedance
Ohms
Output
Level'
and G 11 b
Umber Gray
TV
Satin Chrome
8.
3 For
I
G
Gray
TV Gray
details refer to description of each particular type.
-
(EIA rating).
Also available in TV Gray as MI- 11006-C.
www.americanradiohistory.com
Hand, Desk,
Floor
Desk, Floor
Hand, Desk,
Floor
MICROPHONES
POLYDIRECTIONAL MICROPHONE
TYPE
77 -DX
FEATURES
High quality reproduction with greater sensitivity over entire audio frequency range
Styled for either radio or TV applications
Choice of directional pattern to control
ratio of direct -to- reverberant sound pickup
Three - position voice -music switch allows
selection of best operating characteristic
Efficient shock mounting
USES
The RCA Type 77 -DX Polydirectional Microphone is pri-
marily intended for broadcast use either in the radio or
television studio. Two models are available. The MI- 4045 -F
finished in satin chrome and a low -gloss umber gray
enamel is intended for AM or FM stations, while the
MI- 11006 -C microphone is intended for television use and
is therefore completely finished in a low -gloss umber -gray
enamel which eliminates glaring reflections. Both instruments are high -fidelity microphones of the ribbon type
which may easily be adjusted to obtain a variety of directional patterns. If used outdoors the Type 77 -DX may
require some additional protection against the wind.
As a uni- directional microphone the 77 -DX has a wide
pick -up angle on front which may be used to advantage
as a general programs and announce studio microphone
and for television boom operation. It is recommended for
use on programs where it is desirable to cover a large
area with a single microphone, on programs where studio
acoustics are more live than optimum, and programs where
it is desirable to eliminate audience noise originating behind the microphone. The 77 -DX can also serve as a bidirectional instrument on programs where the players are
grouped around the microphone or are seated on opposite
sides of a table. In the non -directional position, the microphone is excellent for announce work or for out -door
locations.
DESCRIPTION
MI-1 1006-C
MI-4045-F
ment by positioning of a shutter to secure various areas of
opening. The moving element is a thin corrugated metallic
ribbon clamped at the ends and suspended in the air gap
of a magnetic circuit consisting of an Alnico V permanent
magnet and pole pieces. One side of the ribbon is open
and the other is connected by means of a tube to a folded
acoustically damped pipe contained in the center section
of the microphone.
The tube connecting the back of the ribbon to the labyrinth
slotted directly behind the ribbon and fitted with the
shutter which controls the directional properties of the
microphone. When the opening is completely closed, the
microphone operates as a non -directional pressure microphone; at the wide -open position the instrument becomes
bi- directional. With the proper size opening the pattern
becomes a cardioid by virtue of the phase shift which
occurs. Openings smaller or larger than this critical size
produce directional patterns with various sized rear lobes.
Different amounts of low- frequency attenuation are obis
tained by a reactor shunting the output.
The RCA Type 77 -DX Polydirectional Microphone operates
as a uni -directional, bi- directional or non -directional instru-
The shutter opening is operated by turning a slotted shaft
which
is
brought out flush with the rear of the windscreen.
www.americanradiohistory.com
MICROPHONES
The shutter position is indicated on a plate mounted on
the screen and marked "U ", "N" and "B ". Three addi-
tional markings "L -1 ", "L -2 ", and "L -3" are used as reference points for other directional patterns which may be
obtained. If desired, the microphone may be locked in the
uni- directional position by means of a cover plate marked
"U ". This fastens over the indexed plate. The bottom portion of the microphone contains an impedance matching
transformer and switch for selecting response characteristics for voice or music. The switch shaft is slotted and
accessible through a hole in the bottom of the lower shell.
The transformer is exceptionally well shielded against stray
magnetic fields.
The 77 -DX will mount on any stand having a 1/2-inch pipe
thread. Other stands will require a suitable adaptor. The
microphone is cushion- mounted, and a fork mounting is
provided so that the instrument may be fitted to the desired
position. The microphone is connected for an output impedance of 250 ohms at the factory, but it may be adjusted
for an output impedance of 30 or 150 ohms.
SPECIFICATIONS
Directional Characteristics
Frequency Response
Output Impedance
Load Impedance
EIA System
Adjustable, 6 positions (see curves)
50- 15,000 cps
250 ohms, may be changed to 30 or 150 ohms
Unloaded input transformer
G,1
Effective Output Level (all output connections):
-50
-53
-56
Bi- directional
Uni -directional
Non -directional
Hum Pick -up Level
Dimensions (overall)
dbm* GNt
dbm* Gat
dbm* Get
= -144
= -147
= -150
-128 dbm **
111/2" long, 33/4" wide, 21/4" deep
Weight:
Microphone
Cable
Cable (MI -43 -B, 3 conductor, shielded)
Mounting
Stock Identification:
3
30 ft., no plug
1/2" pipe thread
MI- 4045 -F
MI- 11006 -C
Gray
Luster
lbs.
11/2 lbs.
Satin Chrome
Low
db
db
db
Accessory
Protective Cloth Zippered Bag
*
**
MI-4087
_..
Sound Pressure = 10 dynes/cm2.
Referred to a hum field of
x 10 3 gauss.
1
Typical Directional Patterns and Frequency Response
Curves of 77 -DX Polydirectional Microphone
OPEN CIRCUIT RESPONSE
TYPICAL
OF A
TYPE 77DX
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www.americanradiohistory.com
POSITION
FREOUENCY IN
CYCLES PER SECOND
10,000 15000
TUTS0
MICROPHONES
MICROPHONE
ULTRADIRECTIONAL
TYPE BK -1OA
FEATURES
USE
Type BK -10A Ultradirectional Microphone is
designed to provide quality audio pickup under adverse
conditions during television broadcast, radio broadcast,
recording and public address. This is accomplished by a
highly sensitive second order gradient directional characteristic which may be used to increase the signal to
The
Simplifies microphone and camera placement problems -ultra -directional characteristics provide quality pickup under adverse
conditions
RCA
noise ratio of the microphone.
Lightweight for TV boom operation
High quality reproduction over entire audio
frequency range
Maximum sensitivity lies on major mechanical axis
Rugged construction- improved resistance
to gun blasts
Improved long -life flexible cable
is a ribbon type bigradient uniaxial microphone with a frequency response that is essentially uniform
from 80 to 15,000 cycles suiting it for reproduction of
both speech and music. The response pattern and the improved signal to noise ratio simplify microphone and camera
placements; and allows for greater distance between the
microphone and the talent than heretofore possible. It
is especially effective for TV studio boom use in high
noise areas. Other uses indicated for the new microphone
are: situations where feedback from monitor speakers is
a problem; and controlling the level of the leading voice
in a choral group. The microphone incorporates a filter
which effectively reduces the possibility of damage to the
instrument from sharp blasts and other violent noises. The
axial directivity combined with a Boom Stand such as the
KS -3B, make the microphone very easy to handle to keep
the sound source "in focus."
The BK -10A
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MICROPHONES
DESCRIPTION
The Type BK -10A Ultradirectional Microphone is a second
order gradient directional instrument with uniform frequency response from 80 to 15,000 cycles. Excellent directivity is accomplished by matching and combining the
electrical outputs of two unidirectional ribbon microphone
elements.
The unidirectional microphone elements are similar in con-
struction and performance to those used in the BK -5A
Microphone. Each element has a thin corrugated metallic
ribbon clamped under light tension, thus making its natural
frequency of vibration sub -audible. The ribbon is placed
between the poles of a magnetic circuit. One side of the
ribbon is open to the atmosphere, and the other side
opens into an acoustical labyrinth which has phase shift
openings. The labyrinth of each microphone element houses
an impedance matching transformer. Each element has its
own blast filter. In addition, the transformer is exceptionally
well shielded against stray magnetic fields.
The BK -10A will perform satisfactorily in high hum fields
because of its improved wiring and shielding. The elements
are carefully matched so that the performance of each
complements the other. In addition, the shock isolation
mounting provided incorporates improved compact design features. This mount does not generate any noise and
isolates the microphone effectively from its support. There
are no rubber band mountings to wear out. The cable
supplied with the microphone is braided tinsel cord 18
inches long which has been especially designed to attenuate "stand" noise.
The BK -10A has a low -gloss finish, which with compact
mounting arrangement, provide minimum light reflection and
minimum shadow. The output impedance of the microphone
is 200 ohms for 150- and 250 -ohm unloaded input transformers but may be changed at the terminal board to
40 ohms for 30- and 50 -ohm input transformers. The output
level is maintained at -56 dbm, and hum pick -up is reduced to a level of -130 dbm.
SPECIFICATIONS
Directional Characteristic
Unidirectional 2nd Order
Gradient Characteristic
Frequency Response
80 to 15,000 cps
Output Impedance
Load Impedance
_
200 or 40 ohms
Unloaded input transformer
_
-56
Effective Output Level at 1000 cps
dbm
-150 db
-130 dbm
EIA Rating (Gm)
'Hum Pickup Level
Coble
Braided tinsel,
Dimensions (overall)
18
10',2" x
Weight.
2
Ib.,
8 oz
inches long
P4"
x 27/é"
(less cable)
Two Tone, Black and Low gloss gray enamel
Finish
Stock Identification
MI- 11018 -A
Accessories
Microphone Boom and Stand
MI -11056
_
Microphone Boom and Perambulator.
*Relative to a field of
1
x 10 -3
MI -26574
gauss
Frequency Response Curves for BK -10A Microphone.
RESPONSE
AND DIRECTIONAL CURVES
FOR THE RCA TYPE
8K -10A ULTRADIRECTIONAL MICROPHONE
BK -10A
0°
5
0
-5
-10
-15
-20
25
-30
Directional Characteristic.
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www.americanradiohistory.com
MICROPHONES
PRESSURE
MICROPHONE
TYPE BK -1A
FEATURES
Lightweight rugged construction
Attractive modern styling with non- reflective TV gray finish
Convenient swivel mounting
Ideal for interview type programs
Not sensitive to wind or mechanical
vibrations
Frequency characteristic
source distance
DESCRIPTION
USES
The BK -1 A pressure
microphone
is
designed for broad-
cast use in AM, FM and TV stations. Its construction makes
it particularly well suited for remote pickups. The BK -1 A
features a smooth response and frequency range which
make it suitable
Rugged,
is
or reproducing both music and speech.
insensitive
to
mechanical vibration, the BK -1 A
the ideal micrcphone for outdoor use where constant
handling by the announcer
is
independent of
necessary. Pleasingly .tyled,
it effectively serves TV announce desk or conference pro -
g-ams where each participant has a microphone
ii
the
scene.
Characteristics of design and styling make the
he BK -lA is a pressure
actuated type microphone. The
sound pressure actuates a lightweight molded diaphragm
attached to an annular coil assembly which is placed
within a magnetic field. An acoustic circuit, coupled to
tie diaphragm, is proportioned so that the diaphragm
velocity remains essentially constant for a constant sound
pressure from 60 to 10,000 cycles. The coil is connected
to an impedance matching transformer providing output
impedances of 30, 150, and 250 ohms.
Non -directional when mounted vertically, a semi -directional
characteristic is obtained when horizontally mounted, in
which case the BK -lA is essentially non -directional for frequencies below 2000 cycles -the higher frequencies are
attenuated more as the angle with the perpendicular to
the diaphragm increases.
BK -lA
de-
sirable for: broadcasts where the microphone should blend
with the scene; programs where the performer must work
close to the microphone; and public address system use.
Versatility is assured by design which allows the BK -lA to
be stand mounted on desk or floor or to be easily removed
from the stand mountings for use as a hand microphone.
A durable ball and socket joint located at the base of
the stem makes selection of the best speaking angle easy,
when used as a stand mounted microphone.
www.americanradiohistory.com
MICROPHONES
SPECIFICATIONS
-52
Effective Output Level
Frequency Response.
dbm*
Length
30/150/250 ohms (connected for 250 ohms
Output Impedance
when shipped)
EIA Rating (G21):
150 Ohms
30 Ohms
(including mounting)
17/e°
18 oz. (less cable)
3- conductor shielded, 30 feet (no
plug)
1/2" pipe thread
Low luster gray and chrome
Finish
-144 db
-147 db
-148 db
250 Ohms
73/4"
Diameter
Weight.
Cable
Stand Fitting
60- 10,000 cps
Stock Identification
Ml -11007
Accessories
Directional Characteristic:
Semi -directional
Non -directional
Recommended Load Impedance
Hum Pickup Level
When mounted horizontally
When mounted vertically
Unloaded input transformer
-102
Base, Type 1(5 -11A
Flcor
MI -11008
..
Stand
MI- 4068 -G
Referred to one milliwatt and a sound pressure
dbm (.001 gauss)
10 dynes/cm2.
FRONT COVER
FREQUENCY RESPONSE OF A TYPICAL
BK -IA PRESSURE MICROPHONE
SCREEN
DIAPHRAGM
A
+5
VOICE COIL
ACOUSTIC DAMPING
CENTER CORE
ú
5
MAGNET
©-
O
+B
-10
-15
T
50
100
CASE
A
300
FREQUENCY
CYCLES
-- TRANSFORMER
5000
1000
IN
PER
SECOND
TUBE
ACOUSTIC SEAL
TERMINAL
BOARD
BACK COVER
BALL
Br.
SOCKET
SWIVEL
STAND
RETAINING
WASHER
12
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MICROPHONES
UNIAXIAL
MICROPHONE
TYPE BK -5A
FEATURES
Improved unidirectional characteristic with
wide pickup angle on front
Three position voice-music switch allows
selection of most desirable operating characteristic
Simplifies microphone and camera placement problems- maximum sensitivity lies
on major mechanical axis
Small size-ideal for TV boom operation
Rugged construction -improved resistance
to gun blasts
Exceptionally good shielding permits operation in high hum fields
Improved long -life
boom mount
flexible
cable
and
USES
DESCRIPTION
The RCA Type BK -5A Uniaxial Microphone is a depend-
The Type BK -5A Microphone is a unidirectional microphone
able, high -quality ribbon instrument possessing an improved unidirectional characteristic, and designed for
broadcast use in AM, FM and TV stations. The microphone
has a frequency response that is essentially uniform from
50 to 15,000 cycles. Its excellent response and frequency
range, combined with its unexcelled cardioidal directional characteristic makes it ideal for reproducing both
speech and music.
in which the moving element is a thin
The microphone has been especially engineered with the
television studio in mind. Since maximum sensitivity lies on
the major mechanical axis, it is a one axis, or uniaxial
type microphone. This directional characteristic simplifies
microphone and camera placement problems. Incorporated
in the unit is a blast filter which effectively reduces damage
to the microphone from gun blasts and other violent noises.
addition, the small size, light weight, unobtrusive yet
attractive gray finish and appearance render it especially suitable for television, but it is also admirably suited
to general broadcasting and high -fidelity sound systems.
In
corrugated metallic
ribbon clamped under light tension to cause it to vibrate at
its own resonant frequency. The ribbon is placed between
the pole pieces of a magnetic circuit. One side of the
ribbon is open to the atmosphere and the other opens on
an acoustical labyrinth which has phase -shift openings
giving the instrument its improved unidirectional characteristics. The labyrinth of the microphone houses an impedance matching transformer and switch for selecting
response characteristics for voice or music.
A unique feature of the BK -5A is a blast filter consisting of
two separate cloth layers supported by perforated metal
screens. The filters effectively reduce damage to the microphone from gun blasts and other loud noises encountered
in broadcast programming. In addition, the transformer
is exceptionally well shielded against stray magnetic
fields and can perform satisfactorily in high hum fields.
for the sensitive vibrating ribbon a
wind screen is available for use with the instrument. Its use
is recommended if the instrument is to be used outdoors.
As further protection
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MICROPHONES
The integration
of the blast filter, acoustic phase-shift
network and especially designed connector to couple the
ribbon to the labyrinth
is
axial characteristic of the
responsible for the unique uni-
and uniform frequency
BK -5A,
response over the entire aural spectrum. The microphone
is
housed in a tri- sectional casting which blends functions and
appearance into a coherent whole. It
is
supported by a
fork mounting which has a /8" straight pipe thread to
fit RCA cushion mountings for either desk or floor stands.
1
An improved shock mount based on panel meter mounts
designed for military use
is
BK -5A
Microphone with
Wind Screen,
MI- 11011, and
Boom Unit,
MI. 11012.
incorporated in the Boom
Unit. This new mount isolates the microphone effectively
from its support and does not generate any noise. There
are no rubber band mountings to wear out and need re-
placement. A 30 -foot flexible cable, supplied with the
microphone, makes use of tinned cadmium bronze wire to
provide longer life.
The small size and axial directivity aid in
BR -SA MICROPHONE
FREQUENCY RESPONSE OF THE
-
I.
S-
M,-
S
BK -5A in
external parts to reflect light and draw attention to the
OPEN CIRCUIT RESPONSE
FREE FIELD PLANE WAVE
009.129
DO
rV
instrument. The axial directivity combined with the Boom
/DYNE /CM.
Mount (Ml- 11012) make the microphone very easy to
handle to keep the sound source "in focus." The addition
of the wind screen to this combination does not cause a
lI
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25
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40
min
100
IDENT
bin--
B"e
1000
FREQUENCY IN CYCLES PER SECOND
IIIi
1111
10000 15000
171007-0
C
SPECIFICATIONS
Performance Specifications
llMaIi1111R1!11111"9°:
,0111111`11NC1ÑE0NT
of the sense of the pickup axis.
00000 IS000
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DIRECTIONAL CHARACTERISTIC
ABOUT THE VERTICAL AxIS
0
placing the
inconspicuous fixed locations. There are no shiny
Directional Characteristic
Unidirectional
Frequency Response
50 to 15,000 cps
Output Impedance
250 ohms, may be changed to 30 or 150 ohms
Load Impedance
input transformer
Unloaded
Effective Output Level at 1000 cps
EIA Rating (G\1) (150 ohm connection)
"Hum Pickup Level
Cable
3-conductor,
7"
1
dbm
dbm
pound,
11
x
23/4" x 27/e"
ozs. (less cable)
Low luster gray enamel
Finish
/e" straight pipe thread (female)
Mounting
Stock Identification
dbm
shielded, 30 feet, no plug
Dimensions (overall)
Weight
-56
-150
-128
1
MI -11010
_
Accessories
MI -11012
Boom Unit
Wind Screen
..
_
Cushion Mounting Assembly....
Relative to a field of
www.americanradiohistory.com
1
x 10 3 gauss.
MI -11011
Stock No. 93973
MICROPHONES
MINIATURE DYNAMIC MICROPHONE
TYPE BK -6B
FEATURES
Lightweight
microphone
with
excellent
speech balance when talking "off mike"
Easily concealed in man's hand
clothing . . . on TV settings
.
.
.
in
Clip type lanyard for ease of looping
about neck
Wide -range frequency response
...
color and styling
Rugged construction
makes it blend with surroundings
USES
DESCRIPTION
The RCA Personal (Type BK -6B) Microphone is especially
A high quality instrument of the pressure actuated type, the
Personal Miniature Dynamic Microphone has a frequency
response from 80 to 12,000 cycles and a directional characteristic similar to the popular RCA 77 -DX in the nondirectional voice "ONE" position. A special internal acoustic
resonator is employed to support the response to lower
frequencies and a damped resonator placed in front of
the diaphragm reduces high frequency emphasis while
extending the upper frequency limit. The result is a pleasing balance for speech when the microphone is used "off
designed for correct speech balance when used informally
in television broadcasting interviews and public address
applications. The frequency response and directional characteristics are engineered to complement human speech so
that the microphone has excellent balance when the performer is talking "off mike ".
The BK -6B may be worn by the performer; its small bulk and
neutral color make it inconspicuous. The light weight and
flexible cable permit free, unhampered movement of the
performers. It may be wholly concealed in a man's hand
during an interview, or it may easily be concealed on a set.
The styling blends readily with any props, and is pleasing
where it is exposed to direct view. It is best used, suspended
from the neck, resting on the chest, where it attenuates the
low pitched chest sounds while at the same time it points
straight up toward the lips, the position in which it is most
sensitive to the sibilant sounds that would normally be lost.
mike" or worn on the person.
The microphone as shipped from the factory is connected
for an output impedance of 250 ohms. However the impedance may be changed to 30 or 150 ohms by a simple
cable connection change. The special plastic motor diaphragm and coil assembly, output transformer and terminal board and bracket assembly are housed in a rugged
and practically weather -proof case. The entire microphone
www.americanradiohistory.com
MICROPHONES
DIRECTIONAL CHARACTERISTICS
no'
BK -6B
Microphone used as a "necktie" mike. May be positioned
beneath the necktie or exposed.
only 2%" long and
2.3 ozs., less the cable.
is
13'i6'
in
FREQUENCY RESPONSE CURVE
I
diameter and weighs but
The cable, especially designed for
the BK -6B unit, has
unusual flexibility combined with long life under conditions
of severe abuse. The conductors are of cadmium bronze
for high flexibility and long flex life. The shield is carbon impregnated, conducting cotton overlaid with a light
metallic braid. The conducting cotton ensures complete
electrostatic shielding and the light, metallic braid keeps
the series resistance of the shield low without making the
cable excessively stiff. The external jacket gives a tough,
neutral colored, protective covering to the cable. A lanyard is furnished for mounting the microphone conveniently about the neck.
_
MI
_
+10
i5
m
,
a
lo
=Ì
FREQUENCY RESPONSE
BK -6B MICROPHONE
OF
',
I
o
INCIDENT
SOUND
90'
n
,na
,.,.,.
.---
FRFOUENCY IN CYCLES PER SECOND
SPECIFICATIONS
Output Impedance
250 ohms, can be changed to 30 or 150 ohms
Frequency Response
80- 12,000 cps
Directional Characteristics
Semi -directional, see chart
Effective Output Level @ 1000 cps
-67 dbm (referred to a sound
pressure of 10 d/cm2)
EIA Sensitivity Rating
-158 db
Output Voltage (open circuit)
48 my /d /cm2
Hum Pickup
-112 dbm (referred to a hum field of 1 mg.)
Cable
30 ft. flexible, two conductor, shielded, no plug
Mounting
Removable lanyard for suspending about neck
Overall Dimensions
2?6" long x
(o
diameter
Weight
2.3 ozs., less cable
Finish_
_.
low luster gray
Stock Identification
MI- 11017-A
Microphone Holder _
Ml -12086
19" flexible microphone stand for BK -6B
MI -12087
0.
1
New type BK -6B Microphone shown with lanyard
having clip fastener for convenient mounting.
www.americanradiohistory.com
----
MICROPHONES
PRESSURE MICROPHONE
TYPE SK -45 B
FEATURES
Rugged construction
Economical, light weight, small in size
Attractive appearance
High or low impedance
Dynamic type
Excellent for announce work
Swivel mounting
D
E
S C R I P T I
The Type SK -45B Announce Microphone
O N
is
suitable for talk -
back or cue purposes. It may be used indoors or outdoors
where a rugged, light weight microphone with good response to voice is required. It
is
This microphone is o pressure
a "close-talk" microphone.
operated microphone em-
ploying the dynamic principle. The moving element is a
thin molded diaphragm in which a single straight wire
is embedded. This wire which is held in the airgap of a
strong permanent magnet generates a small voltage of the
same wave form as the sound acting on the diaphragm.
The wire is connected to the primary of a small, but effi-
cient transformer, in order to provide an output voltage
sufficiently high to allow the output to be fed directly to
the grid of the first input tube. The two conductor shielded
cable is connected permanently to the microphone.
The change from high to low impedance (or low to high)
is
easily accomplished by changing one soldered connec-
SPECIFICATIONS
Directional Characteristics:
Non -directional
(Below 3000 cycles /sec.)
Semi -directional
(Above 3000 cycles /sec.)
150 to 200 ohms balanced or 15,000 ohmst
Output Impedance
Output Level at 1000 Cycles/sec.:
-56 db*
Low Impedance
G\!
-147 db
-58 db*
High Impedance
-106
Hum Pickup Level
dbm **
70 to 12,000 cycles, sec.
Frequency Range
Mounting
5/6
" -27 fixture thread
Dimensions:
5 1/2 "
1 5/e"
Height (including shank)
Width
tion in the head of the microphone.
2"
Depth
A swivel arrangement allows tilting of the head forward
or back through an arc of approximately 45 degrees each
side of the vertical
position. New streamlined design,
tugged construction and attractive baked low luster gray
enamel finish makes this microphone a welcome addition
to any installation.
Low luster gray enamel
Finish
Weight, with Cable
1
lb.
Stock Identification:
Microphone and Cable (25 feet)
t Stocked
with soldered connection to the 200 ohm tap
* Referred to 10 dynes per cm -.
Hum field 1 x 10
gauss.
1 volt.
0 db
*
=
www.americanradiohistory.com
-3
MI- 12045-B
MICROPHONES
VELOCITY MICROPHONES
ANTI -NOISE TYPE SK -35
PROGRAM TYPE SK -46
FEATURES
Bi- directional characteristics
over
wide frequency range
Light weight, small in size
Modern styling blends pleasingly
with any background
Adjustable impedance taps
Swivel mounting
Extremely rugged construction
USES
DESCRIPTION
RCA Type SK -35 Anti -Noise and SK -46 Program
Velocity Microphones have been designed for AM, FM
and TV announcing. Both models are similar physically
except that the SK -35 Microphone has internal insulation
to adapt it for close announce or program use where it is
desirable to attenuate the pickup of extraneous noise. This
makes it particularly useful for sports announcements and
for use in locations where the announcer can speak within
one inch of the microphone. Its insulation makes it especially insensitive to wind and is highly recommended for
outdoor use. The SK -46 is designed for indoor use especially for "on stage ", announce booth and general program situations.
The RCA SK -35 and SK -46 are velocity microphones in
The
which the moving element
a thin,
corrugated metallic
poles of two small powerful magnets in a magnetic circuit.
Because of its
light weight, the motion of the ribbon
corresponds very closely to the velocity of the air particles;
therefore, the voltage generated by it
is a
faithful repro-
duction of the sound waves that traverse it. The ribbon
is
connected to the primary winding of a small efficient
transformer whose secondary winding matches either 150250 ohms or high impedance, as required. The change in
impedance
Both model velocity microphones feature excellent response
and directional characteristics and their small size makes
them valuable and versatile instruments where quality production of sound is desired. The directional characteristics
reduce unwanted acoustical background noise, reflections
and feedback. The microphones are virtually shock proof
and will take a high degree of abuse without altering
performance characteristics.
is
ribbon supported at the ends and placed between the
is
easily accomplished by changing one sold-
ered connection inside the microphone.
The excellent frequency response, high output level, ab-
sence of excitation due to breath, and anti -feed back
characteristics are truly amazing. Above 1000 cycles, the
discrimination against random unwanted sound
is
19 db
better than that obtained with a conventional pressure
www.americanradiohistory.com
MICROPHONES
microphone used at a distance of six inches. Below 1000
cycles, background noise discrimination increases to a
value of 44 db at 100 cycles. The net result is a high fidelity anti -noise microphone.
nB
--- --
Acoustically designed screens protect the front and the
back of the microphone from dirt and mechanical injury.
Organdy and fiber glass inside the front and back of the
microphone are used to damp the lightweight aluminum
foil ribbon. The motor assembly uses Alnico magnets
shaped to reduce magnetic leakage to a minimum, and
increase the air gap flux density. This magnetic leakage
is further reduced by means of a yoke or keeper.
eJ0
INCIDENT
SOUND
270
SOO
C
S
1000 CPS
- 2000 CPS
-
-
4000
C P S
0.
FRONT OF YCROPHONE
(ABOUT VERTICAL AXIS)
M
11
INCIDENT SOUND
wS
40
S
1O
I..
A swivel arrangement permits tilting the microphone back
approximately 85 degrees. Functional design incorporating excellent performance and rugged construction, attractively finished in low luster gray and satin chrome, makes
this microphone a welcome addition to any installation. A
two conductor shielded cable permanently attached to
the microphone is connected for low impedance operation
as stocked.
FRONT OF
MICROPHONE C
SSO
't25
_l.CB
000C/S
1000 CPS
.41
2H :ZB
2000CPS
4000CPS
-
¡SS.
AXIS)
(ABOUT HORIZONTAL
Directional Characteristics of the SK -35
and SK -46 Velocity Microphones.
SPECIFICATIONS
Bi- directional
Directional Characteristics
Output Impedance
FREQUENCY
200 ohms and 15,000 ohms'
Effective Output Level at 1000 cycles /second:
Low Impedance
Get
-58
dbm
db
db below
1
volt
-94
High Impedance
-113
db below
Frequency Range
1
dbm
IINCH
FROM LIPS
to
-to
o
volt
-15
See charts
Output Voltage:
High Impedance
Mounting
5/8
-27
-3O4
40
fixture thread
Swivel
Approx. 85° backward
Cable
Two conductor, shielded
29/32"
1328"
.5
on
13 ounces
5
Weight (less cable)
Stock Identification:
Type SK -35 Anti -Noise Velocity Microphone
Type SK -46 Program Velocity Microphone
lo
Ml -12035
MI-12046
2
1
5
6 7 89
-.
ROPHONE
MIá2046TS VTrDEI Sx46
11
12111`useCiil
111111/1%1
C.111'';
IN FEES FIELD
EE
IS
MI- 13240 -B
111111
Floor Stand
MI.4096-A
1111111
x 10
-3
4
t
.!gig
vS
100
gauss.
E
S
111111
111
1I2 .1
1111111
1111111
u
1111111
111111
1
1
2
1000
FREQUENCY IN CYCLES PER SECOND
www.americanradiohistory.com
10000
O
-1n111
11
11111
11111
11111
4
5 6 7 89
e -474e5
1111121
11
.111i..11111
Desk Stand
1
3
FREQUENCY RESPONSE
1111111111111
Stock with soldered connection to the 200 ohm tap.
2
1
1000
RCA SOUN
61NCNE
20
Relative to field of
4
1111111
.111''1-EESP°SE=T
Accessories
t
3
IDO
.,""'
Low luster gray with satin chromium plated screen
Depth
6 78 9
111111
51/4"
"
1
5
FREQUENCY IN CYCLES PER SECOND
Dimensions:
Height
Width
SK -35
FREE FIELD
-25
117 µv /dyne /cm2
1020 µv /dyne /cm2
Low Impedance
Finish
,SK -35-
-5
Ln
m
Hum Pickup Level:t
Low Impedance
-35
o
-150
-60
High Impedance
RESPONSE CHARACTERISTICS
OF VELOCITY MICROPHONES AND SK
15
S
4
11
S
10000
20000
MICROPHONES
AERODYNAMIC
MICROPHONE
TYPE SK -39
FEATURES
Light weight -small size -fits palm of hand
Modern streamlined appearance
Excellent for close talking application
May be used outdoors -minimum response
from wind
Unaffected by temperature or humidity
Alnico V magnet -high sensitivity with light
weight
Low impedance output -balanced
SPECIFICATIONS
DESCRIPTION
This microphone has excellent response for close talking
Frequency Response.
announce purposes. Because of its light weight and small
size, it is ideal for remote pickup and mobile use. Performs
Directional Characteristics
very well for cuing and talk back operations and because of its rising
high frequency characteristic it gives
Non- directional for frequencies below
2,000 cps; becoming less sensitive at the rear and sides as the
frequency increases above 2,000 cps.
Output Level:
Effective Output Level
excellent intelligibility. Another application for which this
unit is especially suited, is for use of an individual soloist,
EIA Microphone Rating Gx1
where a second microphone, usually a velocity type,
Hum Pickup Level
is
used
to pick up the musical accompaniment. Either a floor
stand or a desk stand may be used as a mounting or it may
be fitted with a handle for use in sports announce work.
dependable performance and rugged service. It is relatively insensitive to mechanical shock and wind disturbances
and will withstand nominal exposure to moisture or rain
due to its plastic diaphragm. The microphone
is a
-55
dbm, 180 x 10. V; dyne / cm
250 ohm output -open circuit
-150
db
95 db (Hum field 0.001 gauss)
Output Impedance._
250 ohms
5s' -27 fixture thread
Mounting
Finish
This microphone has been designed and constructed for
70 cps to 9,000 cps
Umber Gray
..
Dimensions
3'
Weight
4 '
high, 27,e" wide, 23/4" deep
15 ounces, less
cable
25 ft. -two conductor
Cable Length
Stock Identification
M I -12039 -A
pressure
operated, moving coil type with Alnico V magnet. The
attractively styled case is composed of two zinc die cast
sections. This microphone may be used with any amplifier
having an input impedance of 150/250 ohms.
Accessories:
Desk Stand
Announce Stand
Desk Stand
www.americanradiohistory.com
M I.4092-E
..
M I -4096-A
MI-13240-B
MICROPHONES
MICROPHONE
STANDS
FEATURES
Desk and Floor Stands to accommodate
a
variety of microphones
Rugged construction
Attractive appearance
Easy to assemble or take apart
Optimum design features built into each
stand for its particular application
Compact and convenient for portability
Desk Stand, MI-4092-E.
USES
RCA offers to broadcasters a complete line of microphone
variety of types and models for every
application- station, auditorium, banquet hall, or stage.
stands
in
a
All are sturdily constructed and accommodate a variety of
microphones. Each offers optimum design features to assure
best results for its particular application.
addition to various types of microphone stands, RCA
also offers a wide variety in styling and price range to
meet individual needs. The styling is modern and attracIn
tive, employing attractive metallic finishes for radio and
entertainment applications, but using dull finishes designed
to blend into the background in models which will find their
chief use before the TV camera. A smartly designed table
pushmike stand,
where it
is
Ml -6427,
is
available for applications
necessary to turn the microphone on and off
at the microphone position. Flexible microphone stands
are a convenient type mounting where the operator needs
the microphone as a permanent part of an installation
yet wishes to push the microphone out of the way at times.
Floor Stand, MI. 4090 -A.
www.americanradiohistory.com
MICROPHONES
MICROPHONE DESK STANDS
MI-12066-B
M I.13240-B
J
LS
6427
M I-4096-A
M
Desk Stand, MI -11008
This Desk Stand
specifically designed for use with the
type BK -1 A Microphone. Its construction is simple, rugged
and it
styled in dark umber gray finish. The BK -lA
Microphone fits into the center hole and is secured by a
knurled thumb screw and a retaining washer. A rubber
cushion around its perimeter prevents marring of any
surface.
Weight of Base
19 oz.
43"
Diameter of Bose
Weight, packed
4092 E
Announce Stand, MI- 4096 -A
is
is
I
attractively- designed announce stand is adjustable
from 8 to 101/2", making it ideal for use on a desk or
table. It is finished in chromium and black and features
This
7/2" base. The microphone mounting is a 5/8 " -27 fixture
thread. This stand can accommodate SK Series Microa
phones.
Weight (unpacked)
4 lbs.
Stock Identification
MI- 4096 -A
1/2 lbs.
Finish
Dark umber gray
Stock Identification
MI -11008
Desk Stand, MI- 13240 -B
Desk Stand, MI- 12066 -B
This
attractive base
is
This sturdily constructed desk stand is ideal for use with the
designed primarily for use with the
41" long,
wide and 1" high and is attractively finished in dark
umber gray metalustre. The microphone is held rigidly in
SK -Type microphones.
It is of die cast metal
53/8"
lighter microphones where a low cost stand is needed. The
stand is 6" high and the 43/4 " -diameter base is equipped
with a rubber cushion. The stand is attractively finished in
umber gray with polished chrome trim. As supplied the
stand mounting
position by % " -27 thread bolt. The bottom is rubber
cushioned giving adequate protection to any finely finished
surface.
Weight (unpacked)
Weight (unpacked)
1l/j lbs.
Weight (packed)
Identification
MI- 12066-B
Stock
SK Series
is a
58" -27 fixture thread. For use with
Microphones.
Stock Identification
www.americanradiohistory.com
14 ozs.
11/2
lbs.
MI- 13240-B
MICROPHONES
Pushmike, Stand,
Desk Stand, MI- 4092 -E
This
a heavy -based desk
is
stand
designed especially
for studio or announce use. It is attractive in appearance
and easily mounts the heaviest of studio microphones.
It can accommodate Type 77 -DX, BK -1A and BK -5A
Microphones.
gray with satin chrome trim.
felt covered to prevent marring the surface on
The 91 -C is finished in umber
The base is
which it is placed. The stand is provided with alternate
mounting extensions -one 3/4" and one 13/4 ", the choice
depending on the type microphone to be mounted.
1/2" pipe thread
Microphone Mounting
41/2" x 65/8" x 3/4"
Base Dimensions
Umber gray wrinkle with satin chromium trim
Finish
4
Weight
Stock Identification
lbs.
ES -6427
This smartly designed table stand features a built -in microphone switch and is suitable for use with SK Series
Microphones. The switch is of the D.P.D.T. long leaf anti capacity type and permits turning the microphone on
and off right at the microphone stand. It may also be used
for "push -to- talk" operation or lock -in "Talk" position.
The stand is 43/4" high with 53/4" base and is attractively
finished in chromium. The microphone mounting is for a
% " -27 male or female thread. Stock MI -12055 Adaptor is
available on separate order for microphone with
thread.
1/2"
pipe
Weight (unpacked) .._
11/8 lbs.
Stock Identification
ES-6427
(Includes MI -6425 Pushmike Adaptor and MI -6426 Base)
MI- 4092 -E
MICROPHONE FLOOR STANDS
Floor Stand, MI- 4090 -A
Adjustable from 3'8" to 6'2"
Height of Stand
Standard 1/2" pipe thread or
thread
54e " -27 fixture
Microphone Mounting
This Program Stand is used in broadcast studios where a
stand
is
required which will be attractive in appearance
and give stable support even to the
microphones. It
is
heavier type of
recommended for use with Microphone
Types 77 -DX, BK -1A, and BK -5A.
Pictured on page 21,
is
equipped
with a simple clamping device which permits height adjustments to be made easily and quietly without operating any
release mechanism. The up and down operation
is
smooth
and the locking operation positive. The patented clamp is
mechanically simple and is ruggedly constructed to give
years of service.
The stand as supplied may be used with any microphone
having a
1/2"
pipe thread and by simply removing an
adaptor fitting with any microphone having a
fixture thread.
The stand
is
5/e
Stock Identification
MI- 4090 -A
Accessory Item -Cable Hook
MI- 11099 -A
Portable Stand, MI- 4093 -C
RCA microphones. Cable guides are included to hold the
microphone cord close to the stand at the base. Cable
is
offered as an accessory item to fur-
ther secure loose cables and hold them in place.
DESCRIPTION
This
stand
is
a
folding,
and rugged
stand which is unexcelled
for field use with the
77 -DX, BK -1 A and BK -5A
Microphones. It features a
tripod base and a patented clutch arrangement
which permits height adjustments to be quickly
made without the operation of a mechanical
release.
lightweight
" -27
finished in satin chrome to harmonize with
Hook, MI- 11099 -A
Sarin Chrome
Finish
this sturdily constructed stand which
is
33 lbs.
Weight (unpacked)
will give stability to the heaviest microphones. The base is
weighted and has equalizing projections which assure a
firm position on an uneven floor. The column
121/4"
Diameter of Base
SPECIFICATIONS
Height
_
Adjustable from 3' to 5'
Weight (unpacked)
31/2
lbs.
Satin chrome
Finish
Microphone Mounting 1/2" pipe
thread or 5/e " -27 fixture
thread with adoptor removed
Stock
Identification
www.americanradiohistory.com
MI- 4093 -C
MICROPHONES
in moving from one spot to another. It may be used with
the BK -1A, BK -5A, 77 -DX and SK Series Microphones.
The column and telescoping tube are finished in polished
chrome and the base in dark umber gray wrinkle to har-
monize with RCA microphones. It has a smooth -operating
clamping and release device.
The stand as supplied may be used with any microphone
having a % " -27 fixture thread. It is equipped with a heavy
12 -inch base
and
is
sturdily constructed.
Height of Stand
Microphone Mounting
Diameter of lower Tube
Diameter of Base
Weight (unpacked) _ ..
Adjustable from 34" to 62"
541 " -27 fixture thread
1"
12"
14 lbs.
Finish:
Base
Dark umber gray
Satin chrome
ES- 4068 -G
Stand
Stock
Identification
Sectional Stand,
ES
-6208
The ES -6208 is a convenient and attractive stand for floor
or banquet use. It is especially suitable for portable use
since it may be taken apart into three sections for easy
packing or carrying. The stand, which is in chrome, has a
heavy 10 -inch gray crackle base trimmed with satin -silver
stripes. Use this stand with 77 -DX, BK -1 A and BK -5A
Microphones.
ES-4068-G
Height (for floor use -3 sections)
Height (for banquet use -2 sections)
Microphone Mounting
ES-6208
Floor Stand,
ES- 4068 -G
Finish:
Stand
The ES- 4068 -G Floor Stand is used in broadcast studios
where some stability of support may be sacrificed for ease
Gooseneck Stands
Polished chromium
Umber gray wrinkle with satin -silver stripes
Base
Weight (unpacked)
Stock Identification
11
and be able to be pushed out
of the way if necessary. These stands are particularly suitable for the BK -lA pressure microphone, but may be used
with any of the smaller announce microphones such as
the SK -35, SK -45 and SK -46.
uses
Muting Bracket, Ml- 11747, is designed for use with the
gooseneck stands and may be easily clamped to the side
of a console, desk, or other solid flat surface.
Finish:
Base
Gray wrinkle
6" Stem
..
5 " -27
Base
Stem
thread female
s8 " --27 thread male
_
Weight (Base and Stem)
11
13" Flexible Stand
19" Flexible Stand
Flexible Stand Bracket Clamp
Adaptor, 5713" -27 Stand to 1/2" Mike
MI -11745
MI -11746
MI -11747
MI -12055
Polished chrome
_
,8 "
Weight:
MI-11745
MI- 11746.
Length:
MI- 11745
Mi-11746
-27
thread (male fitting on one end,
female on others
MI
1
11/2
_
lbs.
STOCK IDENTIFICATION
SPECIFICATIONS
Mounting
Polished chrome
Mounting:
STANDS
Finish
lbs.
ES -6233
BRACKET CLAMP
The Ml -11745 and Ml -11746 Flexible Microphone Stands
are especially useful in locations where the microphone
must be a permanent part of an installation yet must be
adaptable to varying
Adjustable from 3' 11" to 5'
Adjustable from 1' 6" to 2' 7
53"-27 fixture thread
11745
lb.
lbs.
13"
19"
www.americanradiohistory.com
MI-11747
-
MICROPHONES
MICROPHONE BOOM AND STAND
TYPE
KS -3B
FEATURES
construction,
tubing and castings
Sturdy
strong
Large base with rubber -tired
casters
adjusted over wide
range of heights and boom
lengths
Easily
Air cushion lowering brake,
releases for easy lift
Lightweight
Positive locking adjustments
The Type KS -3B Boom Stand may be conveniently folded
for storage or transportation as shown in inset.
USES
The RCA Type KS -3B Microphone Boom and Stand affords
proper microphone placement for: programs where the
best microphone position cannot be reached with a conventional floor stand; piano pickup; orchestral pickup
where the stand may be substituted for microphones suspended overhead; television programs where movement of
the microphone is not required. This stand is recommended
for use with the 77 -DX and BK -5A Microphones.
rubber -tired casters with which it is equipped. Once the
stand is properly placed the casters can be locked by
means of foot -operated locks. Cable supports are provided
along the boom for the microphone cable.
For storage or for convenient transport the legs and the
boom may be folded against the center column to make
a relatively small package.
The KS -3B Boom Stand is finished in satin chrome and gray
to harmonize with RCA microphones.
DESCRIPTION
The KS -3B boom length and the counter balance overhang
SPECIFICATIONS
are easily adjustable, and the position selected is securely
locked by wing -type handwheels. The microphone fitting
is swivel mounted, thus eliminating the need of rotating the
microphone when attaching it to the stand. Movement of
the stand is quiet and easy because of the smooth -rolling
Adjustable from 5' 2" to 8' 8"
Height of Stand
3' to 6'
Horizontal Arm Adjustment (with overhang to rear)
Standard 1/2" pipe thread
Microphone Mounting
5é " -27 fixture thread with adaptor removei
64 lbs.
Weight (unpacked)
Satin stainless steel and low luster gray
Finish
Ml -11056
Stock Identification
www.americanradiohistory.com
MICROPHONES
MICROPHONE BOOM AND STAND
MI-11070
FEATURES
Suitable
for both TV and AM
- rotates
"Mike" through 360 by convenient wheel
Permits the operator to "spot" directional
pattern of mike for best pickup
Three sturdy telescopic aluminum sections
provide "length" adjustments from 6 to
18 feet
Shockproof rubber mount for microphone
Mike cable enclosed in boom
Vertical adjustment 4 to 8 feet
Base mounted on
rubber -tired casters
USES
For broadcast AM and FM studio and Television applications the RCA Ml -11070 Microphone Boom and Stand is
used for: programs where the best microphone position
cannot be reached with a conventional floor stand; piano
pickup; orchestral pickup where the stand may be substi-
tuted for microphones suspended overhead; television programs of virtually all types. It is recommended for use with
Type 77 -DX and BK -5A Microphones.
DESCRIPTION
The Microphone Boom Stand, Ml- 11070, telescopes from
6 feet 10 inches to 18 feet with remote control of micro-
phone made possible at all positions by a rear handwheel
which rotates 360 degrees. It is equipped with a self leveling, vibration damping mount. The microphone cable runs
through the boom to avoid "snarls" and interference with
the television scenes.
Perfect balance is maintained by an adjustable, 25 pound
steel counterweight which slides on the boom and locks
securely at any position. The counterweight is made of
steel, plated satin chrome and the boom swivel is cast
aluminum with a bronze stand swivel. The stand swivel has
a tension spring to keep the boom in position when balanced. The stand is a two- section telescoping super strut
which combines rigidity and strength with minimum weight.
The vertical portion of the stand
is constructed of telescopic steel tubing, and is adjustable in height from 4 feet
to 8 feet. A Numo check and safety clamp are provided
for the height adjustment. A spring shock absorber on the
inner telescopic tube protects against shock if the height
adjustment is carelessly loosened. The base is mounted
on 4 -inch rubber tired casters, and may be folded compactly for convenience in transportation or storage. A
horizontal handle is provided at the top of the vertical
section for convenience in dollying the stand.
SPECIFICATIONS
Height of Stand
Adjustable from 4' to 8'
Horizontal Arm Adjustment
Telescope 6' 10" to 18'
Microphone Mounting .- Shockproof rubber mount with 1/2" pipe thread
Microphone Adjustment
Rear handwheel
Weight (approx.)
70 lbs.
Finish
Satin, stainless steel and gray
Stock Identification
MI -11070
www.americanradiohistory.com
MICROPHONES
MICROPHONE BOOM AND PERAMBULATOR
MI-26574
*4*
FEATURES
Boom and perambulator
can
passed
be
through narrow doorways
Duraluminum tubing for boom
rigidity and light weight
assures
"Gunning" device revolves directional
microphones through 280°
Radius of boom can be extended to 17 feet
-retracted to 7 feet, 4 inches
Boom fitted with adjustable countei balance
for different microphones
Quiet in operation
USES
The MI -26574 Microphone Boom and Perambulator is designed for use in broadcast or television studios. li enables
the operator to quickly place the microphone with respect
to the sound source. He can closely follow the sound. or
move from one source of sound to another easily and
quietly. The boom accommodates such microphones as
RCA Types 77 -DX and BK -5A Microphones.
A hand crank governs extension and retraction of the
boom, and a hand rail controls elevation and horizontal
traversal. As the boom is retracted, the microphone cable
is received on take -up sheaves. The movement of the telescoping member is counterbalanced by weights which can
be adjusted to properly balance different microphones.
Since many microphones are directional, the boom is fitted
with a "microphone gunning" device which revolves the
microphone through 280 degrees.
DESCRIPTION
SPECIFICATIONS
The perambulator is constructed of steel tubing with drop rim type wheels and pneumatic tires. The steering wheel
swivels 180 and can be clamped to hold a given radius.
The tiller when pushed back operates a toggle brake on
the steering wheel. It is also provided with steps which aid
the operator in mounting the platform when it is elevated.
Operated by a hand wheel, the elevating column raises
the boom from a height of 6 feet, 5 inches to 9 feet, 5
inches. The operating platform raises with the boom. The
wheel tread of the perambulator can be narrowed to 27
inches and the leaf portions of the table can be lowered
to permit passing the perambulator through a 30 -inch door.
Dimensions:
Maximum Height (with boom pedestal elevated)
Height (with pedestal lowered)
Length of Boom:
Extended
Retracted
9' 5"
6' 5"
17'
7' 41/2"
Weight:
Boom (with gunning device and counterweights)
Perambulator
Stock Identification ....
102 lbs.
421 lbs.
MI -26574
Boom Only
MI- 26574 -1
Perambulator Only
MI- 26574 -2
www.americanradiohistory.com
MICROPHONES
MICROPHONE ACCESSORIES
Type "XLR"
Microphone
Receptacle
(Male)
Microphone
Microphone
Microphone
Plug
(Female)
MI- 11090 -A
Receptacle
(Female)
MI- 11088 -B
Plug
Type "XL"
(Male)
MI- 11089 -A
Receptacle
MI -11069
ip
MI -1 1087-B
4.041
"P"
Type "UA"
4
Receptacle
MI -11063
Microphone
Plug
MI -11062
Wall
Cord
Connector
MI -11061
Receptacle
MI- 4624 -A
Microphone
Plug
MI- 4630-B
Cord
Connector
MI- 4620 -B
MICROPHONE PLUGS AND RECEPTACLES
microphones are sold without plugs in order that
the purchaser may use any type desired. Three series of
Cannon plugs which meet requirements for reliability and
ruggedness are stocked. These include the "UA ", the "P"
Type Connectors and the "XLR" and "XL" matched family
of small 3- contact connectors.
RCA
The
"UA" connectors are splash -proof and shock -proof,
and have gold -plated contacts for low -loss and noise -free
operation. Flat top construction provides positive polarization. All have thumb action latch -lock for quick insertion
and firm engagement and a 134 -inch rubber sleeve handle
for firm easy grip.
"P" connectors are designed as panel receptacles and
cable connectors for audio circuits. They accommodate
wires up to No. 10, 15 ampere contact capacity and feature black phenolic insulation. The Cannon "XL" and "XLR"
The
type plugs and receptacles are miniature connectors especially favored with newer type miniature microphones and
equipment. They have similar functions to the "P" type units.
Description
Cannon
Stock No.
Female Plug for Microphone Extension
Cable (mates with UA -3 -12)
UA -3 -11
Male Plug for Microphone Cable
(mates with UA -3 -11 and UA -3 -13)
UA -3 -12
Flush Mounting Receptacle (mates
with UA -3 -12)
UA -3 -13
Male Plug for Microphone Cords _P3-CG-12S
Wall Receptacle for Above Plug
P3 -35
Note: The MI- 4624 -A Receptacle will fit in
a standard a -c outlet box.
Extension Cord -Female Connector
P3 -CG -115
Male Connector for BK -4A
Microphone Receptacle, Female
X L R-3-31
Microphone Receptacle, Male.
XLR-3-32
Microphone Plug, Female
XLR-3-11C
Microphone Plug, Male.
XLR-3-12C
28_
www.americanradiohistory.com
RCA Stock
Identification
MI-11061
MI-11062
MI-11063
MI.4630-B
MI-4624-A
MI-4620-8
MI-11069
MI-1 1088-B
MI-1 1087-B
MI-1 1090-A
MI-11089-A
MICROPHONES
1/8" PIPE THREAD
1/8" PIPE THREAD
1/2" PIPE THREAD
N
MI-6229
7M1-12051
5/8 "-24
1/2" PIPE THREAD
5/8"-27
1/2" PIPE THREAD
1/2" PIPE THREAD
'\
5/8"
-
(W.E
)
1/2" PIPE THRE4
27
MI-11066-3
MI-12055
1
5/8 "-27
1/2" PIPE
THREAD
5/8" -24 (WE.)
MI -11009
USED TO ADAPT MI- 4092 -E BASE
AS DESK STAND MOUNTING FOR
BK4 -B MICROPHONE
MICROPHONE ADAPTORS
Here
is
a comprehensive stock of microphone
suitable for microphones and stands used by broadcasters.
The
'-"2
-inch standard pipe thread avails broadccsters of
1/2" pipe thread
1/2" pipe thread
1/2" pipe thread
We
adaptors to suit any application.
Microphone
Thread
Stand
Thread
adaptors
5/e
"-24 (W.E.)
" -27
3/4"-27
""
pipe thread
-27
5/a " -24
s
e"
(W.E.)
1/2" pipe thread
1.
y" pipe thread
1/2" pipe thread
1/2" pipe thread
Stock
Identification
MI-12051
MI-12053
MI-11066-2
MI-11066-3
MI-6229
MI-12055
MI-11009
MICROPHONE CABLES
RCA microphone cables are of rugged construction and
are jacketed with a neoprene compound to insure long
life. They are especially designed for broadcast service
either studio or remote.
Cable MI -43 -C
Cable tor low impedance microphone circuits
Three conductor, twisted
Tinned cadmium bronze, stranded,
Conductors
equivalent to #20 AWG
Special rubber compound
Insulation
Tinned copper. Complete coverage without loss in flexibility
Shield
Brown neoprene compound
Outer covering
0.300 maximum
Overall Diameter
MI -43 -C
Stock Identification (specify length in feet)
Use
Type
Cable MI- 13307 -A
Two conductor, twisted
1'pe
Conductors
Stranded, equivalent to #16 AWG
Special rubber compound
Insulation
Shield
Tinned copper. Complete coverage without loss in flexibility
Black neoprene compound
Outer Covering
0.300 maximum
Overall Diameter
MI- 13307 -A
Stock Identification (specify length in feet)
Cable MI -13322
Two conductor, twisted
Stranded cadmium bronze, equivalent to #24 AWG
Special rubber compound
Insulation
Conducting cotton with 60% coverage of tinned copper.
Shield
(Complete coverage with greater flexibility)
Brown neoprene compound
Outer Covering
0.215 maximum
Overall Diameter
MI -13322
Stock Identification
Type
Conductou s
www.americanradiohistory.com
MICROPHONES
INTERCONNECTING CABLES
The majority of cables required to interconnect the various
components of a broadcast audio assembly are of a spe-
cial type and cannot be readily purchased from the local
electrical dealer. In order to avoid unnecessary installation
delays, RCA carries in stock four of the generally used
special type cables.
Solid Conductor Cable, MI -33
Stranded Conductor Cable, MI -35
General purpose Audio Transmission Line
Type
Shielded twisted pair, each conductor solid #20 tinned
copper wire, with Vinyl resin insulation covered with lacquered
rayon braid.
Use
Use
Shield
Tinned cooper braid
Approximately .170"
Overall Diameter
Color Code
Red and black
Rating
300 volts
Stock Identification (stocked in 1000 ft. rolls)
MI -33
Stranded Conductor Cable, MI -34
Stranded Conductor Cable, MI -13306
Recommended for audio circuits where extra
Use
flexibility
required
Type
Shielded, twisted pair, stranded, composed of 7 -.010 tinned
copper conductors equivalent to #22 AWG
Insulation
Vinyl resin insulated with lacquered rayon braid
Shield
Tinned copper braid
Overall Diameter
Approximately .166"
Color Code
Red and black
Rating
is
300 volts
MI -34
Stock Identification (stocked in 1000 ft. rolls)
Especially recommended for 110 volt supply
and filament circuits
Type
Shielded, twisted pair, stranded, composed of 16 -.010 tinned
copper conductors equivalent to #18 AWG
Insulation
Vinyl resin insulated with lacquered rayon braid
Shield
Tinned copper braid
Overall Diameter
Approximately .236"
Color Code
Red and black
Rating
300 volts
Stock Identification (stocked in 1000 ft. rolls)
Ml -35
Use
Type
General purpose Audio Transmission Line
Black Glazed Cotton covered shielded twisted pair, each
conductor #22 AWG Stranded 71010, with Vinyl resin insulation
covered with lacquered rayon braid.
Shield
Tinned copper braid
Overall Diameter
Approximately .200"
Color Code
Rating
Stock Identification (stocked in 1000 ft. rolls)
CABLE HOOK, MI- 11099 -A
Red and black
300 volts
MI -13306
CABLE LACING CORD
USES
Can be quickly attached to or removed from the 90 -A or
any other 11/4" round tube stand. It provides a convenient
method of holding the cable. It saves wear on the cable
when it is not in use.
DESCRIPTION
The Cable Hook is simple to install, and may be easily
adjusted to the proper height. Merely tightening a smooth
locking nut holds it in position.
SPECIFICATIONS
Weight
15 oz.
._
Finish
Satin chrome
Hole Diameter
Stock
Identification
11/4"
_
MI- 11099 -A
Lacing cord is available for general cable lacing and dressing uses. Cord is of strong material such as linen and hemp
and thoroughly impregnated with a beeswax and paraffin
mixture. Supplied in one pound spools as shown above.
Average
Stock
Identification
MI. 11719 -A
30
www.americanradiohistory.com
Type
No. 6 med.
Plys
4
Yds /Ib
580
±35
Break Strength
30 lbs.
CONSOLETTES
STANDARD AUDIO CONSOLETTE
TYPE BC -3C
USES
FEATURES
Complete high -fidelity speech input system
Provides facilities for thirteen inputs
The RCA Type BC -3C Standard Audio
Consolette
is
a
compact, self- contained, high -fidelity speech -input system
providing audio amplification, switching, control and moni-
Modular construction, etched wiring sub-
toring facilities essential to the operation of medium size
assemblies
radio or television broadcast stations. This model incorporates eight mixer positions, which control thirteen inputs.
Compact size -entirely self contained (includes all amplifiers and power supply)
The consolette is sufficiently flexible to accommodate two
Means for supporting script on front panel
tables and auxiliary input circuitry.
Styling matches other RCA audio consol ettes and is compatible with TV terminal
equipment
The BC -3C is suitable for mounting on a
Headphone selection of network, remote,
and program line
low cost. It
studios, announce booth, control room, transcription turn-
is
flat top desk and
similar in styling and appearance to other RCA Audio
Consolettes. The unit provides maximum facilities at very
is
economical to operate, and has been de-
signed for operating convenience and ease of servicing.
www.americanradiohistory.com
CONSOLETTES
SPECIFICATIONS
DESCRIPTION
The Type BC -3C Standard Audio Consolette
is
a
con-
Inputs:
6 Microphones (4 Studio,
Control Room
and
Announce Booth)
_
37.5'150 600 ohms
2 Turntable,
Tape, and
Auxiliary Inputs
150 ohms
2 Remote Lines,
Network and
External Monitor
600 ohms
Outputs:
Program Line 8. 2 Remote Lines Cue
600 ohms
±18 dbm
2 Monitor Speakers
..
16 ohms
3 W each
External Monitor
600 ohms
-6 dbm
Turntable Cue
150 ohms
V rms
1
venient audio control equipment mounted in a smartly
styled housing of all -metal construction and finished in
two -tone umber gray. A hinged front panel and removable
cover provide access to tubes, switches, gain controls and
other interior components.
An etched panel contains all operating controls, an illuminated volume indicator calibrated in VU's, and a rack
designed to hold script. The mixer controls are assigned
so as to offer the greatest flexibility and operating ease.
The BC -3C will handle thirteen separate inputs with provisions for simultaneous mixing of any eight inputs. There
is provision for feeding program cue or talkback to remote lines. Headset switching is provided for network,
program and remote line monitoring. Cue positions are
incorporated on turntable mixers. Separate audition and
program channels are provided for maximum flexibility
and the monitoring amplifier may be switched from the
turntable cue position, program line, audition bus, or external input. The output of an off -air receiver or modulation monitor can be connected to this external position.
All inputs are terminated when the switches are in the off
position.
The BC -3C
is
of modular construction with etched wiring
sub -assemblies. It has self -contained amplifiers and power
supply. Three preamplifiers are utilized in the design plus
monitoring and booster equipment. Recommended operating practice is for the inclusion of separate BA -26A
preamplifiers mounted in each turntable cabinet. The unit
control circuits include two 24 volt relays for control room
and studio speaker and On Air light operation controlled
by microphone selector and program- audition switches.
1
1
1
1
1
1
.
1
1
1
Gain:
Microphone to Program Line
Network or Remote to Program Line
Turntable, Tape or Auxiliary to Program Line
Microphone to Audition Speaker _ _ _ _.
Microphone to Program Speaker
Microphone to External Monitor
Microphone to Remote Line (Cue)
__ __
Network to Audition Speaker
Network to Program Speaker
Frequency Response:
Program ±1.5 db
Monitor ±2.5 db
Harmonic Distortion:
Program 18 dbm Output
a
o-+,
sw
Y r
-1
1% @ 30 cps; .75%
Monitor 6 W Total
db
db
db
db
db
db
db
@a
50 cps;
cps
1.5% @ 50- 10,000 cps
Signal to Noise Ratio:
Program Channel, Mixer and Master Gain controls
set for 68 db Gain
68 db below 18 dbm output
Tube Complement.
2 6V6 -GT, 2 12AÚ7, 2 12AX7,
5R4GY, 5 12AY7, 5 -MI -11299
(selected 12AY7)
Power Requirements
100 -130 volts a -c, 50/60 cycles, 155 watts
Dimensions
33'' wide, 111/4" high, 211/4" deep
Weight
88 lbs.
Finish
Two tone umber gray
Panel
Reverse etched aluminum with dark umber gray
enamel background
Stock Identification
ES- 11103 -A
1
Accessories
Tube Kit
On -Air Light Relay
Warning Lights
BA -26A Equalized Preamplifier
I
VI>
Ml-1 1486 -A
MI -1 1702 -A
MI -11706 Series
MI -11436
**°'"
-I
nn
4
.j"
MUM
iy
.,,
db
db
30. 15,000 cps
30- 15,000 cps
"*"
.ic.o-+-1
__
0.5% @ 100 -15,000
L_JrYLJ
mc
108
32
64
124
144
84
106
48
68
.a.,.,....,
i
Simplified block diagram of the
BC -3C Standard
32
www.americanradiohistory.com
Consoleth.
..uoa
nea
CONSOLETTES
AUDIO CONSOLETTE
TYPE BC -5B
FEATURES
Single
BC -5B
controls nine inputs
-
four simultaneously
Entirely self- contained
Talkback or program cue to remote
lines
Four
preamplifiers -all
amplifiers
etched wiring
Modular construction -complete
cessibility
ac-
Off -air monitoring
Head phone selection of network,
remote, and program line
expanded
broadcast use
Easily
for dual -channel
USES
The Type BC -5B Audio Consolette, ES- 11105 -A, provides
audio amplification, switching control and monitoring
facilities for the operation of a small radio or television
broadcast station. This low -cost consolette is self- contained
with the power supply for amplifiers and relays mounted
in the unit. The exclusive feature of "add -a- unit" audio
control incorporated in the BC -5B permits "block building"
as desired. The consolette is suitable for use either in
combined studio, transmitter or remote studio installations.
A single BC -5B provides high quality switching and control
facilities for accommodating one studio, control booth,
two turntables, network, remotes and tape recorder. Addition of a second BC -5B doubles facilities and permits complete dual -channel operation. It is ideally suited for such
"twin" or side -by -side installations. The audio consolette
may also be used by television stations to provide audio
sub -control, or to permit expansion of existing facilities.
The equipment is styled to match all current RCA consolettes.
DESCRI PTION
The BC -5B Audio Consolette provides extremely flexible
station. It includes
audio facilities for the small broadcast
three mixing channels for low level microphones and
turntable inputs and one high level mixing channel, for
network and remote line inputs. Nine input channels may
be selected; the output of each mixing channel may be
switched to either a program or audition bus. A VU meter
and all switches and mixer controls essential to everyday
programming are front -panel mounted.
Cue positions are incorporated on turntable mixer controls
and terminals are available for connecting a separate
cueing amplifier. Separate audition and program channels
are provided for maximum flexibilty. The monitoring amplifier may be switched from the turntable cue position,
program line, audition bus or an external position providing off -air monitoring from an off -air receiver or
modulation monitor. All inputs are terminated when the
switches are in the "off" position.
completely wired unit and has self contained amplifiers and relay power supply. Four preamplifiers are utilized in the basic design and provision is
made for the addition of external line equalizers. The
fourth preamplifier is supplied wired for low gain to
The
BC -5B
www.americanradiohistory.com
is
a
CONSOLETTES
The BC -5B hinged front panel and removable top cover provide complete access to all components including amplifiers and power supply.
permit its use with a remote line input. It can be easily
modified, however, for high gain when desired.
The Audio Consolette is of all -metal construction finished
in two -tone umber gray. A hinged front panel and re-
movable cover provide complete access to all components,
such as the key -selector switches, controls, mixers, terminal
blocks and wiring. The VU meter is illuminated to facilitate readings. Muting relays provided in the unit may
be used to actuate ON AIR warning light relays when
such accessory signals are desired.
SPECIFICATIONS
Signal to Noise Ratio:
With Mixer, Master and Monitor Gain controls set to
10 and -50 dbm reference signal applied to the microphone or turntable inputs, or 16 dbm applied to the
network or remote line inputs, hum and noise:
68 db below reference at program line output
66 db below reference at monitor output
100 -130 volts, 50/60 cps, 150 watts
Power requirements
Electrical Specifications
Inputs:
4 Microphone (3 Studio,
2 Turntable
2
37.5/150/600 ohms
37.5/150/600 ohms
Control Room)
1
600 ohms
600 ohms
Remote Lines
Network
External
Outputs:
Program
2 Monitor
External
1
1
1
1
2
1
Monitor
150 ohms
Line
Speakers
Monitor
Remote Lines Cue
Turntable Cue
+18
600 ohms
16 ohms
600 ohms
..
600 ohms
50,000 ohms
..
...
3
-12
+18
1
dbm
W each
Tube Complement
dbm
dbm
1- -5R4GY
2 -12AX7
2 -12AU7
5 -MI -11299 (selected 12AY7)
6 -12AY7
2- 6V6 -GT
191/2" wide, 111/2" high, 211/2" deep
Dimensions
66 lbs.
Weight
Two tone umber gray
Finish.. __
E5- 11105 -A
Stock Identification
V
Gain:
108 db
Microphone or Turntable Input to Program Line
125 db
Microphone or Turntable Input to Speaker
Frequency Response:
30- 15,000 cps
Program -±-1.5 db
30. 15,000 cps
Monitor ±2.0 db
Harmonic Distortion:
1% at 30 cps; 0.75% at 50 cps;
Program ( +18 dbm output)
0.5% 100 to 15,000
1.5% at 50 to 15,000
Monitor (6 watt total)
Accessories
1
0-0-t
F
--T
1l/
QJET
PROGRAM
ROOSTER AMP
PREAMP
CR
MIC
r
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MIXER
MI- 11483-A
MI -11706 Series
MI- 11702-A
Tube Kit for BC -5B
Warning Lights
Signal Light Relay.
cps
cps
0
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LINE AMP
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16000.0
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PREAMP
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IOO-130V
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PHONE SEL
www.americanradiohistory.com
AIR
CON SOLETTES
DUAL-CHANNEL AUDIO CONSOLETTE
TYPE BC -6B
FEATURES
Complete high -fidelity speech input system
for larger radio or TV broadcast station with
nine high level mixing channels -two program channels either to feed one or both
program lines
Complete dual channel facility for stereo
programming- easily expanded for stereo
sub -mixing
Compact size -entirely self- contained (includes all amplifiers and power supplies)
Dual monitoring channels, one for program
monitor ;ng and talkback, the other for feeding background to studios and cueing
Incorporates new split -mixer technique
Convenient switch for selecting two channel
or single channel operation with two sub master gain controls
Twenty -two inputs available
Dual power supplies -one for each channel
for greater reliability
Means for supporting script in space between VU meters
Styling matches other audio consolettes and
is compatible with TV terminal equipment
www.americanradiohistory.com
CONSOLETTES
SirInit)
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Etched front panel of the BC -6B Consolette showing entire operating facilities.
USES
RCA Type BC -6B Split- Mixer, Dual Channel Audio
Consolette provides the audio amplification, switching, con-
The nine mixer positions
provided are assigned so as to
offer the greatest flexibility and operating ease. The first
five are low level microphone channels each with dual
microphone input. Positions six and seven are also low
level inputs and may be used for either turntable, tape or
film sources; while the eighth mixer is used for network.
The final mixer has provisions for five remote line inputs
The
trol and monitoring facilities essential to operation of the
larger radio or television broadcast station. This consolette
incorporates nine mixer positions and provides all the
facilities needed to accommodate one or more studios, announce booth microphone, control room microphone, two
transcription turntables, tape, film, five remote lines, net-
selected by rotary switch. The latter four mixer positions
work and three cue circuits.
also provide cue facilities.
Simplified Facilities Diagram for the new RCA Type
STUDIO
Split Mixer, Dual Channel Audio Consolette.
BC-6B
STUDIO
A
WARNING
MIKE
MIKE
2
MIKE
3
MIKE
4
MIKE
5
AA RN ING
LIGHTS
HON
THE AIR
AUDITION
I
v
STUDIO
MONITOR
MIKE
q
3
SPEAKER
I
WARNING
LIGHTS
,...JON
a
8
O
TURNTABLE
NOI
TURNTABLE
NO 2
1=1
LIGHTS
AUDITION
LIGHTS
ANNOUNCE
MINE
STUDIO
MONITOR
SPEAKER
THE AIR
O
"--ION
THE
AIR1
R--I AUDITION
I
0
9999990
CUE
O
0 0 0 0
TAPE REC
NO
I
TAPE REC
NO 2
O
o o o o
1
NETWORK
FEED IN
ñ
REM
LINE-I
IN
F
BC-6
O
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CONTROL
ROOM
SPEAKER
AUDITION
CONTROL
MIKE
MINE
3
BOOTH
STUDIO
MONITOR
SPEAKER
I
CONTROL
ROOM
MONITOR
SPEAKER
CONTROL
ROOM MIKE
WARNING
ANNOUNCE
B
O
1
.l
1
1
1
REM
REM
REM
REM
ExT
LINE-2 LINE) LINE-4 LINES CUE
IN
IN
IN
IN
IN
ROOM
www.americanradiohistory.com
NO
o
90 o
o o 0 0
O
0 0 0 0 0
O
HPROJECTOR
o 0 0
0
0
1
EAT
I
CUE -2
IN
-
CH
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EXT
MON
PROJECTOR
NOI
TRANSMITTER LINE NOI
TRANSMITTER LINE NO2
---
1,
EAT
CUE-3
IN
2
CH 2
EXT
MON
CONSOLETTES
DESCRI
PT
ION
-
remote lines and over -ride the program on the control
room speaker.
An etched panel contains all operating controls. It tilts for-
Highest quality components are used throughout the BC -6B.
Interlocked push- button switches are cam operated leaf
type, assuring years of trouble -free operation. Improved
fast relay circuits for speakers reduce the possibility of
key clicks and audio feedback. The amplifiers are of a
new, compact design of modular construction having dip soldered etched wiring amplifier subassemblies similar to
Audio Consolette is
designed for operating convenience and ease of servicing
all amplifiers, control facilities and power supplies being
contained in a single housing which offers utmost accessibility to all components. The unit is suitable for mounting
on a flat top desk, and is similar in styling and appearance
to the RCA BC -3C and BC -5B consolettes.
The BC -6B Split Mixer, Dual -Channel
ward for easy access to all contacts, switches, gain controls
and other interior components. Two illuminated volume
indicator meters are calibrated in VU's. They indicate level
on each output channel. Monitoring and network headset
jacks are supplied and headphones may be connected to
the output of the program channels, remote lines, or the
incoming network. Talkback facilities are included and
permit talking back to studios, announce booth or remote
lines. An Over -ride -Remote cue switch is provided which
permits the remote operator to call in on any of the
Servicing of
BC -6B
Consolette
is
those designed for the BC -5B consolette.
The BC -6B has two power supplies, each powers a single
channel and alternate pre -amplifiers thus providing greater
continuity of service. Both are completely self- contained
units. The total power input required is only 300 watts,
50 to 60 cps at 100 to 130 volts. The frequency response
from any input to the line output is within ±1.5 db from
30 to 15,000 cps. The total rms harmonic distortion is less
than 0.5 percent from 100 to 15,000 cps at a line output
level of 18 dbm.
greatly simplified by hinged front panel and removable cover.
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CONSOLETTES
SPECIFICATIONS
Inputs:
10 Microphones ..
2 Tape, Turntable or Film
150 ohms
150 ohms
600 ohms
600 ohms
20,000 ohms
5 Remote Lines
Network
3 Cue Lines
Outputs:
1
4
-12AU7
4-
-12AX7
4- 6V6 -GT
-Ml -11299
10
600 ohms
600 ohms
15 ohms
600 ohms
Lines (cue)
-18 dbm
-6
6
38" wide,
+18
±1.5 db
±2.5 db
Monitor
Harmonic Distortion:
Program ( +18 dbm output)
Monitor (6 watt total).
141
db
deep
21 1/2"
127 lbs.
Finish
Two tone umber gray
Panel
Reversed etched aluminum with dark umber gray enamel fill
Equipment Supplied
42 db
48 db
Dual -Channel Audio Consolette including amplifiers,
power supplies, tubes and Instruction Book (IB- 24788)
BC -6B
ES- 11106 -A
30 to 15,000 cps
30 to 15,000 cps
Accessory
1% at 30 cps, 0.75% at 50 cps,
0.5% at 100 to 15,000 cps
1.5% at 50 to 15,000 cps
Signal to Noise Ratio, Microphone to Program Line
(68 db gain, +18 dbm output)
Power Requirement
/2" high,
108 db
Cue Lines to Speakers
Frequency Response:
Program
11
Weight
dbm
watts total
dbm
Gain:
Microphone or Turntable Input to Program Line.
Microphone or Turntable Input to Speaker.
Network or Remote Line to Program Line
(RCA selected 12AY7)
13 -12AY7
Dimensions
Program Lines
2 External Monitors
5 Speakers .. _
2
5 Remote
Tube Complement
2- 5R4 -GY
30'
68 db
300 watts, 100 130 volts, 50 60 cycles a -c
Tube Kit for BC -6B Consolette
MI -1 1484 -A
Announce Booth Speaker Relay
MI -11748
On -Air Light Relay
MI- 11702 -A
Warning Lights
MI -11706 Series
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Simplified block diagram of the BC-6B Dual -Channel Audio Consolette.
B.1114
38
www.americanradiohistory.com
CONSOLETTES
STUDIO WARNING LIGHTS
M.oa
FEATURES
.orE
SEA
construction and insures adequate protection from wires
short -circuiting. The complete interior is a wall mounting
fixture and allows a new lamp to be replaced quickly by
simply removing the outer case by two screws. The warning
light is available with five signs as indicated below.
Modern styling
Satin chrome finish
Available in five types
Uniform illumination
Easily mounted
SPECIFICATIONS
USES
Dimensions: (overall of case)
Length
The MI -11706 series of warning
lights is another new
product to supplement the RCA line of modernistically designed studio equipment. These lights have been developed
after many requests from broadcasters to furnish a studio
warning light that has bold and uniformly illuminated lettering with an external design that would enhance the
appearance of any studio.
DESCRIPTION
The lights are constructed of satin finish cast aluminum
Width
.
Depth
(Glass Sign Aperture)
length
Width
Weight (unpacked)
Stock Identification:
"ON -AIR"
"REHEARSAL"
"AUDITION"
Back
of separate metal
view showing simplicity of construction and
outer case mounting screws
www.americanradiohistory.com
31/2
lbs.
MI- 11706 -1
MI- 11706 -2
MI- 11706-3
MI- 11718 -1 to 5
The interior or mounting base, containing the lamp, sockets
is
93/4"
23/4"
MI-11706-4
MI- 11706-5
"STANDBY"
"SILENCE"
Glass Only
with trimmed etchings and tastefully styled for all studio
furnishings. The sign is an opaque black glass with frosted
translucent 2 -inch letters, using a 40 watt 12 -inch Lumiline
lamp for a light source.
and terminal strip for the a -c supply,
14"
31/2"
21J'6"
Outer case removed showing Lumiline
illuminating lamp
CON SOL ETTES
INTERPHONE EQUIPMENT
1
E-SHELF MI-11735
FEATURES
Convenient intercom with studio personnel
or remote line as desired
Can mount to console, desk, or wall
SINGLE
HEADBAND
ASSEMBLY
MI-11743
Designed to be compatible with RCA TV
equipment
RETARDATION
COIL
MI -11737
Simple circuit with anti -sidetone feature
PANEL
MI- 11736-A
Regulated power supply
USES
RCA Interphone Equipment is designed to provide con-
venient switching and headset connection facilities for an
internal communication system. Such a system is particularly useful for the radio or television broadcast studio
since it allows talking and listening with selected personnel
and with a conference bus or remote private line as desired. Any number of interphone connections may be used.
The 24 -volt d -c regulated power supply provides interphone power for a system using up to 30 headsets
simultaneously.
DESCRIPTION
Heart of the Studio Interphone System is the interphone
Connection Unit, MI- 11734, which consists of a compact
jack box designed for plate mounting. The unit consists of
a simple circuit having an induction coil and capacitor to
provide an anti -sidetone feature. This results in local
sounds being partially cancelled in the local earpiece. The
circuit is housed in a small metal box having two phone
jocks for use either with a single or a double headset as
required, and a two -position toggle switch for selecting a
local circuit or a remote line. A cable plug is mounted in
the rear.
A Retardation Coil, MI- 11737, permits simultaneous use of
four carbon microphones such as one interphone connec-
tion unit and three camera headsets on a common battery
or power supply. The coil permits a d -c power voltage to
be imposed upon the two -wire telephone talking line. This
audio frequency choke minimizes the effect of the power
supply from lowering the two -wire telephone impedance
at voice frequencies, and also allows adequate flow of
direct current.
Mounting Panel, MI- 11736 -A, will permit mounting up to
14 retardation coils in the rack. Either a Single Headband
Assembly, MI- 11743, or a Double Headband Assembly,
MI- 11744, can be used for listening and talking with the
Studio Interphone System.
40
www.americanradiohistory.com
CONSOLETTES
INTER PHONE
UNIT
I
L---YYy_
Yy
t
(_I
--
- L
Jt
I
2
I
SUPPLY
COIL
M1-11737
- ----I
I
HEAOSCT
nn1-11744
i
CUE
RETARDATION
ME-11316
L
---.
Cu! LINE
24v. 3A.I
POWER
LINE 2
LINE
LINE
CONNECTION
MI11734
UNIT
CuE LINE
5
(4)
INTERPHONE
1
LINE 2
¡1
Tel
r-
CÒNNE CTION
Ml-11734
LINE
<l1b-4
r-------J2
S
--------
1
CAMERA CONTROL
I
I
I
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(
I
--/ A/9A ?
1
L
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_____
J1
le
14,
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STUDIO
I
CAMERA
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IlsuJullanlna/l
I
I
UNIT
CAMERA
EUA PMENT
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n^
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O
o
Schematic diagram of typical Interphone System.
Stock Identification of Interphone Components:
SPECIFICATIONS
D -C Resistance
(Headset):
Microphone Switch On
Microphone Switch Off
Inductance at 1000 Cycles (Headset):
Microphone Switch On
Microphone Switch Off
D -C
70 ohms approximately
Infinite
70 millihenries approximately
245 millihenries
.
_
MI-11734
MI -11737
MI -11735
MI- 11736 -A
MI -11743
MI -11744
MI-11316
165 ohms
Resistance (Retardation Coil)_._
Inductance (Retardation Coil)
3.4 henries
Maximum Recommended Load Current
125 ma d -c
Power Supply
Interphone Connection Unit
Retardation Coil
Shelf for Mounting MI -11734
Panel (Accommodating 14 Retardation Coils)
Single Headband Assembly
Double Headband Assembly
Regulated Power Supply
Regulated 24 volts, 3 amps, d -c
Dimensions:
Interphone Connection Unit
Retardation Coil
Mounting Plate
Retardation Coil Panel, MI- 11736
Retardation Coil Panel, MI- 11736 -A
Regulated Power Supply
Weight:
Interphone Connection Unit
Retardation Coil
Retardation Coil Panel, Ml -11736
Retardation Coil Panel, MI- 11736 -A
Single Headband Assembly
Double Headband Assembly
Regulated Power Supply
45,á"
45/e" x
41/4" x 2)j'6"
x
1
45/64"
19"
19"
9"
x
Ws"
11" x
61"
x 13/4" x
Xs"
13/4" x
3e'
x
73/4" x 53/4"
x
lb.,
1
11
ozs.
15 ozs.
19 ozs.
18 ozs.
6 ozs.
(less cord)
9 ozs
(less cord)
25 lbs. (net)
Console Shelf, MI-11735, has mounting accommodations
for two Interphone Connection Units.
www.americanradiohistory.com
CON SOLETTES
FEATHERWEIGHT HEADSETS
MI -11749 AND 11750
FEATURES
Extremely lightweight- smooth,
comfortable fit -can be worn
for extended periods of time
without fatigue
High sensitivity
Sturdy bakelite shells and caps
Six -foot
water- resistant cord
Concealed terminals
Choice of single or double earphones
USES
The Double Headset, MI- 11750, weighs only
The MI -11749 and 11750 Featherweight Headsets are ex-
tremely lightweight offering the utmost wearing comfort
for those engaged
in
control room monitoring, remote
pickups, and other broadcast applications requiring head-
41/2
ounces,
and consists of double earphones identical to those of the
single headset, mounted by spring adjustments to a double
fabric covered double wire band headband. The unit has
a
d -c resistance
of 5000 ohms and an impedance of
24,000 ohms.
phone use. Both Single Headset, MI- 11749, or Double
Headset, MI- 11750, are high quality
units
of durable
molded black plastic, attractive in appearance, sensitive
in response, and
Both headsets are fitted with a 6 foot water- resistant cord
with a popular phone style plug. The bakelite body
practically non -breakable. The plug
comfortable for use.
with 11/2" prong,
is
is
2'/s" long overall,
diameter which fits all standard
1/4" in
jacks. The cord pin tips are held by set screws.
DESCRIPTION
The Featherweight Single Headset, MI- 11749, consists of
a
single durable molded black plastic earphone, 21/4"
in
diameter attached to a
1/4"
wide stainless spring steel
headband adjustable for optimum wearing comfort. The
phone has concealed terminals and
_.
D -C
Resistance
Impedance
extremely sensitive,
Earphones
equaling in clarity and volume most double headsets. The
Terminals
headset has a d -c resistance of 2000 ohms and impedance
Plug
is
of 9000 ohms. The unit weighs approximately 2 ounces.
42..
SPECIFICATIONS
_
_
..
Weight
Stock
Identification
Single Earphone
Double Earphone
2,000 ohms
5,000 ohms
9,000 ohms
24,000 ohms
21/4" dia.
21/4" dia.
Concealed
Concealed
Standard 1/4" jack
Standard 1/4" jack
2 ozs.
41/2
MI -11749
MI -11750
ozs.
CON SOLETTES
TRANSISTORIZED INTERCOM EQUIPMENT
FEATURES
Excellent speech reproduction
Compact, attractively styled cabinets
Transistorized Amplifiers -low power
consumption
Easily installed
Many models available to handle varied
intercom needs
Systems readily rearranged, or expanded
instant call -no warm -up provided
USES
Transistorized Intercom is a new electronic intercommunication system which provides instant two -way
RCA
voice communication. Its application covers all segments
of industry, commerce, and institutions. Multi -Com can be
effectively and economically applied wherever walls and
distance separate individuals who must communicate. The
equipment is easily installed, simple to operate, and requires little maintenance. It features excellent speech
characteristics and reproduction quality, permitting the
user to talk in normal, conversational tones.
The Intercom system has been designed to offer the high
degree of flexibility required to meet a complete range
of intercom functions and requirements. A complete system
may consist:
Entirely of master instruments.
Of one master instrument and one or more remote units.
3) Of a combination of a number of master instruments,
each with one or more remote or multiple remote units.
Master instruments can be wired for confidential telephone
operation.
1)
2)
DESCRIPTION
RCA Transistorized Intercom equipment consists of
master stations and compatible remote units that operate
from a central, low- voltage power supply, rated 2 amperes,
30 watts, the voltage of which does not exceed 15 volts.
The system permits the master station to call up 32 remote units by voice or any of the remote units to call the
selector keys, a red busy light, and a chime to give
audible indication of a call. The master stations are supplied with 8, 16, 24 or 32 selector keys depending on size
system required. The selector keys are of the push type
with a simple release mechanism, and are made of a
translucent plastic that is illuminated by the call lights.
master station
The 8 and 16 key units are housed in cabinets measuring
The
by signal lights. The system
private for all combinations of units.
is
entirely
inches long, 4''2 inches high and 61/4 inches deep.
Cabinets housing the larger 24 and 32 key master stations
are 1934 inches long.
1234
Intercom equipment is compact and handsomely styled to
complement any office decor. Cabinets provided are of
hand -rubbed walnut or blonde finish.
The master station contains a combination of loudspeaker -
remote units are housed in matching cabinets 51/2
inches long, 41/2 inches high and 61/4 inches deep. They
are equipped with a talk -listen switch and a volume con-
microphone,
trol to adjust listening level.
volume control,
talk -listen
switch,
station
The
www.americanradiohistory.com
CONSOLETTES
Both master stations and remote units employ three -inch
dynamic loud- speakers that are acoustically and electrically compensated to provide good speech intelligibility
without loss of fidelity. The gain of the system permits
normal speech at a distance of two feet from the instrument and the sound level output is sufficient for speech
to be understood at a distance of three feet from the
instrument in noise levels of 92 db. Lines connecting the
stations and remote units are at low impedance of approximately telephone level. All amplifiers are completely
transistorized and protected against damage due to the
application of a reverse supply potential equal to that
of the power supply. They consume no power when the
station is not in use, generate no heat, yet provide instant
communication without any warm -up period.
auxiliary equipment the RCA Transistorized
Intercom System can provide many additional service
By means of
functions. Quiet, confidential talks
telephone handsets that eliminate
switch. The receivers mount on a
hook switch. The system is wired for
communication or for telephone to
are made possible by
use of the talk -listen
convenient, desk side telephone to telephone
master communication.
Master Stations are available with an "all -call' switch.
This enables the station to call any number of predetermined master or remote stations simultaneously by merely
depressing the switch before speaking into the station
microphone. Master Stations are also available with a
special relay permitting receipt of "all- call" signals from
other master station equipment, but which are not provided with "all -call" origination switch. Master stations
combining both facilities are also available. In all cases,
the number of stations in the system subject to the receipt
of an "all- call" need not be the same as the number that
can originate an "all- call." Such conference calls are
possible without requiring re- adjustment in volume control
settings for satisfactory operation.
SPECIFICATIONS
12V. dc, 12V oc from central,
ment in noise levels of 92 db.
Carefully constructed walnut and blonde cabinets
with smooth, hand -rubbed finish
Dimensions (overall):
123,4" long, 6' . " deep, 41/2" high
8 and 6 Key Masters
1934" long, 61 4" deep, 41/2" high
24 and 32 Key Masters
51/2" long, 6 4" deep, 41/2" high
Remote Units
Cabinets_
1
.
Weight:
8 and 16 Key Masters
24 and 32 Key Masters
Remote Units
Equipment Supplied
Type
Type
Type
Type
SJR -1 W
SJR -1B
SXJ -2
SXJ -5
Remote Unit Walnut Case.
Remote Unit Blonde Case
Power Supply, 30 watts, 2A
Power Supply, 80 watts, 5A
MI-38505-W
MI-38505.B
MI-38506
MI-38507
Station, Walnut Cose
Station, Blonde Case...
16 Station. Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case
32 Station, Walnut Case
32 Station, Blonde Case
MI-38508-W
MI-38508-B
MI-38516-W
MI-38516-B
M -38524-W
Ml-38524-B
MI-38532-W
MI-38532-B
MASTER UNIT
Type
Type
Type
Type
SJ
-8W
SJ -8B
SJ
-16W
SJ -16B
SJ -24W
Type SJ -24B
Type S.1-32W
Type SJ -32B
Type
8
8
I
MASTER UNIT WITH ALL-CALL ORIGINATION ONLY
Type SJ -8WK
Type S.1-88K
Type SJ -16WK
Type SJ -16BK
Type SJ -24WK
Type SJ -24BK
Type SJ -32w:(
Type SJ -32BK
Station, Walnut Case..
Station, Blonde Case
16 Station, Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case..
32 Station, Walnut Case_
32 Station, Blonde Case
8
8
MI-38509-W
MI-38539-B
MI-38517-W
MI-38517 B
MI-38525-W
M -38525-B
MI-38533-W
MI-38533-B
I
MASTER UNIT WITH FACILITY TO RECEIVE ALL -CALL
low voltage
power supply
50 ohm balanced line
System Impedance
Low to match telephone level
Impedance
Sufficient for normal speech
Gain
at a distance of 2 feet from the instrument
Sufficient that normal speech
Sound Level __
can readily be understood at a distance of three feet from instruPower Requirements
Intercom Remote Unit, MI-38505 -B
51/2 lbs.
71/2 lbs.
2 lbs.
Type S.1-8WR
Type SJ -8BR
Type SJ -16WR
Type SJ -16BR
Type SJ -24WR
Type S.1-24BR
Type SJ -32WR
Type S1 -32BR
Station, Walnut Case
Station, Blonde Case..
16 Station, Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case
32 Station, Walnut Case
32 Station, Blonde Case
8
8
MI-38510-W
MI-38510-B
M I -38518- W
MI-38518-B
M -38526- W
MI-38526-B
I
MI-38534-W
MI-38534-B
MASTER UNIT WITH ALL -CALL TO ORIGINATE
AND RECEIVE REMOTES AND MASTERS
Type
Type
Type
Type
Type
Type
Type
Type
SJ
-8WC
SJ -8BC
S.1-16WC
S.1-16BC
S.1-24WC
SJ -24BC
SJ -32WC
S.1-32BC
www.americanradiohistory.com
Station, Walnut Case
Station, Blonde Case
16 Station, Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case..
32 Station, Walnut Case
32 Station, Blonde Case
8
8
MI- 38511 -W
MI- 38511 -B
MI- 38519 -W
MI- 38519-B
MI- 38527 -W
MI- 38527 -B
MI- 38535 -W
MI- 38535 -B
CUSTOM AUDIO
CUSTOM AUDIO EQUIPMENT
Linear faders replace knobs in this latest RCA custom designed audio control console.
FEATURES
Designs for Exact Customer Requi!emen's
Reduced operating expense
Extensive Custom Engineering Service
available for consultation
Instant "fool- proof" switching
Custom designs provide means for
complete automation later, if desired
Increased operating efficiency
Increased station prestige with clients
Possibilities for new business
programs handled
www.americanradiohistory.com
.
.
.
Mos e
CUSTOM AUDIO
addition to a comprehensive line of standard studio
each installation, ranging from special equipment for small
control equipment, RCA specializes in custom designing
and medium -size stations to more complex systems for the
and building complete speech -input systems to meet indi-
largest installation.
vidual needs of stations and networks. Our engineers have
"Custom- built" equipment service
worked closely with the nation's leading broadcast engi-
AM, FM, or Television station, and it includes the services
neers in the design, production and installation of many
of an entire RCA engineering staff. Broadcast station engi-
custom equipments, a few of which are pictured on these
neers, in some cases, may wish to lay out and design the
are tailor -
system themselves, complete with specifications. In these
In
pages. Studio -control
systems such
as these
In
planning new
is
installations, this
available to every
made, combining just the right facilities for the control of
instances,
program operations and the reproduction of high -fidelity
modify standard equipment to meet these specifications.
sound.
On the other hand, where stations desire, RCA engineers
Since no two broadcast stations have exactly the same
will study station requirements, make overall and detailed
operating requirements, equipment needs will differ for
layouts, and draw up specifications for equipment needed.
RCA
will provide specifically built units or
EXAMPLES OF RCA CUSTOM AUDIO EQUIPMENT
The custom audio console, shown
such as built -in remote control for
46
here, was designed and built for WKRC. It includes many unique features,
two tape recorders including rewind, fast forward, record, start, and stop positions.
CUSTOM AUDIO
on
.y
\fr'
h rY
1F
..
rlll
trYpo
c
I
i
icoVr'L`1.
la
'Contrc aid switch ng units used
It perm
ih switcIig of
15
automation equipment.
preview orog-am sources.
in the WTAE
program or
.o..nws
44)
4,0
1Oa
44
44-.0
0Ú'
.0
.....
Cp-
a custom relay switcher and control panel designed for the
Triangle Publications Stations. Twelve program or pre view program
sources can be switched manually from the control console or by
the automation system.
This is
'Custom
The
use
Control
Co is 31e
cf inear f.dars
provid
adds
wig
for twenty
switchable
inputs.
much to the versatility of the unit.
CUSTOM AUDIO
Custom equipment receises special attention o details, for instance
precision wiring, and tilt ng panel for ease of maintenance.
'',
Precision and high quality design and workmanship make RCA custom
audio equipment the best. Here all panel mounted contacts and cornponenrs are exposed for maintenance.
Design of this deluxe studio control console includes every feature need d f 3r ope-ating ease and convenience. The hinged
sloping frxnt panel, and hinged panel doors to all turrets and
pedcstils, pro -ide cc replete accessibility to every component
AMPLIFIERS
BROADCAST AMPLIFIERS
FEATURES
Uniform performance
Suitable for rack, cabinet or shelf mounting
Excellent frequency response
Tube metering circuits
Small size handling ease
High gain, low noise circuitry
Convenient front panel controls
Reduced size accessories
DESCRIPTION
of high -fidelity speech input amplifiers has
been designed to provide stations with studio, recording
and portable remote amplifiers which will offe, the maximum in fidelity, flexibility, convenience and reliability. All
amplifiers are suitable for FM having a uniform response
to 15,000 cycles. Distortion and noise levels have been
reduced to a very low value through careful engineering
The RCA line
design and construction.
Attention is invited to gain and level references in this
catalog, as follows:
db- refers
to gain.
dbm -sine wave power measurement referred to
1
mw.
VU- refers
to average program level as read on a
standard VU meter. Thi; value is subject to considerable variation from dbm but is generally considered 10 db below peaks.
Allowance must be made for program peaks to avoid
amplifier overloading, for example, a pre -amplifier rated
at } -10 dbm should not be operated at more than 0 V'
www.americanradiohistory.com
AMPLIFIERS
BA-21 A PREAMPLIFIER AND ISOLATION AMPLIFIER
and bridging a 600 -ohm line. Approximately 80 db of
isolation between output and input is obtained with the
amplifier in this arrangement. A switch is provided for
metering a portion of the cathode voltage of each tube
when connected to a high- resistance voltmeter such as the
Type BI -1 B. The unit is designed to operate from the
BX -21A Power Supply or its equivalent. The power requirements are 6.3 volts a -c or d -c at 0.6 amperes and 285 volts
d -c at 10 ma. Up to ten BA -21A Preamplifiers can be
installed in a single BR -22A Panel and Shelf assembly and
operated from one BX-21A Power Supply.
SPECIFICATIONS
BA -21A AS PREAMPLIFIER:
37.5/150/600 ohms
Source Impedance
DESCRIPTION
The BA -21A is an ideal unit for use as a microphone pre-
amplifier, turntable preamplifier or booster amplifier. Its
high output level makes it applicable as a line amplifier.
It may also be used as an isolation and bridging amplifier.
The BA -21A has been designed to obtain high gain using
one RCA MI- 11299, selected 12AY7 tube in the input
stage and one 12AY7 in the output stage. The tubes are
mounted vertically and the first stage is shock mounted to
prevent microphonics. The circuit is conventional with unloaded input transformer, resistance -capacitance coupling
between stages and transformer output. The distortion
and hum level has been reduced to a very low value
through proper circuit design and through the use of
stabilized feedback. Cross talk between units is -75 db,
30 to 15,000 cycles when mounted side by side and operated from the BX-21A Power Supply.
With the addition of the MI- 11278 -E or F volume control
kit to provide a 10,000 ohm input, the BA-21A may also be
used as a bridging or isolation amplifier. The MI- 11278 -E
or F kits can be mounted on the BA -21A chassis and be
adjusted by either knob or screw driver. The MI- 11278 -F
can be used for panel mounting remote from the amplifier.
As a bridging amplifier, the BA -21A has a maximum of
4
db gain with the volume control at minimum loss position
Input Impedance (unloaded input
transformer)
Substantially above source impedance
150/600 ohms
Load Impedance (balanced or unbalanced)
-22 dbm
Maximum Input Level
18 dbm
Maximum Output Level
40 db ±1 db
Gain
BA -21A AS ISOLATION AMPLIFIER (with MI -11278 Series
Volume Control):
_
Source Impedance
Up to 600 ohms
10,000 ohms
Input Impedance (through Volume Control)
150/600 ohms
Load Impedance (balanced or unbalanced)
Maximum Input Level, Volume Control at max.:
14 dbm
Bridging 600 Ohms
20 dbm
Bridging 150 Ohms _ ._
18 dbm
Maximum Output Level
4 db
Maximum Gain _._
BA -21A AS EITHER PREAMPLIFIER OR ISOLATION AMPLIFIER
Frequency Response
Noise Level (Input and Output Terminated):
._ __......_ __ .____
Output ...._._ ... _..... _
Referred to Input
Harmonic Distortion (18 db Output)
_
Tube Complement:
1- Selected 12AY7,
Plate Power Supply
1
db 30-15,000 cps
-82
dbm
dbm
0.75% at 30 cps
0.5% at 50 to 15,000 cps
_
-122
-12AY7
Filament Supply
Dimensions, Overall
285 volts d -c at 10 ma
6.3 volts a -c or d -c at 0.6 amps
Length 121/2 ", width 15e ", height 4fli6"
Umber gray
21/2 lbs.
Weight (unpacked) _
ES -11121
Stock Identification (includes tubes)
Finish
Accessories
Tube Kit (complete tube complement)
Bridging Gain Control Kit
(Screw- driver adjustment)
(Knob adjustment)
BX -21A Preamplifier Power Supply (furnishes filament and
plate power for 1 to 10 BA -21A Preamplifiers)
Type BI -1B Meter Panel (umber gray)
BR -22A Mounting Shelf for rack mounting 1 to 10
preamplifiers or 1 power supply and 6 preamplifiers _.
MI -11482
MI- 11278 -F
MI- 11278 -E
Ml -11317
MI -11388
MI -11597
Typical Frequency Response Type BA -21A Preamplifier.
m
0
I
W
if)
15041 INPUT
Z 0
o
'il
-I
20
00
IKC
FREQUENCY IN CYCLES PER SECOND
www.americanradiohistory.com
IOKC
151(C
20KC
AMPLIFIERS
BA -23A PROGRAM AMPLIFIER
FEATURES
USES
Etched wiring provides compact sire and
The new
BA -23A Program
Amplifier
is
a very versatile
uniform performance
high -fidelity amplifier designed for broadcast service. It
Plug -in type for shelf mounting
incorporates special,
Maximum accessibility
and
dependable
service
Excellent frequency response
High gain -low distortion -low noise level
--high output
Provision for tube metering
Economical in price
Small size
Self- contained power supply
high -quality, long -life components
throughout and provides a maximum of accessibility to all
circuit components. Its high gain and low distortion makes
it ideal for use as: (1) Program or Line Amplifier, (2) Bridging Amplifier, (3) Isolation Amplifier.
The BA -23A is a plug -in type amplifier which has been de-
signed for use with the
BR -22A
Mounting Shelf. This shelf
permits quick and easy removal for servicing or interchanging units. The Type
BR -22A
Shelf provides mounting space
for three Type BA -23A amplifiers with space for one additional preamplifier.
8.1400
www.americanradiohistory.com
Inverse feedback
DESCRIPTION
The BA -23A employs etched wiring to insure uniformity of
performance. It uses resistors with plenty of wattage rating
hermetically sealed transformers. Thus long life, trouble -free operation and extreme accessibility of
parts is assured. Components on the printed circuit board
can be easily replaced.
in reserve and
All connections to the BA -23A are made through a 15
prong connector at the back of the amplifier which plugs
into a socket supplied with the amplifier. Connections are
provided from each cathode circuit through a selector
switch to terminals on the plug. These connections permit
metering of tube conditions by means of a high resistance
voltmeter such as the RCA Type BI-1B.
The BA -23A Program Amplifier has three stages of ampli-
fication with an additional phase splitter driving the push pull- parallel output stage. The input stage utilizes a type
5897 low noise pentode. A 12AX7 twin triode is used as
second stage and phase inverter. The push -pull output
stage consists of two 12AU7 tubes having their sections
connected in parallel. A 6X4 is used as full wave rectifier
in the self -contained power supply.
The gain control follows the input transformer to permit
high level input without overloading the input stage. A continuous composition type control is used in the ES -11123
Program Amplifier, but space has been provided for a step
type attenuator, if desired. A gain reduction of 15 db with
corresponding reduction in noise level may be obtained
by changing a jumper on a voltage divider in the grid
circuit of the second stage.
a
is
supplied from a tertiary winding of
the output transformer to the cathode of the driver stage
to stabilize gain and frequency response and to reduce
distortion.
SPECIFICATIONS
150/600 ohms balanced or unbalanced
Input Impedance (Matching)
150/600 ohms
Input Impedance (Bridging)
20,000 ohms
Load Impedance
150/600 ohms
Output Impedance
25/100 ohms
Maximum Input Level (Matching)
-10 dbm
Maximum Input Level (Bridging)
27 dbm
Maximum Gain (Matching)
70 +1 db high, 55 +1 db low
Maximum Gain (Bridging)
33 -F2 db high, 18 ±2 db low
Frequency Response
db 30- 15,000 cps
Harmonic Distortion
0.5% rms max. at 30 dbm output, 30- 15,000 cps
Noise Level (at output)
-47 dbm at 70 db gain
-62 dbm at 55 db gain
Metering Voltage
1.0 volt
Tube Complement:
1- Selected 5879, 1- 12AX7, 2- 12AU7, -6X4
Source Impedance
1
Power Required
100 -130 v, 50/60 cps 30 w
(Transformer taps at 105, 115 and 125 v)
Mechanical Dimensions:
Length
Height
Width
Weight
Chassis 103/8 ", overall 121/2"
4
21/32"
5"
9 lbs.
Light umber gray lacquer
Mounting
Plug -in mounting on MI -11597 Mounting Shelf, Type
BR -22A. The BA -23A Amplifier requires 3/10 of the shelf space.
Three BA -23A Program Amplifiers may be mounted on one BR -22A
Mounting Shelf with space for one additional BA -21A Preamplifier.
Stock Identification (includes tubes)
ES -11123
Finish
Accessories
Tube
MI -11480
Kit
Meter Panel, Type BI-1B (provides tube metering for
17 amplifiers)
Mounting Shelf (for rack mounting of 3 BA -23A program
amplifiers; requires 51/4" of vertical rack space)
Step Attenuator
MI -11388
MI -11597
MI- 11751 -2
FREQUENCY RESPONSE
PROGRAM AMPLIFIER
TYPE - BA -23A
MI- 11246-A
1
0
1
20
100
I
KC
FREQUENCY IN CYCLES PER SECOND
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101cC 15KC 20KC
AMPLIFIERS
BA -24A MONITORING AMPLIFIER
FEATURES
Self- contained power supply
High gain -used directly in talk -back cil
cuits, without preamplifier
watts output with low distortion -uses
feedback
8
Suitable for cabinet or shelf mounting
Ideal for recording and playback
Tube metering circuits
SPECIFICATIONS
DESCRIPTION
A high quality, high gain amplifier suitable for driving a
loudspeaker directly from a microphone or turntable output. It has four stages of amplification with an interstage
gain control. A phase splitter drives the push -pull output
stage. Negative feedback is utilized to reduce distortion,
stabilize gain and frequency response. The power supply
is self -contained. The hum level is reduced to a minimum
through the use of well shielded transformers, low noise
tubes and careful circuit layout. A metering switch on the
front panel is provided to check the condition of the tubes,
with the metering voltage of 1 volt brought out at the
connector plug.
The BA -24A is a high fidelity, high gain flexible 8 watt
amplifier suitable for monitoring, audition, recording, and
talk -back applications or it may he used in emergencies
as a program or line amplifier. It is ideal for transcription
playback booths since its 105 db gain is sufficient to
operate an (LC -1A) Speaker directly from the output of a
(BQ -51A) Turntable. The high gain feature also allows its
use directly in studio talk -back circuits without an intervening preamplifier. The BA -24A is an excellent recording
amplifier being suitable for both high quality recording
and playback applications. Two may be mounted in a type
BR -22A Mounting Shelf. The BA -24A has a plug -in type
chassis using multi- conductor plugs.
Frequency
Response Type
37.5/150/600 ohms
Source Impedance
Unloaded transformer, high in comparison
with source impedance
Input Impedance
4/8/16/150'600
1.3'1.8/3/21/78
Impedance
Load
Output Impedance (approx.)
Maximum Input Level
Maximum Gain
Frequency Response _. ...
Maximum Output Level
104
±2
Harmonic Distortion
At 8 W (39 dbm output)
Noise Level
1- Selected
12AY7,
ohms
-30 dbm
db ±2 db
db 30- 15,000 cps
10 watts (40 dbm)
than 1% 100 -7500 cps
than 2% 50- 15,000 cps
-122 dbm referred to input
dbm at output at 104 db gain)
volt
Less
Less
(
Metering Voltage ....
Tube Complement:
ohms
-18
1
1- 12AX7, 2- 6V6 -GT /G, 1- 5Y3 -GT /G
Power Requirement
Dimensions:
Length
100 -130 volts, 50 -60 cps, 70 watts
Width
Height
Weight
1038 ", 12'/2" overall
83/2"
4
21/32"
.161/4
lbs.
Light umber gray
Mounting
Plug -in mounting on BR -22A Mounting Shelf. Requires
half the shelf space (two amplifiers may be mounted on each shelf.)
E5 -11124
Stock Identification (includes tubes)
Finish
Accessories
Tube
Kit
MI -11481
Mounting Shelf (mounts two BA -24A)
Meter Panel (for 17 amplifiers) (BI-1B)
Bridging (remote volume control)._
MI -11597
BR-22A
BA -24A Moni oring
MI -11388
MI- 11278-E or F
...
Amplifier.
1
o
-20
100
IKC
FREQUENCY IN CYCLES PER SECOND
www.americanradiohistory.com
IOKC IS.C20KC
AMPLIFIERS
BA -25A AGC PROGRAM AMPLIFIER
FEATURES
Maintains nearly constant average output
level over wide variations of average input
level
The RCA Type BA -25A Automatic Gain Controlled Pro-
Feedback circuits provide excellent frequency response -low harmonic distortion
average output level over wide variations of average input
level. Such variations are often encountered when switching between the output of projectors, turntable pre -amps
and other sound sources.
Small, compact, plug -in construction
Provides automatic fading or remote gain
control
Self- contained power supply
Metering switch provides quick tube check
Convenient front panel controls
Stabilized bias voltage
54
USES
gram Amplifier
is an automatic level control unit designed
to automatically control variations in audio program level.
The unit is capable of maintaining a nearly constant
The amplifier may also be used in conjunction with an
external bias source for remote gain control or automatic
fading. This permits unattended remote audio operation.
It may also be used as a program line compressor or as a
master gain control for program line. The BA -25A may
be used as a microwave input audio control, as an automatic fader control, or as a straight program amplifier
without level control by removal of one tube disabling the
automatic level control circuit.
AMPLIFIERS
DESCRIPTION
new BA -25A Automatic Gain Controlled Program
Amplifier is a small, compact amplifier mounted on a
plug -in chassis for easy maintenance and replacement.
Two amplifiers can be mounted on the Ml -11597 Mounting
Shelf which requires but 5.25 inches of rack space.
PHASE
INPUT
The
LEVEL INVERTER
VARIABLE
GAIN
STAGE
OUTPUT
STAGE
DRIVER
STAGE
OUTPUT
INPUT
EXTERNAL
BIAS
circuitry of the BA -25A is straightforward. The input
signal is applied through an input transformer and input
level control to a phase splitter. The phase splitter drives
a push -pull variable gain amplifier which utilizes a type
6386 remote -cutoff twin triode tube. The gain of this stage
depends on the bias voltage, the more negative, the lower
is the gain. The output of the variable gain stage is fed
to a push -pull voltage amplifier and a push -pull parallel
output stage. Negative feedback is applied over the output and driver stages. A portion of the output signal is
supplied to a rectifier tube. An adjustable positive bias on
this tube delays rectification of the signal until the output
level exceeds the "threshold" value.
VOLTAGE (OP' O'
The
L)
POWER
SUPPLY
100-130V
OB2
SO-60.0
THRESHOLD
Simplified Block Diagram of BA -25A AGC Program Amplifier
all located on the front panel include: a hum control for
adjusting the hum level to a minimum, the power switch,
threshold level control, and input level adjustment control.
An external attenuator may be used for adjusting the
output level where necessary.
The rectified current is filtered through a resistance- capaci-
tance network having a fast charge and slow discharge
time constant. This voltage, which is negative with respect
to ground, is applied as a bias voltage to the grids of the
remote cut -off tubes. As the output level increases, the bias
voltage becomes more negative, reducing the gain of the
amplifier and thus reducing the increase in output level.
This constitutes a closed loop system which tends to main-
SPECIFICATIONS
Input Impedance
150/600 ohms
.
Source Impedance
150/600 ohms
Output Impedance
30/120 ohms
Load Impedance
150/600 ohms
_.
-25
Maximum Input Level
tain a nearly constant output level as long as the input
signal is sufficient to reach the threshold of compression.
Maximum Output Level
Below the threshold level, which is adjustable by varying
the rectifier delay bias, the amplifier is linear and the
output level is therefore proportional to the input level.
Above the threshold level, the increase in output level (expressed in db) is less than the increase in input level (also
expressed in db). The ratio of the increase in input level
Frequency Response
Threshold of Compression:
Compression Ratio
.
Tube Complement:
lected 12AY7,
1
Power Requirements _.
drop across the cathode resistor of either section of the
variable gain stage may be used as an indication of the
amount of gain reduction.
Weight
provided on the BA -25A which measures the cathode current of the amplifier tubes to obtain
a quick indication of the tube conditions. Other controls,
5:1
18 dbm
6:1
21
dbm
12.5 milliseconds
1
2- 12AU7, 1- 12AX7,
-6AL5,
-6386.
bias voltage for the remote cut -off stage may be supplied
by an external source. Since the gain of the remote cut -off
stage is a function of the cathode current, the voltage
db
14 dbm
Recovery Time Constant
-0B2, 1- 5Y3 -GT,
1
5 dbm
Output Level
3:1
4:1
compression ratio.
is
70 db 4
Gain, Maximum Below Verge of Compression
1
dbm
71 db
30- 15,000 cps, less than 1%
Harmonic Distortion
Attack Time Constant
A metering switch
-46
30- 15,000 cps,
to the increase in output level is the compression ratio. This
compression ratio is a function of the threshold level. The
higher the setting of the threshold level, the higher is the
For automatic fading or remote gain control, the negative
30 dbm
I-
Maximum Noise Level, Output
dbm
1
1
-M1 -11299
sec.
se-
100.130 volts, 50/60 cycles, 55 watts
12/2" long,
Dimensions, Overall
83/s" wide, 4
21/32" high
Light umber gray
Finish
15 lbs.
ES -11125
Stock Identification (includes tubes).
Accessories
MI-11487
Tube Kit
Mounting Shelf, Type
BR -22A,
for
2
Amplifiers
Meter Panel, Type BI-1B, for 17 Amplifiers....
www.americanradiohistory.com
MI-11597
MI-11388
AMPLIFIERS
BA -26A TURNTABLE EQUALIZING PREAMPLIFIER
FEATURES
Built -in equalization conforming to
NAB /RIAA specifications
wiring circuits -transistors used
throughout
Etched
Completely self -contained, including
a -c power supply
Free from microphonics
Compact -easily mounted in turntable
Insensitive to hum field pickup
Adjustable high- frequency response
USES
The RCA Type BA -26A Turntable Equalizing Preamplifier
is
designed to provide both amplification and equalization
of the output of studio transcription turntables employing
either the RCA Type MI- 11874 -4 or RCA Type MI- 11874 -5
Pickup Heads. Low Impedance Broadcast types of variable
reluctance Pickup Heads may be used by making a minor
change in terminal connections of the preamplifier.
The equipment employs RCA low -noise type transistors in
a
three -stage amplifier
utilizing selective feedback to
achieve the equalizing curve. Characteristics of this curve
are such that they follow the NAB RIAA recommended
curve from 50 to 15,000 cps. A self -contained a -c power
supply utilizing
germanium rectifier provides essentially
noise -free operation.
The compact BA -26A economically replaces a bulkier com-
bination of amplifier and separate equalizing filter. In
the BQ -2B Turntable it is designed to be mounted in the
same position and space previously occupied by the RCA
Type MI -11887 passive equalizer.
www.americanradiohistory.com
AMPLIFIERS
DESCRIPTION
The Type BA -26A Turntable Equalizing Preamplifier, MI-
11436, is a compact transistorized amplifier with built -in
equalization that conforms to the new industry standards.
It has etched wiring assemblies contained in a shielded
metal chassis which is designed to be mounted inside the
turntable cabinet. A convenient slip -on cover is provided
to allow access to component parts and transistors. An
extended threaded shaft on a three -position filter switch
allows ease of control from a knob on the top of the
turntable. The switch provides for normal equalization, high
frequency emphasis, and high frequency cut -off. This
arrangement allows optimum performance for either AM,
FM or TV broadcast operation.
with Cover Removed.
BA -26A Preamplifier
Preamplifier
conservatively designed for
long life. The RCA Type 2N175 low -noise transistor is
used in the input stage followed by two Type 2N109
transistors to provide the required gain and output capabilities. One Type 1N91 germanium rectifier is used in the
a -c power supply. The preamplifier exhibits complete freedom from microphonics that result from the use of vacuum
tubes. The equalized output level is approximately -20
dbm with distortion less than 1.5 percent from 50 to
15,000 cps. Signal to noise ratio is rated better than 58 db,
and power consumption approximately 2 watts. An output
transformer is employed to provide either balanced or
unbalanced output impedances of 150 and 600 ohms.
The
BA -26A
is
Etched wiring boards are utilized to provide stable trouble -
free operation of the unit. By utilizing selective feedback
within the amplifier itself it is unnecessary to use inductances to accomplish proper low- frequency equalization.
The absence of such units make the BA -26A insensitive to
stray hum field pickup thereby greatly simplifing installation.
SPECIFICATIONS
Output Level (E,,,
11
my at f of 1000 cps)
-
20 dbm
+2
db
Distortion at -20 dbm from 50 to 15,000 cps
Less than 1.5%
Signal to Noise Ratio (Output level of -20 dbm and
150 ohm Resistor used at Input & Output)
Better than 58 db
150 600 ohms
Output Impedance (balanced or unbalanced)
Frequency Response (Using MI- 11874 -4 Pickup)
See Curve
Power Requirements
3 Taps: 105 115 125 volts a -c,
50 60 cycles, single phase, 2 watts
Dimensions (overc.II):
Height (including extended knob shaft)
1034"
2i/2
Width ...
Depth
658"
Weight ..
4 tbs.
Stock Identification (includes transistors)
MI-11436
Accessories
Transistor & Rectifier Kit including
Type 2N175 Transistor, and
1
2
1
Type 2N109 Transistors,
Type 1N91 Rectifier
MI-11779
NARTB TEST RECORD -WESTMINISTER TRC OR -R CA 12- 5 -51
PICKUP USED - RCA -MI- 11874 -4 SERIAL 4655
+I0DB
+5DB
I
O
-5DB
I- PLUS HIGHS
2- NORMAL
3- MINUS HIGHS
-I0DB
50
100
3
10,000 - 15,000
1000
FREQUENCY IN CYCLES
PER
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SECOND
AMPLIFIERS
BA -6A LIMITING AMPLIFIER
FEATURES
Prevents distortion and adjacent channel
interference
Low cost -high -quality performance
Provides for
a
more effective use of trans-
mitter power
Compact, plug -in unit -requires little rack
space
Complete rotary switch selection of metering of all key functions provided
44
USES
Amplifier has been designed to provide economical, yet high -quality operation in the speech
The BA -6A Limiting
input channels of FM and AM broadcast and TV sound
transmitters. It serves as an automatic means of limiting
the audio signal peaks to a certain pre- determined level
thereby preventing overmodulation or overloading with its
consequent distortion and adjacent channel interference.
amplifier also provides for a more effective use of
transmitter power by allowing the system to be operated
as near maximum output as possible. It raises the average
This
percentage modulation level several db without appre-
ciably increasing the harmonic distortion.
maximum degree of reliability. Fewer tubes, fewer types
(only 6) and fewer stages of simplified design result in
lower tube costs, low initial cost and reduced power input
requirements.
The BA -6A Limiting Amplifier also incorporates those fea-
tures which are found in other RCA high -quality broadcast
audio amplifiers. The amplifier with its self- contained
it for use in recording applications. For this use, it pre-
constructed on a plug -in chassis for shelf
mounting and is therefore readily removable for inspection and service. All controls, tubes, and plug -in capacitors
vents over -cutting of the recording disc on heavy passages
are accessible from the front.
power supply
The limiting characteristics of the BA -6A also readily adapt
of music or speech and permits a marked improvement in
the signal to noise ratio. Thus, the BA -6A Limiting Ampli-
fier
is
an essential item for the successful operation of
every broadcasting station and recording studio.
is
A rotary selector switch permits use of the four -inch illuminated meter for measuring gain reduction, the cathode
current of all amplifier tubes, tube balance and d -c filament voltage. Plate and heater power are available for
The BA -6A is a balanced, three -stage amplifier which uses
operating a pre -amplifier in applications where additional
gain is required. The rotary switch (BAL -LIM) provided on
the front panel also permits selection of a filter with either
commonly available tube types that do not require special
a single or dual time constant. In the
selection or matching. The use of high -quality components
attack time
and the straightforwardness of design, employing only 9
recovery time
tubes including rectifier and voltage regulator, insure a
peaks.
DESCRIPTION
58
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is
"single" position the
0.0006 seconds. In the "dual" position the
is
lengthened to two seconds on sustained
AMPLIFIERS
The input transformer matches a 600 and 150 -ohm line.
A dual attenuator controls the input signal which is applied
to the control grids of two 6SK7 remote cut -off pentodes
of the variable gain stage. To minimize "thump" over a
wide range of gain reduction, both the screen and cathode
voltages of these tubes are adjustable and thus any pair
of tubes may be balanced over the entire operating range.
Switches on the front panel permit making the balancing
adjustments quickly and without external equipment by
applying an internal 60 -cycle signal to the 6SK7 grids and
using the front -panel meter to indicate balance.
As an additional means of maintaining balance, the first
transformer coupled to the second stage. The output stage is capable of delivering 10 watts to an adjustable 600 -ohm output attenuator pad which is calibrated
in
db steps. A continuous fine output adjustment is also
provided to set the output level exactly. This is an important feature since a fraction of a db change in output level
might result in a large increase of distortion in certain
types of transmitting equipment. A full wave rectifier, connected to the output stage through coupling capacitors
and isolating resistors, provides the gain control voltage.
stage
is
SPECIFICATIONS
Source Impedance
600/150 ohms
Input Impedance
600/150 ohms, balanced or unbalanced
Frequency Response:
(30 to 15,000 cps, 1000 cps reference)
Below verge of limiting
Up to 20 db gain reduction
+1 to
Input Level:
Minimum (at limiting verge)
Maximum
±1 db at
1
Step -by -step input and output volume controls are provided. These controls are equipped with "dbm" scales to
indicate input and output levels at the verge of compression. Auxiliary adjustable controls are: (1) hum balance,
(2) zero adjustment of gain reduction meter scale, (3) vernier control for output level, (4) balance, and (5) heater
voltage. It also provides two positions for balancing of
tubes in the first stage. A power switch and fuse are provided. For rack mounting the Ml -11599 Shelf should be
used. A special umber gray door panel with meter cut -out
is supplied with the BA -6A amplifier.
N
FISED GAIN
VARIABLE GAIN
INPUT
AMP
VIREO GAIN
AMP
VI V
INPUT
6V6
6SR
OUTPUT
ISOLATING
RESISTORS
OF
dbm
+1 db
1000 cps, 600 -ohm source
to 600 -ohm load
Gain Controls:
Input....
20 steps, 2 db per step
Output
20 steps,
1
db per step and fine adjustment
Signal -to -Noise Ratio
83 db at verge of limiting
Harmonic Distortion (Total RMS) 12 db gain
reduction (100-15,000 cycles)
No gain reduction, 30 dbm output
Limiting Characteristic:
Output at verge of limiting
than 1%
Less
Less
29.5 dbm
than 0.6% 50- 15,000 cps
Less than 1.2% 30 cps
±0.5
dbm, output control
in maximum gain position
Compression ratio above verge of limiting
20 db into 2 db
Time Constants:
Attack
Single
Dual, Fast Action
Release
600 microsec.
0.33 sec.
0.33 sec.
600 microsec.
0.9 sec.
_
Dual, Slow Action
2
sec.
Tube Complement (not included with amplifier):
2 -6SK7,
2 -6J7,
2- 6V6 -GT,
-6H6, 1- 0D3 /VR150,
1
1
-5R4GY
105 watts
Chassis
.163(6' long, 113/4" wide, 3" high
Overall
1636' long, 14" wide, 7%" higi
Weight
6H6
37 lbs.
Finish
RECTIFIER
VT
dbm
Dimensions:
OUTPUT
CONTROL
V
VF
-24
29.5 dbm
Power Required (Transformer taps provided for
105, 115, and 125 v.) (100 to 130 v., 50-60 cy.)
CONTROL
db
38.5 dbm
At verge of limiting with output controls in
minimum attenuation position
54 db
db
-2
+14
Output Level:
Maximum (limiting off) at 1000 cps
Gain
±1
Dark umber gray
DIAS
VOLTAGE
SINGLE
SI
Mounting
DUAL
SAL -LIMIT
SWITCH
C
R ST
DS MEG
Stock Identification (includes tubes).
RII
3
INFO
ES -11126
IMEO
1C IS
ITT UFO
SLOW FILTER
Plug -in mounting on Ml -11599 Shelf
Accessories
FAST TILT EP
Simplified block diagram of BA -6A Limiting Amplifier.
Tube Kit (complete tube complement)
MI -11289
Shelf
MI-11599
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AMPLIFIERS
BN -6B TRANSISTOR PORTABLE REMOTE AMPLIFIER
FEATURES
Completely transistorized
Full 8 VU output to line
High level mixing on all four channels
Self- contained AC and battery power supplies -front panel selection of power
Lightweight -weighs only 15 pounds
Amplified cue signal from studio
Convenient and durable carrying case
All controls are located on the front panel including an
illuminated VU meter, four mixer controls, the master
USES
The BN -6B Transistor Portable Remote Amplifier is an ex-
control, phone jack, cue switch, and power switch. For
tremely lightweight, four channel amplifier designed especially for remote broadcast use. It affords amplification
ease of servicing, the top cover may be detached and
and control facilities for broadcast programs remote from
posing all components. Mercury cell batteries are self -
the studio, amplifying low level signals to a level suitable
contained in a convenient battery storage chamber located
for transmission over
a telephone line to the studio. Four
the amplifier chassis withdrawn from the case thereby ex-
beneath the amplifier chassis. A rear cut-out in the case
separate input channels are provided that can be operated
either single ended or balanced. Complete cuing and
monitoring facilities are included. The equipment uses
transistors and germanium diodes throughout, and
is
BN -6B Remote
com-
pletely self- contained for a -c or battery operation.
DESCRIPTION
The RCA Type BN -6B Transistor Portable Remote Amplifier
is
a single,
functionally styled unit in which an etched
wiring board including all amplifier components and transistors, controls, batteries and alternate a -c power supply
are all contained in a portable carrying case. The steel
case, finished in umber gray, is ruggedly constructed and
provided with a convenient leather handle. The top cover
can be removed easily for quick sat -up of the equipment.
Special hinges permit the lid to be detached, reversed,
and used as a special tilt -rest for the amplifier case in
applications where inclined
panel
is
positioning
of the control
desired.
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Amplifier in metal carrying
case.
AMPLIFIERS
power supply consists of a full wave rectifier circuit using
germanium diodes and an r -c filter.
provides easy accessibility to the a -c power connector,
fuse holder, microphone connectors and the output con-
nections. Clips are provided in the cover of the carrying
case for securing the 8 -foot a -c power cord when not in use.
SPECIFICATIONS
Type XL
Input Connector
__
Input _ .. 4 microphones (all may be used simultaneously) 150/30 ohms
Output (balanced output 600 300 150 ohms)
-f -18 dbm
(5 db isolation provided)
87 db (150 ohm source on 153 ohm input to 630 ohm load)
Gain
Electrically, the BN -6B Amplifier has four separate input
channels that can be operated either single ended or
balanced. Balanced operation is achieved by means of
accessory plug -in transformers. Type 2N175 Low Noise
NPN and PNP transistors are used in the push -pull output
Harmonic Distortion ( +18 dbm output mixer and
Less than 1.5% 30 -50 cps;
master controls set for 65 db gain) _
less than 1% 50- 10,000 cps; less than 2% 10,000- 15,000 cps
need for a phase inverted
stage thus eliminating the
-4-1.5 db from 30 -50 cps; ±1 db from
50- 10,000 cps; and ±2.5 db 10- 000 -15,000 cps
Frequency Response.
Transistors are used in all the input stages. Complementary
driving source. An isolation pad precedes the output transformer to provide isolation from the line.
3 -inch VU
Meters
Transistor Complement:
is
Dimensions
1
...
15 lbs.
Weight
MI- 11221
Stock Identification (includes transistors)
is
Input Transformer (30 150 ohms)
MI -11776
Transistor Kit and Diode (for BN -6B)
MI -11777
Step Type Attenuator for BN -6B Master Controls
MI- 11751 -3
Step Type Attenuator for BN -6B Fader Controls
MI. 11751 -4
SO DB
PAD
r
--1
MIXERS
20 -2 OB
STEPS
PLUG
IN
LINE
MONITOR
PREAMPLIFIERS
MIXERS
20 -2 DB
PLuG
PRE -
STEPS
BOOSTER
AMPLIFIER
DRIVER
SOB
ISOLATr,
MASTER
20-2 DB
PAD
STEPS
[.._)_F
MIXERS
PLUG
10-2
IN
DB
STEPS
NPN
MIXERS
20 -2DB
STEPS
1N91
IIS
V A C
POWER
PLUG
POWER
FILTER
TRANSE
POWER SWITCH
IN9
TO
AMPLIFIER
S-6V
MERCURY
BATTERIES
IN SERIES
POWER
SUPPLY
METER
LIGHT
BATTERY
I
S
-B
Accessories
Block Diagram of BN -68 Transistor Portable Remote Amplifier
INPUT
TRANSFORMERS
(approx.)
Two tone umber gray
Finish
independent, whether balanced or unbalanced operation is used. The VU meter is used both for
monitoring the output level and for battery test. Light
weight and long -life mercury batteries are used as a battery power supply for the BN -6B. A separa-e flash -light
type battery is provided for VU meter illumination. The a -c
This cuing
dbm
illuminated
-2N214
3- -2N109
91 2" high, 181/2" wide, 43,'a" deep
5-2N175
mounted on the control panel for monitoring along with a separate cue switch which provides for
amplification of the cue signal received from the studio.
A phone jack
-122
Noise Level Referred to Input
o
VOLT
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OUTPUT
TRANSF
AMPLIFIERS
SA-10C 10 -WATT AMPLIFIER
FEATURES
Excellent frequency response
Noiseless mixing between channels
High -gain low -noise circuitry
High impedance inputs
Microphone input easily converted to low
impedance
Compact, rugged, light weight construction
DESCRIPTION
The
SPECIFICATIONS
Type
SA -10C Amplifier has been designed for
application in sound systems where a low audio power
output is required. It has its own built -in power supply for
furnishing a -c and d -c power for the audio tubes.
The
RCA SA -10C is a
10 -watt amplifier
especially designed to give constant performance and reliability with
a wide frequency response at low distortion. The front
escutcheon is a reversed etched plate which assures permanent control markings for ease of operation. The bottom
cover extends slightly beyond the ends of the chassis. This
projection protects the microphone and phonograph receptacles and provides a convenient means of securely
mounting the amplifier on a shelf.
High quality microphone receptacle and phonograph jack
are provided on the end of the chassis. Auxiliary a -c outlet and screw terminals for audio output connections
together with a fuse and the a -c cord are located on the
rear of the chassis. A volume control is provided for microphone input and a master control is supplied between the
first and second stage. A treble control is provided. The
output taps are 4, 8, 16 and 500 ohms (70 volts). The
70 volt or 500 ohm tap is balanced or unbalanced to
ground as desired.
Power Required
.....117 volts
Power Output
Input Impedances:
Microphone
250,000 ohms (minimum) at 1000 cps
330,000 ohms (minimum)
Phonograph_
Output Impedances
a -c, 60 cps, 70 watts
10 watts at 100 to 5000 cps
4, 8,
_
16/500 ohms (70 volts`
Gain:
Microphone Input
Phonograph Input
102 db
87 db
±2
Frequency Response
Distortion
Less
+2
±2
db
db
db, 50 to 15,000 cps
thon 5.0% te 5000 cps and 10 watts output
Signal to Noise Ratio
53 db
Tube Complement (furnished with the unit):
1- 5Y3 -GT
2- 6V6 -GT
1- 651.7 -GT
Fuse
1
(furnished with the unit)
Dimensions (overall)
-6SJ7
Type 3AG,
Length 13 ", Depth
Weight, Unpacked
83 ",
1
ampere
Height 63/a"
111/2
lbs.
Chassis and Bottom Cover Finish __
Dull black lacquer
Stock Identification (includes tubes)
MI -12161
The amplifier is designed for either low or high impedance
'nputs. Should it be desired for low impedance, plug -in
nsformers are available for either a 50 ohm input or a
ohm input. (150 to 300 ohms.)
Accessories
Plug -in 200 Ohm Input Transformer
MI-12399
Plug -in 50 Ohm Input Transformer
MI -12398
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AMPLIFIERS
SA-15B 15 -WATT SOUND AMPLIFIER
for paralleling two similar amplifiers to double the number
of mixing inputs and power output. This connection
useful as either an auxiliary input or output.
also
is
for either low or high impedance
inputs. Should it be desired for low impedance, plug -in
transformers are available for either 50 ohm input or
200 ohm input.
The amplifier is designed
SPECIFICATIONS
117 volts a-c, 60 cps, 130 watts
Power Required
Power Output
15
Input Impedances:
Microphone
Phonograph
watts at 100 to 10,000 cps
250,000 ohms (minimum) at 1000 cps
200,000 ohms (minimum)
4, 8, 16, 333 ohms
Output Impedances
Gain:
Microphone
Phonograph
DESCRIPTION
Modern styling, simple operation and top performance
characterize this new 15 watt amplifier. The Type SA -15B
offers high quality, dependable reproduction of sound
from microphones and turntable or tape pickup. It is
110 db
77 db
20 to 20,000 cps (see curve)
Frequency Response
Distortion
than 2% at 400
5% at 100 to 10,000
Less
less than
Signal to Noise Ratio:
Microphone
Phonograph
55 db
.
especially suitable for diversified sound applications such
as music, paging, and speech reproduction.
The RCA SA -15B is a
15 watt amplifier especially de-
signed to give constant performance and reliability. The
perforated heavy steel cover is finished with a dark blue
vinyl plastic. The front escutcheon is a reversed etched
plate which assures permanent control markings for ease
of operation. The bottom and top covers extend slightly
beyond the ends of the chassis. The bottom projection
protects the microphone receptacles and provides a convenient means of securely mounting the amplifier on a
shelf. The cover overhang provides a sturdy hand grip
for ease of carrying the amplifier.
cps;
cps
75 db
_
Tube Complement:
1
2
-7025
-616 -G
Fuse
1
1- 6SL7 -GT
-6AU6
1- 5Y3 -GT
Type 3AG, 1.5 amperes
(furnished with the Unit)
Width 17 ", Height
Dimensions (overall)
81/4
", Depth 11"
301/2 lbs.
Weight, Unpacked
Dark blue vinyl plastic cover
Finish
Stock Identification (includes tubes):
With Cover ._ _
Less Cover
MI- 12156 -A
MI. 12156 -B
Accessories
Input Transformer, Plug -in 150 250 ohms
MI-12399
Two high quality microphone receptacles and one phono-
Input Transformer, Plug -in 30 50 ohms
MI-12398
graph jack are provided on the end of the chassis. One
auxiliary a -c outlet, two polarized speaker outlets and a
screw type terminal board for audio output connections
are located on the rear of the chassis. Electrically, the
circuits provide for mixing the microphone and phonograph inputs ahead of the tone controls. A volume control
is provided for each input. Separate bass and treble attenuation controls are provided. The output taps are 4, 8, 16
and 333 ohms. The 333 ohm tap is a standard 70 volt tap
balanced or unbalanced to ground. A pin jack connection to the phase inverter input is on the rear of the chassis
Remote Volume Control
MI-14831
Kit
MI-12766
Amplifier Carrying Case with Two Speakers
i
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www.americanradiohistory.com
I11111111111111
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500
,000
1000
5000
FREQUENCY /N CYCLES PER SECOND
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AMPLIFIERS
a
Reduced -Size Accessories
Amplifier Accessories such as the Type BR -22A
Mounting Shelf, Type BX-21A Power Supply, and other
accessories used with the printed circuit amplifiers have
been "miniaturized" to reduce rack and mounting shelf
costs. Other improvements include better performance,
greater uniformity and easier serviceability.
RCA
BR -22A Mounting Shelf is only 51/4 inches high, 121/2
inches deep and fits any standard 19 -inch rack. The new
line of amplifiers and power supplies are installed on the
The
Type
Mounting Shelf showing female plug connectors and
guide tracks for mounting RCA plug -in amplifiers.
BR -22A
shelf by means of a guide assembly which is furnished
with each plug -in unit. The shelf can accommodate the following equipment: Ten Type BA-21A Preamplifiers; or
three BA -23A Program Amplifiers and one BA-21A; or two
BA -24A Monitoring Amplifiers; or two BX -21A Power Supplies and two BA- 21A's.
Summary of RCA Broadcast Amplifier Characteristics
.
nr
Usage
Preamplifier
BA -21A
BA -23A
Isolation Amp.
with MI- 11278 -E
or F Bridging
Gain Control
Program Amp.
Line Amp.
Isolation Amp.
Monitor Amp.
Max.
Gain
db
Max.
Input
dbm*
Matching
Matching
or Recording
BA.26A
BA -6A
BN -6B
AGC Program
Amplifier
SA -15B
Public
Address Amp.
Monitoring Amp.
Public Address
Amp.; Monitoring
Amplifier
* Reference level
one milliwatt.
Chassis
Bridging
4
+40
+18
10,000
150/600
Chassis
or
Rack
Matching
Matching
+30
150/600
150/600
Chassis
or
68
-10
Bridging
Bridging
25
27
104
-30
or
Rack
Rack
+40
dbm
10 watts
37.5/150/600
4/8/16/150/600
Chassis
or
Rack
70
-25
_
54
+30
-20
dbm
Minimum
at Verge
of Limiting
+30
-40
+18
150/600
150/600
Chassis
-
150/600
Turntable
Cabinet
150/600
600
90
Microphone
102
Phono
87
Microphone
110,
Phono
77
Microphone
0.01 volt
Phono
Phono
0.2 volt
or
Rack
+40
dbm
10 watts
30/150
150/600
Microphones'
85,000
4/8/16/500
Phono
Portable
Case
Chassis
250,000
0.15 volt
Microphone
0.0045 volt
or Rack
Chassis
-24
Amplifier
SA-10C
150/600
a
Type
Moun e g
Bridging
table Preamplifier
Remote Portable
Ohms
+18
Equalized Turn-
Limiting
Amplifier
37.5/150/600
Load
Impedance in
-10
Amplifier
BA -25A
Source
Impedance
Ohms
40
Monitoring
BA -24A
Max.
Output
dbm*
Mike
41.7 dbm
15 watts
50 or 250.
Phone
4
'8 '16 333
Chassis
470,000
t May
be converted to low impedance by using transforme
www.americanradiohistory.com
MI- 12399.
AMPLIFIERS
AMPLIFIER ACCESSORIES
TYPE BX -21A PREAMPLIFIER POWER SUPPLY
FEATURES
Regulated d -c output voltage
Exceptionally low hum level
Plugs into BR -22A Mounting Shelf
Supplies up to 10 BA-21A Preamplifiers
Heater supply hum balancing potentiometer
SPECIFICATIONS
USES
The Type BX -21A Preamplifier Power Supply is designed
_ Plug -in on BR -22A Mounting Shelf. Requires 2/5 of the
shelf space. Two BX -21A Power Supply units may be mounted on
one shelf with additional space for two BA -21A Preamplifiers, or
BX -21A Power Supply and 6 BA -21A Preamplifiers may be
mounted on one shelf.
Mounting__.
to provide d -c plate and a -c heater power for preamplifiers in which the hum level must be kept to a minimum.
for use as a power supply fopreamplifiers and isolation amplifiers such as the BA -21A.
It is intended especially
1
100 to 130 volts, 50 -60 cycles, 130 watts
Power Required
Fuse
...
._...._._
_
....
2
ampere, type MDL
Power Output:
DESCRIPTION
The BX -21A
is
285 volts, up to 100 ma
6.3 volts, up to 6 amperes
D -c
A -c
designed for operation on any a -c line
voltage between 100 and 130 volts, 50 to 60 cycles. A
two ampere, glass -enclosed, time -delay fuse is mounted
on the front of the chassis. This fuse is unaffected by high
transient currents.
The power supply consists of a full wave, high vacuum
tube rectifier followed by resistance capacitance filtering.
The output voltage is adjustable over a range of 245 to
295 volts and is maintained constant with variations in line
voltage and loading by a series regulator tube in conjunction with a voltage reference and amplifier. This circuit
also functions to reduce the ripple voltage. A metering
voltage of volt corresponding to nominal output voltage
of 285 volts is available at connector plug for wiring to a
meter panel.
_.0.3 my maximum
Ripple Voltage_..
Tube Complement:
1- 5R4GY,
1- 68X7 -0T,
1
-12AX7,
1
--0A2
Dimensions and Weight:
Length
121/2"
Width
Height
Weight
611Ç6"
4
16
lbs.
Light umber gray
Finish
Regulation
21/32"
0.5% no load to full load and line voltage
variation of 5%
Stock Identification (includes tubes)
ES -11111
Accessories
Tube Kit (complete tube complement)
MI-11479
Panel and Shelf, Type BR -22A,
Umber Gray (for 2 Power Supplies)
MI -11597
1
Type BI -1B Meter Panel (for 17 amplifiers or power supplies).. -.MI -11388
www.americanradiohistory.com
AMPLIFIERS
BR -22A
MOUNTING
SHELF
FEATURES
High quality panel mounting for
chassis type units
Quick access to amplifiers and power
supplies
Easy insertion and removal
of units
Hinged front panel
Conveniently installed from front of
rack
USES
The BR -22A Mounting Shelf is capable of mounting the
following quantities of specific equipments:
A white paper designation strip which is protected by a
transparent cellulose acetate strip on the inside bottom
flange of the front panel is provided for marking the type
number and function of the plug -in unit.
10 BA -21A Preamplifiers
Program Amplifiers I 1 BA -21A
2 BX -21A Power Supplies -} 2 BA -21A
2 BA -24A Monitor Amplifiers
2 BA -25A AGC Program Amplifiers
3 BA -23A
The front panel is perforated to provide additional ven-
tilation.
In installations where exposure of the amplifier
controls is desired, the front panel may be disassembled
from the shelf by removing two screws.
The amplifiers and power supplies are installed on the
mounting shelf by means of guide strips and connector
DESCRIPTION
This shelf will mount in the
BR -84 series of racks, or in any
inch rack. It occupies 5'4 inches of rack space.
Since the RCA plug -in amplifiers have a standard dimension in depth, they all fit perfectly in this shelf. They are
slipped into the shelf from the front. The receptacles fit in
19
receptacles which are included with each amplifier and
power supply. The receptacles are assembled to the guide
strip which is then attached to the mounting shelf.
such a manner
that a small amount of free movement is
permitted in all directions. This eases the alignment of the
plugs and receptacles when the amplifiers are pushed into
position. The wiring in back of the receptacles is protected
by a cover which is fastened in place by two machine
Dimensions, Overall:
19"
Width
Height
5
is covered by a hinged
panel, which may be opened to gain access to the amplifiers and any amplifier controls. The bottom of the shelf
has ventilation holes.
Inside Width
Weight, Unpacked
Finish, Front
Stock
Identification
www.americanradiohistory.com
7/32"
121h"
Depth
screws.
The opening in the front of the shelf
SPECIFICATIONS
171
._
B"
10 lbs.
Two tone umber gray
MI -11597
AMPLIFIERS
BR -2A PANEL
AND SHELF
FEATURES
High quality panel mounting for chassis
type units
Quick access to tubes
Easy
insertion and removal of units
Provision for control shafts on front
panel
Conveniently installed from front of rack
DESCRIPTION
The
BR -2A
Shelf
is
designed to mount the BA -6A Limiting
Amplifier, while the panel and shelf can be used to
mount the Relay Power Supply, MI- 11316. This shelf will
mount in either the BR -19A or the BR -84 series of racks,
or in any other standard 19 -inch rack. It occupies 83/4 inches
of panel space. Since the RCA plug -in amplifiers have
a standard dimension in depth, they all fit perfectly in this
shelf. They are slid into the shelf from the front and the
connection plugs pushed into the receptacles at the rear.
Guide bars fitting between the amplifiers assist in guiding
them into position. All the plug -in amplifiers are equipped
with levers which serve either to force them into position or
to eject the plugs when dismounting them. The receptacles
are mounted on individual U- shaped brackets, secured to
the chassis of the shelf. They fit in such a manner that a
small amount of free movement is permitted in all directions. This eases the alignment of the plugs and receptacles
when the amplifiers are pushed into position. The brackets
are constructed with a small protruding stop on the lower
front edge, preventing the amplifier from being forced to
the point where it would exert undue pressure on the receptacle. Provision is made for holding six of these receptacles. The holes in the chassis which are provided for
fastening the brackets are slightly oversize to permit perfect alignment during initial installation. The wiring in back
of the receptacles is protected by a steel cover which is
fastened in place by two machine screws.
The opening in the front of the shelf is covered by a matching panel. This panel is hinged across the center so that
the top half may be opened to gain access to the vacuum
tubes of the amplifiers. The bottom half has five shaft
holes to provide for any controls which the amplifiers may
have. When not in use, these holes are covered by small
removable buttons. The bottom of the shelf has several
round holes for ventilation and also a number of square
holes into which fit the amplifier insertion levers.
The shelf may be obtained separately, if desired, or the
shelf and panel together, as appropriate. It is supplied
Panel removed showing guide bars and receptacles.
complete with mounting brackets, guide bars, and receptacle cover. The receptacles themselves are supplied with
the amplifiers, and therefore need not accompany the shelf.
SPECIFICATIONS
Dimensions, overall:
Width
Height
Depth
._
19"
83a"
..
....
Inside Width
Weight, unpacked:
Shelf
Panel
123/4"
167/e"
12
3
lbs.
lbs.
Stock Identification:
Shelf (Umber Gray)
Panel (Umber Gray)
www.americanradiohistory.com
MI -11599
MI- 11598 -B
AMPLIFIERS
BE-21B VARIABLE SOUND EFFECTS FILTER
filter for the desired characteristics and insert it in the
circuit instantly when required.
filter
The 600 ohm input and output impedances of the
enables it to be connected in any 600 ohm circuit or it
may be used in a 250 ohm circuit with only a slight change
in response characteristics.
SPECIFICATIONS
Source Impedance (unbalanced
600 ohms
Load Impedance
600 ohms
Inout Level
-60 to 4 -23 db'
Output Level (maximum)
+23 db'
Frequency Response
See curves
Insertion Loss
1
db or less at frequencies remote from cut -off
Dimensions, overall
Height
51/4"
DESCRIPTION
furnishes a desirable means for producing a
variety of special or unusual sound effects through control
of the audio bandwidth of the transmitted program. It is
especially useful in the production of dramatic plays for
making programs sound "bossy" or "tinny" or for simulating the sound of telephone conversations, short wave radio
communications or midget radios.
The BE -21 B consists of high and low pass filters assembled
on a panel with two selector panel switches. The switches
have nine positions each and are calibrated for high and
low cut -off frequencies of 100, 250, 500, 1000, 2000, 3000,
4000, and 5000 cycles. There is also an "off" position on
each switch. A key switch is provided for removing the
filter from the circuit thus making it possible to preset the
The BE -21
Width
19"
Depth
B
I,. rr\ ,
Weight (unpacked)
Finish ........
Stock Identification
4
-e
12
le
S
20
- 24
2e
32
Ir
1rI..IÌ`
mmoa
III
i
"
,
1l'
-
-i
\`
11.41111111P
3e
30
NII
ea)Aío
,,,G,,,...."
100
lbs.
Light umber gray
MI -11723
_
o
5"
15
Illl
F
CUTCUT-OFF
1000
FREQUENCY IN CYCLES PER SECOND
20000
10000
BI -1B METER PANEL
DESCRIPTION
The BI-1B Meter Panel provides a convenient means for
checking the cathode bias voltages of amplifier tubes and
thereby furnishes an indication of the operating conditions of amplifier tubes and circuits. Metering terminals
are provided on the miniature series of amplifiers for use
with this panel. The mounting is for a BR -84 Series Standard cabinet rack.
essentially of a meter and switch
mounted on a standard 31/2", 3f6" thick steel panel. The
meter is a 3.0 volt d -c voltmeter having a resistance of
20,000 ohms per volt. The double section switch has
The
BI-1B consists
eighteen positions including the "off" position with the
switch arms connected to the meter terminals. All connections to the panel are made to the switch contacts.
SPECIFICATIONS
Voltmeter
Metering Switch
Dimensions (overall):
Height
Width
20,000 ohm per volt
position and "off," double pole
0 -3.0 volts,
D -c
17
3
15/32"
19"
21/4"
Depth
Weight (unpacked)
Finish
Stock Identification
www.americanradiohistory.com
41/2
lbs.
Light umber gray
MI -11388
AMPLIFIERS
BE -2A
LINE EQUALIZER
FEATURES
Provides line equalization to 15,000 cycles
Equalization variable in steps of
db
3
Small case mounts almost anywhere
Parallel resonant circuits
Convenient rotary selector switch for
selecting different resistance values
adjustment of the equalizer consists of an audio- frequency
oscillator such as the RCA Type WA -28A for use at the
remote point, and a volume -indicator meter such as the
WM-71A for use at the receiving point.
USES
The RCA Type BE -2A Line Equalizer is designed to equalize
the non -linear frequency characteristics of a non -loaded
telephone line. It is suitable for 15,000 cycle FM circuits.
The small, low -cost unit is recommended for use on lines
which are permanently installed and continuously used
such as studio -to-transmitter lines and remote lines.
SPECIFICATIONS
150 or 600 ohms
Source Impedance
Equalization Frequency limit
15,000 cycles
7 db
Insertion Loss (minimum at 1000 cycles)
Equalization Range (see attenuation characteristic curve)
1
Mounting
DESCRIPTION
and a rotary selector switch for selecting different resistance values. The resonant frequency of this circuit is just
above the operating frequencies of associated equipment,
so that the frequency characteristics of the equalizer below resonance are of interest. Examination of these characteristics (shown in the chart) reveals that the more resistance in series with inductor, the less the low- frequency
attenuation of the equalizer. Any of the amounts of
equalization shown by the frequency characteristics chart
may be obtained by rotating the ten position selector
switch to the proper dial setting, thereby inserting the
Weight
Cadmium plate
MI -11752
Stock Identification
Accessories
Mounting Panel 31/2"
x
MI-4591-B
19"
MI-11713
Line Transformer
Frequency characteristic of Type
'
6
BE -2A Line
Equalizer.
nssni
2 MN
so
097
housed in a cadmium plated metal
on a flat surface. It is espemounting
for
case adaptable
on a 3 '/2" x 19" panel
for
mounting
recommended
cially
for standard rack mounting. The equipment necessary for
The equalizer circuit
lbs.
11/2
Finish
desired resistance in the circuit. Varying amounts of
equalization may be obtained in steps of approximately
3 db. The BE -2A does not include line transformers or
master attenuators which should be ordered separately
where required.
3%" deep
21/2" wide, 21/2" high,
Dimensions
The BE -2A Line Equalizer employs parallel resonant circuits
and consists of a capacitor, a reactor, a series of resistors,
to 40 db
Single hole
600.1
NE
is
www.americanradiohistory.com
._
500
100
FREOUENCV
>s
1000
CYCLES PER SECOND
1
5000
!
L'11
I'>ODU
N000
4u111.0
AMPLIFIERS
LINE AND BRIDGING TRANSFORMERS
DESCRIPTION
RCA transformers are of the highest quality de-
sign having excellent frequency
are provided with electrostatic
response. They
shields between
primary and secondary and are furnished with
heavily shielded cases. Cores are steel of high
permeability. Terminals are located at one end,
and diagrams of the connections are stenciled
on the
side of
the case.
Broadcasting stations
may employ the RCA transformers between units
with assurance that the overall fidelity of the system will be maintained.
LINE TRANSFORMER, MI -11713
BRIDGING TRANSFORMER, MI -11712
The core structure, frequency characteristics and shielding
This transformer may be used as an input transformer for
of this transformer makes it an ideal unit for isolating line
a
circuits. Its taps provide several combinations of available
impedances.
bridging line amplifier or
a
monitoring amplifier. It may
also be satisfactorily used where it
is
desired to bridge a
program line to feed programs to other mixing or outgoing
circuits such as normally employed in a master control
room line distribution system.
Specifications (MI- 11713)
Frequency Response
Stock
Specifications (MI- 11712)
'
'?
db 20 to 20,000 cps
Primary Impedances
Secondary Impedances
Ohms
Frequency Response
+Lz
Impedances
Ohms
Ohms
150
150
20,000
600
600
db 20 to 20,000 cps.
Secondary Impedances
Ohms
150
600
Identification
MI -11713
Stock
Identification
MI -11712
GENERAL SPECIFICATIONS for MI -11713 and MI -11712
Dimensions, overall:
Transformer
Baseplate
Mounting
4"
x
2
11
32"
x
31/4" x
17é"
3
á"
Wight
Finish
www.americanradiohistory.com
.
Four holes with center lines 23,4" x 23/4"
2
lbs.
14 ozs.
Aluminum gray
AMPLIFIERS
PADS AND NETWORKS
DESCRIPTION
RCA offers a comprehensive selection of attenuator pads,
bridging pads and dividing networks. The pads and net-
works are well constructed and insulated with precision
wound resistors, assuring no internal reflection. The terminals are accessible and securely mounted with the connections stenciled in an appropriate place. The fixed balanced "H" type is available in four types, introducing
losses of 6 db, 10 db, 20 db or 40 db. The dividing networks are available as tabulated below.
Fixed Pads -Balanced "H" Type
Input Impedance
600 ohms
Output Impedance
.600 ohms
Insertion
6, 10, 20 or 40 db
Loss
Stock Identification,
MI-4171-29
MI-4171-30
MI-4171-32
MI-4171.39
6 db Pad
10 db Pad
20 db Pad
40 db Pad
MI-11704-A
Dividing Networks
Balanced Two -way, 600 ohms
MI-11705
Insertion
Loss
6
_
db
MI -11704
Stock Identification
Balanced Three -way, 600 ohms
Stock Identification
..9.5 db
._-
Insertion Loss
.
MI- 11704 -A
.._
Balanced Four -way, 600 ohms
12
Insertion Loss
Stock Identification
_
db
MI- 11704 -B
Balanced Six -way, 600 ohms
Insertion
Loss
Stock Identification
.
15.6 db
MI 11704-D
Bridge Pad (Balanced)
MI-4171-29
600 ohms to two 600 ohm
Input Impedance
lines- isolation between lines about 45 db
to-
Insertion Loss
Stock Identification
6
1440
www.americanradiohistory.com
10 db
MI-11705
AMPLIFIERS
BRIDGING CONTROLS
DESCRIPTION
The MI- 11278 -E and
-F
Bridging Volume Controls
are
designed to provide a high resistance bridging input cir-
cuit for connections between any low impedance source
and the 150/600 ohm input terminals of an amplifier. The
use
of one of these units makes it possible to pick up
MI-11278-F
MI-11278-E
program material conveniently from a program buss or
SPECIFICATIONS
any low impedance terminated line without disturbing the
operation characteristics of the buss or the line. Any line
of
-f -40
dbm or below may be bridged. The MI- 11278 -F
Volume Control
is
designed to be mounted on the chassis
Input Impedances._
Output Impedances
Insertion Loss*
Maximum Input Level
Overall Dimensions:
is
notched for screwdriver adjust-
ment. The MI- 11278 -E Volume Controls are designed for
rear panel mounting on the same type amplifiers. They
are supplied with dial knobs which mount on shafts extending through the panel.
600 /150 ohms
31/24 db
-} 40 dbm
Length:
MI -1 1278 -E
MI- 11278-F
Diameter
of such amplifiers as the BA -21A and BA -24A. The center
shaft of this control
20,000/10,030 ohms
216"
23fá
13/e"
Weight
Stock Identification:
For Panel Mounting (with knob)
For Chassis Mounting (with screw- driver adjustments)
*
41/2
ozs.
MI- 11278 -E
MI- 11278 -F
Bridging a 600 -ohm line and operating into an amolifier with unloaded input requiring a source impedance equal to the output impedance of the control. The insertion loss when bridging a 150 ohm line
is
42.5/36 db.
VU METER AND ATTENUATORS
DESCRIPTION
VU meters and
attenuators are available as amplifier
accessory equipment for indicating audio volume levels.
Equipment is pictured at the left and may be ordered
as follows:
Simpson VU Meter
Stock #53064
Multiple Pad for calibrating the VU Meter
to the desired reference level
Zero Adjustment Pad
The complete kit is pictured at the left.
www.americanradiohistory.com
Stock =19328
Stock #19327
III
RACK EQUIPMENT
RACKS
STANDARD
BR-84C
BR-84B
BR -84 A
FEATURES
Cabinets are same height as RCA transmitters-84"
Attractively styled to blend with all control
Total panel space 77"
Suitable for fitting in
side or rear wall
Available in many combinations to suit all
studio applications
Accommodates the heaviest equipment encountered in studio use
Drilled and tapped for standard
i
9" panels
room installations
series cabinet rack program
a
DESCRIPTION
another of the
new feature lines of RCA. The cabinet program is presented after years of practical experience in finally developing a flexible scheme for accommodating broadcast
equipment.
BR -84
flush position to
Provides flexibility for future expansion
USES
The
a
is
The five combinations of cabinets and accessories offer a
versatile system for accommodating the user's immediate
requirements with maximum accessibility for any future
growth of the installation. Each rack may be mounted
singly or, where desired, tandem together to facilitate the
www.americanradiohistory.com
RACK EQUIPMENT
SPECIFICATIONS
BLANK PANELS
MI.4590
SERIES
SIDE PANEL
MI30541 -G84
SINGLE TRIM STRIP
MI 30566-084
Panel Width
19"
Panel Mounting Space (height)
77"
Clearance for Door Swing
23"
Weight (BR -84A)
225 lbs.
Finish
Two -tone umber gray enamel except for the base which is black
Dimensions:
Width- BR -84 -A,
SHELF
MI.IIS99
ELECTRICAL SIDE
SHIELD W30546-021
TERMINAL BOARD
MOUNTING ANGLE
REI20527029
POWER STRIP
MI 4568
BR -84 -C,
59 4569
(with side panels)
-B
-D, -E
Width of Frame
Depth of Frame
Depth (including doors and handles)
Stock Identification:
Type BR -84A consisting of one frame, one base, one top
cover, one front door (non -ventilated), one rear door
(ventilates!), one pair of side panels, one set of terminal board mounting angles and one set of panel
mounting angles and instruction book
Type
BR -84B,
less
AUDIO BLOCK
84"
28"
22"
22"
Height
Type
ES-
30951 -A84
ES-
30951 -B84
same as BR -84A,
front door only
BR -84C,
18"
241/4"
same as
BR -84A,
less side panels only
BR -84D, same as BR-84A,
less side panels and front door
Type BR -84E, same as BR -84A,
less side panels,
ont and rear doors
ES- 30951
-C84
ES- 30951
-D84
Type
MOUNTING BRACKET
MI-4570A
f
ES-
30951 -E34
Accessories
BR-84D
BR -84E
with Accessories
grouping of any number of cabinets. The cabinet is of
sturdy metal construction, welded and bolted in one
standard height and width. The ventilated top with slotted
edges provides complete ventilation but protects the equipment from falling articles and dust. Vertical panel mounting angles have tapped holes at RMA standard locations
to provide 77" of standard 19" panel mounting space.
These angles may be installed to mount equipment within
the cabinet, where doors are used, or flush with the front.
When the latter method is desired, trim strips of neat
design for panel mounting and clip fitting provide the
finished appearance. The front and rear doors are of the
universal type and may be hinged on the right or left
side, to rotate in an arc of 180 °. Electrical side shields
are available in two sizes -21" for the center section, and
28" for the top and bottom sections. If found necessary
after assembly, they may be fitted between racks of
equipment. Terminal board mounting angles facilitate the
mounting of power and audio blocks in a vertical or
horizontal position. Additional terminal board mounting
angles (MI- 30527 -G29) are available as accessories.
MI-30530-084
Door (non -ventilated)
MI-30541-084
Side Panel
MI-30535-684
Door (ventilated)
Electrical Shield (for mid -section of rack)
MI-30546-021
One Per Side
One Electrical Shield (for top and bottom sections)
MI-30546-028
Two Per Side
MI-30566-084
*One Single Trim Strip
One Double Trim Strip Used where Two Cabinets
MI-30568-084
Are Placed Together
M -4570-A
Terminal Board Mounting Bracket
MI- 4590 to 4599 Series
Blank Panels
MI-4569
Audio Terminal Block
MI-4568
Power Terminal Strip
MI-30527-029
Set Terminal Board Mounting Angles
MI-30526-084
Set of 2 Panel Mounting Angles
MI-11598-8/11599
BR -2A Panel and Shelf Assembly
MI-11597
BR -22A Panel and Shelf Assembly
MI-11728
Ground Bus Kit
One
One
One
One
I
Trim strips not required if front doors are used.
Units placed adjacently may be rigidly bolted together to
produce a secure assembly. The cabinets are finished in a
two -tone umber gray, with dimensional characteristics
artistically blending with all RCA transmitters.
www.americanradiohistory.com
sfi
Layout and dimensions of cabinet base
RACK EQUIPMENT
CABINET RACK
TYPE BR -19A
11111111111---.
FEATURES
Lightweight cabinets designed to blend
with all control room installations
Provides flexibility for future expansion
Constructed of %b" thick cold -rolled steel
Drilled and tapped for standard 19" panels
Modern streamlined styling
USES
BR -19A
Cabinet has been designed to accommodate
broadcast equipment. The cabinets are of lightweight steel
construction and offer new cost economies. They provide
facilities for mounting standard 19" panels and shelves.
The
DESCRIPTION
The BR -19A Cabinet Rack is constructed of 'ie" thick cold -
rolled steel. It is provided with rear door only. All racks
have quick detachable, new corner trims which are
fastened to the front with two studs. This provides for
rapid, finger -tip removal without the use of screwdrivers,
etc. The cabinets are designed in keeping with modern
streamlined styling, and have adequate ventilation through
the use of rear, side, and top louvers and vents. Vertical
corner mouldings cover the panel mounting screws and
all panels fit into a recess so that the edges of panels are
not exposed when the corner mouldings are removed.
The panel mountings consist of angle irons of 7/64" thick
steel. Holes are accurately drilled and tapped 12 -24
thread on universal centers for all types of panels. The
cabinet is finished in a two -tone umber gray in
keeping with other RCA studio equipment.
BR -19A
SPECIFICATIONS
Panel Width
19"
Panel Mounting Space (height)
77"
Clear Inside Depth
Finish
Material
Overall Dimensions
Weight
Stock Identification
E1.1,02
www.americanradiohistory.com
163/4"
Dark and light umber gray wrinkle
)("
thick cold -rolled steel
831/2" x 22" x 18"
140 lbs.
MI -11550
RACK EQUIPMENT
RACK ACCESSORIES
Power Terminal Block Ml-4568 with cover removed.
Terminal Block Mounting Bracket MI- 4570 -A.
Ground Bus Kit, Ml- 11728.
BLANK PANELS
A complete line of 19" blank panels is carried in stock
for filling spaces on racks and cabinets not occupied by
equipment panels. These blanks are also suitable for
Terminal Block Mounting Bracket Ml- 4570-A
with Terminal Blocks in position.
"
applications where equalizers, transformers, switches or
other items must be panel mounted by the user. The
stock of panels includes all standard widths from 13/4" to
10 15/32 ". They are 3/16" sheet steel and are finished
and notched to match standard racks -the BJ -24 and BJ -12.
Power Terminal Block MI -4568.
40 40,
dlr.
7
e
Panel Width
17(
1
3
5
6
8
10
23/32" Blank Panel, Umber Gray
15/32"
Umber Gray
7/32"
Umber Gray
MI. 4590 -A
31/32"
23/32"
15/32"
Umber Gray
MI- 4593 -A
Umber Gray...
MI- 4594 -B
Umber Gray
MI- 4595 -B
Audio Terminal Block Ml.4569.
76
www.americanradiohistory.com
MI- 4591 -B
MI- 4592 -B
RACK EQUIPMENT
BI -5A VU METER PANEL
FEATURES
Measures audio volume levels
from 4 to 40 vu
point selector connects up
to 10 circuits
Ten
Calibration curve supplied for
loads other than 600 ohms
Large illuminated VU meter
attenuator are calibrated for use with a
600 ohm line, however, a calibration correction curve furnished with the instrument permits its use with loads other
than 600 ohms. The ten point selector switch may be connected to any ten lines (or circuits). If one or more switch
positions are connected to a jack strip, the number of circuits that may be monitored is unlimited. The meter is provided with the 6.3 volt lamp for illuminating the meter
scale.
The meter and
DESCRIPTION
-5A Meter Panel employs the industry standardized
VU Meter which embodies closely controlled electrical
and dynamic characteristics combined with deliberate
pointer action, moderate pointer speed, and small pointer
overswing. It is intended as an audio level indicator for
broadcasting, recording or wherever it is desired to read
the level of one or more audio circuits with a rack mounting type of instrument.
The
BI
indicator panel assembly includes the VU
meter, a two circuit ten point selector switch, a variable
step -by -step attenuator (4 to 40 db attenuation), and a
vernier control for making a fine adjustment of the level
reading over a range of ±0.5 db. The attenuator has a
1
milliwatt reference position which enables a level reading of zero VU.
The volume
arranged with percent volts in black
figures from "0" to "100" as the principal scale above the
arc, and "vu" levels from " -20" to "0" to "--l-3" as
supplementary figures in red below the arc.
The VU meter scale
is
SPECIFICATIONS
Input Impedance (except on
Attenuator Steps
1
milliwatt step)
milliwatt position,
1
in 2
No. of lines that may be measured
Mounting
7500 ohms
to +40 db
db steps and off position
1
to 10 inclusive
Standard Cabinet Rack
+4
Dimensions:
Height
Width
57/4"
Depth
33/4"
19"
Light umber gray
7t /s lbs.
MI- 11265-F
Finish
Weight (unpacked)
Stock Identification
57 -D SWITCH AND FUSE PANEL
DESCRIPTION
On this panel are mounted and wired an indicator lamp
with red cap, two single fuse blocks of the screw -plug
type and a double -pole single -throw power switch. A removable door permits front panel access to fuses and
pilot lamp.
SPECIFICATIONS
D.P.S.T., 250 volts, 30 amperes
Switch
Fuses
(not furnished)
Screw -plug type (rating depends upon
equipment to be protected)
Dimensions, overall (panel thickness 3(61:
Height
Width
The Type 57 -D Switch and Fuse Panel is designed
for
master
input control of the a -c power supply. Ordinarily one such panel is
used with each rack or channel of speech input units. The mounting
is for a BR -84 Series Standard cabinet rack.
use as
a
Depth
Weight (unpacked)
Stock Identification:
Light Umber Gray
www.americanradiohistory.com
5
7/32"
19"
37/2"
87/2 lbs.
MI-4395 -G
RACK EQUIPMENT
JACK PANELS, MATS AND CORDS
FEATURES
Offset ground lugs
easy to wire
-
Spacing of jack pairs
prevents cross -circuit
patching
Bakelite strip reinforced to prevent
warping or breakage
USES
S P E C I F I C
Jack Panels, with their associated patch cords, are
used with broadcast speech input systems to improve
the overall operating flexibility. In addition to pro-
viding a convenient termination for program and
order wire telephone circuits, closed- circuit jacks may
be connected to provide "patch cord" access to the
input and output circuits of individual units of the
speech assembly. When connected for this purpose,
the regular circuits are continuous through the jacks
until a patch cord is inserted to make an external
connection. With properly connected jacks, patch cords
may be freely used in emergencies or for test purposes to interchange or transfer telephone lines, amplifiers, mixers, microphones, or other equipment
A
T I
O N
S
Number of Jack Pairs
BJ -24
24
BJ -12
12
Type of Jacks
Double jacks of standard closed circuit type
Dimensions
BJ
21/8' x 19"
-24
BJ -12
P.," x 19"
Weight (unpacked)
BJ -24
51/2
Stock Identification
BJ -24 (RCA Standard)
BJ -12 (RCA Standard)
lbs.
B1
-12
3
lbs
.
MI -11645
MI -11646
Photo below shows Convenient Offset Ground lugs
items.
DESCRIPTION
The BJ -24 consists of two rows of twelve double jacks
mounted on thick black bakelite and furnished with desig-
nation card holders. The
BJ -12 is
similar to the
BJ -24
but
has only one row of twelve double jacks. The jack sleeves
of the
BJ -24
OFFSET
and B1-12 are chromium plated.
GROUND LUGS
8.1508
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RACK EQUIPMENT
JACK MATS
PATCH CORDS
Jack Mats are available for covering 1, 2, 3, or 4 type
RCA maintains a stock of patch cords for the conven-
BJ-24 Double Jack Strips.
ience of broadcasting stations. The cords are standard
telephone type using two double plugs. The MI- 4652 -B
series has black shielding and the MI- 4652 -C series has
SPECIFICATIONS
Single
BJ -24
gray shielding. Three lengths of patch cords are available
'9"
Jack Strip Mat, overall size
x 3
15/32"
as listed below:
MI- 11647 -1
Umber Gray
Double BJ -24 Jack Strip Mat, overall size
Umber Gray
19"
x 5
Black
Gray
Length
MI- 4652 -B2
MI- 4652 -C2
Four Foot Cord Length
MI- 4652 -84
MI- 4652 -C4
MI- 4652-B6
MI- 4652 -C6
7/32"
MI- 11647 -2
Two
Six
Foot Cord
Foot Cord Length
00100100100100100 100100100100:00 OG
00100100100100100100100,00 00H00 00,
Jrk+'!e+ccjrgxi.t=_.JS =k.-,_
C010010010010010010 0100100100'001001
OO10 010 010 010 010 0'OO10 010 010 010 010 0'
Shielded Type Patch Cord
MI.11647 -2 Double Jack Mat shown with two doublie jack strips
MI- 11647.2 Double Jack Mat
View of RCA
BR -84 Standard Racks as used at
Radio Station WHBO, Memphis, Tenn. RCA BJ -24
Jack Mats are used in these racks.
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RACK EQUIPMENT
SWITCH,
PANEL AND
HOUSING
DESCRIPTION
Simple and inexpensive manually- operated switching
equipment is made available by RCA in the form of
unassembled Switch Panel, MI -11754 to which may be
assembled up to nine MI- 11755 -2 lever -type, low- capacity
leaf switches, lights, or other type switches which mount
in single 15/32 -inch hole. The equipment is designed to
fit in Switch Housing Assembly, MI- 11756.
switch panel is made of reverse etched aluminum
with nine 15/32 -inch holes for mounting. Dummy plugs
are supplied for all mounting holes left blank. An erasable write -in designation strip is provided for proper
identification of the switching facilities. The housing is of
sturdy steel construction with removable back panel for
accessibility. The case has rubber feet which will not scar
desk, table or shelf mounting area. The panel mounts
in the case so as to provide a 15 sloping front for easier
identification of the switching functions.
The
FEATURES
Compact accessory item with facilities for
9 switches
Easily mounted at any convenient location
-desk, shelf, console or rack
Long -life palladium switch contacts
Styling matches RCA Audio and TV Studio
Equipment
Write -in designation strip
The MI- 11755 -2 switches are lever type low capacity leaf
with 3 Form C contacts (single pole, double throw) on each
side. The center position is neutral with one locking and
one non -locking position. The construction of the key is
such that the switch may be adjusted to be locking or
non -locking in either position. The actuating lever has a
nylon hub for long life, while all contacts are of long -life
palladium. Switch contacts are rated 3 amperes, 120 volts,
a -c non- inductive load. Two cable clamps provide secure
fastening for all switch wiring installation to the front panel.
USES
SPECIFICATIONS
The Switch, Panel and Housing Assembly provide an ideal
and inexpensive means of augmenting any present switch-
Switch Contact Capacity Rating
ing installation. The compact Switch Housing Assembly,
MI- 11756, and removable Switch Panel, MI- 11754, are
designed to house up to nine manually operated Switches,
MI- 11755 -2. The panel is styled to match RCA audio and
TV studio equipment.
Finish
Station Engineers may use the Panel and Housing Assembly to accommodate pilot lights or other switches for
special applications as well as the MI- 11752 -2 switches.
The new switching assembly may be used to provide
switching of audio outputs and inputs for tape recorders,
intercom equipment, remote lines, etc. It is designed
for desk or shelf mounting, but may be mounted in a
1311,2 -inch TV console housing by means of a Basic Mounting Panel, MI -26252 or in a 22 -inch console or standard
rack by means of Rack Adaptor, MI- 26254.
3 amps.,
120 volts a -c,
non -inductive load
Umber gray
Dimensions Overall:
Width
Height
Depth
Depth
111/2"
2-3/5"
(top) ._
(bottom)
Weight
23/4"
31/2"
Approx.
Stock Identification:
Switch Housing Assembly
Switch Panel
Switch, 6 Form C, Single Pole, Double Throw, Contacts
5 lbs.
MI -11756
MI -11754
MI- 11755 -2
Accessory Equipment
Basic Mounting Panel (for mounting 11754 switch panel
in TV Console housing)
Rack
MI -26252
Adaptor (for mounting MI -11754 switch panel
in 19" rack)
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MI -26254
RACK EQUIPMENT
REGULATED POWER SUPPLIES
Ml- 11318 -A and MI -11316
SPECIFICATIONS
Constant Voltage DC Power Supply, MI- 11318-A
100 -130 volts a -c, 60 cps, single phase, 144 watts
Input
6 amperes, 24 volts d -c
Output
Approx. 72%
Efficiency
Line regulation within ±1 %,
Regulation.
load regulation of less than 4% between 20% and 100% load;
less than 0.8% ripple voltage
65
Ambient Temperature
C
max.
Light umber gray
Finish
19" wide, 51/4" high, 93/4" deep
Size
Approx. 45 lbs.
Weight
MI- 11318 -A
Identification
Regulated Power Supply, MI -11316
100 -130 volts, 60 cps, single phase, 117 watts
Input
Output._
3
Better than 5% voltage regulation, no load to full load
Regulation
Regulated Power Supply, MI. 11316.
60 and 120 cycle components, less than 3% at full load
Ripple
Length 9 ", Width 73/4 ", Height 53/4"
Size
DESCRIPTION
25
Weight
Compact size and low weight in proportion to power out-
Light gray baked enamel over zinc chromate primer
on 16 gauge steel
Finish
Supply, MI- 11318 -A. The equipment employs selenium rectifiers and provides very good load regulation over the
is
designed
lbs.
Approximately 30 lbs.
Shipping Weight
put are prime features of the Constant Voltage DC Power
entire operating range. The unit
amperes, 24 volts d -c
MI -11316
Stock Identification
MI -11316 POWER SUPPLY SCHEMATIC DIAGRAM
to mount in standard 19 -inch racks.
T
-I
10
t
The MI -11316 is a selenium rectifier type
power supply. It provides
3
amperes maxi-
mum 24 volts d -c, operating from a nominal
117
volts 50 60 cps source. This
supply
is
24V
60 CPS
3A
power
recommended for use with relay
switching equipment. It
operate
AC INPUT
117V
the
BCS -11A
is
also required to
Master
Switching
CONDENSERS
Console.
C -I
2500
-I 91000
R-3
standard RCA panel and Shelf,
BR -2A.
I-I
'(EL
MISCELLANEOUS
3AMP FUSE, BUSSMAN
-I .1W LAMP NE -5I
SR-I SELENIUM RECTIFIER
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5
o
F -I
I
RESISTORS
OHM. IW
FTR °132D7033
176 OHM
50W
PLUG PIN NUMBERS
TRANSFORMERS
T -I 902 -A SATURABLE REACTOR
T-2 116-A POWER TRANSFORMER
L -I 218 -A CHOKE
R
This power supply may be mounted on a
MFD, 50V
o-
CHASSIS
GROUND
DC
RACK EQUIPMENT
AM -FM RADIO TUNER
TYPE ST -5
FEATURES
Extended audio frequency range
.-j
Extremely sensitive; minimum
distortion
1...T.
High signal -to-noise ratio
Drift -free automatic frequency control; variable control
Equipped with
tuning
a
tuning eye for easy
Cathode -follower output stage
Minimum radiation -well within
and EIA requirements
FCC
Low impedance loop antenna
Wide and narrow AM tuning
DESCRIPTION
SPECIFICATIONS
The RCA ST -5 AM FM Radio Tuner is designed
for use
where a central radio receiver is to be used with a sound
distribution system. Due to its wide range frequency characteristics and low distortion rating, the ST -5 Tuner is
especially adaptable to broadcast systems. It is also handy
for off -air monitoring. When connected to a high -fidelity
audio amplifier and speaker it will provide radio reception
at its very finest. Special care has been taken in minimizing radiation to prevent interference with other radio
receivers and television sets. Radiation is well within the
FCC and EIA Limits over the entire FM band.
is carefully designed to meet rigid specifications and conservatively rated for flawless performance. This sensitive tuner has frequency response of 20,000
+-2 db from 50 to 15,000 cps. It is a 13 tube (including
tuning eye and rectifier) AM FM Tuner with a FM tuning
The MI -12116
range of 88 -108 megacycles and an AM tuning range of
520 -1650 kilocycles. The tuner is designed for use with an
audio amplifier of 10,000 ohms or greater input impedance. The output of the tuner
phonojack
simple
Tuner.
mounted in the
is
fed into a standard
rear chassis apron. Three
controls are used for operating the MI -12116
Audio Frequency Response
Audio Frequency Response Overall
Tuning Range:
Flat
+2 db from
50 to 15,000 cps
20 to 20,000
88 -108 me
AM 520 -1650 kc
Intermediate Frequencies.
FM 10.7 me
AM 455 kc
Sensitivity: FM 2 microvolts for 20 db noise quieting (on 300 ohm input)
AM 2 microvolts for 0.2 volt audio output
Audio Output:
FM 1.5 v. with 75 kc deviation
AM 1.5 v. with 60% modulation
Output Impedance
For use with audio amplifier of 10,000 ohms
or greater impedance
Oscillator Radiation
Well within the FCC limit for maximum oscillator
radiation over the entire FM band
Signal to Noise
_
60.5 db
(75 kc deviation 20 mv signal)
FM
_
Distortion
1.5% at 1.5 volt output
(75 kc deviation 20 mv signal, 400 cycles)
Power Required
105 -125 v. 50/60 cps, a -c, 50 watts
Controls.......
Tuning Selector -OFF, FM, FM (AFC),
AM (Wide), AM (Narrow), level Set (screwdriver adjustment)
Recommended Audio Cable Length
Up to 200 feet of shielded cable; or
low- impedance cable up to 10,000 mmf total distributed capacitance
Antenna Inputs:
FM input, 300 ohms
AM low impedance, high impedance
Tube Complement:
-6AB4, 2 -6BA6,
-6BS8, 3 -6AU6,
1- 12AT7,
-6CN7,
1-6AL5, -6BE6, 1- 6BR51EM80, -6X4
1
1
1
1
1
Whistle Filter:
An audio whistle filter provides at least 20 db rejection at 10 kc
Dimensions
61/2" high, 141/4" wide, 123/4" deep
Weight
17 lbs. (shipping)
Stock Identification
MI -12116
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TURNTABLES
MULTI -PURPOSE TURNTABLE
Type BQ -51A
AIL
USES
The RCA BQ -51A Multi- Purpose Turntable fulfills the broad-
caster's need for a high -quality turntable mechanism
to accommodate commercial disc recordings up to 12
inches in diameter at speeds of 331/3 and 45 rpm. It is
also used for recording and playback of magnetic discs
at
331/3
rpm.
The BQ -51A
is
available as
in custom -built arrangements.
a
mechanism for mounting
It may also be obtained
as a complete assembly with a styled cabinet, MI- 11809.
supplied with the BQ-51A accommodates
Heads, MI- 11874 -4, MI- 11874 -5, for
the
playing conventional records, or the RCA Magnetic Head,
MI- 11955, for use with magnetic discs. It will also accept
any standard, low impedance, reluctance -type pickup
that conforms to EIA standards.
The tone arm
Pickup
RCA
Provision for mounting a second tone arm, permits the
selection of either standard or magnetic disc playback.
Mounting facilities are provided for both the BA -26A Tran-
sistorized Preamplifier and the BA-51A Record 'Reproduce
Amplifier.
DESCRIPTION
The BQ -51A Multi- Purpose 12 -inch Turntable
rim -drive
motor. It
mechanism, utilizing
a
is
a 2- speed,
hysteresis synchronous
available for operation with a 60 -cycle power
supply, MI- 11810, or for 50 -cycle use, MI- 11810 -A.
is
The turntable platter is a sturdy aluminum casting. The
FEATURES
High- quality, 2 -speed rim -drive mechanism
for 32'3 and 45 rpm records
Pre -assembled tone arm on
turntable saves
installation time
Provis on for mounting second tone arm
for greater versatility
Accommodates conventional recordings and
magnetic discs
rapid starts within
Smooth and
revolt- tion
Available as
installations
a
half
platter and spindle assembly is held in the main support
casting by oilite bushings and the thrust is supported by
a single ball at the bottom end of the spindle. A foam
rubber belt on the outside rim of the platter eliminates
resonance effects. The drive motor is mounted on a separate plate, supported by vibration mounts to eliminate
rumble. All posts and shafts which provide bearings for
cams and arms are assembled to a common plate to insure proper alignment. The Cabinet Assembly, MI- 11809,
affords a simplified mounting for the drive assembly
mechanism, operating controls, preamplifiers and other
accessories.
speed selector switch is provided on the
turntable assembly. An "Off -On" selector control operates
A 2- position
mercury motor switch and simultaneously engages or
disengages the rubber idler wheels. This feature relieves
the idlers from pressure when set to the "Off" position.
a
a
mechanism for custom -built
8.1610
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TURNTABLES
A cabinet of functional design is available to house the
turntable equipment. It has a durable, umber -gray fabrikoid covering which is resistant to scuff and scratches. A
175á by 195/á -inch hinged door is located on the front of
the cabinet to permit ready access to the interior and
mounting facilities have been provided to accommodate
either the BA -26A Transistorized Preamplifier, Ml- 11436,
or the BA -51A Record/ Reproduce Amplifier, Ml- 11903, or
both equipments. Each turntable mechanism is supplied
with an 8 -foot power cord.
Multi -Purpose Turntable, Type BO51A, showing the turntable mechanism,
platter assembly and tone arm.
The
Simplified sketch showing how the
BO-51A is adaptable to custom -built
installations.
www.americanradiohistory.com
TURNTABLES
the
The tone arm provided with
BO -51A accommodates pickup heads
for playing conventional records or
magnetic d;scs. It will also accept
any standard pickup that conforms
to EIA standards.
equipped with a second tone
rm, permits the selection of either standard or magnetic disc playback. Note the
compactly designed cabinet to accommodate the Multi -Purpose Turntable, the
Record /Reproduce Amplifier and the TranThe BO -51A
:.
sistorized Preamplifier.
SPECIFICATIONS
Equipment Supplied
Performance Specifications
Turntable Speed
Wow or Flutter:
At 331.3 rpm.
33.
Motor....
1
Power Supply
Power Consumption
Turntable Diameter
Hub and Spindle Diameter:
Hub for 45 rpm records
Spindle for 331/3 records
Overall Dimensions:
Turntable Drive Unit
Cabinet._
Cabinet
Finish.
_0.3%
0.25% half of peak to peak
0.20% half of peak to peak
100 h.p., 1800 rpm a' 60 cycles
'125 h.p., 1500 rpm at 50 cycles
At 45 rpm
Weight:
Turntable Drive Unit
and 45 rpm
or 1
105 -125 volts, 50 60 cycles single phase
40 watts
12"
1.5"
0.2835"
-
18" wide, 16,, 2" deep
height below top surface motor board, 9
height above surface motor board, 11/2"
22" wide, 22" deep and 29" high
"-
31 lbs.
47 lbs.
Light umber gray fabrikoid
Mult- Purpose Turntable includes turntable mechanism, platter assembly and Tone Arm, MI- 11894:
MI-11810-A
For 50 -cycle operation
BQ -51A
For 60 -cycle operation
Cabinet assembly to house turntable mechanism
MI-11810
MI-11809
Accessory Equipment
12" Tone Arm (less pickup head).
MI-11894
1.0 Mil Fine Groove Diamond Stylus Pickup
MI-11874-4
2.5 Mil Standard Groove Diamond Stylus Pickup
MI-11874-5
BA-51A
Magnetic Disc Record Reproduce Amplifier
Magnetic Record / Reproduce Head.
MI-11903
MI-11955
Magnetic Eraser
MI-11821
Magnetic Disc (set of five)
MI-11990
BA -26A Turntable
www.americanradiohistory.com
Equalizing Preamplifier
MI-11436
TURNTABLES
LIGHTWEIGHT TONE ARM
MI-11894
FEATURES
Designed for use with both magnetic disc
record /reproduce head and standard record
transcription pickups
High -quality reproduction
four degrees tracking error on
any standard record
Less than
Low mass and anti -friction pivots permit
tracking on warped and eccentric records
Finger -tip control
USES
Lightweight Tone Arm, MI- 11894, fulfills the need for a
high quality broadcast pickup combination for playing
magnetic and standard transcriptions. It has been designed primarily for use with the Magnetic Record/
Reproduce Head, MI- 11955, and RCA's plug -in Lightweight
Pickup Heads, MI- 11874 -4 and MI- 11874 -5. In addition,
it will also accept any pickup which mounts on standard
'/2 -inch
centers.
DESCRIPTION
arm can be mounted on any RCA 12" turntable. All necessary mounting hardware is included.
SPECIFICATIONS
Tracking Error, 12 -inch Record_
4
max.
Pivot Bearings
Anti -resonant in vertical and horizontal planes
Tone Arm Head Receptacle _... ..
Plug -in type
Arm Finish
Light umber gray
Length of Arm
12"
Width of Arm
Tapered 11/2" to 1/2"
Height of Arm
Tapered 3/4" to 1/4"
Approx. Shipping Weight (arm, assembly, etc.)
11/2 lbs.
Mounting
Approx. 8" from spindle center
"
Stock Identification
The MI -11894 Lightweight Tone Arm accommodates
the
RCA Magnetic Record, Reproduce Head used in the Mag-
netic Disc System as well as RCA one mil or 21/2-mil
Lightweight Pickups. The heads are readily interchangeable. The anti -friction vertical and lateral pivots and low
mass allow the tone arm to track warped and eccentric
records with a tracking error less than four degrees.
Tone arm assembly (less pickup heads) complete with tone
arm rest and mounting hardware
MI -11894
Accessory Equipment
Magnetic Record, Reproduce Head
Lightweight Pickup, 1 mil
Lightweight Pickup, 2.5 mil
The lightweight tone arm has an adjustable counterweight
controlled by an accessible thumb nut at the rear of the
tone arm to allow accurate selection of stylus force.
The tone arm is hinged at the pivot center to allow easy
access to the underneath portion of the arm, thus pro-
viding immediate
tone arm handle
finger -tip control
enabling the user
accurately where
access to the pickup and wiring. The
introduces a new concept by providing
directly behind the pickup stylus, thus
to sense by touch as well as to see more
the stylus is being set down. The tone
Magnetic Record /Reproduce Head, MI- 11955.
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MI-11955
MI- 11874 -4
MI- 11874 -5
TURNTABLES
LIGHTWEIGHT TONE ARM
MI-11885-A
FEATURES
with RCA plug -in heads, provides
high quality reproduction of 45 rpm and
33'3 rpm fine groove records, standard
transcriptions and commercial records
Used
May be applied to any 16 -inch turntable
than 4 degrees tracking error on any
standard record
Less
Low mass and anti- friction pivots permit
tracking on warped and eccentric records.
USES
The new lightweight pickups and tone arm (Ml -11874 serie,
and 11885 -A respectively) have been designed to fulfill the
need for a high -quality broadcast pickup combination for
playing fine groove records and standard transcriptions.
A popular application of this new design
is in
combination
D
E S
with the present Universal Pickups and 16 -inch turntables.
In such
installations, the new unit provides the broadcaster
with pickup and tone arm facilities for groove sizes asso-
ciated with all three speeds.
C R I P T I
O N
designed to function with
two diamond stylus sizes (1 mil stylus for fine groove
and 21/2 mil stylus for standard transcription and 78
rpm records). These are readily interchangeable as
low mass allow the tone arm to track warped and
eccentric records.
"plug -in" units.
was formerly considered necessary, thus assuring
longer life for both the stylus and the record. Design
The
lightweight tone arm
is
Tone arm resonances have been carefully placed so
that they are outside of the operating frequency range
of the systems, thus assuring smooth response characteristics. Distortion due to tracking error in the arm
and pickup has been reduced to a minimum by careful
design. The anti- friction vertical and lateral pivots and
The required stylus forces are only a fraction of what
of the pickup system permits interchange of the magnetic heads without necessitating any adjustment for
correct stylus pressure. The stylus is readily visible,
providing means for accurately spotting the pickup on
the record.
B.1612,
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TURNTABLES
LIGHTWEIGHT TONE ARM (Cont'd)
SPECIFICATIONS
4° max.
Tracking Error, 16 -inch Record (C. D. 12 ")
Pivot Bearings
Anti -resonant bearings in vertical and
horizontal planes
Tone Arm Head Receptacle
Quick -lock, plug -in type
Aluminum casting
Construction of Arm
15"
Length of Arm
Width of Arm
Tapered 11/2' to %"
Height of Arm
Tapered %" to 9/32"
Approx. Shipping Weight (arm, assembly, etc.)
3 lbs.
Approx. 12" from spindle center
Mounting
Stock Identification:
Tone Arm (less pickup heads) includes assembly complete
MI. 11885 -A
with tone arm rest and mounting hardware
70 -F Turntable with Pickup and Tone Arm installed at rear
LIGHTWEIGHT PICKUP HEADS
MI- 11874 -4 AND MI- 11874 -5
SPECIFICATIONS
Lightweight Lateral Magnetic Pickups
135 ohms L
Output Pickup Impedance
Load
1000 cycles
Filter Output should be connected to unloaded
Impedance
input transformer of amplifier designed to operate from a 150 ohm
source such as the BA -21A Preamplifier or the BA -26A Equalized
Preamplifier.
Compensation Required
Frequency
MI -11888 Equalizer or BA -26A Amplifier
Response
See
curve)
Voltage Output
Open circuit voltage at terminals of pickup
head, reproducing 1000 cycle band of 6.1 cm /sec. test record is
11 millivolts.
Output Level at MI -11888 Equalizer Output
._.
Approx.
Hum Level
Pickup Weight
-65
dbm
-120
dbm
Plug -in Type Pickup Mead, MI-11874-4
MI- 11874 -4 (0.37 oz.); MI- 11874.5 (0.51 oz.)
Stylus Force in combination with Tone Arm, MI- 11885 -A:
MI. 11874.5
8 grams
MI- 11874 -4
Stylus Tip Radius (Polished Diamond Stylus):
MI- 11874 -4 (for fine groove)
MI. 11874 -5 (standard transcriptions)
Overall Dimensions (plug -in pickup heads):
Width 3/4 ", Depth
Excluding contact pins
Stock Identification:
1
mil, Pickup, Fine Groove (color, Red)
2.5 mil, Pickup, St'd Transcription (color, Green)
12
¡25
f
grams
1.0 mil
SD e
2.5 mils
3. ", Thickness
20
MI- 11874 -4
MI. 11874 -5
_..
I0
1
7/16"
MIL STYLUS
12 GRAMS
I
MIL STYLUS
e GRAMS
FREQUENCY
10000
1000
100
IN
CYCLES PER
SECONO
Typical response of Pickup, Tone Arm and Filter
b
88
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1512
TURNTABLES
PICKUP EQUALIZER
MI-11888
FEATURES
Adjustable high frequency response
Follows NAB curve
i. *00
01
Insensitive to hum pick -up
Economical
Compact -easy to mount in transcription
turntables
SPECIFICATIONS
USES
The MI -11888 Pickup Equalizer
is
used to filter the re-
created audio frequencies of transcriptions before introduction into the audio amplifier system of broadcast and
TV stations to achieve the most desirable response over
the entire audio frequency range. The equalizer may be
mounted in RCA transcription turntables and is designed
for use with the MI- 11874 -4 Pickup Head for the reproduction of 45 or 331/3 rpm lateral cut fine groove records
and the MI- 11874 -5 Pickup Head for the reproduction
of 78 or 33 1'3 rpm lateral cut standard groove records.
DESCRIPTION
Variable over range of 30 to 10,000 cycles
Frequency Response
(see response curves)
Output level (using MI- 11874 -4 or
-5
Approximately
Pickup Heads)
-65
dbm
(measured using RCA Test Record 12 -5 -51
at 1000 cycle reference level)
Output Impedance
150 ohms
Noise Level
Less
-120
than
dbm
The output of the filter should be connected to the
unloaded input transformer of an amplifier having a flat response
and designed for operation from a 150 ohm source.
Load Impedance
The MI-1 1 888 Pickup Equalizer consists of a capacitor -
resistor network mounted on a plate, and separate dial
plate, control knob, and hardware for mounting it in a
transcription turntable. The right hand front corner of
RCA turntables has been designated as best site for the
equalizer in order to reduce noise pickup to the lowest
Dimensions Overall
3516"
long
27/s" wide
x
x
Weight
51/2" htgh
Ibs.
31/4
Stock Identification
MI-11888
possible value.
The equalizer is designed to be used with any amplifier
having an unloaded input transformer and which has a
i
microphone input of any RCA consolette. In order to compensate for variations in transcriptions, three responses
can be chosen: (1) flat, (2) increased high frequencies,
or (3) decreased high frequencies.
I
I
(11111
1
TYPICAL RESPONSE OBTAINED
WITH Mi 11914- 4 PICKUP HEAD.
-NSIS PICKUP EQUALIZER AND
RCA TEST ACCORDS 12 5.49/1:5.51
flat response when operated from a 150 ohm source.
Examples of this type of amplifier are the RCA BA-21A
Preamplifier, the BA -24A Monitoring Amplifier and the
PI
NORMAL
4
lo
20
SO
www.americanradiohistory.com
o
ZDD
SOD
MOO
2000
'RCOUERCY M CYCLES PER SECOND
5000
IDDDD
B-UNS2
20000
0
TURNTABLES
BQ103 AUTOMATIC
TURNTABLE
FOR PLAYING 45 RPM RECORDS
FEATURES
Integral unit in RCA automation system of
studio programming
High record capacity -100 records or 200
selections -at your fingertips
Automatic record cueing
Remote
control- random or sequential op-
eration on one turntable
Longer pickup head life
Less
handling -longer record life
Self- contained power supply
Remote preset and clearing of selections
USES
The new RCA BQ -103 Automatic Turntable with its feature
of fixed sequential or random type of play provides high
record capacity with an efficient, accurate and economical
means of record programming and handling. The auto-
matic turntable provides a means of playing a maximum
of 100 "45" rpm records (200 plays) on a push button
control basis. The turntable with its provisions for electrical
remote control becomes an integral part of RCA's automa-
tion system of studio programming.
The new type turntable offers greater operating efficiency
for the broadcast audio studio. Not only does it conserve
control room space, but the capacity of the changer allows
for the loading of the machine at relatively infrequent
intervals. A savings results from decreased record handling
and increased record life. Pickup head life
is
also increased
since the exact placement of the styli is accomplished by
an exact and gentle mechanical motion. This avoids broken
diamonds and also results in less record damage than
is
possible by human operation. Less skilled operating personnel are able to operate the new type turntable.
www.americanradiohistory.com
TURNTABLES
DESCRIPTION
The Type
BQ -103 Automatic Turntable consists
of two
of equipment -the record handling and playing
pieces
mechanism, MI- 11845, and a separate control unit, MI11844. The former consists essentially of a record magazine assembly, record transfer assembly, turntable assem-
bly, memory assembly which is part of the selection system, a pulse receiver, mounting casting, and self- contained
power supply all housed in a metal cabinet 3134 inches
wide, 35'2 inches high and 22'2 inches deep.
The control box contains the control circuits with the nec-
essary push buttons for record selection and the functions
of start, reject, etc., with suitable lamp indications of the
operational status of the equipment. The BQ -103 has 23
push- buttons that permit selecting any of 200 record
selections that can be housed in the magazine assembly.
A check light is available for checking selection information. Two toggle switches are provided, one for designating
either selective or sequential mode of operation, and a
transfer switch for transferring selection information from
the control box to the pulse receiver. Three illuminated
BO.103 Control Unit, MI- 11844.
sturdily constructed of cast iron. This provides the high
inertia necessary for smooth operation. As a convenience
for loading records in the BQ -103, a toggle switch on
the chassis in the housing permits rotation of the record
magazine.
is
push buttons include the start button, which lights up green
when a record is on the turntable ready to play; a reject
button which lights up red when the record is playing;
and a clear push button for clearing all information stored
in the memory mechanism.
Below the handling mechanism in the base of the cabinet
housing is mounted the junction box which houses control
circuits, the d -c power supply and the fuses. The junction
box serves to distribute electrical power to the various
functioning parts of the turntable and control box. The
equipment is designed to be operated from a line- voltage
source of 100 to 125 volts, 60 cycles a -c only. The output
of the equipment is normally fed to a standard equalized
preamplifier such as the Type BA -26A. Ample space for
mounting an accessory BA -26A pickup equalizer is available in the cabinet.
The control unit has an etched aluminum control panel 10
inches wide by
143/4 inches high; mounted at a slope, it
provides convenient operation. This control unit may also
be rack mounted or set in other console housing equipment in the studio as desired.
handling and playing mechanism
cabinet is gained through a removable front panel. When
the front panel is removed, service lights illuminate the
interior. All components are easily accessible. A hinged
top provides further access to units within the housing for
routine playing and record changing operation. When the
housing is "buttoned up" a small door in the front panel
provides access to power switches. Cable access doors
are located at the rear and in each side of the housing.
Easy access to the record
handling mechanism is mounted on a slide
type frame which enables the entire mechanism to be
pulled out cf the cabinet and rotated for easy servicing.
It is shock mounted to protect the automatic playing
mechanism. The record magazine provides storage for
one hundred "45" rpm records.
SPECIFICATIONS
Record Handling Capacity
Turntable Speed
Power Supply
Wow and flutter
Rumble referred to
45
record handling mechanism is fully automatic and
sturdy. The record turntable is puck driven. The tone arm
accepts standard EIA pickup mountings. The base on
which the entire record handling mechanism is mounted
rpm
100 -125 volts, o-c, 60 cycles, single phase
0.2 per cent or less
1
The record
The
100 records (200 sides)
kc
standard
35 db 30 cps high pass filter
-43 db 60
-45 db 120
cps high pass
cps high pass
filter
filter
Dimensions (Overall):
s
BQ -103 Automatic Turntable
Control Unit
Finish
Weight
_
Stock Identification
3134" wide,
351 2" high, 221/2" deep
10" wide, 6" high, 143/4" deep
Light & dark umber gray
200 lbs. approx.
MI -11845 11844
Accessories
BA -26A Equalized
Preamplifier
GE Replacement Stylus Tip, 1.0 mil
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MI-11436
diamond
4G-01D
RECORDING
MAGNETIC RECORD /REPRODUCE AMPLIFIER
Type BA -51A
USES
FEATURES
The BA-51A Amplifier is designed for both recording and
Records from microphone or bridging pro-
gram line
Illuminated volume indicator for record
and reproduce functions
AC bias provided for magnetic head
Push -button controlled cue signal oscillator
Cue -signal detection
for operation with
reproducing in the Magnetic Disc System. The amplifier
with its self -contained power supply may be installed
either in the BQ -51A Manual Turntable or in the BQ -104
Automatic Turntable. Facilities are provided to record a cue
signal at the beginning and ending of the program. These
signals are utilized in the BQ -104 Automatic Turntables
to "cue in" the disc to the start of the message and to
"trip out" the change mechanism at the end of the message. Recordings may be made directly from a microphone
plugged into the amplifier or from a program line. The
output may be fed to a console or other speech input
equipment. Provisions have been included in the design
to guard against accidental erasure.
automatic turntable
DESCRIPTION
Self- contained power supply
Amplifier is designed for both recording and
reproducing, the function being determined by means of
the record -play switch. A red signal light is lit on front
The BA -51A
All controls conveniently accessible
www.americanradiohistory.com
RECORDING
panel when selection is on record. An illuminated volume
indicator is provided for indicating levels which may be
adjustable by means of independent gain controls for
both record and reproduce functions.
SPECIFICATIONS
Matching:
Minimum Input Level..
Maximum Input Level
Input Impedance
_.
Bridging:
Minimum Input Level
Maximum Input Level
Input Impedance
Output:
Load Impedance
Maximum Output Level
feature is the push-button controlled 10 kc
oscillator for supplying the cue signal at the beginning and
ending of a program on a BQ -104 Automatic Turntable.
To prevent a 10 kc signal component which may be
present in the audio signal from actuating the cue circuit,
a twin T -notch filter is inserted in the amplifier. The same
circuit also prevents the cue signal from being reproduced
in the program output when playing back and forms part
of the tuned amplifier for detecting the cue signal.
A special
-60
-30
dbm
dbm
150 ohms
-17
dbm
dbm
20,000 ohms
+13
600 ohms
0 vu
84 kc (approx.)
10 kc
100 -130 volts; 50 -60 cycles; 45 watts
Bias Frequency.
Cue Signal Frequency
Power Required
Width
Height
Depth
Weight
16.81"
4.66"
8.86"
17
lbs.
Dark umber gray panel
Versatility
Mounting in BQ -51A or BQ-104 Turntables
Metering
Record and playback level shown on illuminated vp meter
Stock Identification (includes tubes)
MI -11903
Finish
A fuse and an on -off switch for the self- contained power
supply are located on the front panel. Included also is
phono -jack which permits monitoring with headphones.
amplifier every possible precaution
was taken to minimize hum and noise. The input transformer is extremely well shielded and the heater power
of the input tube is obtained from a dc supply.
a
Accessory Equipment
In the design of the
Electron Tube Kit containing the following
-6X4
-12AT7
2 -12AU7
MI -11488
3 -12AX7
1
1
-MI -11298
1
(Selected 5879)
Schematic diagram of the RCA Type BA -51A, the Magnetic Record/Reproduce Amplifier.
LINE
INPUT
MIC
)
ECk
RECORD/PLAY
P
PLAY
PLAY
COMPEN-
oR
SATION
/
Y2 NI__
12AX7
III
RECORD
COMPEN
OR
\
QR
/
10
KC
NOTCH
FILTER
`
112 A X
7
RECORD
_
SATION
HEAD
AMPLIFIER
PUSH -PULL
PHASE
OUTPUT
INVERTER
41110-
OUTPUT
BIAS
HF PRE-
TRAP
EMPHASIS
84 KC
BIAS
OSCILLATOR
POWER SUPPLY
Rp
R_
CUE
\
`2AX7
12AX7
/
CUE
CUE AMPLIFIER
PLAY- IOKC AMP
RECORD -IOKC OSC.
1/2\
12AT7
www.americanradiohistory.com
7
1/z
12AT7
N
IN34 -A
DETECTOR
t
-t
CUE SENSE
RELAY
RECORDING
MAGNETIC RECORDING DISC
USES
The Magnetic Recording Disc is designed
for the recording of short announcements, such as spot commercials,
station identification, special sound effects, etc. The available recording time is 60 seconds in duration, plus an
additional 10 seconds for recording "cue -in" and "trip out" signals on each side of the disc. The disc may be
conveniently recorded and played back on the BQ -51A
Manual Turntable, and may also be reproduced on the
BQ -104 Automatic Turntable which stores up to 100 discs
and makes available 200 selections.
DESCRIPTION
RCA Magnetic Discs are molded from a uniform dispersion
of iron oxide particles in a synthetic elastomer (rubber
type) binder with various plasticisers, lubricants and additives to give material the desired physical properties. An
aluminum plate is imbedded between the two magnetic
layers to provide rigidity. Grooves are molded for the
guidance of the record, reproduce head. In addition, the
grooves are separated by lands for better guidance of
the head and magnetic isolation from the adjacent tracks.
A distinctive label is provided with spaces for title, artist's
and sponsor's names, recording time and date. The disc
is identical in size and shape to the standard 45 -rpm
record. It is designed, however, to be played at 33 1'3 rpm
when used in conjunction with the Magnetic Disc Head
Ml -11955 and the BA-51A Magnetic Record Reproduce
Amplifier, Ml- 11903.
FEATURES
Optimum handling convenience
Provides extreme durability
Easy erasure
Quick identification of recorded programs
SPECIFICATIONS
Magnetic surface with premolded grooves on both sides of disc
Outside Diameter
Greater programming convenience
Center Hole Diameter
._
_
Number of Program Grooves
6.875
±0.015"
1.504
-!-0.002"
39
Lead in, lead out and concentric grooves conform to specifications for
45 -rpm discs
Both manual or automatic cueing
Maximum Record Time
Interchangeable with B0-51A Manual or
BQ -104 Automatic Turntables
Stock Identification
Each side at 331/3 rpm -70 seconds
MI -11990 (ordered in sets of five only)
Optional Accessories
Magnetic Eraser
MI-11821
Set of Gummed Labels
MI-11989
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RECORDING
MAGNETIC ERASER
MI-11821
FEATURES
Provides fast, complete erasure of recordings on both sides of 7 -inch magnetic discs
and '4 inch tape reels
Permits virtually unlimited reuse of discs
and tape
Minimizes disc and reel inventory problem
Operates semi -automatically
Housed in lightweight portable case
USES
Inside the case, a motor driven V- shaped pulley causes the
disc or reel to rotate in the magnetic field set up by an
for
inductance coil. Two revolutions are sufficient to demag-
assuring maximum utility from magnetic discs and reels
netized the iron oxide filings and thereby completely erase
by erasing
the recording, making it ready for immediate reuse.
The Magnetic Eraser, MI- 11821, is a convenient device
recordings clearly, completely and quickly.
Thus, each disc and tape reel can be used over and over
The Magnetic Eraser, MI- 11821, does an
important job
again -many thousands of times. Inventory and investment
at modest cost. It
for discs and reels can be kept to a minimum. The com-
to the RCA Magnetic Disc Recording System.
pletely self- contained unit
is
is
an especially efficient companion tool
extremely simple to operate.
SPECIFICATIONS
D
E
S C R I P T I
O N
Power Supply
The Magnetic Eraser is housed in a case approximately
10 x 61/2 x 71/2 inches, weighing only 12 lbs. It operates
from 110 120 power controlled by an on -off toggle switch.
To erase, the disc is merely inserted into a
slot which
can be widened to accommodate a 7 -inch 'eel of audio
tape. A red pilot light
is
the "equipment -in -use" indicator.
Complete erasure of both sides
taneously in 20 seconds.
is
accomplished simul-
117 volts ac, 60 cycles, single phase
Current Required
Apparent Power Required
Power Consumption
Coil:
Electrical Rating.
58.5
115 volts, 60 cycles, 4.5 amps
8 ohms
600 gauss
Resistance
Field (center)
Motor
Thermostat
Dimensions (over -all)
Weight
Finish
Stock Identification
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5 amperes
voltamperes
175 watts
5 oz.
torque; freq. 50 -60 cps; 115 volts;
speed 60 rpm ±20%
Klixon- contact opens 200° 15
closes 170
-*5°
101/2" wide, 6146" high, 71/2" deep
12 lbs.
Dark gray fabricord
Ml -11821
RECORDING
AUTOMATIC
BQ104
TURNTABLES
FOR PLAYING MAGNETIC DISCS
FEATURES
Designed specifically for playback of magnetic disc recordings
Affords very
high
degree of
program
flexibility
Large disc capactiy -up to 200 messages at
your fingertips
Remote control- random or sequential operation
Compact unit may be located in most convenient area -conserves valuable control
room space
Integral unit
in
RCA
audio automation
system
Very tight cueing possible when used with
the BA -51 Record Reproduce Amplifier
USES
Efficient,
simplified,
automatic
handling
of
broadcast
messages recorded on RCA magnetic discs is made possible
on the BQ -104 Automatic Magnetic Disc Turntable. Since
all manual operations such as selection, cue, start, stop,
are made fully automatic, fewer operator "fluffs" result,
and program flow
is
smoother for the listening audience.
The BQ -104 provides a convenient method of storing and
playing back up to 100
331/3
rpm magnetic discs (200
messages) on a push button control
basis. The control
permits selection of the discs in either random or sequential
order. The sequential operation restricts selection to the
order in which the recordings were placed
in the machine.
Memory facilities permit preselection of any number of
recordings provided they are in an ascending numerical
order. A clear button removes all preselections from the
mechanism, thus last- minute
program changes can be
made seconds before a selection
turntable with
its provisions
becomes an integral
to be played. The
part of RCA's automation system
for audio programming.
www.americanradiohistory.com
is
for electrical remote control
RECORDING
DESCRIPTION
The Type BQ -104 Automatic Magnetic Disc Turntable con-
of two pieces of equipment -the disc handling and
playing mechanism, MI- 11846, and a separate control
unit, MI- 11844 -A. The former consists essentially of a disc
magazine assembly, disc transfer assembly, turntable
assembly, memory assembly which is part of the selection
sists
pulse receiver, mounting casting, and self contained power supply all housed in a metal cabinet
313/4 inches wide, 351/2 inches high and 221/2 inches deep.
system, a
The control box contains the control circuits with the nec-
essary push buttons for disc selection and the functions
of start, reject, etc., with suitable lamp indications of the
operational status of the equipment. The BQ -104 has 23
push buttons that permit selecting any of 200 recorded
commercials or other material housed in the magazine
assembly. A check light is available for checking selection
information. Two toggle switches are provided, one for
designating either selective or sequential mode of operation, and a transfer switch for transferring selection information from the control box to the pulse receiver. Three
illuminated push buttons include the start button, which
lights up green when a disc is on the turntable ready to
play; a reject button which lights up red when the disc
is playing; and a clear push button for clearing all information stored in the memory mechanism.
circuits, the d -c power supply and the fuses. The junction
box serves to distribute electrical power to the various
functioning parts of the turntable and control box. The
equipment is designed to be operated from a line- voltage
source of 100 to 125 volts, 60 cycles a -c only. The output
of the equipment is normally fed to the BA-51A Record
Reproduce amplifier. Provisions for mounting the BA-51A
Amplifier are available in the mechanism cabinet.
The control unit has an etched aluminum control panel 10
The BA -51A Amplifier is designed for both recording and
inches wide by 143/4 inches high; mounted at a slope, it
provides convenient operation. This control unit may also
be rack mounted or set in other console housing equip-
reproducing in the RCA Magnetic Disc System, the function being determined by means of the record -play switch.
An illuminated volume indicator is provided for indicating
levels which may be adjustable by means of independent
gain controls for both record and reproduce functions.
Facilities are provided to record a cue signal at the beginning and ending of the program. These signals are
used in the BQ -104 to "cue" in the disc to the start of
the message and to "trip out" the change mechanism at
the end of the message.
ment in the studio as desired. Thirty feet of rubber jacketed
cable are provided for interconnection between the control unit and the turntable. One or more control units may
be parallel connected to permit operation of the BQ -104
from more than one location.
The disc handling mechanism is mounted on a slide type
frame which enables the entire mechanism to be pulled
out of the cabinet and rotated for easy servicing. It is
shock mounted to protect the automatic playing mechanism. The disc magazine provides storage for one hundred 331/3 rpm magnetic discs.
The disc handling mechanism is
fully automatic and sturdy.
The turntable is puck driven. The tone arm accepts the
Magnetic Record Reproduce Head, MI-11955. The base
on which the entire disc handling mechanism is mounted
sturdily constructed of cast iron. This provides the high
inertia necessary for smooth operation. As a convenience
for loading discs in the BQ -104, a toggle switch on
the chassis in the housing permits rotation of the disc
magazine.
is
Below the handling mechanism in the base of the cabinet
housing is mounted the junction box which houses control
BQ -104 Control
Unit, MI- 11844 -A.
SPECIFICATIONS
100 records (200 sides)
Handling Capacity
331/3 rpm
Turntable Speed
100 -125 volts, a -c, 60 cycles, single phase
Power Supply
0.2 per cent or less
Wow and Flutter
kc standard
-35 db 30 cps high pass filter
referred to
-43 db 60 cps high pass filter
-45 db 120 cps high pass filter
Dimensions (Overall):
3134" wide, 351/2" high, 221/2" deep
BQ -103 Automatic Turntable
10" wide, 6" high, 1434" deep
Control Unit
Light 8, dark umber gray
Finish
200 lbs. approx.
Weight
MI-11846 1844 -A
Identification
Disc
1
1
Accessories
BA -51A Magnetic Record Reproduce Amplifier (one required) ...MI -11903
MI -11955
Magnetic Record /Reproduce Head
MI -11821
Magnetic Eraser
Ml -11990
Magnetic Disc (set of five)
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SPEAKERS
LOUDSPEAKERS AND ACCESSORIES
FEATURES
Wide choice of speaker mechanisms offering excellent frequency response
Alnico V magnets
Low non -linear distortion
Ideal for monitoring AM, FM and television
programs
Rugged construction
Attractively styled housing for any location
Transformers designed
variety of outputs
to
couple
wide
GENERAL INFORMATION
RCA offers to broadcasters a complete line of studio and
station monitoring loudspeakers for use in monitoring and
auditioning booths, hallway installations, talk -back applications, elevators and executives' offices. All RCA loudspeakers are designed to handle adequate power for the
particular application for which they are designed. The
LC -1A, representing the greatest advance in loudspeaker
design, is obtainable for use in a choice of cabinet styles
and finishes, thereby making it possible to conform to any
of several interior decorating schemes. In addition, the
LC -1A speaker mechanism may be obtained for those
applications where it is desirable to use a special type,
or custom -made, mounting.
In order to serve the wide
variety of needs for loud-
speakers around broadcasting stations, there
is also included in this line a choice of permanent- magnet loudspeaker mechanisms. These mechanisms are intended to be
mounted in one of the wall- mounting speaker housings.
Loudspeaker Impedance Matching Transformers, Ml- 12368,
Ml -12369 and Ml -11731 are designed for coupling a wide
variety of outputs to these and many other types of loud-
speakers. The quick -selection chart provides a convenient
reference for selecting the proper RCA loudspeaker com-
bination.
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SPEAKERS
DUO -CONE SPEAKER
LC -1A
FEATURES
Excellent frequency response, uniform 5015,000 cycles
Low non -linear distortion
Ideal for monitoring AM -FM television programs
Alnico V magnets
Wide angle sound radiation of all frequencies
DESCRIPTION
The LC-1A is a "Broadcast
Quality" loudspeaker with a
The low frequency system employs a large
diaphragm
ance makes it ideal for wide frequency range wide angle
with a high mass voice coil and produces the most desirable directional pattern with a handling capacity of
20 watts. Low distortion has been accomplished by a
carefully designed balance of many contributing factors. Distortion usually experienced when handling
large power in the 100 -1,000 cycles range is eliminated by using a high mass coil and a massive rigid
cone, coupled with a low fundamental frequency peak
of 40 to 50 cycles. Above this frequency the stiffness
of the suspension system of the cone does not appreciably affect the velocity and, therefore, minimizes
radiation.
distortion.
The LC-1A is a duo -cone speaker mechanism of the direct
A feature of construction is the use of acoustical
domes -largely responsible for smooth response. The
series of domes placed on the speaker's large cone
low distortion, wide angle distribution, of extended frequency range, and specifically designed for use in recording studios, executive offices, reception rooms, sponsors'
booths or any location that warrants a pleasant setting
and tasteful styling.
For applications where it
is
desired to mount the mech-
anism on a wall baffle, ceiling, etc., the speaker mechanism
may be used with assurance that the entire frequency
range will be realized. The speaker's outstanding perform-
radiated type, consisting of high and low frequency units
mounted co- axially together. The 2 -inch high frequency
cone to effect its remarkable directional pattern (see curve).
breaks up the unit's symmetry and eliminates the interference normally characteristic of the symmetrical
shape without sacrifice of either highs or lows.
An equilibrium has been reached between the electrical
The cross -over network utilizes the physical character-
and mechanical design to impart a high frequency radia-
istics of the cones to mutually vibrate in unison over
tion of 120 degree arc with a loss of approximately 6 db
at 15,000 cps. This eliminates the conventional "beam
the cross -over frequency region and merely employs
one capacitor in the high frequency unit to limit its
effect" usually experienced at this frequency.
current at low frequencies.
cone and the aluminum wound voice coil has a low mass
utilizing the wide angle of the shallow, low frequency
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SPEAKERS
SPECIFICATIONS
LC-1A Speaker Mechanism
Impedance (nominal)
15 ohms
Frequency Response (see curve)
..__.__ _ _
40- 16,000 cps
Directional Characteristic
See curve
Power Handling Capacity
20 watts
Non -linear Distortion (for 10 watt output, 50- 15,000 cycles)
Less than 4% at 60 cycles
Weight (unpacked)
21 lbs.
Dimensions:
Diameter (cone)
15 5/16"
Diameter (bolt fixing circle)
16aá"
Diameter (overall frame)
17"
Stock Identification
MI- 11411 -A
(Mechanism only)
for LC-1A Loudspeaker may be mounted
vertically or horizontally as shown.
The Ml -12464 Floor Cabinets
Accessories
Speaker Cabinet (Blonde)
Speaker Cabinet (Mahogany)
LC -1A Wall Speaker Housing
Power Attenuator
LC -1A
MI-12464-B
MI-12464-M
MI-11406
MI-11708-A
LC -1A
The cabinet
MI- 12464 -M
bass reflex or phase inverter type. The
is a
high luster, mahogany cabinet with 6 -inch
is a
matching legs. A blonde version of the MI -12464 model
is
available. Cabinets measure 32 by 25 by 16 inches and
weigh approximately 50 pounds. The Wall Baffle, MI11406, measures 371/2 by
213/4
by
171/8
inches and weighs
45 pounds.
:
mom
m^n...s.r:11!
r%IlllmumiilllonnnIIn\i
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s
l/111111=111111111111111111111all
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.00
eco
ENEOUENCY
iN
.0000
CYCLES PEN SECOND
Frequency Response Curve of
LC -1A
20000
VIII ME-O
The MI -11406 Wall Mount Speaker Housing accommodates the LC -1A
Speaker Mechanism. This housing has been popular with broadcasters
for many years as a space- saving unit which maintains the LC-1A
Speaker "Broadcast Quality"
Speaker.
H
Wu
4
10
ú3
O
I
1
60
20
s-
Directional Characteristics of
LC -1A
/'M,,
i\'1'
1111111
2wkiM1.
Speaker.
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WOO
100
fREOUENCY
N
Harmonic Distortion of
CYCLES PER SECOND
LC -1A
Speaker.
-
6000
SPEAKERS
SL -123 12 -INCH SPEAKER
FEATURES
Extended range tweeter has wide angle
distribution
Concave center radiator construction with
off- center tweeter provide smoother crossover response
Uniform frequency response 40 to 16,000
cycles
rubber damping on both high
and low frequency units for smoother
frequency response
Unique
Alnico V magnets
Ideal for monitoring AM, FM and TV
DESCRIPTION
SPECIFICATIONS
The Type SL-123 Speaker Mechanism provides extended
Uniform from 40 to 16,000 cycles. Usable
3
of an octave below lower value and a
considerable amount above the upper value.
watt input
97 db at 4 ft. with
Axial Sensitivity
5000 cycles
Crossover Network
Input Impedance
8 ohms
15 watts
Power Handling Capacity
Alnico V
Magnet Material
Magnet Weights:
14.5 ozs.
Low Frequency
1.47 ozs.
_.
High Frequency
12- 7/32"
Over -all Diameter
Mounting Data
8 equally spaced holes on 11916" circle
6-5/32"
Depth ..
4 lbs.
Weight
MI -12654
Stock Identification
frequency response with excellent spatial distribution wher
used
with a companion floor housing, Ml- 12464.
This
combination may be used in large executive offices, reception rooms, sponsors' booths or any location requiring
broadcast quality reproduction.
The SL -123 Speaker Mechanism is an extended -range cone
speaker coupled with a highly efficient tweeter unit designed for remarkably faithful reproduction over the 40
to 16,000 cycle range with excellent spatial distribution.
A special shape has been used for the curvilinear cone,
and in addition the material for the cone has received
particular attention. A further refinement
is
the damping
ring in the outer suspension of both sound and tweeter
cones which provides optimum acoustical
Frequency Response
response extends about
1
.
Accessories
impedance to
effectively eliminate standing waves in the suspension
Frequency Response Curve of
+10 db
+5
and cone.
o
This development gives improved efficiency at the bass
-5
end and relatively smooth response at the high end of the
-10
-15
spectrum. The method of cementing the concave center in
MI.12464-M
MI-12464-B
Floor Console Cabinet (Mahogany)
Floor Console Cabinet (Blonde)
12" Speaker Cabinet (Wall Mounting)
the tweeter widens the angle of high frequency response.
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Ml-1 1407-A
SL -123
Speaker.
SPEAKERS
SL -12 12 -INCH SPEAKER
plate for 10 -inch speakers, which may be removed when
it
is
desired to house a 12 -inch speaker mechanism. The
grille
is
of plastic woven cloth and covers the entire front
panel. The housing presents a neat, compact appearance
and
is
of the smallest practical size commensurate with
good performance.
SPECIFICATIONS
Speaker Mechanism
Voice Coil Impedance
8 ohms
50 to 16,000 cycles
Frequency Response
Power Handling Capacity
10
watts
Overall Diameter
12
7/32"
5/32"
Overall Depth
6
Weight
Stock
4 lbs.
MI -12458
Identification
Wall Housing
Dimensions (exterior):
Overall Height
Overall Width
Overall Depth (front to back)
1631'6"
25"
111/2"
2700 cu. in.
Volume
DESCRIPTION
Approximate Weight (unpacked)
The Type SL -12 Speaker Mechanism provides "Broadcast
Finish
Quality" reproduction when used with companion hous-
Stock Identification
ings,
MI -12464
or MI- 11407 -A. This combination
may
be used in executive offices, reception rooms, sponsors'
booths or any location requiring a pleasant setting and
12 lbs.
Dark umber gray
MI- 11407-A
Accessories
Floor
Cabinet
MI- 12464-M
(Mahogany)
MI- 12464 -B
Floor Cabinet (Blonde)
tasteful styling.
The SL -12 Speaker Mechanism is an extended -range single
12" Speaker Cabinet (Base Mounting)
MI- 11407 -A
Matching Transformer (4, 8,
MI-11731
15 ohms)
cone speaker. Its design provides uniform response from
50 to 16,000 cycles -avoiding frequency discrimination.
The smooth response of the SL -12 is obtained by employ-
ing a curve -linear-shape cone of special pulp material. An
outer suspension damping ring provides a matched terminating acoustical impedance. A distribution angle of more
than 40°
is
obtained with the
SL -12
Speaker Mechanism.
The MI- 11407 -A Housing is designed to house either 12-
inch or 10 -inch speaker mechanisms and projects sound
downward at an angle of 30
or 60 °. This permits mount-
ing of the unit to provide either a long or short "throw ".
The housing is solidly constructed of
1/2
-inch plywood with
dark umber gray finish. The housing comes with an adaptor
e
MI. 11407 -A Wall Housing used to house the
MI-11408 Speaker Mechanism
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SPEAKERS
12 -INCH SPEAKER MECHANISM,
MI- 12418 -B
FEATURES
High sensitivity
Smooth frequency response
Balanced listening characteristic
Equipped with transformer
Alnico V permanent magnet
Excellent power handling capability
DESCRIPTION
12 -inch Speaker Mechanism when used
with its wall housing, MI- 13253 -A or MI- 11407 -A is suitable
for use in many locations such as: reception rooms, corridors, offices, dressing rooms, workshops, etc. It may be
used as a talk back and cue speaker in studios.
The MI- 12418 -B
edge cone permanent magnet type
speaker mechanism of good sensitivity. The permanent
magnet uses the new Alnico V metal, which is the best
available material for the purpose. It permits high flux
density in a smaller and lighter magnet, which contributes
to the high efficiency of the speaker. The MI- 12418 -B also
has the corrugated cone feature, which, by introducing
just enough additional compliances, smooths and improves
the frequency response characteristic. External metal parts
of the MI- 12418 -B speaker are finished in umber gray
metalustre. The speaker comes equipped with a matching
transformer in place and wired to the speaker from the
This
is
a straight
6 ohm tap. Transformer impedances are 625, 1250, 2500,
and 5000 ohms.
The top, front and bottom of the Wall Speaker Housing,
MI- 13253 -A, is one -piece walnut finish veneer. The sides
are 1/2-inch solid wood. To insure extra strength, it is constructed with curved edges. The speaker opening is covered with two tone grille cloth of woven plastic in a
finish that matches the wood. The back of the unit is open
and mounting brackets are furnished. The housing measures 161/2 by 14 by 8' inches maximum and weighs 3 lbs.
and 10 ounces.
SPECIFICATIONS
Voice Coil Impedance
Frequency Response
Power Capability __
Axial Sensitivity
6 -8 ohms
50 to 8500 cycles
10 watts maximum
_
97 db at 4 ft. with
Magnet Material
Diameter
Depth
_
watt input
Alnico V
1218"
55iá"
___
Mounting Data
Net Weight
Stock Identification
1
8
equally- spaced holes on
119 ¡y" circle
4 lbs. 4 ozs.
MI- 12418 -B
Accessories
12" Wall Housing
Wall Housing
MI. 13253 -A Wall Housing for use with 12 -inch Speaker MI-12418-B.
Transformer
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MI- 13253 -A
MI- 11407 -A
MI -12368
SPEAKERS
10 -INCH SPEAKER, MI -11408
10 -INCH SPEAKER, MI- 6333 -D
DESCRIPTION
DESCRIPTION
The MI -11408 Speaker Mechanism with its associated
Wall
Housing (MI- 11407 -A) is designed specifically to provide
economical Broadcast Monitoring. Such applications include AM /FM and TV control rooms, clients' booths, offices
and studios.
The MI -11408 Speaker employs a high -quality Alnico V
permanent magnet and is capable of producing an undistorted output of 10 watts. The frequency response characteristic is such that the mechanism will give well balanced
sound when used with its companion baffle. Speaker
matching transformer MI -11731 is available for connecting
to an 8 -ohm or 15 -ohm source. (Speaker voice coil impedance is 4 ohms).
SPECIFICATIONS
Frequency Range
_
Power Handling Capacity
Voice Coil Impedance
Overall Diameter
60 -7000 cycles
10 watts
4 ohms
101/e"
Overall Depth
Weight (unpacked)...
Stock Identification
41/4"
21/e
lbs.
MI-11408
:
10 -inch permanent magnet
cone type mechanism. The cone is of one piece and is
corrugated, which results in smoother characteristics and
improved performance. The permanent magnet is of
Alnico V metal insuring permanence and stability of the
field. To make the speaker more rugged, the cone is made
moisture- resistant and a baking -type resin cement is used
throughout. This speaker has an unusually good frequency
response characteristic and capably handles large amounts
of power. The gap flux density is high, contributing to the
speaker's high sensitivity.
SPECIFICATIONS
Impedance
Frequency Range
Power Capacity
Axial Sensitivity
60 ohms at 400 cycles
60 to 7000 cycles
20 watts
95 db at 4 ft. with
watt input
Gap Flux Density
9500 lines /cm2
Magnet
Alnico V
Magnet Weight
6.8 ozs.
Diameter
101/4"
Depth
55/e"
Mounting Data__... 4 equally spaced 9/32" x 7/32" holes on 95/e" circle
Net Weight
31/2 lbs.
Shipping Weight
5'/2 lbs.
Stock Identification _
__ _ _ _
MI- 6333 -D
1
Accessories
Accessory
10" Wall Housing
The MI- 6333 -D Speaker is a
M I-11407-A
12" Wall Speaker Housing
Reducing Baffle
_.
104'
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MI-13253-A
MI.13245-A
SPEAKERS
8 -INCH SPEAKER MECHANISM, MI- 12454 -B
impedances of 700, 1400, 4000, 8000 or 16,000 ohms to
loudspeaker line.
a
The MI -6104 baffle
molded of walnut grained fire rehas four heavy reinforcing
provide additional strength
for the removable speaker
covered with an attractive
two -tone plastic grille cloth. The housing measures 151/4
by 121/4 by 55/e inches maximum overall.
is
sistant thermosetting plastic. It
ribs on the inner surface which
and rigidity and form a frame
insert. The face of the insert is
The speaker, MI- 12454 -B, factory- mounted in a compact
walnut baffle, 10'/a inches high, 111/4 inches wide and
61/4 inches deep, is available as MI- 38300 -3.
SPECIFICATIONS
Power Handling Capability
Axial Sensitivity
Frequency Response
Magnet Material and Weight
Gap Flux Density
DESCRIPTION
The MI- 12454 -B is an eight -inch cone -type speaker with a
permanent magnet field. The Alnico V magnet is the best
commercially available material providing high flux density, permanence and stability with a minimum of size and
weight. The cone, voice coil assembly and suspension are
moisture resistant. A multi -tap line matching transformer
is provided to enable the 3.2 ohm voice coil to present
8 -inch
Plastic Wall Speaker Housing, MI -6104.
Voice Coil Impedance
Voice Coil Size
Outside Diameter
Depth
Mounting Data
Net Weight
Shipping Weight _ __
Transformer Data:
16,000 Ohms
8,000 Ohms
4,000 Ohms
1,400 Ohms
700 Ohms
10
96 db
_
(á)
4
ft. with
1
watts
watt input
50- 15,000 cycles
3.16 oz. Alnico V
9000 lines /cm2
3.2 ohms (a7 400 cycles
3/4"
81/4"
31/3"
4 equally spaced holes on 75.8" bolt circle
31 oz.
16 to a carton -351/2 lbs.
Red -Black
Red- Red /Black
Red -Red /Yellow
Black- Red /Black
Red /Yellow- Red /Black
Stock Identification:
MI- 12454 -B
8" Speaker Mechanism
MI -6104
8" Plastic Wall Speaker Housing
8" Speaker Mechanism factory enclosed in Walnut Baffle _ MI- 38300 -3
MI-38300.3 Speaker Mechanism encased in Walnut Cabinet.
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SPEAKERS
8 -INCH HIGH FIDELITY SPEAKER, MI -12480
FEATURES
High sensitivity
Smooth frequency response 50 to 18,000
cycles
Balanced listening characteristic
Alnico V permanent magnet
Excellent power handling capability
Curvilinear cone plus
a
mechanically
coupled high frequency cone
DESCRIPTION
This High Fidelity Duplex 8 -inch cone type loudspeaker,
MI- 12480,
is
designed to fulfill
requirements for high
quality reproduction of voice or music
in studios,
executive
offices, reception rooms, sponsors' booths or any location
SPECIFICATIONS
50 to 18,000 cycles
Frequency Response
Power Handling Capacity
where the finest in an 8 -inch speaker both as to frequency
response and to styling is desired. It may be used with any
Magnet Weight
standard 8 -inch baffle, but it is recommended that for
quality reproduction a minimum baffle size of 21/2 cubic
feet be used.
Overall Diameter
10 watts
...
6.8 ounces
..
Input Impedance
8
Depth
4946
Weight
23/4
Axial Sensitivity at
4
ft.
1
watt, see curve
The smooth frequency response of the SL -8A Speaker is
Cone Resonance (61/2 cubic ft. cabinet)
the result of extensive research. A special shape has been
Mounting Data (EIA)
for the curvilinear cone, and, in addition, the material
for the cone has received particular attention. These two
factors play important roles in giving a broad pattern to
the speaker. A further refinement is the damping ring in
the outer suspension of the cone which provides optimum
acoustical impedance to eliminate effectively standing
the high end of the spectrum.
mechanically coupled high frequency cone extends
the smooth high frequency response well out beyond the
normal listening range of the average listener.
92 db
4
equally spaced holes
75B' bolt circle
on a
Stock
Identification
MI -12480
.IIIII111111111111
11111IIIIIIIIII
1IIIII
191I1111
IIII1!__
,riL1i11111\
8 1I/III II11II11111I1
GIIIII1IIIII111111
11111IIIIIIIIII
1IIIIIIIIIII1IIIII
D. 4TYON
V.
The
inches
pounds
74 cps
used
waves in the suspension cone. This gives improved efficiency at the bass end and relatively smooth response at
ohms
81/8 inches
AXIS
10
1111111IIIIII1IIIII
20
www.americanradiohistory.com
0000
1000
FREQUENCY N CYCLES
ER SECOND
100
SPEAKERS
7 -INCH ACCORDION CONE SPEAKER
i
SPECIFICATIONS
Speaker Mechanism
Voice Coil Impedance
Primary Impedances
Overall Frequency Response
Axial Sensitivity
Power Handling Capacity
3.2
700, 1400, 4000, 8000, or 16,000
30- 14,000
92 db at 4 ft. with 1 watt
input
8 watts
Alnico V
Magnet Material
9800 gauss
3.16 oz.
Density
Flux
ohms
ohms
cycles
Magnet Weight
Overall Diameter
Overall Depth
Mounting Data
Net Weight
Shipping Weight
Stock Identification
7"
31/2"
4 equally- spaced 0.187" holes on 6, a" circle
34 oz.
lbs.
41/2
MI- 12435 -C
Wall Baffle
Wood veneer front and 1'2" solid wood sides
Walnut
Two tone woven plastic grille cloth
900 cubic inches
17,8" high, 123í4" wide, 67/a" deep (max.)
Material
Finish
Grille Cloth
Cubic Content
Dimensions
Weight (unpacked)
Stock Identification
43/4 lbs.
MI -12845
DESCRIPTION
The MI- 12435 -C is a 7 -inch duplex accordion cone, per-
manent magnet type speaker mechanism with line match-
equipped with a mechanical coupled
high frequency cone. The magnet is Alnico V metal which
permits high flux density and permanence of the field
characteristics in a relatively small, light weight unit. The
accordion edge cone, by introducing additional carefully
controlled cone compliance, allows o lower resonant frequency than can ordinarily be obtained with conventional
design. The frequency response of the MI- 12435 -C is thus
comparable to that of much larger mechanisms. The
speaker is furnished with a universal matching transformer
with nominal primary impedance of 16,000; 8000; 4000;
1400 and 700 ohms; .3; .6; 1.2; 3.6 and 7.2 watts on
70 volt tap. The speaker has excellent frequency response,
sensitivity and power handling capability. The exterior
metal parts are protected against rust or corrosion by
heavy plating.
ing transformer. It
is
db
100
95
90
85
80
75
70
20
The MI -12845 sloping front speaker housing is made with
1/2-inch solid wood sides and a one piece,
walnut finish,
wood veneer front, top, and bottom panel. The heavy
wood sides and curved edge construction minimize the loss
of low frequency sound energy in side vibrations normally
inherent in enclosed housings. When used with the MI12435 type accordion edge speaker, the housing provides
exceptional tone quality with full low frequency response
ordinarily lacking in reproducers of a comparable small
size.
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100
1000
FREOUENCV RESPONSE CURVE
MI-12845 Wall Baffle.
10000 20000
SPEAKERS
LINE MATCHING TRANSFORMERS,
MI- 12368, MI -12369 AND MI -11731
DESCRIPTION
transformer has separate primary and secondary
windings on a 7/8" x 3/4" core. The primary is tapped with
10" color coded leads to permit matching to a number of
different speaker line impedances. The secondary is tapped
with 10" color coded leads to match voice coil impedances
of 4, 8, or 16 ohms.
This
PRIM.
SPECIFICATIONS
+I12 db from 60 to 10,000
Frequency Response
Distortion
2% max. from 100 to 10,000
Power Handling
8
@a
Max. 16 watts of program material
Mounting Centers
Dimensions
1,250
625
31,'e"
Height 2'4 ", Length 336 ", Width 2"
1
lb. 6 oz.
_.
MI -12368
Net Weight
o
Stock
watts
Identification
_.
DESCRIPTION
4
transformer has separate primary and secondary
windings on a 5/8" x 5/8" core. The primary winding is
tapped with 10" color coded leads to match several different line impedances used in multiple speaker installations. The secondary matches any 3.2 to 4 ohm speaker
This
MI -12369
PRIM.
16,000
SPECIFICATIONS
SEC.
4
Frequency Response _.1 db from 100 to 12,000 cycles
Distortion
8,000
2% max. from 100 to 8,000
@a
5 watts
Max. 8 watts program material
Power Handling
Mounting Centers
4,000
Dimensions
23-e"
Height 15e" Length
21316
", Width
Net Weight
Stock
4
MI-11731
1976"
10 oz.
MI -12369
Identification
DESCRIPTION
Ml -11731 is a single -winding transformer used to match
any combination of 4, 8 and 15 ohm speaker impedances.
Soldering lugs are provided for making connections.
SPECIFICATIONS
+1.0 db from 60
Frequency Response
Power Handling
Mounting Centers
Dimensions..._ Height
Net Weight
Stock Identification
108
to 10,000
2% max. from 100 to 10,000
Distortion
8
watts
23's"
1
21/32 ", Length,
2 ",
Width 3á"
10 oz.
MI -11731
SPEAKERS
CHART SHOWING SPEAKER APPLICATIONS,
RECOMMENDED HOUSINGS,
AND
SPECIFICATIONS
Voice
Power
MI
Diameter
Number
(Inches)
MI- 11411 -A
15
LC-1A
Coil
Frequency
Range
Master program monitor, executive offices, clients' rooms,
reception rooms, any application requiring maximum quality of sound reproduction
20
40- 16,000
Program monitoring, executive offices, clients' rooms, reception rooms
15
40- 16,000
cps
8
MI- 12464 -M
B
MI- 11407 -A
MI- 12464 -M
B
MI- 11407 -A
Im p e_
dance
(Ohms)
15
cps
MI -12458
12
Program monitoring, executive offices, clients' rooms, reception rooms
10
50- 16,000
cps
8
12
Utility monitoring, spare program monitor, studio and an-
15
50 -8500
8
cps
MI- 6333 -D
MI -12454
10
10
8
MI- 12454 -A
Utility monitoring, spare program monitor, studio and announce booth, cue, offices
Public Address, Studio talkback, and intercom systems
dressing
cuing,
Turntable
rooms, intercom, paging sys-
10
60-7000
MI- 13253 -A
MI- 11407 -A
nounce booth cue, offices
MI -11408
MI -11406
MI- 12464 -B
(Blonde)
(Mahogany)
12
MI- 12418 -B
Housing
MI- 12464 -M
MI -12654
SL -123
SL -12
Wall
Floor
Cabinet
Handling
Capacity
(Watts)
Uses
4
M1- 11407 -A
6
MI- 13253 -A
with
MI- 13245 -A
4
MI -6104
ps
20
60 -7000
cps
10
50- 15,000
cps
tems.
MI- 38300 -3
8
dressing
cuing,
Turntable
rooms, intercom, paging sys-
10
50- 15,000
4
Mounted in
8" baffle
cps
tems.
MI -12480
8
Program monitoring,
tive offices, clients'
reception rooms
MI- 12435-C
7
Public address, cuing, intercorn systems
execurooms,
10
50- 18,000
cps
8
MI- 11407 -A
MI -6104
8
30- 14,000
cps
3.2
MI -12845
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TEST EQUIPMENT
DISTORTION AND NOISE METER
TYPE
WM -71A
FEATURES
USES
no direct connection to audio
Distortion and Noise Meter, RCA Type WM-71A, is a compact precision instrument for measuring the total distortion
and the level of noise and hum in audio- frequency circuits.
It permits continuous coverage of the audio frequency
range, indicating directly the percentage of a -f distortion
in modulators, speech amplifiers, a -f generators, receivers
and other equipment employing audio frequencies. The
instrument will give full -scale readings for distortion percentages as low as 0.3 %, and is capable of measuring
noise components at frequencies from 30 to 45,000 cycles.
Audio oscillator distortion can be measured
The instrument has many uses in the communications laboratory and in the production testing of radio receivers as
Quick frequency selection
wide range highly sensitive voltmeter or VU meter
Can be used as a
Distortion measurements, as low as 0.1%,
quickly and easily made by one tuning
adjustment
Requires
oscillator
a wide -range,
Tapped power transformer permits operation on either 105 -125 volts or 210 -250
volts
Audio frequency range 50 to 15,000 cycles
for distortion measurements; 30 to 45,000
cycles for noise and hum measurements
highly sensitive voltmeter for such measurements as signal -to-noise ratio, AVC characteristics and hum
level. With the aid of an oscilloscope, individual hum and
distortion components can be identified. When used with a
linear detector such as the RCA Type BW -66F Amplitude Modulation Monitor, the distortion and noise characteristics
of broadcast and other radio -telephone transmitters can be
measured.
TEST EQUIPMENT
NOME
CAL/eRrE0
r7AVIn'Nr
S
/XCE AMPLIFIERS
PULL CIRCUIT
IMP
P
Elementary schematic circuit diagram of the WM-71A Distortion and Noise Meter.
SPECIFICATIONS
DESCRIPTION
The WM -71A Distortion and Noise Meter consists essen-
tially of a high -gain amplifier, an r -c interstage coupling
unit, a calibrated attenuator for adjusting the sensitivity,
and a panel meter to indicate amplifier output.
The r -c interstage coupling unit balances to a sharp null
at the frequency to which it is tuned, the null frequency
being continuously variable and controlled from the panel.
Degeneration is employed to maintain high stability in the
amplifier and to provide flat transmission characteristics
except within an octave of the null point.
distortion the audio- frequency signal is applied to the instrument and the null point is obtained to
balance out its fundamental frequency, leaving only its
harmonics and other distortion components which are indicated in percentage directly on the panel meter. When the
modulated output of a radio transmitter is to be measured,
a linear rectifier is required to produce the audio envelope.
Any linear detector system having an undistorted output
of 1.5 volts can be used.
In measuring
A switch on the front panel provides for switching out the
null circuit so that the instrument can be used as an extremely sensitive voltmeter for measuring hum and noise
levels. Since the WM -71A has only one tuning control plus
a small trimmer, it can be quickly set to any frequency
over its range. This is a time -saving feature in making a
series of measurements. Two input circuits are provided:
a transformer for bridging a 600 -ohm line, and a direct
connection to the 100,000 -ohm gain control. Input terminals are provided at the rear of the instrument for direct
connection to the modulation monitor.
The instrument is relay rack mounted. All essential controls
are located on the front panel. A large meter with an
easily read, illuminated scale is provided, and percentage,
decibel and dbm calibrations are included. The power
supply is voltage regulated so that line surges have no
appreciable effect on the instrument.
Distortion Range
Full scale deflections for 0.3 %, I %, 3 %,
10% or 30% distortion
Noise Measurement Range -80 db below reference calibration level,
or 80 db below an audio -frequency signal of zero dbm level, at
maximum sensitivity.
50 to 15,000 cycles (fundamental), for
Audio -Frequency Range
distortion measurements; 30 to 45,000 cycles for noise and hum
measurements.
Power -level range is from +20 to -60 dbm
(0 dbm is one milliwatt in 600 ohms)
1.2 to 30 volts for the 100-kilohm input, and
Input Voltage Range
0.8 to 30 volts for the 600 -ohm bridging input
For distortion measurements +5% of full scale for each
Accuracy
residual distortion as noted below; for noise and dbm
range
measurements, ±5% of full scale.
Dbm Range
±
Residual Distortion Level:
100 -kilohm Input
Bridging Input
Residual Noise Level
0.05%, max., below 7500
0.10 %, max., above 7500
c.
c.
0.10 %, max., between 50 and 70 c.
0.05 %, max., between 70 and 7500 c.
0.10 %, max., above 7500 c.
Less than -80 db
Input Impedance.... .100,000 ohms unbalanced, and 600 -ohm bridging
input (10,000 ohms), balanced or unbalanced
Tapped primary provides for operation on a-c line
voltages of 105 -125 volts, 50/60 cycles, single phase, or 210 -250
volts, 50/60 cycles, single phase.
65 watts
Power Consumption
Power Line
Tube Complement:
4 -6J5
1
-6H6
1- 65N7-GT
Dimensions
1- 6X5 -GT
1- 6K6 -GT
2- 0D3 /VR150
19" wide, 7" high, 12" deep
373/4
Weight
lbs.
Umber gray lacquer
Finish
Equipment Supplied
MI. 30071 -A
WM -71A Distortion and Noise Meter
Including electron tubes, line connector, interconnecting
cable, instruction book (IB- 4071 -1), and spare fuses.
Optional and Accessory Equipment
WA -28A Low Distortion Oscillator
BI -11A
Transmision Measuring Set
MI- 30028 -A
MI -11350
TEST
EQUIPMENT
AUDIO PUSH -BUTTON OSCILLATOR
TYPE
WA -28A
E0UEM0
30
aww:
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EQUENCY MULTIPLIER
FEATURES
USES
The Type WA -28A
Very low distortion
A high degree of frequency stability which
makes this oscillator particularly adaptable
for use with distortion meters employing
r -c null networks
Push -button selection of any one of 27
frequencies from 20 to 15,000 cycles
Any other desired frequency within the
normal range can be obtained by the use
of plug -in resistors
Duplicate output terminals on rear for relay rack installation
Chassis designed for mounting in standard
equipment racks
Ease
of operation from front panel controls
Oscillator was designed particularly for
use as a tone source for distortion measurements and as a
power source for bridge measurements at audio frequencies. It is also satisfactory for use as a general- purpose
laboratory oscillator.
The output frequencies include those recommended by the
FCC for distortion measurements on broadcast transmitters.
This oscillator is thus ideal
for use with the Type WM -71 -A
Distortion and Noise Meter for rapid distortion measurements. The unusually pure waveform delivered by this
oscillator at low frequencies makes distortion measurements possible at low frequencies.
DESCRIPTION
The WA -28A
oscillator is of the resistance -capacitance
type and uses an inverse feedback. Separate feedback
networks control the frequency and amplitude independently, thus providing high stability and low distortion. The
degenerative feedback which controls the frequency is
obtained by means of a parallel -T network including mica
capacitors and wire -wound resistors. The regenerative network includes an automatic control system whereby a high
TEST EQUIPMENT
DapanerONon PIEe
5000A
lrr:uenst SeSÇrif Nar..áA
OUTPUT
QJCrpLr
QUTPUT
_saECEON
oorror
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Elementary schematic circuit diagram of the WA -28A Low Distortion Oscillator.
degree of stability is obtained together with low harmonic distortion, without requiring any manual feedback
adjustments.
The instrument is mounted on a chassis fitting standard
equipment racks. Controls on the front panel include ten
frequency push- button switches. Three other push- buttons
select the output impedance and a control is provided for
adjusting the output voltage. Three frequency multiplier
switches and two output jacks are also provided. Terminals
are located inside the instrument which permit any specific frequency between the limits of 20 and 15,000 cycles
to be obtained by insertion of a set of three calibrated
resistors. The values of these resistors for any frequency
may be obtained from the chart.
available are: a constant 600 -ohms
balanced to ground, a 600 -ohms unbalanced, and a 5000 ohm unbalanced. The 600 -ohm output positions use transformer coupling and therefore can be operated either
into a balanced line or a grounded line. The internal impedance is essentially constant at 600 ohms. The 5000 -ohm
output position can be operated unbalanced only. The
output control is a potentiometer, and consequently the
output impedance is not constant. The total harmonic distortion of any of the outputs will not exceed 0.1 % when
operating between 40 and 7500 cycles, and is never more
than 0.25% when operating at extreme frequencies. The
operation of the instrument is substantially independent
of climatic changes in temperature and humidity.
The output impedances
Jack -top binding posts with standard 3/4 -inch spacing and
standard Western Electric double output jack are provided
on the panel. A ground terminal is also provided. A
standard multipoint connector provides duplicate output
terminals on the rear of the instrument for relay -rack
installation. These terminals are disconnected when a plug
is inserted in the Western Electric -type panel jack. The
instrument is provided with power cord, multipoint connector and spare fuses.
SPECIFICATIONS
Frequency Range
27 fixed frequencies between 20 and 15,000 cycles
Adjusted within 1 V2% ±0.1 cycle
Frequency Calibration
than 0.02% frequency drift per hour
after the first 10 minutes of operation
18 milliwatts into 600 ohms load, or 6.6 volts open
Output Power
circuit; 100 milliwatts into 5000 ohm load, or 30 volts open circuit;
constant within -±1 db throughout frequency range.
600 -ohm balanced to ground
Output Impedances
600 -ohm unbalanced
5000 -ohm unbalanced
Waveform Distortion:
Less than 0.1 % between 40 and 7500 cycles
5000 -ohm Output
Less than 0.15% at other frequencies
Less than 0.1 % between 40 and 7500 cycles
600 -ohm Output
Less than 0.25% between 20 and 40 cycles
Less than 0.15% above 7500 cycles
105 to 125 (or 210 to 250) volts,
Power Supply
50/60 cycles, single phase
45 watts
Power Consumption
Tube Complement:
Frequency Stability
1
1
1
Less
-6Y6 -G
-NE -17
-6B4 -G
1
1
-6SJ7
1-6SK7
-65Q7
1-6X5
1-0D3/VR150
1- 6SL7 -GT
19" wide, 7" high, 12" deep
Dimensions
321/2 lbs.
Weight
Finish
_.
__....
Light umber gray
Equipment Supplied
MI-30028 -A
WA -28A Low- Distortion Oscillator, complete
Including electron tubes, line connector, multiple point
connector, instruction book (IB- 4028 -1) and spare fuses.
Optional and Accessory Equipment
Noise and Distortion Meter, Type WM -71A
Transmission Measuring Set, Type BI -11A
www.americanradiohistory.com
MI-30071-A
MI-11350
TEST
EQUIPMENT
TRANSMISSION MEASURING SET
TYPE BI -11A
FEATURES
Simplifies audio measurement
Eliminates lengthy calculations-di rect reading
0.1 db accuracy over frequency
range of 20 to 20,000 cycles
Automatic correction for changes in
load impedance
DESCRIPTION
The Transmission Measuring Set, Type
-11A, is a simplified, accurate and direct -reading instrument designed for
use in the following applications: (1) audio gain measurements; (2) audio loss measurements; (3) measurements of
matching and bridging devices; (4) complex circuit measurements; (5) measuring mismatch loss and frequency
response measurements. The instrument also may be used
as an independent volume level indicator.
BI
SPECIFICATIONS
Frequency Range
20 to 20,000 cycles
Accuracy (independent of level from
Overall
+4
to
-110 dbm):
±0.1 db, 20 cycles to 20 kilocycles
Source and Load Impedances for Dial Indicators
Over Entire Range
Within -1-2%
Network Resistors
±1.0%
Source Characteristics:
Shielded Output can be used equally well on either balanced or
unbalanced equipment
+4
-10
Ranges (in steps of 0.1 db)
-110
-124
to
to
db
db
Range of Impedance:
The instrument facilitates overall system measurements and
may be used with the WA -28A Low Distortion Push -button
Oscillator and the WM -71A Distortion and Noise Meter.
It eliminates lengthy calculations and intricate setups. It is
designed to provide accuracies conforming to FCC regulations and is particularly useful for broadcast stations in the
master control room or at the transmitter.
Internally Terminated
600 -150 ohms
Unterminated
600 -250- 150-30 ohms
Internal isolation network for operating into non -linear devices.
Load Characteristics (resistive load, ungrounded):
+4
to +42 VU @ 600 ohms
600-250- 150- 16 -8 -4 ohms
19" wide, 7" high, 8V /a" deep
Range of Load Levels
Range of Impedance
Dimensions
Weight
19 lbs.
light umber gray
Finish
Stock Identification
(includes tubes)
MI -11350
The BI -11A Transmission Measuring Set consists of a volume
indicator meter, input and output attenuators, an impedance matching system and jacks for convenient connections. A meter multiplier, which is geared to the load
impedance shaft, provides an automatic correction for
changes in load impedance. Convenient switches allow the
volume indicator to be connected to the input of the
attenuator system or to jacks for external connection. An
output impedance switch allows matching to 600- 250 -15016 -8 -4 ohm circuits.
Accessory Equipment
Low Distortion Push Button Oscillator
MI-30028 -A
Distortion and Noise Meter
MI-30071-A
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60:
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161
600
1
599
1
599/
Level controls, switches, jacks and VI meter are located on
the front of a standard 19 inch rack -type panel. The panel
hinges forward to provide ready access to attenuators,
jacks, switches and other components. Unit type assemblies
(individual sections, such as source, attenuation and load)
are readily removable for servicing. Each section is a complete assembly with its own jacks and terminal block.
/ `
605
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03
LOAD SECTION
-
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200
rNEOUENCT
400 600
N00
2000
CYCLES PER SECOND
4000
.3000
30000
TEST
EQUIPMENT
TRANSMISSION MEASURING SET
Audio Signal Generator and Level Meter -Model 452A
«rtrwT aN41
iroTá DIN
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OR MON
IMEOYCI
DESCRIPTION
FEATURES
Direct reading eliminates lengthy calculations
Simplifies measurement of transmission
characteristics of audio systems and their
components.
Generates signals ranging from mike to
line level
Measures signals from noise to line levels
Wide frequency range
Self- contained low distortion oscillator
The Waveforms, Inc., Model 452A transmission measure-
ment set makes all previous transmission measuring and
generating instruments obsolete. Unlike other types of
transmission measuring instruments, the 452A combines
both measuring and generating devices into one compact
and easily mounted instrument. Whereas, other equipment
used for the same purposes consist of a separate measuring set and separate generator, this new instrument
combines all of these functions into one unit with interlocking controls. With the 452A, the engineer no longer
is required to spend considerable time in complicated
calculations, but merely turns a switch and automatically
obtains a reading of the output level and measurement
of the return signal.
The precision AC volt meter incorporated
USES
The Transmission Measuring Set, Model 452A, is a simpli-
fied, accurate and direct -reading instrument designed for
use in the following applications: (1) audio gain measurements; (2) direct audio voltage and level measurement;
(3) signal to noise ratio; (4) frequency response measurements; (5) low distortion signal source for distortion measurements. This unit should be standard equipment in
broadcast stations, sound engineering laboratories and
central telephone exchanges.
in the 452A
permits direct measurements of all levels from noise to line.
This is the only instrument which by the nature of its circuitry does not require correction of readings for different
setting of input or output impedance. Unlike the now obsolescent fixed switch -tuned generators, the 452A has a
continuously variable oscillator that permits the analysis
and correction of unwanted "peaks" and "holes" in the
response of a transmission system.
The OUTPUT section of the instrument consists of a continu-
ously variable oscillator which delivers +20 dbm into a
precision decade attenuator followed by a repeat coil. A
www.americanradiohistory.com
20
+
70
3
ro
TEST EQUIPMENT
AMPLIFIER
r-
INPUT RANGE
(10 DB /STEP)
REPEAT
0-
"METER
READS"
IMPEDANCE
SELECTOR
1
INPUT
METER
METER
PA
FINE OUTPUT
LOSS)
D
OUTPUT RANGE
(0 -8008 LOSS
(0-3008
IN IO
r:
REPEAT
COIL
STEPS)
IOCPSIOOKC
IMPEDANCE
OSCILLATOR
SELECTOR
I-0
-O
OUTPUT
BLOCK DIAGRAM OF WAVEFORM 452A
panel switch permits instantaneous strapping of the repeat coil to match loads of 50, 150, 250, or 600 ohms,
all balanced. The frequency range of the instrument so
used is 15 cps -50 KC. A panel switch permits the repeat
coils to be by- passed in which case the frequency range
is 10 cps to 100 kc into a 600 ohm unbalanced load.
The positions of the decade attenuator in dbm are j 20,
10, 0, -10, -20, -30, -40, -50, and "No Signal." A
Fine Output Control permits adjustment of signal output
to any point between these settings. When the "Meter
Reads" switch is in the "Output Level" position, the output
is read automatically on the meter. The meter reading is
simply added to the reading of the decade attenuator.
No correction factor for impedance setting is required.
The
INPUT
section
consists
of an
amplifier AC volt-
meter which is accurate over the range 10 cps -l00 kc.
An input repeat coil is switch strapped for matching or
bridging circuits of 50, 150, 250, or 600 ohms balanced
or unbalanced. A fifth position on this Input Impedance
Selector connects the set's input terminals directly to the
voltmeter, by- passing the repeat coil. With the repeat coil
in the circuit, the meter range is 15 cps -50 kc. With
the repeat coil out of the circuit, the meter range is 10
cps -500 kc, and the instrument input impedance is 10
megohms unbalanced. The meter range switch is a decade
attenuator of twelve positions marked -60, -50, -40,
-30, -20, -10, 0,
10,
20,
30,
40 and -j 50
dbm. Levels of above
20 dbm may only be read with
the repeat coil out of the circuit ( "high impedance" position). Because a linear meter movement is used, levels as
low as -80 dbm may be read directly.
SPECIFICATIONS
GENERATOR:
Frequency Range:
600 t) unbalanced
50, 150, 250, and 600 `- -' balanced
Frequency Accuracy
Output Level Accuracy:
600 t! unbalanced
150 and 600 9 balanced
Output Level Range
10 cps -100 kc
15 cps -50 kc
-mil'
50 and 250 '
-'
Noise
11
cps)
+_!ia db lOcps -100 kc
db 15 cps -15 kc
+'.,
+1'2 db
15 cps -50 kc
Relative
_
Output Impedance Accuracy:
600 9 unbalanced
150 and 600 `! balanced
50 and 250 9 balanced
Distortion
0.1% max. 30 cps -15
(-I-1
-5%
+5%
10 cps -100 kc
30 cps -15 kc
Relative
to I- 10 dbm output
80 db below full output
kc up
Continuously variable from
-I 20 dbm to
-60
dbm
LEVEL -METER:
Calibration Accuracy:
Unbalanced (10 Meg
150, 600 =! balanced..
'-
-')
±''i
db 10 cps -100 kc
db 15 cps -15 kc
±''2 db 15 cps -50 kc
Relative
+'á
50, 250 !! balanced
Input Impedance Accuracy (Matching):
150, 600 '! balanced
+5% 30 cps -15 kc
50, 250 '! balanced
Relative
Input Impedance (Bridging)
Above 10 k t!
Meter Scrsles
0 -1 and 0 -3 volts; -12 to ( 2 dbm
Meter Ranges in dbm at all
nominal impedances
-60 dbm to -( 50 dbm in 10 db steps
Meter Residual Noise
35 db below full scale on all ranges
TEST EQUIPMENT
WAVEFORMS' AUDIO TEST EQUIPMENT
AUDIO OSCILLATOR, MODEL 510 -B
The Model 510 -B is a precision source of sinusoidal sig-
nals in the Audio and Ultrasonic range. It has a frequency
range of 18 cycles to 1.1 megacycles, with constant out1/2
db and calibration accuracy of *2%
put of
(
1% on special order). The stability is -'_1/2% with temperature and line voltage. A distortion of less than 2/10%
over most of useful range and maximum output of 10
volts or 4 ma ( +15 dbm into 2000 ohms) is provided.
Source impedance is 400 ohms. Logarithmic output control
is calibrated approximately in volts. The unit is briefcase
portable weighing less than six lbs. The power requirements are 95 -130 volts, 50 -400 cycles, 40 watts. Unit
measures 8" high, 6" wide, 101/2" deep and weighs 12
pounds. Power consumption is 60 watts.
The
following accessories are available:
Model T -10 Balanced Matching Transformer attachment for the 510 -B
provides 150 or 600 ohms balanced source. Flat ±1/2 db from 18 cycles
to 50 kc, Output +2 dbm. A T -11 Balanced Matching Transformer
attachment for the 510 -B provides 135 or 600 ohm balanced source.
600 ohms +1/2 db from 30 cycles to 200 kc. 150 ohms ±-1/2 db 20
cycles to 150 kc. Output +10 dbm.
FEATURES
Briefcase portable
Constant 1/2 db output
The Series 100 Attenuators conveniently provide low signal levels from
any oscillator or signal generator with standard 3/4" terminals. Dc
to 2 mc, Model 101 has a 10:1 ratio; Model 102, 100:1 ratio; Model
103, 1000:1 ratio with ±1% accuracy.
Very low distortion
18 cycles to 1.1 megacycles
GENERAL PURPOSE OSCILLATOR, MODEL 401 -C
FEATURES
9 cycles to 120 kc
distortion
watt output
1/4%
1/2
Step attenuator
The Model 401 -C is a general purpose Audio Oscillator
featuring half watt power capability and an output attenator. It has extended frequency range of 9 cycles to 120
kc, with constant output
1/2 db and calibration accuracy
-2% (' 1% on special order). The stability is
of
1/2% with temperature and line voltage, and maximum
output is 20 volts open circuit or 1/2 watt into 600 ohms
17.3 volts). Distortion is less than 1/4% An
( +27 dbm,
attenuator switch and logarithmic output control calibrated
millivolt is
approximately in volts, for levels down to
provided. Source impedance is less than 100 ohms.
r
}
1
117
TEST EQUIPMENT
SINE -WAVE GENERATOR, MODEL 512
FEATURES
9/10 cycle to 510
1/10% distortion
kc
watts output
Step attenuator
2
The Model 512
is a precision source of sinusoidal signals
from subaudio through the ultrasonic range. It has a
frequency range of 9 10 cycle to 510 kc, with a constant output of
1/2 db and calibration accuracy of -' -2%
(
% on special order). The stability is
with
' /s%
temperature and line voltage. Distortion is less than
10%
over most of useful range and the maximum output is 50
volts open circuit, or 2 watts into 600 ohms (34.5 volts,
+33 dbm). The output is calibrated in four decade
ranges from 5 millivolts to 50 volts, -'-10 %. Source impedance is 50 ohms or less. The Model 512 is readily portable,
weighing less than 18 lbs. The power requirements are
105 -130 volts, 50 -400 cycles, 110 watts.
1
1
AMPLIFIER -VOLTMETER, MODEL 520 -A
FEATURES
10 cycles to 2 megacycles
1.0 millivolt full scale
12 ranges to 300 volts
Null indicator
5 cycles
to 4 mc
The Model 520 -A
is a stable, general purpose AC voltmeter, null indicator, and decade amplifier, featuring high
input impedance for negligible circuit loading, full -wave
average rectifier for minimum waveform error, and extremely low pick -up from stray fields and power line.
It has a meter range from 1.0 millivolt full scale to 300
volts, permitting measurement to 100 microvolts and useful indications at still lower levels; -70 to +50 dbm in
10 dbm ranges. Its accuracy is
3 %, 20 cycles to 1 mc;
or - 5% 10 cycles to 2 mc and stability is ' 1% with
line voltage from 105 -130 volts. The input impedance is
10 megohms shunted by 24 mmf; and amplifier gain is
1000. The meter is protected against overload. The equipment is briefcase portable weighing 6 lbs. An illuminated
meter and mirror scale are available on special order. The
voltmeter is rated 40 watts, 50 -400 cycles.
TEST
EQUIPMENT
RECOMMENDED WIRING PRACTICES
Loudspeaker and other lines above +30 vu.
At times further subdivisions are made for convenience in bulk or because levels are widely
separated.
Each cable is bound with lacing cord so the shields
are in tight contact for their entire length. Where two
audio cables cross or join, they should either be definitely insulated or bound together. It is better to have
tight contact than to risk an intermittent noise source
made by casual contact.
The ends of the individual shields are terminated
either with "wedge -on" collars or with plastic tape.
The shields are grounded to a main ground bus near
the terminal block. A shielded ground lead is run from
each amplifier chassis to the ground bus.
The a -c and d -c power circuits are handled similarly.
All a -c circuits should be in twisted pair, shielded
cable. The a -c current should be balanced in each pair.
That is, one pair should not be used for one side of a
circuit and a second pair for the other side. If more
than one pair is needed for the load, two or more
pairs should be used with part of the load on each.
Plus and minus plate potentials should be carried in
single conductor shielded cable. Shields are tied off
and grounded the same as the audio circuits.
(c)
(d)
Photo of terminals at bottom of rack. Power terminals are at left,
ground bus in center and audio terminals at right.
Almost every studio undergoes minor modifications
from time to time, and the subject of proper wiring
practice is raised. Modern standards require careful
elimination of noise and crosstalk from the program
circuits. It is not uncommon to spend many hours
wiring in new components, only to find their performance reduced by the wiring itself. A tested and proven
standard practice can avoid much wasted time.
There are two basic philosophies employed in practical approaches to the noise problem. In one system
every circuit shield is carefully isolated from its neighbors and grounded at one point only. In the other, all
the shields of one unit (such as a rack) are put in such
close contact that a brute -force ground is provided for
any stray currents that might be present. This latter
approach is taken in RCA equipment with modifications as follows:
Every rack, cabinet or desk is wired as a unit to terminal boards. The terminal boards are placed as near
as possible, consistent with accessibility, to the point
where the external circuits enter the unit. See Figs.
and 2 for examples.
In a rack, as viewed from the back, all audio cables
are run on the right side of the rack; and all signal, a -c
and d -c power cables are run on the left side. All audio
circuits are twisted pair conductors shielded with a
tinned copper braid. Separate cables are formed for:
(a) Microphone outputs, preamplifier outputs and
other audio circuits with levels below -20 vu.
(b) Mixer, line and channel circuits up to +30 vu.
1
View of wiring at rear of a typical audio relay switcher and
control panel. Equipment is mounted in standard broadcast rack.
TEST EQUIPMENT
Id&
Signal circuits do not require shielded wire.
The frames of jacks should be tied together and
grounded with a shielded wire the same as amplifier
SHIELDED
TWISTED PAIR
H.-
chassis.
In installing the equipment in a studio or control room
the following rules have been found useful:
The pairs run in conduits should be grouped in the
same general way as the cables in the racks. The
audio conduits should be kept free from grounds to
power conduits or power circuits. Low level audio
circuits (less than -30 vu) should have the shields
insulated from the conduits and from each other.
RACK AUDIO
TERMINALS
Typical good practice for microphones is shown in Fig
No. 3a. In this case two conductor shielded wire, with
insulation over the shield, is used for the conduit run
and the microphone cord. Fig. No. 3b shows somewhat
better practice in which 3- conductor shielded, insulated cable is used for the conduit run and microphone
cord. This latter practice removes any ground current
from the shield.
Turntable pickup circuits should be handled like microphones with particular care being taken to keep the
PREAMPLIFIERS
SHIELD
TO MIC
FROM
(A)
MICROPHONE
MICROPHONE
OUTLET
SHIELDED -TWISTED
INSULATED FROM CONDUIT
3 WIRE
M CROPHONE
OUTLET
SHIELD TERMINATED
WITHOUT CONTACT
TO MICROPHONE
TH RD WIRE CONNECTED
TO MICROPHONE GND
(a)
motor power circuits and their shields away from the
audio circuits.
The input to mixer circuits is usually at comparatively
high level, but the output is frequently very close to
microphone level and the circuits should be treated
in the same way. Fig. No. 4 shows typical good
grounding practice in this respect. Unbalanced circuits
may be used but are usually more difficult to handle
if there is noise present. It will be noted that the only
ground to this part of the system is at the point of
lowest level and that all the circuits are balanced to
ground. The center taps of the mixer attenuators are
only tied to ground if special noise difficulty is encountered and tests indicate improvement. This occasionally happens on circuits which connect to remote
lines or studio equipment with separate ground
systems.
MIXER
ATTENUATORS
MAIN
AMPLIFIER
RACK GROUND
DESK
RACK
RA
RACK
CONNECTED
FRAME (GNO)
CONDUIT
II
GROUND
DESK GROUND
RACK
--
COMPONENT TERMINAL
DESK TERMINALS
O -RACK TERMINALS
STATION GROUND
O
Fig. 4.
GROUND
SHIELDED-TWISTED
PAIR INSULATED
Signal and telephone circuits should not be run in the
same conduit with program or power circuits. Telephone leads should be twisted pair. Power and audio
grounds should consist of separate, heavy shielded
leads to the main station ground.
shield grounded only at the point of lowest level.
RACK
CONDUIT
Splices should be avoided. Low level conduits should
be well spaced from power conduits.
TV circuits in general should be considered high level
circuits and should therefore be kept away from low
level audio circuits. In particular, pulsed lamp circuits
should be routed as far away from projector photocell
and preamplifier circuits as possible. Shields should
be insulated from ground and the audio circuit and
SHIELDED SINGLE CONDUCTOR
SHIELDED WIRES BOUND INTO
THEIR RESPECTIVE CABLES
IN RACK.
o
0-
AUDIO DATA SECTION
AUDIO
DATA
SECTION
CONTOURS OF EQUAL LOUDNESS TO THE EAR
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INDEX
INDEX
MICROPHONES
Page
Type Number
7 -8
77-DX
7 -8
77-DX
8
9 -10
11 -12
13-14
14
14
14
15 -16
16
16
17
18-19
18 -19
20
Description
BK -10A
BK -IA
BK -5A
ßK -611
SK-458
SK -35
SK -46
SK -39
Polydirectional Microphone
Polydirectional Microphone (TV Low Luster Gray)
Protective Cloth Zipper Bag (for 77 -DX)
Ultradirectional Microphone
Pressure Microphone
Uniaxial Microphone
Boom Unit (for BK-5A)
Wind Screen (for BK -5A)
Cushion Mounting Assembly
Miniature Dynamic Microphone
Microphone Holder (for BK -6B1
19 -Inch Flexible Microphone Stand (for BK-68)
Pressure Microphone
Anti -Noise Velocity Microphone
Program Velocity Microphone
Aerodynamic Microphone
4045 -F
11006 -C
11187
11018 -A
11007
11(110
11012
11011
Stock #93973
MICROPHONE STANDS AND BOOMS
Desk Stand (for BK -1A
Desk Stand (for SK -Type Microphones
Announce Stand, % " -27 Thread
22
22
22
22
23
23
I
Desk Stand, % " -27 Thread
Desk Stand
Pushmike Stand
Floor Stand
Portable Stand
Floor Stand
Sectional Stand
23
23
24
24
26
27
27
Cushion Mounting Assembly (see page 14)
Microphone Holder for BK-6B (see page 16)
19 -inch Flexible Microphone Stand for 13K -611 (see page 16)
Flexible Microphone Stand, 13"
Flexible Microphone Stand, 19"
Flexible Stand Bracket Clamp
Microphone Cable Hook (see page 30)
Boom Stand (6 ft. extended)
Boom Stand (18 ft. extended)
Boom and Perambulator (17 ft. extended)
Microphone Boom Only
27
Perambulator Only
24
24
24
25
MI Number
General Information, Microphones
5 -6
KS-3B
11017 -A
12086
12087
12045 -B
12035
12046
12039A
11008
12066 -B
4096 -A
13240 -B
4092 -E
ES -6427
4090-A
4093 -C
ES- 4068-G
ES -6208
11745
11746
11747
11056
11070
26574
26574-1
26574 -2
MICROPHONE PLUGS AND RECEPTACLES
28
28
28
28
28
UÁ3.11
UA -3 -12
UA -3 -13
28
P3CGIIS
28
28
28
28
28
P3-CG-12S
P3 -35
XLR -3 -31
XLR-3-32
XLR -3-IIC
XLR -3 -12C
Female Plug for Microphone Extension Cable (mates with UA-3-12)
Male Plug for Microphone Cable (mates with UA -3 -11 and UA -3.13)
Flush Mounting Receptacle (mates with UA-3-12)
Male Plug for Microphone Cords
Wall Receptacle for Male Plug P3- CG -12S
Female Plug for Microphone Extension Cords
Male Adaptor for Plug Connection
Female Microphone Receptacle
Male Microphone Receptacle
Microphone Plug, Female
Microphone Plug, Male
MICROPHONE ADAPTORS
Adaptor W' Pipe Thread Stand to %" Mike
Adaptor t/2" Pipe Thread Stand to 3¡, " --27 Mike
Adaptor t/2" Pipe Thread Stand to W.E. %" - -24 Mike
Adaptor W.E. % " -24 Stand to 1/2" Pipe Thread Mike
Adaptor %"-27 Stand to t/a" Pipe Thread Mike
29
29
29
29
29
29
29
Adaptor % " -27 Stand to 1/2" Pipe Thread Mike
Adaptor t/z" Pipe Thread Mike
29
29
29
CABLES
Microphone Cable, Three Conductor, #20 A. W. G
Microphone Cable, Two Conductor, #16 A. W. G
Microphone Cable, Two Conductor, #24 A. W. G
1
11061
11062
11063
4630 -B
4624 -A
4620 -B
11069
11088 -B
11087 -B
11090 -A
11089 -A
12051
12053
11066-2
11066-3
6229
12055
11009
43 -C
13307 -A
13322
1
INDEX
CABLES (Continued)
Page
Description
Type Number
Pair,
Pair,
Pair,
Pair,
Interconnecting Cable, Shielded
Interconnecting Cable, Shielded
Interconnecting Cable, Shielded
Interconnecting Cable, Shielded
#22 A. W. G
Cable Hook
Cable Lacing Cord #6
30
30
30
30
30
30
MI Number
#20 A. W. G. Solid
#22 A. W .G. Stranded
#18 A. W. G. Stranded
33
34
35
Cotton Braided Outer Cover
13306
11099 -A
11719-A
CONSOLETTES
31-32
32
32
33 -34
34
35 -38
38
38
BC-3C
BC -5B
BC-6B
Standard Consolette
Tube Kit (for BC -it
On -Air Light Relay
Audio Consolette
Tube Kit (for BC -5B)
Dual- Channel Audio Consolette
Tube Kit (for BC-6B)
Announce Booth Speaker Relay (for BC -6B
1
ES- 11103 -A
11486 -A
11702 -A
ES- 11105 -A
11483 -A
ES- 11106 -A
11484 -A
11748
CONSOLETTE AND STUDIO ACCESSORIES
"On Air" Studio Warning Light.._
"Rehearsal" Studio Warning Light
"Audit " Studio Warning Light
"Standby" Studio Warning Light
"Silence" Studio Warning Light
Glass for Warning Lights
On Air Light Relay (see page 32)
Announce Booth Speaker Relay (see page 381
-ee page 108)
Transformer I Speaker Coupling
Fixed, Dividing and Bridge Pad. -ee page 71-72)
39
39
39
39
39
39
....
11706-1
11706 -2
11706.3
11706 -4
11706 -5
11718-1
to
t
INTERCOM EQUIPMENT
Interphone Connection Unit
Retardation Coil
Shelf for Interphone Connection Unit
Panel for 14 Retardation Coils
Single Headband Assembly
Double Headband Assembly
40 -41
40-41
40-41
4041
40.41
40 -41
40 -41
42
42
43-44
43-44
43.44
43 -44
Daven 90
SJR -1W
SJR -1B
SXJ -2
SXJ-5
43 -I1
43.11
43 -11
43 -II
43-11
SJ-8W
SJ-8B
SJ -16W
SJ -16B
SJ -24W
43.11
43-44
43.11
SJ -248
43 -44
43 -44
SJ -8WK
SJ -8BK
SJ -16WK
SJ -16BK
43.44
43.41
SI-32W
SJ -32B
43 -11
43 -II
43-11
43 -1I
S.1-24WK
43 -II
43.11
43 -11
SJ -8WR
SJ -8BR
SJ -16WR
SJ -24BK
SJ 32WK
SJ -32BK
Headset
11734
11737
11735
11736 -A
11743
11744
Amplifier
Single Headphone (9,000 ohms impedance)
Double Headphone (24,000 ohms impedance)
Remote Unit, Walnut Case
Remote Unit, Blonde Case
Power Supply, 30 watts
Power Supply, 80 watts
Master Unit,
8 Station, Walnut Case
8 Station, Blonde Case
16 Station, Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case
32 Station, Walnut Case
32 Station, Blonde Case
Master Unit, All -Call Origination Only,
8 Station, Walnut Case
8 Station, Blonde Case
16 Station, Walnut Case
16 Station, Blonde Case
24 Station, Walnut Case
24 Station, Blonde Case
32 Station, Walnut Case
32 Station, Blonde Case
Master Unit, Receive All -Call Only,
8 Station, Walnut Case
8 Station, Blonde Case
16 Station, Walnut Case
www.americanradiohistory.com
11749
11750
38505 -W
38505 -B
38506
38507
38508 -W
38508 -B
38516 -W
38516 -B
38524 -W
38524 -B
38532 -W
38532 -B
38509-W
38509 -B
38517-W
38517 -B
38525 -W
38525 -B
38533 -W
38533 -B
38510 -W
38510 -B
38518 -W
5
INDEX
INTERCOM EQUIPMENT (Continued)
Page
43-44
43.44
4344
4344
4344
43-44
43-44
43-44
43.44
43.44
43-44
4344
4344
Type Number
SJ -16BR
SJ -24WR
SJ -24BR
SJ -32WR
SJ -32BR
S.1-8WC
SJ -HBC
SJ -16WC
SJ -16BC
SJ -24WC
SJ -24BC
SJ -32WC
SJ -32BC
Station,
Station,
24 Station,
32 Station,
32 Station,
Master Unit,
8 Station,
8 Station,
16 Station,
16 Station,
24 Station,
24 Station,
32 Station,
32 Station,
16
24
MI Number
Description
Blonde Case
Walnut Case
Blonde Case
Walnut Case
Blonde Case
Originate and Receive All -Call,
Walnut Case
Blonde Case
Walnut Case
Blonde Case
Walnut Case
Blonde Case
Walnut Case
Blonde Case
38518-B
38526 -W
38526-B
38534 -W
38534-B
38511 -W
38511 -B
38519 -W
38519 -B
38527 -W
38527-B
38535 -W
38535 -B
CUSTOM EQUIPMENT
45-48
Custom Audio I.yuipmwit
50
50
51.52
Preamplifier and Isolation Amplifier (includes tubes)
Tube Kit (for BA -21A)
Program Amplifier (includes tubes)
Tube Kit (for BA -23A)
Step Attenuator
Monitoring Amplifier (includes tubes)
Tube Kit (for BA -24ÁI
atic Gain Controlled Program Amplifier (includes tubes)
Aut
Tube Kit (for BA -25A)
Turntable Equalizing Preamplifier (includes transistors)
Transistor and Rectifier Kit (for BA -26A)
Limiting Amplifier (includes tubes)
Tube Kit (for BA-6A)
Transistor Portable Remote Amplifier (includes transistors)
Input Transformer (30/150 ohms)
Transistor Kit and Diode (for BN-6B)
Step Type Auenuator for BN-6B Master Controls
Step Type Attenuator for BN -6B Fader Controls
10 -Watt Amplifier (includes tubes)
Plug -in 200 ohm Input Transformer
Plug-in 50 ohm Input Transformer
15 -Watt Sound Amplifier (with cover and tubes)
15 -Watt Sound Amplifier (on chassis only, with tubes)
Remote Volume Control Kit
Amplifier Carrying Case with Two Speakers
Summary of RCA Broadcast Amplifier Characteristics
Magnetic Record /Reproduce Amplifier (see page 92-93)
BROADCAST AMPLIFIERS
52
52
53
53
54-55
55
56 -57
57
5859
59
60-61
61
61
BA -21A
BA -23A
BA -24A
BA -25A
BA -26A
BA-6A
BN-6B
61
61
62
62
62
63
63
63
63
64
SA -IOC
....
BA -51A
65
BX-21A
SA -15B
SA -15B
ES -11121
11.182
ES-11123
11180
11751.2
ES-11121
11181
ES -11125
11187
11136
11779
ES -11126
11289
11221 -B
11776
11777
11751 -3
117514
12161
12399
12398
12156 -A
12156 -B
14831
12766
AMPLIFIER ACCESSORIES
65
66
67
67
68
68
69
70
70
71
71
71
71
71
71
71
71
71
72
72
72
BR -22A
BR -2A
BR -2A
BE -21B
BI -1B
BE -2A
Preamplifier Power Supply (includes tubes)
Tube Kit Ifor BX -21A)
Mounting Shelf
Panel, Umber Gray
Shelf, Umber Gray
Variable Sound Effects Filter
Meter Panel
Line Equalizer
Line Transformer
Bridging Transformer
Fixed Pad (6 db) "H" Type
Fixed Pad (10 db) "H" Type
Fixed Pad (20 db) "H" Type
Fixed Pad (40 db) "H" Type
Balanced Two -Way 600 ohm Dividing Network
Balanced Three -Way 600 ohm Dividing Network
Balanced Four -Way 600 ohm Dividing Network
Balanced Six -Way 600 ohm Dividing Network
Balanced Bridge Pad
Bridging Volume Control (with knob for panel mounting)
Bridging Volume Control (with screw-driver adjustments)
Simpson VU Meter
ES -11111
11479
11597
11598-B
11599
11723
11388
11752
11713
11712
4171 -29
4171-30
4171 -32
4171-39
11704
11704 -A
11704 -B
11704 -D
11705
11278 -E
11278 -F
Stock #53064
AMPLIFIER ACCESSORIES (Continued)
Page
Type Number
72
72
Description
Multiple Pad for Calibrating the VU Meter
to desired reference level
Zero Adjustment Pad
MI Number
Stock #19328
Stock #19327
RACK EQUIPMENT
73.74
73-74
73.74
73.74
73-74
BR -84A
BR -84B
BR -84C
BR -84D
BR -84E
BR -19A
74
74
74
74
74
74
74
74
ES- 30951 -A84
Standard Cabinet Rack
ES- 30951 -B84
Standard Cabinet Rack, less front door
ES- 30951 -C84
Standard Cabinet Rack, less side panels
ES- 30951 -D84
Standard Cabinet Rack, less side panels and front door
Standard Cabinet Rack, less side panels and front and rear doors ES -30951-E84
Cabinet Rack (see page 75)
30530 -G84
Door (Non -Ventilated)
30541 -G84
Side Panel
30535 -G84
Door (Ventilated)
30546-G21
Electrical Shield (for mid rack section)
30546-G28
Electrical Shield (for top and bottom rack sections)
30566 -G84
Single Trim Strip
30568 -G84
Double Trim Strip
4570 -A
Terminal Board Mounting Bracket
RACK ACCESSORIES
74
74
74
74
74
....
....
75
76
76
76
76
76
76
77
BR -22A
BR -2A
BR -2A
BR -19A
57 -D
BI -1B
77
BI-SA
....
18
78
79
79
79
79
79
79
79
79
II
11550
4590 -A
4591 -B
4592 -B
4593 -A
4594 -B
4595-B
4395 -G
11265 -F
JACK PANELS, MATS AND CORDS
Interconnecting Cables see page 30
Lacing Cord (see page 30)
Jack Panel
Jack Panel
Single BJ -24 Jack Strip Mat
Double BJ-21 Jack Strip Mat
Patch Cord, 2 -Foot Length (Black Shielding)
Patch Cord 4 -Foot Length (Black Shielding)
l'atch Cord, 6 -Foot Length (Black Shielding)
Patch Cord, 2 -Foot Length (Gray Shielding)
Patch Cord, 4 -Foot Length (Gray Shielding)
Patch Cord, 6 -Foot Length (Gray Shielding
Switch Housing Assembly
Switch Panel
Switch, 6 Form C, SPDT Contacts
Basic Mounting Panel (for console mounting)
Rack Adaptor (for mounting in 19" rack)
I
131-21
13J -12
)
80
r
4569
4568
30527-G29
30526 -G84
11728
Audio Terminal Block
Power Terminal Strip
Set Terminal Board Mounting Angles
Set Panel Mounting Angles
Ground Bus Kit
Mounting Shelf (see page 66)
Panel (see page 67)
Shelf (see page 67)
Cabinet Rack
1- 23/32" Blank Panel, Umber Gray
3- 15/32" Blank Panel, Umber Gray
5. 7/32" Blank Panel, Umber Gray
6-31/32" Blank Panel, Umber Gray
8-23/32" Blank Panel, Umber Gray
10- 15/32" Blank Panel, Umher Gray
Switch and Fuse Panel
Meter Panel (see page 68)
VU Meter Panel
80
80
80
80
81
81
BX -21A
SXJ-2
SXJ-5
POWER SUPPLIES
Constant Voltage DC Power Supply
Regulated Power Supply
Preamplifier Power Supply (see page 50)
Intercom Power Supply, 30 Watts (see page 41)
Intercom Power Supply, 80 Watts (see page 41)
www.americanradiohistory.com
11615
116 -16
11647-1
11647 -2
4652 -B2
4652 -B4
4652 -B6
4652 -C2
4652 -C4
4652 -C6
11756
11754
11755-2
26252
26254
11318 -A
11316
INDEX
TUNERS
Page
82
83.85
83 -85
83.85
86
86
87-88
88
88
89
90 -91
91
92-93
93
94
94
95
96-97
98
99-100
100
100
100
100
101
102
102
103
103
104
Type Number
Description
STS
AM -FM Radio Tuner (includes tubes)
BQ -51A
BQ -51A
BQ -103
4G -01D
BA-51A
BQ -104
LC -1A
SL-123
SL-12
105
105
105
106
107
107
108
108
108
109
112 -113
114
115 -116
117
117
118
118
119.120
12116
TRANSCRIPTION EQUIPMENT
Multi -Purpose Turntable, for 511 -cycle Operation
Multi -Purpose Turntable, for 60 -cycle Operation
Cabinet Assembly to House BQ -51A Turntable Mechanism
Lightweight Tone Arm
Magnetic Record /Reproduce Head
Lightweight Tone Arm
Lightweight Pickup, 1 mil Fine Groove
Lightweight Pickup, 2.5 mil Standard Transcription
Pickup Equalizer
:tut
tic Turntable
GE Replacement Stylus Tip. 1.1) mil Diamond
DISC RECORDING
Magnetic Record /Reproduce Amplifier (includes tubes)
Tube Kit (for BA-51A)
Magnetic Recording Disc (set of five)
Set of Gummed Labels
Magnetic Eraser
Automatic Turntable for playing 33t/3 I: I' \I \I;ignetic Discs)
(
LOUD -SPEAKERS AND ACCESSORIES
General Information on RCA Loudspeakers
Duo -Cone Speaker
Speaker Cabinet, Blonde (for LC-IA)
Speaker Cabinet, Mahogany (for LC -1A
Wall Speaker Housing (for LC-1A)
Power Attenuator
1.2 -Inch Speaker
12 -Inch Speaker
Wall Housing (for SL -12 and SL-123)
12 -Inch Speaker
Wall Housing (for 12 -Inch Speakers)
10-Inch Speaker
10 -Inch Speaker
Reducing Baffle
8 -Inch Speaker
Plastic Wall Speaker Housing (for 8 -Inch Speakers)
8 -Inch Speaker complete with Walnut Baffle
8 -Inch High Fidelity Speaker
7 -Inch Accordion Cone Speaker
Wall Baffle for 7 -Inch Speaker
Line Matching Speaker Transformer (16 watts)
Line Matching Speaker Transformer (8 watts)
Line Matching Speaker Transformer (8 watts, single winding)
(:hart showing Speaker Applications, Recommended Housings and
Specifications
1
104
104
110-111
MI Number
WM -71A
WA -28A
BI -11A
452 -A
510 -B
401 -C
512
520 -A
TEST EQUIPMENT
Distortion and Noise Meter,
Audio Push- Button Oscillator
Transmission Measuring Set
Transmission Measuring Set
Audio Oscillator
General Purpose Oscillator
Sine-Wave Generator
Amplifier-Voltmeter
Recommended Audio Wiring Practices
AUDIO DATA SECTION
121
122
123
Loudness Level Contours
Attenuator Networks
VU -DB vs Power
www.americanradiohistory.com
11810 -A
11810
11809
11894
11955
11885 -A
118744
11874-5
11888
11845/11844
11903
11488
11990
11989
11821
11846/11844 -A
11411 -A
12464 -B
12464 -M
11406
11708 -A
12654
12458
11407 -A
12418 -B
13253 -A
11408
6333 -D
13245 -A
12454 -B
ri
6104
38300 -3
124811
124.35 -C
12845
12368
12369
11731
30071 -A
30028 -A
11350
'4111
Atlanta 3, Ga.
1121 Rhodes -Haverty Bldg., Jackson 4-77D
Boston 16, Mass.
200 Berkeley Street, Hubb
Camden 2, N. J.
,lawn
Front & Ccoper Streets
3 -8000
Chicago 54, III.
1186 Merchandise Mart Plaza, Delaware 7 -0700
Cleveland 15, Ohio
1600 Keith Bldg., Cherry
RCA REGIONAL
1
-345C
Dallas 35, Texas
7901 Empire Freeway, Fleetwood 2 -3911
OFFICES
Hollywood 28, Calif.
1560 N. Vine Street, Hollywood 9 -2154
Kansas City 6, Mo.
1006 Grand Avenue, Harrison 1-6480
New York 20, N. Y.
36 W. 49th Street, Judson 6 -3800
San Francisco 2, Calif.
420 Taylor Street, Ordway 3-8C27
Seattle 4, Wash.
2250 First Avenue, South, Main 2 -8350
Washington 6, D. C.
1625
K
Street, N. W., District 7 -1260
RADIO CORPORATION OF AMERICA
CAMDEN, NEW JERSEY
BROADCAST AND TELEVISION EQUIPMENT
AM-51859
Tmk(s)
(F.
www.americanradiohistory.com
.
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