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THE SOUND ENGINEERING MAGAZINE
DECEMBER 1979
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Coming
Next
Month
Next month. %tic finish the old year by
concluding our series on microphones,
with features on the Pressure Recording
Process. and the use of instrumentation
microphones in recording sessions. Next,
we take a look at some of the latest developments in analog audio. At least one
manufacturer is bucking the digital tape
recorder trend, and we'll find out a little
more about this in the January issue of
db -The Sound Engineering Magazine.
THE SOUND ENGINEERING MAGAZINE
DECEMBER 1979
VOLUME 13, NUMBER 12
EDITORIAL
18
BUILD A HEATER FOR A CONDENSER MICROPHONE
20
Bob Katz
CMOS MICROPHONE CABLE TESTER
Kirk Elliott
26
DIRECTORY OF MICROPHONE MANUFACTURERS
33
STEREO MICROPHONE TECHNIQUE
Bruce Bartlett
34
THE FRAP POINT- SOURCE -MICROPHONE
Arnie Lazarus
47
LETTERS
THEORY AND PRACTICE
r
Norman H. Crowhurst
CALENDAR
SOUND WITH IMAGES
Martin Dickstein
klip:41
Microphones on the cover: (fop row:
left to right) Neumann U -87. Shure SM58, Electro -Voice R F. -20. Sennheiser 44
(Bottom row: left to right) Audio-Technica AT -813. Sennheiser 421, Shure
SM -81, Neumann KM -84.
I :
Cover photograph courtesy of: The M ike
Shop. Division of Omnisound, Ltd..
P.O. Box 336A, Elmont, NY 11003.
Photographer: John I-cc
Agency: Daedalus Associates
is
12
NEW PRODUCTS AND SERVICES
16
CLASSIFIED
52
ANNUAL INDEX
54
listed in Current Contents: Engineering and Technology
Larry Zide
PUBLISHER
John M. Woram
EDITOR
Suzette Fiveash
ASSOCIATE EDITOR
Sam Zambuto
ASSOCIATE EDITOR
Ann Russell
ADVERTISING PRODUCTION
Eloise Beach
CIRCULATION MANAGER
Lydia Anderson
BOOK SALES
Bob Laurie
ART DIRECTOR
Crescent Art Service GRAPHICS AND LAYOUT
db. the Sound Engineering Magazine is published monthly by Sagamore Publishing Company. Inc. Entire contents copyright
1979 by Sagamorc Publishing Co., 1120 Old Country Road. Plainview. L.1., N.Y. 11801. Telephone (5161433 6530. db is puhItshed for those individuals and firms in professional audio -recording. broadcast, audio- visual. sound reinforcement, consultants.
video recording. film sound. etc. Application should be made on the subscription form in the rear of each issue. Subscriptions arc
59.00 per year (5111.00 per year outside C.S. Possessions and Mexico: $10.00 per year Canada) in U.S. funds. Single copies are
SI.95 each. Controlled circulation paid at Brattleboro. V r05301. Editorial. Publishing,and Sales Offices: 1120 Old Country Road,
Plainview. New York 11803. Postmaster: Form 3579 should be sent to above address.
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article, "An Automatic Broadcast Con-
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sole":
The console Joel describes is fine in
the automatic mode. It is a substantial
improvement over conventional program automation systems, since it places
the operator in the same room as the
system, with the controller in front of
him. It also eliminates the need for a
separate piece of gear for live inserts.
However, I feel that the console is
not human -engineered well enough for
operation in the semi -automatic mode:
First, Joel states that "low profile"
console design is unnecessary, due to
the proliferation of "combo" operation. There are objections to his reasoning: In many stations, the news originates
in another studio. In that situation, good
visibility is of prime importance, not
only for cueing, but to help the newscaster and operator see each other in
any on -air dialogue. Additionally, having a high, essentially flat surface in front
of the operator tends to make the operator feel closed in, and such a surface
close behind the microphone may have
undesireable effects on its directional
characteristics and /or tonal quality.
Second, while Joel's system of alert
leds and other indicators is good, it could
be improved, along with the location of
the "play" and microphone "on-off"
switches. The relative positions of the
input modules with their associated
push- buttons and the VU meters can
cause problems; when the operator starts
equipment, the meters can be hidden by
his arm. Experience (and discussions
with other engineers) leads me to believe
that it is not efficient to place frequentlyused push- buttons at a height requiring
the operator to raise his arm(s) off the
table top.
The clock/ timer is something no
control room should lack. But the
location on Joel's console could be
improved. Ideally, the clock/ timer
should be directly over the VU meters.
The second choice would be on the right
side of the front panel. Right-handed
people have a tendency to look to their
right, and are more comfortable doing
so. It is important that combo operators
(who may be non -technical) be as
comfortable as possible. (Of course,
if there are a lot of left- handed operators
at the facility where this console is to
be used, the timer and clock are correctly
positioned.) The headphone jack shows
a similar dislocation. Many types of
stereo headphones must be worn with
the cord coming out on the wearer's left
side. or they don't fit properly -which
N
Circle 37 on Reader Service Card
ADC
Ampex
.
. 41
28 -29
.
Andrews Audio Consultants
42
22
43
Audiotechniyues
Bose Corporation
BTX Corporation
Burns Audiotronics
Garner
Gerard Tech
Industrial Research
James B. Lansing
Lexicon. Inc
14
19
44
44
35
15
39
Magnefax
6
McMartin Industries
Midas Audio
Keith Monks Audio
R. K. Morrison Illust. Mats.
MXR Pro Products
Northwest Sound
Orban Associates
Penny & Giles
Phoenix Systems
PML
Polyline Corporation
Quad-Eight
Russco Electronics
Sagamore Publishing Co.
Sescom
Shure Brothers
SME Ltd.
Standard Tape Lab
Strand Sound
Studer Rev ox America
Switchcratt
Technics by Panasonic
Telex Communications
40
Cover 2
24
8
Cover 4
42
38
10
10
21
8
30
4
12
45
3 5
2
6
27
17
37
23. 25
.
.
7. 9.
I
The Mike Shop
I. 13
14
Cover
3 -M
UREI
White Instruments
Yamaha
tV
3
31
4
12
sales offices
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Circle 35 on Reader Service Card
www.americanradiohistory.com
SH URE
Shure Brothers Inc. 222 Hartrey Ave.
Evanston. Il 60204
Canada: A.C. Simmonds 8 Sons Limited
Outside the U.S. or Canada, write to Shure Brothers
Inc.. Attn: Dept. J6 for information on your local
Shure distributor.
Manufacturers of high fidelity components,
microphones, sound systems and related circuitry.
RUSSCO has your next turntable ready to deliver. The Mark V gives you
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Phone 1209) 291 -5591
may adversely affect their frequency
response. With the headphone jack on
the right side, the headphone cord has
to run across the desk, the operator's
lap, or both.
Some provision should be made for a
copy stand at eye level in front of the
operator. It is difficult to speak clearly
while looking down, let alone see anything on the front of the console. A built in copy stand would fulfill Joel's goal of
keeping the weather forecast from in
front of the VU meters.
While I agree with most of Joel's
reasoning, I think the execution of his
thought could be better. One final
question remains: With all of the information this console provides for the
operator, shouldn't some sort of outside
thermometer and indicator lights (leds?)
for the telephone be provided? I have
built a few control rooms, and worked
in many, and the above items rank right
behind the time, and the remaining
length of what's on the air in importance.
I
would enjoy any feedback from
Irving Joel, or anyone else interested
in the human-engineering of consoles
and control rooms.
ROBERT E. BARMORE, JR.
Staff Technician, WLBC AM/ FM
Muncie, IN
Circle 28 on Reader Service Card
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Lircle
21 on Keader Service
Lard
Mr. Joel Replies:
I'd like to thank Mr. Barmore for his
comments on my article.
A great deal of attention during design
was given to human design engineering
and function accessibility. The console is
supported by two formica covered
wooden end bells and the height can be
reduced to suit individual installations.
Normal operation of the console in
the semi -automatic mode is performed
with one button marked START! N EXT
EVENT, which can be easily reached
without lifting one's elbows off the table.
If for any reason this position is not suitable. a remote START/ NEXT EVENT
button connection is provided for and the
button could be located at any remote
location desirable. This is also true of the
earphone jack which can be remotely located and placed well under the desk to
completely get the cord out of the way. It
so happens our mechanical design engineer is left handed but I don't feel this
entered into the decision of the clock
placement. Rather, consideration for the
operator has placed them close to the
microphone controls.
We felt that the microphone ON / OFF
buttons should be located as close to the
fader as possible, hence the position
and it might be wise to note here that all
ON AIR functions are completed only
after the switch has been released, which
allows the operator to put his finger on a
button anticipating a cue and being as-
-
1 fact:
this condenser microphone
sets a new standard óf
technical excellence.
& it sounds superb!
The Shure SM81 cardioid condenser is
a new breed of microphone. It is a truly
high -performance studio instrument
exceptionally well- suited to the critical
requirements of professional recording,
broadcast, motion picture recording,
and highest quality sound
reinforcement
and, in addition, is
highly reliable for field use.
-
-
-
and found
Shure engineers sought
ingenious new solutions to common
problems which, up to now, have
restricted the use of condenser
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As the following specifications indicate,
the new SM81 offers unprecedented
making it a
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new standard in high quality
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SM81 puts it all together!
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Conventional condenser microphones have
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Shure Brothers Inc., 222 Hartrey Ave., Evanston, IL 60204, In Canada: A. C. Simmonds & Sons Limited
Manufacturers of high fidelity components, microphones, sound systems and related circuitry.
Circle 25 on Reader Service Card
www.americanradiohistory.com
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Circle 47 on Reader Service Card
it will not switch until it
is
The copy stand is placed under the
console for easy access and when reading
copy, the V U meters are in full view. The
angle of the stand is adjustable. In actual
operation, we found this position to be
quite wnrkable.
As far as the telephone is concerned,
we provide muting while the microphone
is on the air and feel that the minimum
wattage for the phone light should be 150
watts, not easily available in the console.
"S & H" C'rowhurst
To THE
EDITOR:
I have read and enjoyed db for a
number of years now, but each and every
month my attention has been drawn
more to the articles by Norman Crowhurst.
The content of his column is invariably
interesting, but of increasing importance
to me is the discrepancy between the
middle initial assigned to Mr. Crowhurst
on the contents page and on the heading
of his column.
I have been following this for probably
two years now, and I am amazed each
and every month that the initials don't
agree.
Please... let us all in on the secret!
Is he an "H" or an "S"???
Possibly your magazine will become
even more enjoyable with this mystery
solved.
ROBERT W. CAMBRELENG
Engineering Department
WOR -TV, New York
ma9nefex..
Serving the Recording Industry
for 20 years.
Endless Belt Automatic Tape Degausser.
The first endless belt degausser was
designed and marketed by Magnefax
in 1966. Continuing research has produced the current model which offers
high flux, reduced heat build -up and
one -fourth the power requirements of
competitive brands.
The Magnefax ATD -7 will degauss 5"
or 7" reels, audio cassettes and carts.
Video cassettes may be degaussed it
two passes with turnover.
The current requirement is only 4.5
amps. at 120 volts. The size is 26" x
11" x 4 ". The unit weighs 65 lbs.
The ATD -7, shown above, reduces The unit is conditionally warranted for
noise level to that of virgin tape. Erasure
three years and will provide years of
is complete and over 1,000 tapes may
dependable service.
be degaussed in a twenty minute pinning period. RFD 1. ROGERS. ARK 72756. 501/925 -1818
db replies:
Finally!
In July. 1977. the style of our column
logos was updated. And somehow,
Norman H. became Norman S. (Our
typesetter is a not -so- distant relative of
Edsel Murphy.)
Of course everyone here at db caught
the error immediately. (Then why didn't
you guys fix it ?- typesetter.) However.
we decided to wait until the letters
started pouring in. In fact, we even had
a little contest arranged-520,000 a week
for life, to the first person who contacted
us to point out the goof. Unfortunately,
your letter arrived just minutes after the
contest deadline. (The deadline wasfixed
at five minutes before the first letter
arrives.)
In any case. Norman's "H" has been
restored to its rightful place. and Robert
W. Cambreleng gets a free one -year
subscription to db for being so attentive.
After all. now that the mystery is solved,
db should be even more enjoyable -so,
it's the least we can do.
.
To THE EDITOR:
I
was quite impressed with your
September article on the ITC series "99"
co
Circle 13 on Reader Service Card
www.americanradiohistory.com
tape cartridge system and cartridge evaluation. We are currently involved in a
project of deciding upon a tape cartridge
to use when we start carting up our a.m.
music in stereo. I was pleased to see the
results of Mr. Nikanorov's tests as they
reflected what we had discovered out
here in "radio land" using just a "prim itive" ITC RP series stereo cart recorder.
We had purchased over 1,000 of a newly
introduced cart that was billed as being
the ultimate cart for stereo usage and
phase stability. We found after testing for
phase response that up to 25 per cent of
each case of carts were not meeting specifications of the manufacturers. Approximately a dozen carts that I rejected were
sent td this company's lab and were
verified as defective due to various
reasons.
I) Case Warpage.
2) Incorrectly
Sound Reinforcement?
manufactured plastic
tape guides.
We decided to give this company one
more shot at producing us one good case
of carts with no rejects, as they have
been very concerned and cooperative.
The result was again 25 per cent failure
out of a case of 24 carts. To check these
carts against another brand I ordered a
random case of 24 carts from the "top"
rated cart, per Mr. Nikanorov's list. The
result was 100 per cent of these carts
producing excellent phase response.
Both companies' carts were of the same
length and checked in a manner in which
our original supplier approved and
recommended.
We are currently considering return-
ing all 1,000 plus carts to the first manufacturer and going with the second
because of what appears to be the increased superior phase stability of the
later.
One additional point I would like to
make in regard to the series "99" ITC
machine. This unit will "mask" or cover
up for these manufacturing inconsistancies of any cart. If you have a cart
that is recorded correctly out of the series
"99" machine how does one know that
these "mechanical" problems that result
in phase discrepancies between one
brand might cause drift and playback
problems down the line?
I believe in the series "99" and we have
one on order with "ELSA," however, I
wonder if certain manufacturers are
hoping it will cover up their manufacturing or quality control problems? I
want to be sure that I start out with a
good cart and I plan to check every one
out that we use with the RP series
machine. After all these stereo carts are
demanding a premium price, shouldn't
we expect the claimed performance
from the manufacturer?
CuRIS J. CAIN
Engineering Director
Midwest Family Stations
Madison. Wisconsin
urner
h
ore!
Turner sound reinforcement microphones allow the audio professional the wide selection he needs to find just the right microphone
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size, mounting, directional pattern or cost there is a Turner micro pone to fit any application. And it doesn't stop there. Turner offers
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Gooseneck
Omnidirectional
Cardioid
mounted Handheld Lavalier On -off Switch Locking Switch.
And, that's only the beginning. Turner has a full line of paging
microphones as well. Turner does have more, and now, with the
additional product development strength of Telex Communications,
Inc., there will be even more to come.
Quality Products for The Audio Professional.
TELEX TURNER
TELEX COMMUNICATIONS, INC.
9600 ALOFICH AVE SO. MINNEAPOLIS. MN 55420 U S A
EUROPE. 22 rue de la Legion Honneur. 93200 St Denis. France
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i
J
NORMAN H. CROWHURST
STANDARD TAPE MANUAL
444 Theory & Practice
This valuable
data
hook is for the AUDIO
recordist, engineer or
designer. Offered at
$45.00 you may order
direct from publisher.
MAGNETIC REPRODUCER
More Systems Design
CALIBRATOR
This is induction loop equipment of labora
tory quality for primary standardization of
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tape
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MORRISON ILLUSTRATIVE
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CA
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As last month's column showed, any
time you want to design a new system,
you must consider how it correlates with
systems already accepted and in existence.
The advent of the 45 rpm EP and the 33
rpm LP are an example of different
systems in this regard. The 45 rpm disc.
with its large center hole, was an attempt
to design a completely new. independent
system, not related to prior systems at
all. The 33 rpm disc took an alternate
approach. to optimize the existing form.
But does that mean such systems will
stay separate? Now we find systems
record players -with a variety of ways
in which they can accommodate both.
One way is to put those little spiders in
the center of 45 rpm discs, so they will
fit on the standard phonograph spindle.
Another way uses adaptors on the phonograph spindle. to enable it to accommodate either type of record in its
changing.
That relates to the mechanical aspects.
A similar thing happens in the electronic
part. Then we have the part that bridges
both -the transducers. Disc is an electromechanical recording medium. in which
a stylus mechanically follows a groove.
and produces electrical signals. or vice
versa. at recording. Tape uses electromagnetic properties of the tape to
transcribe.
Disc has the advantage over tape. in
that the groove is 3- dimensional. so it
is possible to devise the 45, 45 stereo
system, in which two channels of "information" can be conveyed independently.
using directions of movement mutually
at right angles, to one another, and to
the direction in which there is relative
movement along the groove by the st lus.
The fact that the groove moves, while
the cartridge stays put does not alter the
relative movement involved.
Tape. on the other hand, does not have
the depth capability or, if it does, nobody
has yet found how to use it. You have.
essentially a surface of tape. which moves
relative to a scanning magnetic gap. But
you can stack up these heads, or gaps.
to get a lot of them onto a relatively
narrow piece of tape. And, to enable a lot
of program to be stored in a small space.
the tape itself can be made very thin.
6001
co
Circle 39 on Reader Service Card
THE SPACE PROBLEM
This space problem is somewhat
aggravated, every time we decide we
want to record, or convey, more channels
of information: when we move from
mono to stereo, and when we move from
stereo to quadraphonic. And even more,
of course. when we move to multi -track
facilities. or however many tracks we
decide to use.
But as usual, there is an offsetting
factor. The modulation, power requirement. or whatever corresponds to it.
needed to convey a given "loudness"
impression in mono. has been shown
to be more than that needed in two channels to convey an equivalent impression
in stereo. which means that stereo doesn't
necessarily need twice as much "space"
as mono.
Now we come to the question of how
we extend the already established stereo.
in its various forms of 2-channel implementation. to quadraphonic. It is generally conceded that the loudspeaker
position is in the form of a quad: 2 in
front and 2 behind. The question is. how
do we convey the 4 signals that are to be
distributed to these 4 speakers. so the
reproduction does what we want it to?
HOW TO FIT 4 CHANNELS
For the conversion from mono to
stereo. both disc and radio came up with
a way to put 2- channel information over
a single channel: disc by using mechanical movements mutually at 90 degrees
to each other: radio by using an ultrasonic switching frequency. 38 kHz. How
can we extend that to squeeze in 4
channels?
Some systems designers thought of
other ideas that had been tried for stereo.
For disc. for example. one alternative
offered had been to use a higher frequency subcarrier to do substantially
what stereo f.m. did. Now that we have
45,' 45 for stereo. couldn't we get the other
2 channels in by using a subcarrier on
each? What came to the rescue, once
again, is a closer consideration of the
natural relationship of signals.
Why are the back channels needed?
Ideally, of course. they should be completely independent, so it does not
matter how their content inter- relates.
But how does it normally tend to interrelate? In most situations. the front
channels convey the complex source of
the original sound. to present. for
example the impression of various instruments in an orchestra, located left, right
and various points in between.
And what comes from the back
speakers? Res erberation of the same
sounds presented from the front speakers.
to convey an illusion of the auditorium in
which you are listening to that orchestra.
And what is characteristic of reverberation? Some proponents of pseudo stereo
had already exploited this, by taking
mono, splitting it between two loudspeakers to represent "direct" sound,
then delaying it, and splitting it between
the same two loudspeakers. but this time
out of phase, to represent the "reverberated" sound.
And that form of pseudo stereo certainly "had something." It could not
convey impressions of left and right.
with points in between, of course. But
it did convey the impression of reverberant sound, as a separate entity from
the direct sound. as well as the real thing
could. What does this mean?
If you 'se conducted phasing tests,
you'll know. Putting the same program
into two loudspeakers, in phase, makes
the apparent source of the sound a position in between the two units. But putting
it out of phase produces what has been
called the dissociation effect: the sound
seems to come from nowhere in particular: all around _you, but not from the
loudspeakers.
PSEUDO QUADRAPHONIC
This is done by "fooling" our hearing
faculty. And, regardless of whether it's
nice to fool mother nature, it works.
Since the advocates of pseudo stereo
demonstrated that bit of trickery, a
similar group of people, who wanted to
make "super stereo" have produced
similar effects, using stereo program as
the source, to generate pseudo quadraphonic.
Do you begin to see a pattern that we
could use? Using the stereodisc, 45,45 as
reference, lateral movement of the stylus
represents center front as the source of
sound. equal level in left and right, in
phase. From the effects already observed,
equal level in left and right, but out of
Desk Paging?
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ore!
Turner desk paging microphones allow the audio professional more
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A minimum amount of electronic modification is required because
Turner has engineered its products to meet virtually all applications.
Twelve distinctly different microphones in two desk -top case styles.
There is a quality Turner desk paging microphone with features to
meet the following applications requirements:
Normally Open Switching
Omnidirectional Low Impedance
Zone Paging
High Impedance
Normally Closed Switching
Lift -To -Talk
Press -To -Talk
Noise Cancelling
Cardioid
Amplified.
And. that's only the beginning. Turner has 13 other paging microphones in gooseneck. handheld and wall mount versions. as well
as a full line of sound reinforcement microphones. Turner does
have more, and now, with the additional product development
strength of Telex Communications. Inc. there will be even more
to come.
Quality Products for The Audio Professional
phase, could well represent center back.
That would be vertical movement of the
stylus. Extending that combination,
circular movement one way would be
back right and circular movement in the
opposite rotation would be back left.
That represents left and right at 90
degrees.
This is, in fact, the basis for the
quadraphonic system adopted. It uses
logic circuitry to determine the phase
relationship of various frequency components of the left and right signal, as
TELEX® TURNER.
TELEX COMMUNICATIONS. INC.
9600 ALDRICH AVE SO. MINNEAPOLIS. MN 56420 USA
EUROPE: 22. rue de la Legion -0 Honneur. 93200 St Denis. France
Circle 45 on Reader Service Card
www.americanradiohistory.com
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well as their amplitude components, and
to route them accordingly. Amplitude
differences shift left or right. phase
differences shift front or back. essentially.
Now. having deduced that logic system
as applicable to produce a consistent
means of coding and decoding 4 channels
into 2. it doesn't matter whether they are
being transcribed on disc or not. because
it is not the manner of movement that
"does it." but the amplitude and phase
relationships associated with that manner of movement. So we have a basis for
converting stereo multiplex into quadraphonic multiplex. In fact. if the radio f.m.
is transmitting a stereodisc that was
quadraphonically recorded, the radio
won't know the difference.
The decoding system will reconstruct
the quadraphonic. regardless of whether
there is a stereo f.m. link in the transmission, or not. While man -made systems cannot actually think, a useful
device in thinking through ideas for new
systems is. "How can it know the difference ?" Coded "instructions" built
into the system must be unambiguous.
that is the point. If they are not, then
the system has no means of "knowing
the difference."
Now, while all this has been going on.
in systems that are essentially analog
(using computer technology terms for
the moment), meaning that we are dealing with the qualitative shape of waveforms, and their analysis in frequency
and phase, tremendous advances have
been made in digital technology, which
deals with coded position and time.
EXAMINING THE HUMAN
HEARING FACULTY
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o
How can this he applied to audio?
Many old time audio engineers probably
reacted that it was inappropriate. if not
impossible. But if they had studied how
our hearing faculty functions. maybe
they would not be so quick to make that
judgment. For the human nervous
system transmits impulses with timing
differentiations that cannot resolve
anything less than a few milliseconds.
So how is it we can hear sounds representative of frequencies up into the
kilohertz. whose period goes down to
less than a tenth of a millisecond?
Human hearing must somehow analyze the content in these frequencies, at
the ear, and then code that information
in nerve impulses that the human system
can handle, for transmission to the
brain, where further analysis in the
brain's "computer" puts it together, so
we can identify the sound that caused it,
and probably its direction from our head
at the time. If the human hearing faculty
can do that, why could not an electronic
system do something similar.?
For years, the reason was a matter of
complexity: it would take millions of
vacuum tubes, and some extremely sophisticated circuitry. Even its logistics
would require the Empire State building
Circle 36 on Reader Service Card
www.americanradiohistory.com
to house it. But a lot has happened
since that was true: solid state. integrated
circuits, microcircuitry. large scale integrated circuits (in which "large" does
not refer to physical size. but to the
amount of circuitry squeezed into a chip
that can rest easily on the tip of your
little finger). And the precision achieved
by such devices is unbelievable. That is
the attractive thing.
Here, analog audio designers have
been trying to get distortion down to
tiny figures. like fractions of a percent
that represent much better than 60 dB,
and digital devices can calculate mathematical functions, instantly. out to many
more decimal places - many times more
accurate than the best sliderule, used by a
person with fantastic eyesight.
Obviously, the possibility is there,
and we have a natural antecedent for
it. in our own hearing faculty. So what
were we waiting for? Some imagination,
to see how to use it. When somebody
else has done it, it always seems obvious.
But for the first person who does it. it
requires imagination. creativity. It does
not just happen. because it's obvious.
That is perhaps the single most cogent
flaw in the evolution theory: it does not
answer the question, "Where do ideas
come from ?"
But even imagination applies principles. We need to follow a problem -tosolution approach. Where does audio
most need precisiim help? Organ makers
had one place: tuning the instrument.
Electronic dividers could solve one part
of that. by deriving lower octaves from
the top octave of master oscillators. But
tuning the top octave was still a skilled,
and time consuming process. And of
course, it could "go off." How nice it
would be to have an organ that "tuned
itself" automatically.
Well, most of today's electronic
organs do just that. And the process is
digital. Starting with a single master
oscillator, operating up in the megahertz
region. precision counters derive the
whole set of 12 master oscillator frequencies in absolute lockstep with that
single master. Musicologists define pitch.
which electronics people call frequency.
in terms of semitones. each of which is
the twelfth part of an octave. and "cents"
each of which is one hundredth of a semitone. A musical instrument tuned within
a few cents is well tuned.
The preprogrammed counter. that
produces a set of 12 master tones from
that single master frequency in kilohertz,
tunes the whole octave within a few
cents -far closer than most tuners could
do it. whatever they might like to think!
is, in fact.
And it does it instantly
built in. And the tuning of the whole
organ can be changed. still in tune,
merely by changing the frequency of
that one master oscillator. How's that
for a hard job made easy? And there's
more. That's just one application. We 'll
pursue others another time.
-it
Calendar
Handheld Paging?
DECEMBER
II14
International Entertainment Exposition. Las Vegas Convention
Center. I.as Vegas, Nevada. For
more information contact: American Expositions. Inc.. One Lincoln ('lain, New York. NY 10023.
(212) 691 -5454.
5 -8
1980
JANUARY
Internat'
I
Winter ('on-
sumer
Electronics
Show.
I.as
\rxada. I.as Vegas ('on%ention ('enter, .locke Club
Vegas.
Hotel. and the Grand Ballroom
of the Las Vegas Hilton. For Inlormation contact: William Glasgow, Show Manager. Consumer
I leetronics Shows.
Iwo Illinois
('enter Suite 1607. 233 N. Michigan. Chicago. II. 60601. (312)
861 -104(
FEBRUARY
1
-2
The 14th :Annual Television ('onference of the Societ of Motion
Picture and Television Engineers
(SMl''l'E).
I
pronto, Canada.
Sheraton ('entre Hotel. For more
inlornurtion contact: SM
F.1V
Conlerenee. 862 Scarsdale Avenue. Scarsdale. NY 10583
25 -28 :AES 65th Convention (London).
I ondon
Hilton and ('ark Lane
Hotels. l'or more information
contact: Audio Engineering Society. Inc. 60 fast 42nd St., New
York, NY 10017.
26 -28 "Sound 80" Cunard Hotel, Hammersmith. London.
MOVING?
Turner
a
ore!
Turner has four handheld paging microphones from which to
choose. Handsome contemporary styling with coil cord and push to -talk switch. In impact resistant cycolac with strain reliefs to withstand the wear and tear of heavy. daily use. In choice of dynamic
or close talking noise cancelling dynamic versions -an ideal selection when background noise is a problem. Your choices don't end
here. Turner also offers more economical and more traditionally
styled versions including the noise cancelling feature. Whatever
your choice, all Turner handheld paging mikes come with dynamic
elements for dependable performance and smooth, voice range
frequency response.
And that's only the beginning. Turner has over 20 other paging
microphones in desk top, gooseneck and wall plate versions, as
well as a full line of sound reinforcement microphones. Turner
does have more, and now, with the additional product development
strength of Telex Communications, Inc., there will be even more
to come.
Quality Products for The Audio Professional
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TELEX COMMUNICATIONS, INC.
9600 ALDRICH AVE SO. MINNEAPOLIS. MN 55120 U S A
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Experience Is The
Best Teacher
Although I had planned to do a completely different type of column this
month, I can still find situations from
my travel experiences that could be
helpful to db readers. Sometimes, nice
things happen and I try to relate them, so
they might be of some help. Sometimes,
just the opposite is the case. and I tell of
these incidents so that they can be
avoided. This time there are two trips
to discuss.
The first was to a hotel in the Southwest. The client was a large manufacturer, and the occasion was a yearly
sales meeting for almost 200 regional
managers. Arrangements for the show
were started several months before the
meeting date. The show was to consist
of a live portion, on stage, between
speeches, on each of the three days of
the conference, with a multi -image slide,
film show on a rear screen, which was a
single stretch material 22' wide. The slide
presentation was to be programmed and
projected on 3 screens. that is, 3 side -byside images.
When the client asked me to assist
them on this project, they told me that
they would design the stage -set themselves and have it put up by a local contractor with whom they had already been
in contact. The set-up was to consist of
the rear screen in the center of the stage
(with space for projection equipment
behind) and enough room in front for the
live acts. The local contractor was to put
up drapes on both sides of the -screen,
extending out beyond the ends of the
stage to carry out the motif of the program. Symbols of the motif were to be
hung on the drapes with the client's art
department designing and executing all
the art work. The contractor was also
hired to set up the stands needed to raise
the projectors to the level of the center
of the screen. I submitted a drawing to
help the contractor in this work. (At first,
I suggested to the client that it could
probably be done more easily by the
people at the hotel, but they insisted that
www.americanradiohistory.com
the contractor would construct something special according to the client's
design in keeping with my requirements.)
PRIOR ARRANGEMENTS
During my discussions with the hotel
on the show's audio -visual requirements,
several months prior to the date of the
meetings. I was told that they only had a
limited amount of equipment. that the
ceiling- speaker sound system was poor
and they were in the process of installing
a better system. and that my best bet
would be to work with an outside audiovisual contractor for the necessary equipment. I knew one of the AV rental corn panies in the area from a previous
successful presentation and arranged
with them to have the necessary equipment delivered and set up. and explained
the situation with the drape contractor.
The client's art director was to arrive
a day before anyone else to be sure the
stage was set up according to his design.
I was to arrive the following day, and the
arrangement was that the screen, drapes,
and equipment would be in place ready
for me to set up the soft -ware, and ready
for me to test all systems.
When I arrived, the AV contractor had
set up the screen according to my specifications, but the drapes and risers and
the local contractor responsible for these
were nowhere in sight. The AV contractor had waited for my arrival, but
since there was nowhere to set up the
equipment, this could not be done. The
client insisted that his contractor would
be there shortly, but this didn't happen.
Finally, after having waited for several
hours in vain. the AV contractor asked
to be relieved of that part of his contract
and left, leaving all the necessary hardware. It wasn't until several hours later
that the draping contractor finally arrived and started to cut material for the
drapes, with no thought of setting up
the risers. With the help of the client, we
got the contractor to start setting up a
place for the equipment, leaving the
drapes to be done later.
COMPLICATIONS SET IN
fhe contractor started h setting up a
massive rigging of hewn steel pipes. and
putting rough hoards on top for the
equipment. The level of the hoards
turned out to be almost 9" too high (considering that the projectors would have
to go on top with slide projectors stacked
3 high, and the film projector having a
lens height approximately 9" abose its
base). When told of this, the contractor
said his steel piping would only allow
a lowering of about 6 ". and that the
screen would have to be raised. they
refused to consider any other solution.
as they had a contract and they were
going to finish the job. Fortunately. we
could raise the screen, and this seemed
the easy way out not to waste any more
time. We were already about 9 hours
behind schedule.
TIME & COST
When I told the client, whose art
director stayed with us all the way
through the ordeal, that it could have
been done in a small fraction of the time
with the AV contractor and the help of
hotel personnel., he admitted his error,
and he realized, even more, how wrong
the whole idea was when he saw the
"special" set -up that was rigged. The
drapes were not put up completely
until several hours after the rigging,
incidentally, so the total cost for the
complete job, if paid for by the hour.
must have been enormous.
LESSONS TO BE LEARNED
he lesson here is that it could save an
awful lot of time and money to just have
a simple set -up of platforms and stacked
tables, usually available in -house at most
I
hotels.
The second trip was to a large city on
the east coast. The meeting was to take
place in a large conference room with
rear screen projection. The technician
at the site told me on the phone, in a
conversation well in advance of the
presentation date, that all the equipment
I needed would be available, including a
remote slide control for the speakers at
the podium. It was a simple type of
presentation with a single slide projector
and a 16mm film projector. as well as a
1/4-inch tape. When I arrived. I found that
he was right. The equipment was there.
However, he had never had a presentation before in which film and slides were
mixed. It was necessary to turn a large
front -surface mirror to show slides, then
film. Both projectors were permanently
set and it was the mirror setting that
determined which projector would hit
the screen. This meant that there was a
pause of almost five seconds or more,
depending on how smoothly he could
turn the mirror from one position to the
other and get it locked -in with as little
wobble as possible.
Gooseneck Paging?
/4/
urner
as
More!
Turner gooseneck paging microphones are available in seven
different models. Each model has features that make it uniquely
suited to specific installation requirements. A minimum amount of
electronic modification is needed because Turner has engineered
its products to meet virtually all gooseneck applications. There is
a quality Turner gooseneck paging microphone with features to
meet the following application requirements:
Noise
Low Impedance
High Impedance
Zone Paging
Normally Open Switching
Normally Shorted in
Cancelling
Press -to -Talk Switch
No Switch.
off Position
And, that's only the beginning. Turner has 18 other paging microphones in desk top, handheld and wall mount versions as well as
a full line of sound reinforcement microphones. Turner does have
more, and now, with the additional product development strength
of Telex Communications, Inc.. there will be even more to come.
Quality Products for The Audio Professional
TELEX. TURNER
co
co
TELEX COMMUNICATIONS. INC.
9800 ALDRICH AVE SO MINNEAPOLIS. MN 55420 U S A
EUROPE: 22. rue de la Lemon, Honneur. 93200 St Denis. France
Circle 22 on Reader Service Card
W
Another annoying condition was that
the sound system, with the tape recorder,
was in another room. This meant that he
would have to go from the projection
booth to a control room to start the tape,
and then come back when it was necessary to start a film (after turning the
mirror).
And to top it all off, the projector was
a random -access type with two drums
using their special slide mounts, and the
technician did not know how to load the
slides. It also turned out there were other
presenters whose presentations also
included slides, and they did not know
how to load the slides either. Since the
projector was the type which used an
internal mirror (in addition to the large
one), the slides in one drum had to be
loaded normally (as for front projection,
because of the double reflection), and
the other had to be mounted for rear
projection (using only the single large
mirror to reverse the image). I finally had
to load all the slides, using my own
blanks to separate the speeches as no one
had their own blanks-including the
technician.
An interesting lesson. Know as much
as you can about the different types
of equipment, get as much information
beforehand including types and model
numbers so you can be fully prepared
for anything, and keep your cool in spite
of all the nervousness around you.
mikes by mail? for less?
why not!"
ot!
a«d owe-4 "gene/
The Mike ShopTM now sells audio equipment
as well as mikes by mail! for less!
Write or call us with your requirements or for our price sheet.
The Mike Shop"
PO Box 366A, Elmont, NY 11003 (516)
437 -7925
A Division of Omnisound Ltd
Circle 24 on Reader Service Card
4600 SMPTE Tape Controller
Before you do another multi -track session, call us for a personal introduction to electronic audio editing.
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Boston Post Road, Weston, Massachusetts 02193 (617) 891-12.39
62iá Sunset Boulevard, Hollywood, California 90028 . 1213) 462 -1306
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The BTX Corporation
HOURS
MOVE
L.
MODE
JBL. WHEN EXCELLENCE COUNTS.
Whenever and wherever excellence in
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No other speaker is good enough for
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Because no other speaker is created
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And no other speaker has the benefit
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The JBL heritage of excellence and
reliability can be found in a wide variety
of applications.
At outdoor concerts ranging from
rock to Beethoven, thousands of listeners
can hear the artists clearly ... thanks
to JBLs.
In recording studios, you'll find more
JBLs than any other monitor. In fact. most
major albums are mixed or mastered on
JBLs, according to a recent Recording
Institute of America survey.
Under the lights at discos around the
world, more dancers are moving to
JBLs... by far the leading disco speakers
(Billboard's International Disco sourcebook).
Night club performers rely on JBL's
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James B. Lansing Sound, Inc.,
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FIRST WITH THE PROS.
CASSETTE DUPLICATOR
New Product:
& Services
maaoOdi
' ° .a ,.t,
-
.,o.
j,
HARMONIZER
Capable of changing the pitch of an
input signal by three octaves (one up.
two down), the model H949 Harmonizer
has two outputs, each with 400 ms. of
delay. In addition to pitch change and
delay. other effects include flanging.
repeat. random delay (for automatic
double- tracking). and a new effect called
"reverse." Incorporating two different
algorithms to handle the pitch change
'glitches', the user can select whichever is
optimum for the program material. Delay is selected via incremental push-buttons: while pitch change is controlled
either by a knob ( manual mode) or by the
HK940 keyboard. which varies the pitch
in discrete musical steps. Switchable for
115 or 230 volts, the H949 offers a frequency response of 20 Hz to 15 kHz. ±1
dB. and a dynamic range greater than
96 dB.
tllr. I.vollide
Clockworks. Inc.
Price: 52.400.00
Circle 60 on Reader Service Card
VOCODER
A sixteen channel vocoder, the
model 7702 features 16 analyzer and
16 synthesizer channels in the vocoding range. extending from 50 Hz to
5080 Hz. In addition, the performance
of the model 7702 is enhanced by a
high frequency channel which extends
from 5080 Hz to 15 kHz, and covers
the region of "s" sounds and explosive
consonants. The analyzer outputs and
synthesizer inputs are accessible
through phone jacks. Cross patches
for sound scrambling can be made
and activated, or de- activated, by manual or foot control. The unit employs
a built -in voiced /unvoiced sound selector, a noise generator for the "s"
sounds, a hiss /buzz balance control.
various mode switches, overload indicators for voice and carrier inputs.
and a Mic -Line switch for the voice
input. A sample /hold control holds
entered vowels when desired. Maximum output level is +15 dBm and
the signal -to -noise ratio is better than
70 dB. Input impedances are 20k
ohms minimum, while output impedance is 600 ohms.
Mfr:
co
Bode Sound Co.
Price: $5,600.00
Circle 61 on Reader Service Card
Employing vacuum tape chambers for
Automated Cassette Duplicator (ACD) system uses a reel -to-reel bi- directional
master (available in /, -. -. and one-inch
formats) and a line of Cassette Slave
Loaders. The system is capable of reproduction rates of 32 to 64 times normal
speed with frequency response to 15.000
kHz. An attachment for the Cassette
Slave Loader. the Automatic Cassette
Feeder (ACF) automatically performs
the tasks of cassette insertion, leader
extraction and threading of the leader
into the splicing platform. Then, the
automatic operation of the Cassette Slave
Loader takes over to cut the leader, splice
safe. high speed tape handling. the
/
the tape to the leader and load the cassette with tape while recording the signals
from the master. When duplication is
finished. it cuts the tape and splices the
leader at the end of the program material. and winds the remaining leader
into the cassette, ejecting the finished
product from the loader.
bllr: Recortec
Circle 62 on Reader Service Card
PASSIVE EQUALIZER
Foam
Boasting no insertion loss, the model
4320 passive equalizer features 27 one third octave filters on I.S.O. centers from
40 Hz to 16 kHz. The unit provides filter
attenuation up to IO dB. an EQ in out
switch. and two accessory octal sockets
on the rear panel-one for a bi -amp or
tri -amp crossover network: the other for
the insertion of a response shaping filter.
1/%r: White Instruments. Inc.
Price: $550.00
Circle 63 on Reader Service Card
The logic behind the
Revox B77.
The logic is the logic which is built -in.
It's an ingenious and highly sophisticated system
much like the human nervous system -which controls
the deck's functions.
You can push any button in any order with no chance of
damaging your tapes. Our motion sensing system constantly feeds status reports to the logic circuitry which
activates your commands in proper sequence.
The logic also permits full -function remote control, and an editing mode that keeps the playback circuitry live, even when the motors are stopped. You can
make your splices right on- the-beat, and our built -in
splicing block makes it easy.
The design and construction of the Revox B77 further
guarantee smooth and accurate operation. 'lb get the
-
,I,N1E
1819
long -life advantage of ferrite without static build -up or
heat degradation, we use Revox's exclusive Revodur
heads, made of metal to dispel heat and static, and
vacuum- coated with permalloy for durability.
The B77 has a unique capstan motor that's monitored by
a tacho head to precisely control speed and limit wow
and flutter to professional studio standards.
Revox offers many options with the B77 including a full
range of speed configurations from 15/16 IPS to 15 IPS,
variable speed control, '/a track record /playback and more.
All this professional quality is neatly engineered
to fit in a deck you can carry. After all, if you own a
machine this good, it's logical to take it with you.
Experience the B77 and the full line of Revox and Studer
professional products at your franchised dealer today.
,.«
REVOX America, Inc.
Broadway, Nashville, TN 37203 615 329 -9576/ In Canada: Studer Revox Canada, Ltd.
Circle 33 on Reader Service Card
www.americanradiohistory.com
41): Editorial
The Last Word
on Microphones
IF 'tO(RF I ooKING for the last word on microphones.
we'd like to pass on the following suggestion: Keep
on looking. for you won't find it in this issue of db.
Or in any other issue. for that matter.
No we are not awaiting some major breakthrough in
microphone technology. As far as we know. there are no
immediate plans for digital microphones or automated
polar responses. Of course. microphones are getting
more sophisticated, but the basic designs don't seem to
he changing at the rate one finds in consoles and signal
processing devices.
While yesterday's console may be getting "old-fashioned." chances are yesterday's microphone is still as
good as new. and you wouldn't dream of trading it in.
Hut. we're not yet ready to write the final chapter on the
art of the microphone. And probably, never will be.
There's still no "right" way to mike the drums, no
"correct" equalization for the rhythm guitar pickup. and
no answer to "What do I use on the (you- name -it) ".
However, there is one immutable rule that we can pass
on to you. It's Edsel Murphy's closed -loop theorem of
microphone movement. (Remember, you read it here
first.)
I. Place any microphone at any distance from an
instrument.
2. Describe your set -up to ten engineers.
3. Receive ten explanations of what's wrong.
4. Follow the recommendations of any one engineer.
5. Go to line 2. and repeat. until you get the message.
Now that we've all gotten the message, let's move on
to some words that may help you to better cope with the
Murphy's -loop syndrome.
We start off with some applications- oriented features.
For example, what about a nice little heater for your
favorite old condenser' lope. this is not meant to keep
it cozy on those long winter nights. It's to keep it from
making impolite little noises at the wrong time. (Or.
as Murphy tells us. "Microphone noise level is inversely.
and perversely, proportional to signal strength. ") For
the latest generation of condenser microphones. there's
probably no need to bother, but everyone has some older
favorites. and sometimes these get a little finicky whenever the THI changes too quickly. Bob Katz' heater
project may be just the thing to keep these mies behaving
themselves.
Of course, you'll need good microphone cables. and
there's no shortage of cable testers around these days.
However, the tinkerer may want a little something extra.
and Kirk Elliott's CMOS cable tester is surely ¡tut that.
And. be sure to check out our directory of microphone
manufacturers immediately following K irk Elliott's
article.
In his era of the twenty -four track recording studio.
it's important to remember that there is a world of
difference between stereophonic sound and multi-track
mono. If your last extravaganza lacked a little dimension,
perhaps you're overlooking some of the advantages of
stereo miking. Obviously. it's not right for every session,
but how about trying it out on the next string overdub?
Bruce Bartlett describes how to begin.
Of course. you can't stereo -mike the strings on an ELP
live gig. In fact, you just might not be able to hear them
at all if it were not for Arnie Lazarus and the FRAP.
When it's necessary to "go direct." and the instrument is
acoustic, the FRAP Point -source -microphone may be
worth its weight in gold- -and you know how much gold
costs these days.
Well. it seems we're just getting started on the subject
of microphones. and here we've run out of room this
month. So, we'll continue this next month, with a few
more features, but still. no last words on the subject.
www.americanradiohistory.com
Eight good reasons to be
a Beyer Buyer.
one
five
two M
stands and booms. A full
range of mic mounts for floor
and desk use, with fixed and
folding bases. Available with
collapsible tubes for easy
packing. Also heavy -duty
stands for speaker cabinets.
six Beyer microphone accessories. Wind screens, im-
The first reason is Beyer. We have fifty years
experience making the world's finest microphones and
headphones. And an unmatched reputation for quality,
reliability and innovation. The choice of professionals
everywhere.
160. One of the world's best -loved and most
versatile microphones. Warm, soft sound
favored by vocalists and
musicians alike. Dual
ribbon design for
high strength and
pedance matching transformers, in -line switches,
power supplies, wireless
transmitters, stereo arms,
goosenecks, clamps, thread
adapters, anti -shock sus-
fast transient response.
three
Beyer microphone
Beyer headphones. A
full range of high quality professional
models for critical monitoring and reliable
communication. DT 109 combines stereo headphones
and boom -mounted microphone, ideal for on -air use
and disco deejays. DT 4445 wireless headphone receives sound from an infra -red LED transmitter up to
pensions, and even a mic
stand ashtray! The whole
works. If you can use it with a
mic, we make it.
300 feet away. Full 20- 20,000Hz frequency
response. Six hour stereo operation on rechargeable NiCad batteries.
four The new M 400. A great performer's mic. Supercardioid pick -up
pattern to minimize feedback. Rugged
design for long life. Tapered frequency
response with rising high end and
rolled off lows, plus midrange presence boost. Built -in humbucking
coil and pop filter. Dynamic design is unaffected by heat
and humidity.
We're looking for a few more
great dealers to handle the Beyer line.
Contact Norm Wieland at Burns
Audiotronics.
seven M
B eyer
713.
One of our unsurpassed studio condenser
mics. Modular system: accepts different transducer capsules and power supplies. Gold- vapored mylar
diaphragm for high transient response. Mumetal shield. Temperature and humidity stable.
eight See your dealer or write for information on our product line. You'll have
many more reasons to be a Beyer buyer.
i
Dy n a m e
BURNS AUDIOTRONICS, INC.
5
-05 Burns Avenue. Hicksville, NY 118W
In
(516) 935 -8000
Canada. H. Roy Gray. Ltd.
www.americanradiohistory.com
cD
BOB KATZ
Build a Heater for a
Condenser Microphone
High humidity situations can often cause havoc with some
of the older condenser microphone models; here -in are plans for
a built -in heater for your condenser microphones.
IN MANY CASES. high humidity is no problem for condenser
microphones. In fact, some manufacturers claim their
microphones will perform in up to 99 per cent humidity.
However, a high- humidity environment, coupled with an
ambient temperature rise, can create precipitation problems
within condenser microphones, especially older models, with
stainless -steel diaphragms. Television recording engineers often
encounter this problem in large, air -conditioned, heavily -lit
studios. During breaks between rehearsals and takes, the
lighting is often shut off, to allow the studio to cool. Before
shooting, the studio may be at 60 degrees Fahrenheit, but by the
time of the first break, the temperature may have risen to 75 or
even 80 degrees. In conditions such as these, the microphone
diaphragm can be compared to an ice -filled lemonade glass on a
summer's day.
EARLY SOLUTIONS
The tv recording engineer soon learns that when his
condenser diaphragm begins to sweat, he can expect to hear
some bad sound. The first symptom is often an increase in the
low frequency noise level of the microphone, with "shotgun
bursts" of noise, resembling the sound of
a
constant
thunderstorm. The output signal -level begins to drop and the
microphone soon becomes unusable. Older, high-voltage tube
microphones may even arc in high humidity.
o
N
Bob Katz is an instructor and lab supervisor at the
Institute of Audio Research in New York City and a freelance recording engineer. Initial technical help and
materials were supplied hr Steve Washburn, an audio
and computer design engineer with Mantra Sound.
Glastonbury. CT. The Nichrome wire modification described in this article has been successfully built and
used by Ray Rayburn of Rayburn Electronics. New
York City.
Of course. the engineer can run out to the studio (hopefully
between takes) and shake the microphone like a fever
thermometer. This gets the musicians'attention. and sometimes
even cures the problem. A somewhat -more elegant solution is to
borrow a 500 -watt light. and heat the microphone over it for
about ten minutes. As long as the microphone does not become
too hot to touch, it is probably safe to dry it over a lamp. (One
manufacturer specifies the integrity of its capsules and preamps
to 60 degrees C.. which is 140 degrees F.)
I used to dry my "waterlogged" microphones overnight in a
dessicator until I found I could dry them with heat. I also
practice two additional preventive measures:
I. Warm a microphone with body heat before bringing it
from a cool control room to a hot studio. (Producers may look
aghast at this practice. fearing that the engineer is becoming too
attached to his equipment.)
2. Very carefully clean the diaphragm, since dust and other
pollutants can cause centers where moisture will stick and take
longer to evaporate. The cleaning process is not difficult;
however, do not attempt to clean the diaphragm unless you feel
confident to take the capsule apart. Even if the microphone is
not under warranty. it might be preferable to send it to the
manufacturer for cleaning and calibration at regular intervals.
If you wish to clean the microphone yourself, and can gain
access to the diaphragm with confidence, open the capsule in a
clean, dust-free environment. Obtain absolutely pure -grain
alcohol. Do not use freon, because its low boiling point may
cool the diaphragm, causing moisture to re- condense. Do not
use any brand of rubbing alcohol, because these contain
glycerine or lanolin.
Take a clean, soft camel's hair brush. Dip just the tip of the
brush in the alcohol and apply it to one edge of the circular
(usually) diaphragm. Gently "paint" from one side to the other.
In the process you will sweep dust to the other side and off the
diaphragm, as well as dissolve minor deposits that may also be
there.
To keep dirt and deposits from building up on microphone
www.americanradiohistory.com
EVERYONE KNOWS THAT
SWEDISH PRODUCTS ARE
DUILT TO LAST.
PML
HANDCRAFTED IN SWEDEN
SINCE 1941
DC73 CARDIOID CONDENSER
MICROPHONE
Cardioid condenser microphone for 48 volt
Symsi powering. Features an integral
electrical "pop" filter which has no effect on
high frequency response, and a built -in
shock resistant elastic suspension to reduce
hand noise to a minimum. A large diameter
circular condenser element provides full
natural sound in highly rugged package with
a steel mesh protective grille. A two position
slide switch on the case permits selection of
either flat response or 100 Hz high -pass for
vocal work.
Excellent hand -held vocal microphone.
Also for brass or percussion where cardioid
pattern is demanded. Studio, broadcast and
especially recommended for live
performance. 5295
DC96 CARDIOID CONDENSER
MICROPHONE
The DC -96 is a cardioid condenser
microphone for 48 volt Symsi powering. The
DC -96 employs the unique rectangular dual
membrane capsule similar to the DC -63 and
ST -8 Stereo microphones with FET preamplifier. Features: very low noise, high
output level and extremely smooth
frequency response both on and off -axis.
The small size of the DC -96 further enhances
its use where larger mikes become
obtrusive.
For all live performances and studio work
where a high quality cardioid microphone
pickup is required; for both close and distant
pickup. $465
VM -40 (Omni) and VM41 (Cardioid)
CONDENSER MICROPHONES
The VM -40 (Omni- directional) and VM -41
(Cardioid) condenser microphones both
feature a 1.5 cm diameter circular condenser
element. Small in physical size and very
rugged, they operate on 48 volts Symsi
power. A four position ring switch is
incorporated to permit selection of either
full range frequency response or 100 Hz
high -pass and for each position there is a
10 dB pad.
All high quality studio and broadcast
work, but particularly impressive for close
range brass, strings, percussion, and close
to medium distance orchestral pickup. $360
PML. THE SWEDISH STEAL
For a catalog of additional PML microphones. contact your favorite Pro Sound dealer, or your nearest PML factory representative:
San Francisco: Brian Trankle & Assoc., (415) 344 -1133 / Nashville: Technicon, (615) 865 -6040 / Dallas: Sound & Comm. Mktg.,
(214) 243 -8436 / New York: Harvey Sound Co., (212) 921 -5920 U.S. Distributor: In Los Angeles:
Cara International, LTD., P.O. Box 9339, Marina Del Rey, Ca. 90291 (213) 821 -7898
Worldwide Marketing: CREATIVE TRADE. CTAB AB. Knutsgatan 6, S -265 00, Astorp, Sweden, Tel: 4642/515 21
NAME
CITY
_
ADDRESS
STATE
www.americanradiohistory.com
ZIP
That's when cool musicians, cool engineers, and cool
microphones begin to sweat simultaneously.
One weekend. a microphone failed duc to the temperature
THREADED END OF MIC
change. As
PC COPPER STRIPPING
BONDED TO A PLASTIC BACKING
(BACKING NOT SHOWN FOR CLARITY)
INSULATED CONNECTING WIRE
1# 22 OR #20) HELD IN PLACE
WITH TEMPORARY MASKING
TAPE; HERE.
Figure
shell.
1.
PC copper stripping applied to the microphone
diaphragms. be sure to follow Lou Burroughs' recommendation: put windscreens on all vocal microphones.
A NEW SOLUTION
A humidity problem during an August recording session
prompted me to consider a more -permanent solution for my
microphones. This solution should work with almost any make
of half- to one -inch cylindrical microphones. The session was
the summer "Music Mountain" concert series in Falls Village.
Connecticut. The non -airconditioned concert hall is a wooden
building with many screen doors, open to the summer heat. The
inside stays cool all morning. and into the early afternoon, but
within minutes after the audience files in on a hot and muggy
day. the hall temperature and humidity rise tremendously.
BUILDING A
RECORDING STUDIO?
Make us your first call.
Audiotechniques
(203) 359-2312
We're not only the biggest, we think we're the best, by far! We've been
building studios for nearly eight years and have more years of combined professional audio engineering experience than we like to
admit. Initial planning, financing, designing, equipment installation,
maintenance ... they're all our business. If your business is recording, you should be talking to us.
I
segued to my backup microphones.
I
began to
think about a built -in heating element. This would function like
the heater incorporated into certain calibration microphones.
After a little experimentation, the following "field modification" was devised. and seems to work quite well.
RECIPE FOR A HEATING ELEMENT
There are two methods which hate been proven successful.
Material availability will probably determine which you use.
One method uses very -thin nichrome wire, encased in very thin shrink tubing. The tubing electrically insulates one turn of
nichrome from the next. and from the microphone body. The
other method uses flat I. 16 -inch wide PC copper stripping
bonded to a thin. transparent backing. The plastic backing
provides insulation as above, and (when the paper backing is
removed) also has an adhesive which sticks to the microphone
body. Described below is the PC stripping method. The
nichrome wire method is easily derived from this.
Ingredients: Copper PC stripping,
16 -inch wide and 12
inches long. with adhesive plastic backing: four feet of small gauge insulated wire: one -inch -diameter heat shrink tubing.
I
Remove the capsule from the microphone case and place it
in a safe location.
2. Remove the preamplifier from inside the microphone shell.
and place it in a safe location. (This guarantees neither capsule
nor electronics will be damaged by the heat of heat-shrinking.)
3. Cut two 2 -foot long pieces of insulated stranded wire: strip
back one end of each wire by
16th of an inch. and tin it.
4. Trim the plastic on both sides of the copper stripping to
approximately I 16th of an inch beyond the stripping.
5. Remove ooh an inch of backing from the plastic. exposing
some of the adhesive. then stick it to the end of the microphone
shell. (See FIGURE I ) You are beginning what is to become a
fine- pitched spiral of copper ribbon that will go around the
preamp cylinder. from the capsule end to less than an inch
I
.
I
below this.
6. Using a razor blade. slice under the end of the copper
ribbon and lift about a I/ -inch of it from the plastic. fin this
copper piece. Lay the previously- tinned wire along the length of
the cylinder so that its tinned end lines up with the end of the
copper. A temporary piece of masking tape further down the
shell will hold the wire in place. Fold the tinned copper back
over the wire and solder. wit /tout melting the plastic
underneath.
7. Continue the spiral neatly around the microphone. The
lines of copper should be as close to one another as possible. so
as to concentrate the heating effect in the area nearest the
capsule. With each revolution. the stripping will go over the
connecting wire and hold it in place. When you reach the end of
the strip. cut the copper on an es en revolution so that the second
connecting wire will line up with the first. Masking -tape the
second two -foot stripped and tinned wire to the microphone.
locating it to line up at the bottom of the spiral. Solder it to the
copper stripping as above. (If using N ichrome wire. silver solder
and a torch must be used.)
8. Check for a complete circuit with an ohmmeter. A DVM
will show almost 0 ohms (0.I to 0.2 ohm). Also. at this time
check that there are no shorts from the copper to the metal shell
:f the microphone.
9. Cut a piece of one -inch diameter heat shrink tubing.
transparent is nice because you can see the fruits of your work)
quarter -inch or so longer than the spiral on the microphone.
When heated. the tubing w ill shrink or curl a little at the edges,
:o account for that as you shrink it down. (a gas flame stove w ill
do the trick.)
10. Remove the tape holding the connecting wires in place
and tie a knot just where they come out from the tubing. This
will add mechanical strength to the second connecting wire.
which is not covered by the full width of the tubing.
Circle 16 on Reader Service Card
www.americanradiohistory.com
The SP-15 has two things our best
turntable doesn't have: Quartz- locked
pitch control and a lower price.
know what made the SP -10 MK2 our best turntable,
and why so many radio stations use it: Wow and Flutter
of 0.025% WRMS. Rumble of -78dB (DIN B). Speed
accuracy within an astonishing 0.002 %. And amazingly
high torque for a start -up time of 0.25 second.
Yet for $300 less,' the SP -15 has exactly the same
high degree of speed accuracy, the same wow and flutter
and the same rumble as the SP-l0 MK2 while delivering
an incredible start -up time of 0.4 second.
Technics quartz -locked pitch control is pretty incredible,too.Unlike the pitch control in many other turntables,
it lets you vary the speed with the unvarying accuracy of
quartz. In precise 0.1% steps above or below any of the
three standard speeds up to a maximum of ±9.9 %.What's
more, the exact speed variation you choose is shown
right up front in bright digital display. And with Technics
you can lock the pitch at the pitch you choose.
Another reason you'll choose the Technics SP -15 is
durability. It has an electronic brake that can stop the
platter in 0.4 second, even though a tracking force of
You
2.2 lbs. (or the weight of 250 tonearms tracking at
2 grams) can't begin to slow the platter down. And to
help minimize acoustic feedback, it has a heavy -duty
aluminum diecast chassis plus a double- damped platter.
And when you add the optional SH -15B2 base (shown
with SP -15) you'll get the extra protection needed to
cope with high volume levels.
There's also Technics SP -25, a two -speed version.
With the same accuracy, quartz -locked pitch control
( ±6 %) and many of the great features of the SP -15.
The SP -15 with quartz - locked pitch control. It
has the same phenomenal performance as the Technics
turntables many FM stations use and discos abuse:
MOTOR: Quartz -locked DC direct drive. SPEED: 331/3,
45 and 78 RPM. STARTING TORQUE: 3.0 kg. cm. STARTUP TIME: 0.4 sec. (90° rotation at 331/3 RPM). WOW
AND FLUTTER: 0.025% WRMS.RUMBLE: -78dB (DIN B).
PITCH ADJUSTMENT RANGE: ± 9.9 %.
The SP -15. We added quartz -locked pitch control,
we subtracted from the price.
'Bored on Technics recommended price for
SP -I0
MK2 and SP -15 (e.cludirg bases).
Technics
Professional Series
Circle 48 on Reader Service Card
www.americanradiohistory.com
Korn-mi m01'1KS
WE HOLD THINGS UP
ALL ROUND
THE WORLD
Figure
Ito
2. A
condenser microphone outfitted with heater.
I I.
Small- diameter heat shrink tubing around the two connecting wires will keep them together. I cut them to one -foot
length and put banana plugs on the ends. An XLR -to- banana
adapter allows using standard microphone cable for the d.c.
feed to the heating element. (The sex of the adapter is rexcrsed
to avoid "deadly error. ") Return the preamp to the shell and
screw on the capsule. Your microphone with heating element is
now complete. Steps -I take about 20 minutes.
12. Next step is to build a well -littered. variable d.c. power
supply. The simplest supply uses a step -down transformer to 12
volts or 24 volts maximum. This feeds a variable autoformer
with a similar maximum voltage rating. The autoformer will
enable you to "dial -up" the voltage necessary to produce the
current to heat the coil. Ultimately. the voltage across each
coil may end up being as little as 2 to 5 volts, but you must be
able ut+ deliver more into the feed cable(s) to overcome losses.
Full wave rectification. substantial filtering (40.000 to
48.000 of of filter capacitance minimizes hum induction at high
currents), and an output ampere meter complete the supply.
I
I
USING THE HEATER AND POWER SUPPLY
he heating ettcct is rcasonab! > proportional to the square
of the current. Therefore the ampere meter on the power
supply provides a monitor on the microphone temperature
without a fancy thermostatic control. If you use nichrome wire.
about I to I'/ amps of current will make the microphone feel
warm to the touch (between 90 and 105 degrees F.) in a normal
I
New Stand MT/1
Today, everyone gets used to things being held
up. In a studio the only "hold up" that is welcomed is a mike on a good stand. When you use
Keith Monks stands, you can set them and forget them. The versatile design, together with
a wide range, means that Keith Monks stands
deal with those difficult jobs as easily as the
simple ones.
Keith Monks produces what is probably the
most complete range of mike stands that are
generally available the world over.
Find out for yourself why só many people now
rely on them.
KEITH MONKS (AUDIO) INC.
652 Glenbrook Road
Stamford, Conn. 06906
(203) 348 -4969
Telex 643678
Canadian Distrmi.to
B.S.R. (Canada) Ltd.
Keith Monks (Audio) Ltd.
P.O. Box 7003. Station B
26 -28 Reading Rd. So.. Fleet
Clairville Drive.
Aldershot. Hampshire. England
Rexdale. Ont.. Canada M9V 4B3
Tel. (02514) 20568
Tel. (416) 675 -2425
Telex: 858606
ti
Circle 41 nu Reader Service Card
temperature room. As much as 4 to 5 amps may be needed if
you use the PC stripping.
Start with
ampere and gradually increase to find the
proper current temperature. Experiment to find the correlation between the ampere meter and the microphone temperature. After each adjustment. wait five minutes before increasing the current again. as the microphone takes time to
come up to temperature. Once you have found the current -level
for your microphones, make a note of it. and simply set the
meter when you turn the supply on. Varying cable lengths will
contribute to voltage losses but the required current will be
I
approximately the same.
If you wish- four microphones can be put in series parallel.
This will double the current requirement at the supply. If you
do not use a thermostat, you should use equal lengths and equal
type cable to each parallel leg, to guarantee equal heating.
The heated -microphones are used as before, except an extra
cable goes up to each. Of course. you can no longer slide -on a
microphone holder from the front. If your microphone does
not permit sliding a holder on from the back, or snapping it
onto the body, then you will have to use a clothes -pin type
holder instead of the original slip -on type.
Using microphones with heaters will not guarantee that
"warm" sound you are looking for, but will certainly help worried engineers and producers to keep cool.
-M85 MK2 with metal tape.
We pushed performance to a new high.
But kept the old price'
Technics
RS
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Last year you could get the precision of direct drive
and the unparalleled accuracy of quartz with Technics
RS -M85. The cassette deck Audio magazine (June'79)
said "had the best tape speed characteristics ever
measured in a cassette deck." This year you can get
that same accuracy with the RS -M85 MK2. Along with
the additional benefits of metal tape. Yet we didn't
and instantly applies corrective torque whenever the
slightest speed deviation is detected.
Another one of the RS -M85 MK2's bright spots
is its two -colored fluorescent (FL) bar -graph meters.
A device attack time of just 5 millionths of a second
proves they're fast. While no more than 0.1dB deviation from the 0 VU level proves they're accurate.
What we did add is more dynamic range, a wider
frequency response and sendust -formulation heads
that easily handle the difficult jobs of recording and
erasing metal tape.
One more difficult job the RS -M85 MK2 easily
handles is keeping wow and flutter down to a microscopic 0.035% while maintaining excellent speed
accuracy. But that's not surprising. At least not with
Technics quartz -locked direct drive. This servo system
compares the rotation of our direct -drive motor with
the unwavering frequency of a quartz oscillator,
Still, the RS -M85 MK2 has even more: Like a
separate,coreless DC motor for reel drive. Dolby `NR.
A low- noise, highly linear amplifier section. Full IC
logic controls. A 3- position bias /EQ selector with bias
fine adjustment. And an optional full- function infrared
wireless remote control (RP -070).
Technics RS -M85 MK2. We pushed the performance up. Not the price.
FREQ. RESP. (Metal): 20- 20,000 Hz. WOW AND
FLUTTER: 0.035% WRMS. S/N RATIO (Dolby in):69dB.
SPEED DEVIATION: No more than 0.3 %.
'Bored on Tcchn,
s
recommended price for
RS -M85
and
RS
(Dolby is o trademark al Dolby Laboratories.
Technics
Professional Series
M85 MK2.
KIRK ELLIOTT
CMOS Microphone
Cable Tester
Leds indicate microphone cable's status.
\\I
(5)
i IORs and cables are among the elements
most likely
ly to fail in a professional sound system.
he constant use and ahuse to \\ hick they are sub toutjected. both in the recording studio and on the road.
make them especially susceptible to damage. Moreover, the
high pressure circumstances of recording sessions and concerts
necessitate the speedy identification of and technical problems
that may arise.
A
I
(( untinurd on page
3111
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ICI,
ICIb
IC2b
IC 2a
IC3b
IC3a
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Figure 1. Schematic diagram for the
microphone cable tester.
)
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04
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Kirk Elliott
is employed as
Toronto. Canada.
a
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IC3c
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technician at O wp a Audio.
www.americanradiohistory.com
The new Stran ound
Intercom System
-a
Strand Sound has it
rugged, high quality,
low noise, closed circuit intercom system designed
expressly for the theatre and eltertainment
industries. The new Strand Sound Intercom can
withstand tough treatment on tie road foolproof
inter -connection of components assures quick and
easy setup.
Master Power Unit serves as the main cgntïol
t
n and drives the entire syste
-u io 50
rnóte stations per ring. (inset
-
he new Strand Sound InteÉco t ishompatible with
omponents of the!!Ri rindie rem system in most
co
on use
y
B
ck- lightweight, rugged construction
specially designed to protect control switches from
damage when dropped or severely knocked.
Headset connector is at base of pack to keep
controls clear and minimize excessive wear.
Mini Power Unit -the high quality Strand Sound
Intercom alternative where 5 or fewer stations
are needed.
The new Strand Sound Intercom -a complete
system for touring or permanent installation.
Lend us your ears -you'll like what you hear.
STRAND SOUND
A Division of Strand Century Company Limited
A Company Within the Rank Organisation
6520 Northam Drive, Mississauga, Ontario
Canada L4V 1H9 Tel. (416) 677 -7130
Circle 31 on Reader Service Card
www.americanradiohistory.com
Introducing a present
f
Once you go
through a recording session with the
new ATR -124 24channel recorder
by Ampex, you'll
want to go through
another. Because with
each new session you'll discover something new you can
do. Things that you can only do
with a recorder that's full of features of the future.
ATR -124 gives you the unheard of:
i;
r
Time on your hands.
Which means you can use that time to give clients
more of what they're paying for -your creative skills.
With the ATR -124 microprocessor -based control
system, you can pre -program what you want to do
ahead of time so you won't waste studio time setting
things up. When their time starts, you're ready to
record by touching a single recall button.
ATR -124 also lets you duplicate a technique
you may have used earlier in the session without
having to rethink what you did. Just touch the
memory button and it'll all come back to you.
ATR -124 lets you rehearse what you've got in mind,
without recording it, to make sure
what you've got in mind is right.
Tape can be manipulated faster
which means you'll get the
sound you want sooner. And
the chance to try something "a
little different." All because of
the speed and accuracy that
A1R -124 puts at your fingertips.
ATR -124 doesn't take away
your creativity, it adds to it.
The less time spent setting up,
correcting, and redoing, the
more time spent creating. And
when you add features that
help you create to the ones that
help you save time, you've got one very potent
piece of audio machinery. Take the control panel
for instance. It's like nothing you've ever seen.
Pushpads linked to a microprocessor give you a
new level of creative flexibility. Program a setup,
then change it. Then change it back, all with a
single fingertip.
A repeatable, variable speed oscillator for pitch
correction and special effects is built in. In addition
www.americanradiohistory.com
rom the futu re: AiR-124.
to the standard output, there is an optional auxiliary output with each channel that enhances
flexibility. So don't think that ATR-124 is going to
Memory, and Record Mode diagnostics. The
point is this: If you like the ATR -100, you're going
to love working with the ATR -124.
AMPEX
F
R
m
e
.
. . . . . .
mmm
u
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s
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u
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A7R -124's Control Paiàèf. Speed and accuracy at your fingertips.
replace anything that you do. On the contrary, it's
going to improve the skills you have, if not help
you develop some new ones.
ATR-124 picks up where ATR -100 leaves off.
It's only natural that the people who brought you
the ATR -100 should be the ones to bring you something better. ATR-124 offers you 24 channels
instead of 4. You also get many new and exclusive
features. The kind that have set Ampex apart from
the crowd for the last 30 years. Features like balanced, transformerless inputs and outputs; a
patented flux gate record head; 16" reel capability;
input and output signal bus for setup alignment;
membrane switch setup panel; fingertip-operated
shuttle speed control; and microprocessor-based
synthesized Varispeed -50% to +200% in .1% steps
or in 1/ tone steps. ATR -124 also features microprocessor -based control of Channel Grouping,
multiple 24- channel Setup
Memory, Programmable Monitoring,
Stay Alive
EI
-
- ®-:
®®s
-
ATR-124 options.
As impressive as the ATR-124 itself.
With the addition of a built-in Multi-Point Search -ToCue (MPSTC), you can rehearse edits and control
five tape -time actuated events and be compatible
with SMPTE time code. Separately controlled auxiliary output amplifiers with each channel provide
simultaneous
monitoring of normal and sync playback as well as all
7
8
9
other monitoring
6
5
6
IN.AL--Ale411&`
modes. A roll 2
3
around remote
o
+
control unit can
also be added to
the ATR -124
which contains all
control features
normally found on
ATR -124's Mu'.'i -Point Search To Cue (MPSTC)
the main unit.
Provides 1(X) cue locutions.
Ns
--
_
EN
1
® ®
®
ATR -124. Your next
step is to experience it firsthand.
As you scan the points we've covered, remember
that you're scanning just a small portion of ATR -124's
story. We haven't even begun to discuss the
accessibility of key components for easy servicing and minimal downtime, or the features
we've built in to give you greatly improved tape
handling. To find out more, write to us at the
address shown below. We'll send you a brochure
on ATR -124, our latest audio effort. Better yet, call us
and we'll set up a demonstration. It's really the only
way to listen to the future.
ATR -124. Pure 24- Channel Gold From Ampex.
ATR -124's
rugged, precisionmachined casting provid
unsurpassed mechanical
stability.
AMPEX
Listen tO the fUtUt'e
Ampex Corporation, Audio -Video S,,stems Division,
401 Broadway, Redwood City, California 94063 415/367-2011
www.americanradiohistory.com
the connectors) is indicated by the illumination of leds
2/ 3, and is thus easily identified.
CP
0,
02
03
2.
shown in FIGURE 2.
Each of pins Q -Q5 is connected so as to sequentially enable
goes high, it
a pair of analog switches. For example. when
enables switches ICla and !Cie. If a good connection exists
between pin I of the male end of the cable and pin of the
goes low and QI goes
female end, led I flashes on. When
high, switches ICI a and !Cie are disabled. and led I goes off. At
the same time. switches IC2a and IC2c are enabled. testing for
continuity between pin 2 of the male end and pin 2 of the female
end. Q, enables IC3a and IC3c, testing for continuity in the
number three conductor.
Q
0,
Figure
and
WHY CMOS LOGIC?
CMOS logic was chosen to minimize power consumption
and allow battery operation. 1C4 operates as a single square
wave generator and clocks IC 5. which is connected as a scale -ofsix ring counter. Pins Qo Q5 of IC5 produce the waveforms
00
5
I
-
Q
IC5 wave forms.
FAULTY CABLES AT A GLANCE
This cable tester allows the technician to identify faulty
microphone cables at a glance. Both ends of the cable are
plugged into the device, and six leds indicate the cable's status.
The procedure is fast and neat, avoiding the awkwardness of
interfacing ohmmeter test probes with cable plugs. Furthermore- intermittent failure is easily detected by plugging in the
cable and tugging or shaking it.
l.eds I.2 and 3 (FR;uRe I) indicate continuity, while leds I / 3,
2/ I. and 3, 2 indicate shorts. Any break in the connection
between pins I, 2. or 3 of the male end, and the matching pin on
the female end, causes the corresponding continuity led to go
out. If a short exists between any pair of conductors, the
appropriate led lights up. Thus, a good cable will light up leds I.
2, and 3. while blanking the others. Any other combination of
leds indicates not only a faulty cable, but also the nature of the
fault. Phase reversal (wires for pins 2 and 3 reversed at one of
I
Similarly, when Q3 goes high, switches ICId and IC3b are
enabled. If conductors and 3 are shorted together. then led I / 3
flashes on. Q4 and Q5 enable switches to test the other two
possible short -circuit combinations.
IC4 oscillates fast enough that the flashing leds appear to be
on continuously. evtn though they draw current only once
every six clock pulses. Each led draws an average of about 5mA.
Although Switchcraft sockets were installed in the unit to
facilitate the testing of standard microphone cables, there are
other possibilities. Appropriate jacks would allow the verification of virtually any audio cable with up to three conductors.
such as standard '/ -inch phone plug cables or professional RTS
patchbay cords. The device has proved useful in the shop for
identifying bad cables, and for giving a final check once the
cables have been repaired.
I
The Versatile Quad-Eight CL22
Can Make It Better
Compress. Limit. & Expand.
the heart of the most versatile signal conditioning
device available lies an exclusive, advanced feed-forward
VCA controlled circuit design. This helps to eliminate
common control and distortion problems in ordinary,
conventional compressors and limiters. Like all
Quad -Eight precision modular products, the CL22 is
available in 19" rack and standard 1 -1/2" console
configurations. Contact us now for more juicy details.
At
. ,rr
r!,25,
M1 NO
ni
For the Artist in Every Engineer.
Quad-Eight Electronics /Quad-Eight International,
11929 Fose Street,
North Hollywood, California 91605, 12131 764-1516 Telex: 662 -146
0
M
Circle 40 on Reader Service Card
Model 501 Sub-Sonic Processor.
Saves Speakers
Saves Power
Solves Problems
ujii
MC
Ever watch the bass speaker cones in a typical disco system or studio monitor
try to jump out of their baskets? Most of these excessive excursions which ruin
can't be heard. UREI's Model
speakers and rob amplifier power are sub -sonic
501 two-channel Sub -Sonic Processor saves speakers and amplifiers by greatly
the culprits which cause
attenuating frequencies below the audible range
those great cone movements. Turntable rumble, warped records, acoustic
coupling of turntables to speakers and wind blast in microphones no longer
need distort your programs or put you out of business for repairs. Especially
when the dual 501 costs about what you'd spend on one speaker reconing.
The 501 has a two -position response switch: (1) "FLAT ",
3 dB at 30 Hz and down more than 50 dB at 5 Hz,
18 dB per octave; (2) "BOOST ", which
actually enhances LF response,
by boosting 5 dB at 40 Hz, but
is down 3 dB at 27 Hz and
more than 40 dB at 5 Hz ...
also 18 dB per octave.
The mighty mite dual -channel
501 comes with its own
SUB -SONIC
model 501
4.
PROCESSOR
r
miniscule power supply for
direct plug -in to mains.
Save your speakers and power
solve your sub -sonic problems with 501's from your
-
UREI dealer.
MIS
O
11
8460 San Fernando Road, Sun Valley, California 91352
Worldwide: Gotham Export Corporation, New York;
Canada:
E. S.
(213) 767 -1000
Gould Marketing, Montreal
Circle 18 on Reader Service Card
How serious are you about a power amp?
We build our Professional Series power amplifiers as if our
reputation were at stake. Because it is. And so is yours, when you select
an amplifier. That's why you should consider Yamaha power amps. They
come through for both of us. Because we both designed them. Comments
and suggestions from professionals like yourself were incorporated into
the final design. As a result, Yamaha power amps excel in the areas that
can make or break a power amp -performance, reliability, and flexibility.
Take the P-2200 for instance.
Performance. The very conservatively rated specs tell the story. The
P-2200 produces 200 watts continuous power per channel, from 20Hz to
20kHz, with less than 0.05 °o THD, both channels driven into 8 ohms. I.M.
and THD are typically less than 0.01 °o @ 150W for powerfully clean sound.
Peak -reading meters accurately display a full five decades (50dB) of output level for accurate
monitoring of program dynamics, transient power demands, and headroom. Frequency response is 20Hz
to 20kHz, +0dB/ -0.5dB, ensuring transparent highs. The high damping factor of over 300 (8 ohms,
20Hz to 1kHz) provides tighter low -frequency driver excursion and efficient power transfer.
Reliability. Large toroidal power transformers, multiple protection circuits, heavy front panels,
serviceable printed circuits, massive heat sinks, and fully vented chassis are some of the reasons
Yamaha power amps have a proven reputation for reliability.
Flexibility Detented, log -linear input attenuators, marked in 22 calibrated dB steps, allow you precise,
repeatable setups, accurate input sensitivity adjustments, and simultaneous adjustment of the level of
two channels or programs on separate amplifiers. The P-2200 has one male and one female XLR
connector plus two parallel phone jacks for each channel for convenient chaining to another amp and
adaptor -free connection to any mixer. A polarity switch satisfies DIN /JIS or USA wiring practice. The
P -2200 is readily suited for monaural operation as well as 70 -volt commercial applications.
The P -2201 is identical to the P-2200 except it does not have the peak -reading meters. The P-2100
and the P -2050 differ primarily in rated power output and size. Each model offers the maximum in
performance, flexibility, reliability and value for the dollar in its category.
We have a technical brochure covering all four models. Write Yamaha, P.O. Box 6600, Buena Park,
CA 90622. Or better yet, visit your dealer for a demonstration of the Yamaha power amps that take
their job as seriously as you take yours.
Because you're serious.
0
YAMAHA
Circle 43 on Reader Service Card
Directory of Microphone Manufacturers
MICROPHONES
AKG Acoustics
Philips Audio Video Systems Corp.
McKee Drive
Mahwah, New Jersey 07430
91
Audio -Technica U.S., Inc.
33 Shiawassee
Avenue
Rohde & Schwarz
Rohde& Schwarz Sales Co., (U.S.A.) Inc.
14 Gloria Lane
Fairfield, NJ 07006
(201) 575 -0750
Schoeps
Fairlawn.Ohio 44313
c/o Studer ReVox America, Inc.
(216) 836-0246
1819 Broadway
Nashville, Tennessee 37203
Beyer Dynamic
Burns Audiotronics, Inc.
(615) 329 -9576
(Distributor)
Sennheiser Electronic Corp.
IO West 37th Street
New York, New York 10018
(212) 239 -0190
Burns Avenue
Hicksville, New York 11801
(516) 935-8000
5 -05
Bruel & Kjaer Instruments, Inc.
51 I I W. 164th Street
Cleveland, Ohio 44142
(216) 267 -4800
Calrec
Edcor (Distributor)
16782 Hale Avenue
Irvine, California 92714
(714) 556 -2740
Countryman Associates
424 Stanford Avenue
Redwood City. California 94063
(425) 364 -9988
Electro- Voice, Inc.
600 Cecil Street
Buchanan, Michigan 49107
(616) 695-6831
Nakamichi, U.S.A. Corp.
1101 Colorado Avenue
Santa Monica. California 90401
Shure Brothers, Inc.
222 Hartrey Avenue
Evanston, Illinois 60204
(312) 679 -4020
Sony Industries
9 West 57th Street
New York, New York 10019
(212) 371 -5800
PICKUPS
Countryman Associates Inc.
424 Stanford Avenue
Redwood City, California 94063
(415) 364-9988
WIRELESS MICROPHONE
SYSTEMS
Beyer Dynamic
Burns Audiotronics, Inc. (Distributor)
5 -05 Burns Avenue
Hicksville, New York 11801
(516) 935 -8000
Cetec Vega
P.O. Box 5348
Elmonte, California 91731
(213) 442 -0782
Edcor
16782 Hale Avenue
(714) 556 -2740
HM Electronics (hme)
Technics
One Panasonic Way
Secaucus. New Jersey 07094
6151
(201) 348 -7000
The Ken Schaffer Group, Inc.
10 East 49th Street
New York. New York 10017
Turner Microphones
Division of Telex Communications, Inc.
9600 Aldrich Avenue South
Minneapolis, Minnesota 55420
Neumann
Gotham Audio Corp. (Distributor)
741 Washington Street
New York. New York 10014
Wahrenbrock Sound Associates, Ltd.
PZM" (Pressure Zone Microphone)
12115 -A Woodruff Boulevard
Downey, California 90242
(212) 741 -7411
(213) 861 -0397
Marina Del Ray, California 90291
(213) 821-7898
Folsom
(503) 638-6551
(612) 884 -4051
4145 Via Marina, Suite 120
1061
San Francisco, California 94103
(415) 431 -9350
Sunn Musical Equipment Co.
Amburn Industrial Park
Tualatin, Oregon 97062
(213) 451-5901
PMI. (Pearl)
Cara International. Ltd.
(Distributor)
POINT -SOURCE MICROPHONES
FRAP (Flat Response Audio Pickup)
Irvine, California 92714
Fairmont Avenue
San Diego, California 92120
(714) 280 -6050
(212) 371-2335
Sennheiser Electronics Corp.
10 West 37th Street
New York. New York 10018
(212) 239 -0190
Sony Industries
9 West 57th Street
New York, New York 10019
(212) 371-5800
Swintek Enterprises Inc.
1180 Aster Avenue
Unit J
Sunnyvale, California 94086
(408) 249-5646
a
Cr
BRUCE BARTLETT
Stereo Microphone
Technique
Listening tests and evaluations of several microphone -pair
arrangements, for recording in stereo, provide a varied'
of interesting localization effects.
THE ADVENT OF DIGITAL RECORDING
and improvements
in the sound reproduction chain have drawn attention
to a critical link in the recording chain: the microphone
technique used during the recording session. For.
despite all manner of control -room advances. the accuracy of a
recording is still largely determined by the selection and placement of the microphones.
This article will explore several two -microphone stereo
techniques. which capture the sound of a musical event as a
whole. letting the conductor. composer. or musicians determine
the musical balance. Methods which require multiple microphones or matrix devices will not be covered.
INITIAL PLACEMENT
Imagine that we are setting up two microphones to record an
orchestra. We place the microphone stand(s) about 6 to 20 feet
in front of the front -row musicians. and finally settle on a spot
where we monitor a tasteful balance between direct sound and
hall reverberation. .fThe microphones are raised high on the
stand (10 to 20 feet) to keep the front row of the orchestra from
over- balancing the back row, and are tilted down to aim at the
orchestra. Due to their close, high placement. the microphones
Bruce Bartlett is a development engineer. Electrocoustleal Development at Shure Brothers. Inc..
Evanston. II..
1
`
the automatic mixer
automatically the better choice
The Voice -matic Mixer will introduce you to a new way of
mixing for multiple microphone sound systems. The unique
principle of Dynamic Threshold Sensing differentiates
between active and inactive channels. Also, simultaneous
inputs from several microphones will be amplified without
loss of feedback margin, assuring maximum house gain.
By drastically reducing background noise, improved sound
clarity and overall system quality will be achieved. Its modular
design makes it ideal for boardrooms that may require only
two microphones or Council Chambers, Churches,
Conference Rooms and Convention Centres that require
many more.
Sophisticated circuitry suppresses feedback "howl ".
Dynamic Threshold Sensing (DTS) eliminates gating
common to VOX systems.
Adjustable attenuation for active or inactive channels.
Low noise. Wide dynamic range.
Transformer balanced inputs.
Modular design -2 to 12 microphone inputs -allows
economical selection of inputs.
Multiple chassis may be tandem connected if additional
inputs are needed.
Second fully mixed output for tape recording, offpremises transmission, etc.
Front panel input Channel status LED's.
Flexibility is provided by many options giving a
custom -made system for each installation.
INDUSTRIAL
RESEARCH
PRODUCTS, INC.
ORCHESTRA
f
SOUND
SOURCE
X45°
I
`J.
RIGHT CH
OUTPUT
LEFT CH OUTPUT
-6dB RELATIVE
TO RIGHT CH
(
Figure 1. Coincident -pair technique. Cardioid
microphones crossed at 90 degrees.
pick up a brighter sound than an audience would hear, so some
high- frequency roll -off in the playback system may be necessary
to restore a natural spectral balance. (See Roy F. Allison's
article in the Recommended Reading Section.)
ORCHESTRA
SOUND
SOURCE
STEREO MICROPHONE PLACEMENT:
GOALS AND TECHNIQUES
One goal of stereo recording is to place the microphones so
that each instrument will be reproduced in the same relative
location as it was during the recording.
Suppose that we are listening to the recording over a pair of
loudspeakers. We want instruments in the center of the
orchestra to be reproduced exactly between the two speakers.
We want instruments at the sides of the orchestra to be
reproduced from the left or right speaker. Instruments located
slightly off-center should be reproduced off-center, and so on. I
would like to call this objective "localization accuracy" or
r+SPACING{
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"directional fidelity."
RIGHT CH
OUTPUT
LEFT CH OUTPUT
(DELAYED AND
-6dB RELATIVE
TO RIGHT CH
Figure 2. Near -coincident technique. Cardioid
microphones crossed and spaced.
Figure
3.
Spaced -pair technique.
SOUND
SOURCE
(O
M
LEFT CH. OUTPUT
(DELAYED RELATIVE
TO
RIGHT CH.
RIGHT CH OUTPUT
Also, we want the reproduced reverberation to simulate live
reverberation. The reproduced reverberation should either fill
the listening room (apparently coming from every direction
or it should at least spread evenly between the speakers.
Three simple methods used for stereo recording are the
"coincident- pair," the "near- coincident," and the "spaced- pair"
technique. The coincident -pair arrangement mounts two
directional microphones with their diaphragms one above the
other, angled apart to aim at approximately the left and right
sides of the orchestra (FIGURE I). Near -coincident placement
also angles the microphones apart, but with the microphone
grilles spaced a few inches apart horizontally (FIGURE 2). In
spaced -pair recording, two matched cardioid or omnidirectional microphones are placed several feet apart, aiming
straight ahead toward the group (FIGURE 3).
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Call Ron Larson
at (312) 792 -2700 for full details and
Catalog No. NPB -341.
Circle 49 on Reader Service Card
A Raytheon Company
1N\tt.aAZ
IM(.+-
5555 N. Elston Avenue, Chicago, Illinois 60630
(312) 792 -2700
www.americanradiohistory.com
HOW THESE SYSTEMS WORK:
LOCALIZATION BY INTENSITY DIFFERENCES
The location of "phantom images" between two loudspeakers
depends in part on the signal intensity differences between the
loudspeakers. Suppose a musical signal is sent to two stereo
loudspeakers. with the signal to each speaker identical except
for an intensity (level) difference. FIGURE 4 shows the approximate sound image location between speakers vs. the
intensity difference between channels. (The information in this
article is based on carefully -controlled listening tests. The data
is the average of the responses of ten trained listeners. They
auditioned a pair of high-quality loudspeakers in a "typical"
listening room, while sitting centered between the speakers at a
60- degree listening angle.) A 0 dB difference (equal level from
each speaker) makes the phantom image of the sound source
appear in the center. Increasing the difference places the image
farther away from the center. About a 20 dB difference makes
the image appear at only one speaker.
Suppose two cardioid microphones are crossed at 90 degrees
to each other, with the grille of one microphone directly above
the other (FIGURE 1). The microphones are angled 45 degrees to
the left and right of the center of the orchestra. Sounds arriving
from the center of the orchestra will be picked up equally by
both microphones. During playback, there will be equal levels
from both speakers and, consequently, a center image is
produced.
Let's say the extreme right side of the orchestra is 45 degrees
off -center, from the viewpoint of the microphone pair. Sounds
arriving from the extreme right side of the orchestra will
approach the right- aiming microphone on -axis, but they will
approach the left- aiming microphone at 90 degrees off -axis. A
card ioid polar pattern has a 6 dB lower level at 90 degrees off axis than it has on -axis. So, the extreme -right sound source will
produce a 6 dB lower output from the left microphone than
RIGHT
SPEAKER
LEFT
SPEAKER
I
20
16
10
6
0
6
LEFT CH
LOUDER
RIGHT CH
LOUDER
16
20
I
Figure 4. Approximate image location between
loudspeakers vs. intensity difference between channels
in dB. (Listener's perception; listener sitting centered
between speakers at a 60- degree listening angle)
from the right microphone. Thus, we have a 6 dB intensity
difference between channels. According to FIGURE4. the image
of the extreme -right side of the orchestra will now be
reproduced right -of- center. Instruments in between the center
and the right side of the orchestra will be reproduced
somewhere between the 0 dB point and the 6 dB point.
If we angle the microphones farther apart. say 135 degrees,
the difference produced between channels for the same source is
around IO dB. As a result, the right -side stereo image will
appear farther to the right than it did with 90- degree angling.
Note that it is therefore not necessary to aim the microphones
exactly at the left and right sides of the ensemble.
The farther to one side a sound source is, the greater the
intensity difference between channels it produces. and so. the
farther from center is its reproduced sound image.
LOCALIZATION BY TIME DIFFERENCES
Phantom image location also depends on the signal time
differences between loudspeakers. Suppose we send the same
musical signal to two speakers at equal levels, but with one
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orban
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Orban Associates Inc.
645 Bryart Street, San Francisco, California 94107 (415) 957 -1067
Circle 15 on Reader Service Card
www.americanradiohistory.com
our seat may be three decks up in the end zone. But.
acoustically. you're on the 50 -yard line. A Delta -T audio
delay system is what does it. By synchronizing sound from
multiple speaker locations in massive Giants Stadium in East
Rutherford. N.1.. this advanced system provides complete
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nouncement
Performance like this has made Delta-T today's most
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world's finest concert halls to school auditoriums.
Write for full information. Or call us.
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exicon
Export: Gotham Export Corpo:.t on. Aew York.
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from the center of the orchestra, the greater the time difference
between channels and so, the farther from center is its
reproduced sound image.
2.01.0
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LEFT CH.
LEADING
0
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LOCALIZATION BY INTENSITY
AND TIME DIFFERENCES
RIGHT CH.
LEADING
Figure 5. Approximate image location between
loudspeakers vs. time difference between channels
in milliseconds. Identical signal sent to both channels.
(Listener's perception; listener sitting centered between
the speakers at a 60- degree listening angle)
channel delayed. FIGURES snows the approximate sound image
location between speakers, with various time differences
between channels, in milliseconds. A 0 msec difference (no time
difference between speaker channels) makes the phantom
image appear in the center. As the time difference increases, the
phantom image appears farther off-center. A 2 msec time
difference is sufficient to place the image at only one speaker.
Spacing two omnidirectional or cardioid microphones apart
horizontally -even by a few inches -produces a time difference
between channels for off -center sources. A sound arriving from
the right side of the orchestra will reach the right microphone
first, simply because it is closer to the sound source (FIGURE 3).
For example, if the sound source is 45 degrees to the right, and
the microphones are eight inches apart, the time difference
produced between channels for this source is about 0.4 msec.
For the same source, a three -foot spacing between microphones
produces a 2 msec time difference between channels, placing the
reproduced sound image at one speaker.
With spaced -pair microphones, the farther a sound source is
Phantom images can also be localized by a combination of
intensity and time differences. Suppose 90-degree angled
cardioid microphones are spaced eight inches apart (FIGuRE2).
A sound source 45 degrees to the right will produce a 6 dB level
difference between channels, and a 0.4 msec difference between
channels. The image shift of the 6 dB level difference adds to the
image shift of the 0.4 msec difference, to place the sound image
at the right speaker. Certain other combinations of angling and
spacing will accomplish the same thing.
In review, if a musical signal is recorded on two channels, its
reproduced sound image will appear at only one speaker when
(I) the signal is 20 dB lower in one channel, or (2) the signal is
delayed 2 msec in one channel. or(3) the signal in one channel is
lower in level and delayed by a certain amount.
We have seen that angling cardioid microphones (coincident
placement) produces intensity differences between channels.
Spacing cardioid or omnidirectional microphones (spaced -pair
placement) produces time differences between channels.
Angling and spacing cardioid microphones (near- coincident
placement) produces both intensity and time differences
between channels. These differences localize the reproduced
sound image between a pair of loudspeakers.
LOCALIZATION ACCURACY
If the orchestral width as "seen" by the microphone pair is 90
degrees, then we want sources 45 degrees to one side of center to
be reproduced out of only one speaker. Sources 22.5 degrees
off -center should be reproduced half -way between the center of
the speaker pair and one speaker.
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Tuners
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McMartin Industries, Inc. 4500 S. 76th St. Omaha, NE 68127 (402) 331 -2000 Telex 484485
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Black Beauty
ADC's ultra -reliable audio connectors are available in black
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Most important, Professional Audio Connectors are available immediately. They're
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Here's a case in point why more and
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Another good reason is that these units
are highly reliable. Tested to 5,000 insertions. And all Professional Audio Connectors and Receptacles are completely inter-
29 -0321.
ADC Telecommunications
A
DIVISION OF MAGNETIC CONTROLS
4900 West 78th Street. Minneapolis. MN 55435 (612)835 -6800
TWX 910-576 -2832 TELEX 29 -0321 CABLE ADCPRODUCT
Sales offices in Atlanta. GA (404) 766-9595 Dallas. TX (214) 241 -6783 Denver. CO (303) 761 -4061 Fairfield. CT (203) 255 -0644 Los Angeles. CA (213) 594 -6160
Melbourne. FL (305) 724 -8874 Minneapolis. MN (612)835 -6800 Mountain View. CA (4151964-5400 Washington. DC (2021452 -1043 Montreal. Quebec 1514) 677 -2869
Circle 50 on Reader Service Card
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PRESSURE ZONE MICROPHONES
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A fundamental advance in the art
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IMAGES "A" THROUGH "E"
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DAVID ANDREWS
A
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C
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(D)
Circle 42 on Reader Service Card
1
Figure 6. Stereo localization effects. (A) letters "A"
through "E" are live sound source positions; (B) accurately- localized sound images between speakers
(Listener's Perception); (C) "exaggerated separation"
effect; (D) "narrow stage width" effect.
an
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A\CHO
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Manufacturing Division
D
P.O.
15031
Bar 3586. Popland.
OR. 9720"
223-1924
NAME
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ADDRESS
CITY
STATE
ZIP
FIGURE 6 illustrates what we are discussing. In FIGURE 6A,
the letters A through E represent live sound source positions,
relative to the microphone pair. In FIGURE 6B, the
corresponding images of these sources are accurately localized
between the speaker pair.
Spacing, or angling, the microphones more than is necessary
to achieve a full stereo spread produces an "exaggerated
separation" effect; instruments near the center are reproduced
to the extreme left or right, rather than slightly off-center.
Instruments exactly in the center are still reproduced exactly
between the speakers (see FIGURE 6C).
Conversely, too -little angling or spacing gives a poor stereo
spread or a "narrow stage width" effect (see FIGURE 6D).
A listening test was performed to determine the localization
accuracy of various stereo microphone techniques, for a 90degree orchestral width. Recordings were made of a speech
source at 0, 22.5, and 45 degrees relative to the microphone pair
(as in FIGURE 6A). Tests were made in an anechoic chamber,
and in a reverberant gymnasium. Listeners were asked to note
the reproduced sound image locations for several techniques.
The image locations of the anechoic and reverberant recording
rooms were averaged, with results shown in FIGURE 7. Since
results may vary under different listening conditions, this
information is meant to be indicative, rather than definitive.
If the orchestral width is more than 90 degrees, the stereo
spread of all these techniques is wider than shown in FIGURE 7.
The closer to the ensemble a microphone array is placed, the
greater is the orchestral width as "seen " by the microphone pair,
and so, the wider is the stereo spread (up to the limit of the
speaker spacing).
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The Bose 1800.
When you turn the power up,
it won't let you down.
short circuits and other abnormal load
The Bose Model 1800 power amplifier
delivers 400 watts RMS per channel
with both channels driven. Its massive
power transformer and filter capacitors
prevent power supply voltage droop,
allowing the amplifier to deliver large
amounts of solid, sustained bass.
Not only that, the Bose 1800 is so
reliable, we gave it the longest warranty of any professional amplifier on
the market. What makes it so durable?
The use of 14 power transistors per
channel results in unusually low
thermal stress. And massive heat sinks
reduce the operating temperature
even further. Computer -grade electro-
lytic capacitors increase reliability
by providing extra temperature and
voltage safety margins. A turn -on delay
circuit limits power supply inrush currents to extend the life of the components. Electronic current limiting acts
instantly to protect the amplifier from
conditions.
If you want to take your Model 1800
traveling, it can take the beating of
hard road use. Its optional transit case
has built-in fans and air -flow baffles to
keep it cool. even under continuous
high -power use.
rBose Corporation, Dept.
SE
100 The Mountain Road
Framingham, MA 01701
Please send me a copy of the Bose
Professional Products catalog and
a dealer list.
Name
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With all its ruggedness and reliability,
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GARNER INDUSTRIES
Dept. db-12 4200 N. 48th St.. Lincoln, NE 68504, Phone: 402 -464-5911
Circle 32 on Reader Service Card
DEE
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B
PENT
OMNIDIRECTIONAL
ON SLOOP
2
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A
B
C
D
E
Figure 7. Stereo image localization of various stereo
microphone arrays. Images "A" through "E"
correspond to live sound sources "A" through "E"
in figure 6A.
EXAMPLES OF COINCIDENT -PAIR TECHNIQUES
According to FIGURE 7, it may seem reasonable to angle two
coincident cardioid microphones 180 degrees apart to achieve
maximum stereo spread. However, sounds arriving from
straight ahead will now approach each microphone 90 degrees
off-axis. The 90- degree off-axis frequency response of some
microphones is weak in high frequencies, giving a dull sound to
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Circle 26 on Reader Service Card
instruments in the center of the orchestra. In addition, it has
been the experience of another experimenter, Michael Gerzon,
that 180- degree angling places the reproduced reverberation to
the extreme left and right.
A 120 to 135- degree angle between microphones might be a
better compromise. Gerzon has reported that the 120-degree
angle gives a uniform spread of reverberation between speakers.
while the 135- degree angle provides a slightly -wider stereo
spread. These angles are useful where maximum stereo spread
of the source is not desired. For still -wider stereo images. a near coincident or spaced -pair technique may be required. However.
the I35- degree angle just described can provide a full stereo
spread if the orchestral width, or "source angle," is 150 degrees.
Angling at 90 degrees tends to reproduce most of the
reverberation from the center. It gives a narrow stage width,
unless the ensemble surrounds the microphone pair (180-degree
source angle).
The "Blumlein" or "Stereosonic" technique crosses two bidirectional (figure- eight) microphones at 90 degrees. with no
horizontal spacing between microphones (see FIGURE 8).
Again. according to Gerzon, this particular set -up provides
accurate localization, and gives the most -uniform -possible
spread of reverberation across the reproduced stereo stage.
EXAMPLES OF NEAR -COINCIDENT TECHNIQUES
The listening tests summarized in FIGURE 7 reveal that
the I10- degree angled. 17 cm spaced array (the ORTF.
French Broadcasting Organization. system) and the 90degree angled. eight -inch spaced array provide the most
accurate localization. In general. near-coincident techniques
give wider stereo spread than coincident techniques.
Another method (not included in the listening tests) is
the Stereo 180 System developed by Lynn T. Olson. It
employs two hypercardioid pattern microphones, angled
ORCHESTRA
90°
WITH
Figure
135
8.
LIMIT
AD
THIS
OFFER
EXPIRES
THREE
JANUARY
UNITS
1980
31,
Blumlein technique.
which create the illusion that the reproduced reverberation is coming from the sides of the listening room as well
as between the speakers. The localization accuracy of the
array is reported to he very good.
EXAMPLES OF SPACED -PAIR TECHNIQUES
Listeners commented that the spaced -pair methods give
vague. hard -to- localize images for off -center sources These
methods would be useful when clearly -defined sound images
are not desired (for special effect). Spacings greater than three
feet give an "exaggerated separation" effect. in which
instruments slightly off-center are reproduced full -left or
full- right. Instruments directly in the center of the ensemble are
still reproduced exactly between the speakers.
A disadvantage of the three -foot spaced arrangement is that
the microphone pair is most sensitive to instruments in the
center of the orchestra, with reduced pickup of the sides.
Spacing the microphones farther apart. say ten feet, may be
necessary to cover the whole orchestra adequately, but this
would produce exaggerated separation. (An exception to our
limitation of two microphones would use a third microphone
between the other two. mixed in at an approximate equal level.
split to both channels, to reduce stereo separation while
maintaining full orchestral coverage.)
When two spaced microphones are placed on the floor, the
sound source is above the plane (the floor) of the microphones.
As a result, for full stereo spread, floor- placed microphones
require a greater spacing than stand- mounted microphones.
Listening tests showed that a six -foot spacing between
microphones is suffficient for a full stereo spread. when the
sides of the musical ensemble are 45 degrees away from the
center of the orchestra. from the viewpoint of the center of the
microphone array (see FICA! RI 6A).
IT'S REM PRODUCTS
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PRO FEATURES AT
SEMI -PRO PRICES
When floor space is available, floor placement has several
benefits. No microphone stands are needed, simplifying set up
and giving a nonobtrusive appearance. Sound waves reflected
from the floor combine in phase with the direct sound waves
from the orchestra, giving approximately a 6 dB level boost,
and preventing phase cancellations.
When a floor- placed pair is used to record an orchestra, the
front -row musicians are usually reproduced too loudly, due to
their relative proximity to the microphones. Musical groups
with little front -to -back depth, such as small chamber groups,
jazz groups, or soloists, may be the best application for this
system.
A special variation of the spaced -pair, floor- placed method is
the "PRP" system (Pressure Response Pickup) developed by
Ron Wickersham and Ed Long. Two omnidirectional pressure response microphones are placed next to the floor, with a
recommended spacing of 22 feet between microphones
(although listeners reported an "exaggerated separation" effect
with this spacing). Each aims downward toward a metal plate
scorn IIITRODUCES
SE
degrees apart, and spaced 4.6 cm horizontally. The
hypercardioid patterns have out -of -phase rear lobes
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rs
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the angle between microphones and the microphones can be
adjusted axially in their swivel adapters to vary the spacing.
Vertical clearance between microphones is adjustable.
MICROPHONE REQUIREMENTS
The sound source dictates the requirements of the recording
microphones. Live acoustic sources produce frequencies from
about 40 Hz (bass viol and bass drum) to about 20,000 Hz
(cymbals, castanets, triangles). A microphone with uniform
response between these frequency limits will do full justice to
the music. The highest octave, from 10 kHz to 20 kHz, gives the
added touches of" transparency," "air," "realism, "and transient
clarity to the recording. Frequencies below 80 Hz may need to
be rolled -off to eliminate rumble from trucks and air
conditioning, unless it is desirable to record very deep organ or
drtim sounds.
An orchestra or band
bass
Figure 9. A Shure A27M microphone adapter which
will accommodate a variety of coincident and
near -coincident stereo microphone techniques.
placed on the floor. The microphone -to-plate spacing is 0.015
inches. This arrangement gives each microphone equal
frequency response at all angles of incidence. A microphone
constructed in this manner is referred to as a Pressure Zone
Microphone (PZM' ").
MONOPHONIC COMPATIBILITY
If two recorded channels are mixed to mono, any time
differences existing between channels will result in dips in the
frequency response of the mono signal because of phase
cancellations. Coincident techniques, in which the microphone
grilles are aligned vertically, have no time difference between
channels and so are mono-compatible. Other techniques will
produce dips in mono frequency response which may or may
not be audible. If monophonic reproduction is anticipated, it is
wise to monitor the recording alternately in stereo and mono to
listen for differences in tone quality.
PHONOGRAPH COMPATIBILITY
If records are made from the original tape recording, the
spaced -pair technique can cause problems. The sound -path
length from source to microphone is different for each
microphone. The difference in path length creates lowfrequency phase differences between the two channels. Strong
low- frequency out -of-phase signals cause excessive vertical
modulation of the record groove, resulting in serious cutting
problems unless the recorded level or stereo separation is
reduced. The coincident and near -coincident methods allow
records to be cut from tapes with less difficulty.
HEADPHONE COMPATIBILITY
Full stereo spread on headphones can
be defined as stereo
spread from ear to ear. Coincident cardioid techniques produce
less stereo spread over headphones than over loudspeakers. If
you are monitoring your recording over headphones or
anticipate headphone listening to the playback, you may want
to use the near -coincident or spaced -pair techniques.
HARDWARE
CONCLUSION
You can demonstrate to yourself the degree of localization
accuracy provided by your chosen stereo microphone
arrangement, for your own particular recording and listening
conditions. Record yourself speaking from various positions in
front of the microphone pair while announcing your position
(e.g., "left side," "mid -left," "center "). If the reproduced stereo
stage is too narrow, increase the angle or spacing between
microphones. Do the opposite to reduce excessive separation.
We have investigated several microphone pair arrangements
for recording in stereo. Each has its own advantages and
disadvantages. Which method you choose depends on what
sonic compromises you are willing to make. With a little
practice, and with some understanding of these techniques, you
can achieve quality stereo recordings.
Recommended Reading:
Allison, R. and Berkovitz, R.. "The Sound Field in Home Listening
Rooms," Journal of the Audio Engineering Society, Vol. 20, No. 6,
pp. 459-469, July/ August 1972.
Bevan, W., Schulein, R., and Seeler, C. E.,"Design of a Studio -Quality
Condenser Microphone Using Electret Technology," Journal of the
Audio Engineering Society. Vol. 26, No. 12, pp. 947 -957, December
1978.
with coincident and near -coincident techniques, the
co
is a wide -angle sound source.
Consequently, sound approaches the microphones from a
broad range of angles. If the tonal qualities of all instruments
are to be reproduced equally well, the microphone ideally
should have a broad, flat response at all angles of incidence
within at least ±90 degrees. Stated another way, the polar
pattern should be uniform with frequency. Microphones with
small- diameter diaphragms usually meet this requirement best.
Note that some microphones have small diaphragms inside
large housings.
If microphones used in a coincident -pair array are noticeably
more directional at high frequencies than at middle -to-low
frequencies, instruments which boost the high frequencies of
their spectra when played loudly will appear to shift away from
the center when played loudly. Again, the polar pattern of the
microphone ideally should be the same at all frequencies.
Since classical music can encompass a wide dynamic range
(as high as 80 dB), the recording microphones should have very
low noise and distortion.
To optimize sound image focusing, the microphone pair
should be well- matched in frequency response, phase response,
and polar response.
microphones should be rigidly mounted with respect to each
other so that they can be moved as a unit without disturbing
their arrangement. Angling and spacing should be useradjustable to permit stereo spread control.
A device for this purpose is shown in FtGURE9. It consists of
two vertically -aligned rotating sleeves with studs to accept each
microphone's swivel adapter. The sleeves can be rotated to vary
Ceoen, C., "Comparative Stereophonic Listening Tests. "Journal of the
Audio Engineering Society, Vol. 20, No. I, pp. 19 -27. January/
February 1972.
Eargle. J., Sound Recording. Van Nostrand Reinhold Co., New York,
1976.
Gerzon, M., "Why Coincident Microphones?" Studio Sound, March
1977, pp. 117, 119, 140.
Wickersham, R. and Long, E., "How to Make Convincing Stereo
Recordings," High Fidelity Magazine. August 1978.
www.americanradiohistory.com
ARNIE LAZARUS
The FRAP
Point-Source-Microphone
Commonly known as a "pickup, " the Point -Source- Microphone
is a professional- quality alternative to microphones, for use
in live gigs, state- of=the-art studios, and live recordings.
'PICKUP- is a general term which describes a transducer that is directly attached to a musical instrument,
in order to respond to the instrument's vibrational
energy or pressure variation. In the last ten years. it has
e'iilvcd from a thirty -nine dollar music store accessory to a
state-of-the-art device, used side -by -side with two thousand
dollar microphones in direct-to -disc recording. Because the
term pickup is indiscriminately used to describe all these
systems and also connotes the cheaper music store accessory. I
would like to propose an alternate term, " l'oint-SourceMicrophone" for transducer systems like the FRAP (Flat
Response Audio Pickup).
The term " Point -Source -Microphone" accurately describes a
transducer that integrates an instrument's energy in such a way
as to correlate to the phenomenon we know as musical sound.
Ideally, "Point- Source -Microphones" also eliminate many
sounds that should not reach the listener, such as fingers sliding
on a guitar, how hair setting violin strings in motion, key noise
of a flute. sax or clarinet, or the valve thump of a trumpet.
In the last ten years, FRAI' has developed professional
transducer systems based on two types of transduction: (I
vibrational and (2) pressure.
THU
1
VIBRATIONAL TRANSDUCERS
Instruments such as the violin, guitar, banjo, piano and
kalimba utilize a resonant body to amplify their basic sound producing machanism. The "amplifier" is also a tone modifier,
adding coloration and distortions to create the tonal qualities of
the musical instrument. Since the acoustic "amplifier" operates
by vibrating, we may assume the instrument's characteristics
may be detected via vibration detection. Since musical
Arnie l.a_arus is the invendu of FRAI' (Flat Response
Audio Pickup). N "orking on several unusual projects
involving FRAP.Air. l.a :arus lias recorded the Golden
Gate Bridge. designed stethoscopes fOr ASA. and
/rapped the entire \I.), Thinly orchestra which toured with
Emerson. Lake und Palmer in 1977.
instruments vibrate in three dimensions,
a
transducer capable
of detecting all three dimensions would be in order.
Three- dimensional transduction also lends itself to other
areas of detection. In fact, FRAP triaxial transducers have been
used to develop a state -of-the -art hydrophone, to record the
cables of San Francisco's Golden Gate Bridge, and to reproduce
and amplify the sounds of such instruments as hammer
dulcimer and salt shaker percussion.
FRAP's triaxial transducers consist of three wide -bandwidth
accelerometers, oriented orthogonally and vector -summed to
give an instantaneous single- vector resultant output. The
three vectors may be represented as:
X-axis
line parallel to the strings
Y-axis--a line at a right angle to the strings
Z- axis
line normal to (i.e. passing through the surface ol)
the guitar.
The X, Y and Z axes are illustrated in FüiURP I. The
accelerometers are piezo- electric. and display extremely -high
impedance. (Piero -electric defines any, material which, upon
deformation, produces a voltage. Deformation occurs by
compressing, bending, or twisting. or by any combination of the
above. When an instrument vibrates. the acceleration forces the
piezo- electric material to deform microscopically.)
-a
-a
Figure
1.
The three vibrational axes on a guitar.
Z
SADDLE
GUITAR STRINGS
range are at least as great as the instrument's, usually fine
speaker and amplifier systems are required for accurate
determinations to be made.)
In 1977, Emerson, Lake and Palmer were scheduled to tour
with a 60 -piece symphony orchestra. (FIGURE 3) Their goal was
to duplicate the music on their album "Works Volume I," which
featured full orchestra and choir. To do this, Audio Analysts, a
Montreal -based sound company, was instructed to integrate
the sound of the band with that of the orchestra, so that the
band would not overpower the orchestra, nor be forced to play
with reduced intensity in order to hit a sonic balance.
Additionally, Audio Analysts was asked to meet these
(I) a natural, not electronic sound; (2)
undistorted, clean sound with no feedback; (3) a living room
atmosphere, even in the largest arenas; (4) stereo sound; and (5)
specifications:
fast sound check.
FRAP was called in to help solve these problems.
The symphony orchestra had the following complement:
Wood -Winds
Figure
2.
2
To convert the extremely -high impedance of the transducer
(seen in FIGURE 2). to generally -usable impedances. a preamp
based around a discrete low noise FET input operational
amplifier is required. The preamp allows users to couple the
FRAP to such devices as tape recorders or console inputs
without degradation or distortion, and further adds tone
control and bass roll -off capability.
The problem of mounting the FRAP on fine instruments was
solved by using an inert wax that has excellent vibrational
transfer characteristics. According to Mechanical Vibration
and Shock Measurements. published by Bruel and Kjaer in
1972, a thin layer of wax gives excellent frequency response
fact, almost identical to mounting with a steel stud (Pages 121
-in
and 122).
A thin layer of silicon rubber, such as Dow Corning 3145 or
738, can also yield similar results. When using wax, air voids
below the 'z' element may produce a "thin" sound. This may be
avoided by sliding, rather than pressing, the transducer in place.
Placement of the transducer system is as important as the
method of transduction. and a great deal of research has gone
into accurate prediction of placement. Today, we can specify
with a high degree of accuracy the placement of FRAP triaxial
transducers for entire families of musical instruments.
If the overall tonal characteristics of a musical instrument, or
the transient or overtone structures do not sound correct, the
FRAP is either incorrectly placed or the monitor system is
deficient. (Because FR AP's transient response and dynamic
Figure 3. The ELP Orchestra in rehearsal.
op
Brasses
Strings
The FRAP triaxial transducer.
clarinets
4 C flutes
alto flute
I
bassoons
I contra-bassoon
2 oboes
I oboe d'amour
I alto sax
soprano sax
2
1
I
I
piccolo
bass clarinet
16
violins
6 violas
5
celli
viols
guitar
piano
4 bass
I
I
trumpets
trombones
I bass trombone
4 French horns
I tuba
4
2
Plus 3
percussion instruments
All of the instruments were fitted with FRAP triaxial or Type
W pressure transducers, except the brass and percussion
instruments, which used microphones. Also fitted with FRAPs
were Greg Lake's rare guitars
Zemaitas 12 string, a Martin
00-45 circa 1910, and another Martin of similar vintage.
Having this "laboratory" to work with. in addition to a
critical listening committee consisting of ELF, Godfrey Salmon
(conductor) and Bruce Dukoff (concert master and virtuoso
violinist), the excellent sound system (costing almost a
megabuck) gave us an ideal opportunity to pin down some
accurate placement positions for the FRAPs.
We started with the violin family. The thirty -one instruments
spanned about thirty makers and three centuries. After an
afternoon of experimentation and careful listening, we
discovered the spot was the same for every one of the violin
family instruments! That position was located on the back, with
the 'z' axis element directly over the sound post, as seen in
FIGURE 4. (The sound post of a violin is less than a quarter -ofan -inch in diameter.) If placement was off by even a fraction,
the instrument would not sound right.
The string players did not use wax to attach their transducers.
because the wax attachment took too long to adjust. Moreover,
in the case of instruments finished with thin brittle layers of
spirit varnish, some spots of varnish would cling to the
transducer during removal. This almost caused a mutiny among
the players and embarrassment of a spectacular magnitude to
this author. (This does not occur with instruments finished with
oil varnish, as is generally the case with Italian instruments).
We solved the problem by taking the wax off the FRAPs and
replacing it with a gob of silicon rubber adhesive. covered with
Saran Wrap. The FRAP- with -adhesive was placed directly
over the sound post on each instrument, to custom -fit the contour of the back, then lifted off and left to cure overnight. The
transducers were ultimately held on the instruments with
rubber bands stretched across the corners -or. in the case of the
bass, held in place with an elastic strap,
FRAP placement on the piano proved to be more difficult.
The piano is a large sound -collecting mechanism that uses 'stiff
-a
RECORDING LAURINDO ALMEIDA
WITH FRAP AND MICROPHONE
In June 1979. Laurindo Almeida was recorded direct -
FRAP transducer -sensitive part placed
directly over the sound post.
to -disc by Crystal Clear Records. a San Francisco -based
company. Their goal was to capture all the intricacies of
Almeida's instrument. On the right track, engineers used
a special $2.000 condenser microphone with ultra fast.
low noise, low distortion capabilities. On the left track.
engineers used a FRAP triaxial transducer. As Chief
Engineer Patrick Maloney wrote: "With the FRAP I got
the crispness and attack so necessary for the natural
projection of the guitar, while capturing the warmth and
richness of the entire instrument. With the microphone. I
got a slightly- different perspective, along with some
room sound which I wanted in order to avoid an isolated.
over -dubbed, sterile-type sound. My intention was to
capture as natural a guitar sound as I could, and as
wasn't using any equalization, limiting, compression or
special effects at all, it was important that the transducer
he as transparent and undistorted as possible. The FRAI'
.. was a joy to use. And speaking of joy, you should have
seen the look on laurindo Almeida's face when he
stepped into the control room and heard the sound of his
1
Rubber
band -in the case where
they
corners are worn or in the case of basses
without violin corners, use an elastic band
that will go around the instrument. It can
fasten or unfasten with velkro.
guitar..."
Figure 4. The transducer is placed directly over the
sound post.
strings' (See "Physics of the Piano," Scientific American.
December 1965.) Moreover. many piano strings lose their
fundamental almost immediately, and the overtone or 'partial'
predominates. This effect, especially when amplified. can be
confusing or annoying to both the listener and the player. The
piano also has three basic resonance modes which have to be
dealt with when used either with a P.A. system, monitors, or
both. These are (II the stage. (2) the piano, and (3) the
combination of and 2. These often- conflicting resonances can
be reduced or eliminated by graphic or parametric equalization.
Most important, the piano sounds very different to the player
than to a listener. At the player's ears, the piano sounds more
percussive, and the transients display a bite or edge that often
disappears with distance.
The best placement of the three -dimensional transducer is on
the beams underneath the piano, in the area where the beams tie
to the harp (Fl alRt:5). Generally, two FR APs are used. as well
as a microphone. However, there are other possibilities, such as
on the skirt of the piano or. more-or -less centered on the body.
FRAI' production manager Walter Rapaport -who devised
these placement techniques -adds. The main thing to keep in
mind when placing the FRAP on the piano is to listen to each of
these placements without preconception. letting your ears be
your guide."
1
Figure
5.
Transducers placed on the beams of
a
piano.
PICKUPS
Finding the correct placement on guitars usually takes a
matter of minutes for those familiar with FRAPs and guitars.
However, many store salespeople reported problems, and since
placement is critical to the sound. we needed to find a method
which made placement fast and predictable.
After working with literally thousands of guitars over a ten year period, including building FRAP systems for the C. F.
Martin Company and the Gurian Guitar Company. we
developed some 'constants' about placement. Best response is:
( I) on the treble side of the bridge: (2) closer to the end of the
bridge than near the strings and: (3) with the 'z' axis element
behind the saddle- nor in line with it. Our limited experience in
working with classical guitarists, due to their sense of 'acoustic
purity' resulted in placing FRAPs on the crest of the bridge.
However. while working with guitarist Laurindo Almeida
during direct-to -disc sessions. we found the best placement of
the FRAP was just behind the crest- in line with where the
strings tied la the hotly.
This astounding placement led us to our breakthrough the
finding of placement constants that would work for virtually
any guitar! As this is the first time this placement is being
offered, I would welcome any comments or explanations.
The transducer's 'z' axis element must lie on a line formed by
the strings entering the body or. in the case of a twelve -string
guitar. the line somewhere between the two lines. This
coordinate will work for any type of guitar: steel string,
classical. flamenco. or archtop. (The archtop generally has a
trapeze tailpiece. and due to the variance of construction in
relation to arching and tailpiece, these designs will probably
contain some anomalies relating to placement.)
A partial explanation for this placement of the "Z" -axis
element along the "Y" axis, is as follows: If one works out the
static force equations of a string on a guitar, one will easily
observe that the vertical force of the sáddle holding up the
strings is equal and opposite to that of the body of the guitar
holding the strings in place. As the top of the saddle is a node,
very little vibration occurs here. Therefore most of the energy is
transferred to the guitar top at the point where the strings are
anchored to the body.
The "X" coordinate is determined this way: If we take the
string length from nut to saddle and divide by seven, we get the
www.americanradiohistory.com
to
Figure
6.
The Type W flute transducer.
Figure
distance that the vertical element would be from the low E (6th)
string. The distance will be taken along the line created as the
strings enter the body. My estimation is that this is good for plus
or minus an eighth of an inch.
Empirically, these coordinates work, although the above
explanation is by no means complete. While I'm confident
about stating this as a "formula." the supportive data is still
being analyzed by the author at the time of this writing. As soon
as I have more- complete information. I will submit it in a letter
to db.
PRESSURE TRANSDUCERS
Instruments such as the flute. saxaphone or clarinet depend
upon a resonating air column to produce sound. The
instrument derives its characteristic tones from instantaneous
pressure deviations in the basic air column.
The FRAP Type W transducer detects the sound of a wind
instrument via the vibrating air column. If just pressure changes
are monitored. and if the transducer does not really move or
flex, except at the molecular level, the structure of the
instrument will not change. The transducer will respond only to
sounds in the air column and not mechanical noises such as key
clicks or breath intake. (Instrument structure is mentioned
because as soon as the transducer is attached to the instrument
Figure 7. A Type W screw -mount transducer on
saxaphone mouthpiece.
o
a
8.
The Type W piccolo transducer.
a nipple introduced to the air column. it becomes part of the
structure.) The Type W transducer satisfies the above premise
and the evolution of its development is worthy of note.
Type W transducers come in three versions: Flute.
Screwmount and Piccolo. (FiGuREs 6. 7 and 8) The flute and
piccolo pose no major problems as both are primarily straight bore instruments. The sound inside is very similar to the sound
outside.
In the flute. the main problem is to create a situation where
the sound is not changed acoustically. and the transducer's
presence remains undetected within the flute. This is done by
replacing the cork and faceplate assembly with the transducer.
In order to reflect the standing wave in the air column
efficiently. the faceplate must be a metal such as silver. stainless
steel. etc. So as not to disturb any of the flute's subtleties or
tuning. the hole in the plate that introduces the pressure to the
transducer must be sufficiently small. Moreover. there must be
virtually no displacement of air in the detector. The tube leading
to the diaphragm must be very short or high -frequency response
will suffer.
As a result of meticulously working out these details. the
Type W flute transducer will give very accurate reproduction
and will not feed back. even in extremely high level sound fields.
As it is a non -accelerometric device. it also does not detect key
noise nor does it hear' the air blast and 'edge' tone one gets with
close miking.
A past criticism in Type W transducer's use in recording has
been the lack of ambient sound or reverb. This can be remedied
with artificial ambience or by using a combination of mike and
transducer. The benefits of using the Type W transducer for
recording are (1) overdubbing without headphones, (2) using
effects that require a very smooth signal to trigger them, such as
a pitch to voltage follower; and (3) performing in extremely
loud environments with a minimum of problems.
The Type W piccolo transducer is exactly like the flute design
but is much smaller in diameter.
A very interesting set of problems confronted us for the Type
W screwmount transducer for wind instruments. In order to
sample the pressure variations. the air had to enter the
transducer via a nipple. If we made the tube straight. we had an
acoustical low -pass filter, due to the tube resonance. The tube
had to be as short as possible. If these requirements were not
satisfied, the transducer would have the tubby. bassy sound
associated with microphone use. The tube was kept to a
minimum length and the resonance removed by turning the
nipple into a horn. (Thanks here to Cliff Hendricksen. horn
designer at Altec- Lansing. and Dr..lames McGill. president of
Digital Recording Corp.. for their help and analysis.)
and
www.americanradiohistory.com
NOTE COUNTERBORE
Figure
9.
Installation of
a
screw -mount transducer.
A further problem was caused by the difference in sound
between the inside and the outside of the instrument which
occurs in conical -bore reeds. When we first began this project,
we noticed the sound was very tubby for saxophones and
clarinets. I contacted Professor Arthur Benade of CaseWestern Reserve University. one of the most knowledgeable
people about the physics of musical instruments, and the author
of several excellent books on the subject. Professor Benade
'explained that the latticing of open holes in the instrument
creates a 6 dB -per- octave treble boost which flattens out at a
certain frequency for each type of instrument in the family. We
then devised an equalization network which is adjustable for
each type of wind instrument. Thus, both aforementioned
compensations worked and removed a characteristic tubbyness
which masked the sound of the instrument. Ironically, to trigger
a synthesizer, the opposite must occur, so that the pitch -tovoltage converter is not confused by complex upper-order
harmonics.
The mounting techniques for the screwmount transducers are
illustrated in Ftat,Rrs 9 and 10. Note that a double reed is
included. The double reeds are different from the single reeds
insolar as the toneholes are small compared to the diameter of
the bore. I- his is different from the clarinet type of instruments
which are built around the Boehm system, where the tone holes
are of a size comparable to the bore. It is largely this geometry
that gives the oboe and the English horn their high pressure and
characteristic tone. Indeed, when an oboe was once built on a
Boehm design, it sounded like a double -reeded clarinet.
Being the smallest and highest- pitched instrument of the
double reeds, the oboe has the most difficult sound to reproduce
with the transducer. Its constricted sound results in
considerable phase shifting. In fact, Paul McCandless. reed
player for Oregon. claims the only way the amplified oboe
begins to sound right is when it is run through a phascr! And,
according to David Friend of AR P. the oboe has a predominant
tone within it which interferes with other tones at all times.
Moreover, the addition of the transducer to the staple (where
the reed is wound) adds enough geometric volume to put it out
of tune, and an equal tolume to that added by the transducer
nipple must he removed from the staple by filing.
The trumpet displays similar problems as the saxophone but
instead of having tone holes to push up the treble. it has an
impedance -matching system called a bell. The equalization
method is the same as for the reeds roll off the lows. The
Figure 10. Double -reed mounting technique. Epoxy
holds the 10 -32 nut in place, and a 1/16 -inch hole
is drilled into the bocal.
Figure 11. Carlos Montoya and FRAP, on
to -disc recording.
a
direct -
transducer is mounted with a screw into the stem of the
mouthpiece. "as in the conical bore reeds. "(The mouthpiece is
drilled and tapped for a 10 -32 thread.)
Only one other serious problem confronted us with wind
instruments they are wet. A bubble can form across the
nipple. We solved this problem by slotting the top with a
jeweler's saw to break surface tension.
CONCLUSION
The ability to accurately specify placement for the FRAP
Triaxial Transducer and the FR AP Type W Pressure
Transducer provides a professional- quality alternative to
microphones for many situations - including live gigs, state -ofthe -art studio. and live. recording. The major difference
between studio use and P.A. (or live recording) is that the
room ambience will at feet the tonal qualities of the instrument
and result in some acoustic distortion. This is true because the
instrument is a receiver as well as a transmitter. In a studio, the
ambience is controlled. The sound vibrations impinging on an
instrument such as a guitar or piano or even a horn will effect
and distort the outgoing vibrations. However, it should be
noted that these problems also occur when a microphone is
used.
The recording studio also gives users the advantage of lower
acoustical distortion. Moreover. with direct transduction. setup time is reduced. The FRAP's built -in isolation helps keep the
semblence of a group together if one does not want to lay down
tracks. The FRAP's distinct advantage to microphones is that it
can feed effects and synthesizers.
The mixture of a professional grade FRAI' transducer and a
microphone. as was donc recording both I.aurindo Almeida
and Carlos Montoya I Fiat RI
I) by Crystal Clear Records.
will gise the performer the best of both worlds.
o hear how FRAPs sound when used in recording.
recommend that the reader listen to the Crystal Clear
Recordings of Montoya and Almeida, John McLaughlin's
Shakti album on Columbia and Herbie Mann's Sunbelt album
on Atlantic.
I
l
IVIE SOUND ANALYZERS, all models in
stock -demo models and discounts available -sales and rentals. Theatre Technology, 37 W. 20th St., New York, NY
10011. (212) 929 -5380.
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I
Minimum order accepted $10.00.
Rates: 50e a word.
Boxed Ads: $25.00 per column inch.
db Box Number: $1.00 per issue.
CROWN QUAD RECORDER. $750.00.
Ampex 300 V. and 1/2 inch transports with
consoles $400.00 each. 400 half -track with
cases $250.00. 351 electronics, $160.00.
Magnecord 1028 -2 new heads $250.00.
1028 no electronics $75.00. PT6A, PT6J (2),
PT6M $100.00. Ashley (215) 338 -1682.
Frequency Discounts: 3 times,10(7( ; 6 times,20 %; 12 times,33 %.
ALL CLASSIFIED ADS MUST BE PREPAID.
FOR SALE
dbx 155: FOR IMMEDIATE DELIVERY.
UAR Professional Systems, 8535 Fairhaven, San Antonio, TX 78229. 512 -6908888.
CETEC -ELECTRODYNE
modules and
spare parts 711L input modules, active
combining networks, line amps, and
more Modu -Trend Industries, P.O. Box
602. Rockville, Ct. 06066 (2n3) 872 -7750.
IVIE ELECTRONICS REAL -TIME ANALYZERS, etc. Very slightly used demonstrators at discount. Full factory warranty.
Money -back guarantee. JML Company,
Highway 128, Cloverdale, CA
39,000
95425.
AMPEX, OTARI & SCULLY recorders in
stock for immediate delivery; new and
rebuilt. RCI, 8550 2nd Ave., Silver Spring,
MD 20910. Write for complete product
list.
THE LIBRARY
Sound effects recorded in STEREO using Dolby throughout. Over 350 effects on ten discs.
$100.00. Write The Library, P.O. Box
18145, Denver, Colo. 80218.
.
.
.
ALL RECORDING STUDIOS and sound
companies should own the Sounder
"Phase Checker" for easily determining
the Phase Polarity of ALL speakers. mics,
cables, transformers, crossovers, etc.
Model 500 is reliable, durable, with phone,
phono, and cannon connectors. and
drives speakers direct. Built -in mic and
hi -gain preamp. Avoid being "Phased
Out." Free info. SOUNDER ELECTRONICS, 21 Madrona St., Mill Valley, CA
94941. (415) 383 -5811.
WANTED
RECORDING
EQUIPMENT
OF ALI. AGES AND
VARIETIES
microphones, outboard gear,
consoles, tape decks, etc.
Dan Alexander
6026 Bernhard
Richmond, Ca. ')4805 USA
(415) 232 -7933 or (715) 232 -7818
SCULLY- 100 -16 track,
AKG, E/ V, Sennheiser, Shure, Neuman:
FOR IMMEDIATE DELIVERY most models. UAR Professional Systems, 8535
Fairhaven, San Antonio, TX 78229. 512690 -8888.
8
track head nest,
remote, excellent condition; $10,900.
(617) 435 -3760, after 6:00 p.m.
AMPEX SPARE PARTS; technical support; updating kits. for discontinued professional audio models; available from
VIF International, Box 1555, Mountain
View, Ca. 94042. (408) 739-9740.
REELS AND BOXES 5" and 7" large and
small hubs; heavy duty white boxes. W -M
Sales, 1118 Dula Circle, Duncanville,
Texas 75116 (214) 296-2773.
For SALE: IF YOU are looking for well
maintained recording equipment, try
calling Criteria Recording Studios (305)
947-5611. We are always up- dating our
studios and can offer consoles, tape
machines, and many other items at a
good price.
TEST RECORD for equalizing stereo systems; Helps you sell equalizers and installation services; Pink noise in 1/3 octave bands, type OR- 2011 -1 @ $20. Used
with various B &K Sound Level Meters.
B &K Instruments, Inc., 5111 W. 164th
St., Cleveland, Ohio 44142.
CANARY MIXING DESKS in stock. 24/4/2,
24/2, Direct London imports. Custom
Audio Services. (814) 237 -1351.
BEST PRICE ON TEAC, Tascam, Ampex
Sennheiser, Allison, Eventide, Sound
Workshop, UREI, BGW, Electro- Voice.
Lexicon, ADR, Marshal, Orban, JBL and
more. Paul Kadair's Home and Commer-
cial Audio, Baton Rouge, Louisiana
(504) 924 -1006.
FOR SALE: JH 114 -16 with Auto locate &
8 -track heads; MCI JH 416 16 -track console with many extras; MCI 6 stereo Dolby
301's with auto change; Eventide Phaser;
Eventide 1745A DDL;
pair Audiotechniques Big Red Monitors; 2 Scully 280's
2- track; Crown DC 300. All equipment in
prime condition and currently in use. Call
Bill at (802) 425 -2111.
1
STOCK CLEARANCE
REVOX, OTARI, TECHNICS & other
quality recorders, mixers, headphones,
mics, pre and power amps, speakers,
etc. Lists from -Entertainment Sound
Services, Inc., P.O. Box 66, Madison,
Ala. 35758. (205) 772 -0251.
REINFORCEMENT, RECORDING. DISCO
equipment featuring Electro- Voice. Tapco,
Numark, Whirlwind. etc. Competitive
prices with fast competent mail order
service is our specialty. Write or call Sonix
Co., Dept. D, Box 58, Indian Head, MD
20640 (301) 753 -6432.
AMPEX. OTARI. SCULLY -In stock; all
major professional lines: top dollar trade -
ins; 15 minutes George Washington
Bridge. Professional Audio Video Corporation, 384 Grand Street, Paterson,
New Jersey 07505. (201) 523 -3333.
USED RECORDING equipment for sale.
Dan (415) 232 -7933.
INFONICS USED RM 212 high speed reel
master $1265.00. CM204, $990.00. Both in
fine running and cosmetic condition.
F.O.B. Atlanta. Tape and Production
Equipment Company, 2065 Peachtree
Industrial Court, Suite 215, Chamblee,
Georgia 30341. (404) 458 -8273.
CAPITOL Q19 v." mastering tape. New
1800' 7" reels factory sealed. Cartons of
12 reels $32.00 per carton. Tape and Production Equipment Co., 2065 Peachtree
Industrial Court, Suite 215, Chamblee,
Georgia 30341. (404) 458 -8273.
MCI 428 SERIES CONSOLE with Producers desk, 28 -in 24 -out, P *G faders. excellent condition, extras. MCI plug -in
Nontronics 16 track
track, heads like
new, with bridge ready for operation
$3,000. Call Studio Consultants (212)
586 -7376.
-8
PREMIUM
8 -TRACK & CASSETTE BLANKS
Lear Jet style cartridge with rubber roller,
3M Professional duplicating tape, 90 lengths
in 1 min. increments.
8 -Tr. Cas.
min. to 45 min. any quantity .. 80e 65e
46 min. to 65 min. any quantity .. 904 72e
66 min. to BO min. any quantity .. 98C 85¢
81 min. to 90 min. any quantity $1.08 89e
1
Shrink Wrapped & Labeled add 14C 134
Reel -to -Reel 3m tape 1800'
$5.00
Blank VHS 2/4 hr. video tapes
$19.00
Low Cost Shrink -Wrap Equipment Available
PROFESSIONAL 8 -TRACK DUPLICATORS
$1,495.00
CASSETTE & 8 -TRACK CALIBRATORS &
ERASERS ($35.00 minimum order)
.
BAZZY ELECTRONICS CORP.
39 N. Rose, Mt. Clemens, Mich. 48043
Phone: (313) 463 -2592
Master Charge and Visa Welcome
FOR SALE:
Complete
16 -Track
Studio
Studer. MCI. Revolt JBL. Allec. AKG. Allen 8 Heath. WC
Mn Beyer Snore Neumann RCA. E V. et. M%14 Crown.
White etc Plus many instruments &Xtras
Details: R L HAMMEL ASSOCIATES R. 04; Boa
041C; Alexandria. IN 44001. Evenings (late) st
31716427030.
ONE DATA -MIX (30 x 24) recording console and one data -mix 28 input mixing
console built by Stoddard, like the one at
NY's Record Plant, for $20,000.00. Many
hits recorded on it (e.g. Kiss's last album,
Peter Frampton, etc.). 16 & 24 track machines for sale too. Jerry (516) 781 -2223.
NAB ALUMINUM FLANGES. We manufacture 8 ". 101/2", and 14 ". Also large
flanges and special reels to order. Stock
delivery of assembly screws & nuts & most
aluminum audio, video, & computer reels.
For pricing, call or write: Records Reserve
Corp., 56 Harvester Avenue, Batavia, NY
14020. (716) 343 -2600.
UREI: FOR IMMEDIATE DELIVERY most
items UAR Professional Systems, 8535
Fairhaven, San Antonio. TX 78229. 512690 -8888.
SCULLY LATHE. serial #484, variable
pitch. Good condition. HAECO SD -240A,
stereo cutting amp. PRESTO 14B cutting
lathe, in console, 20 built -in pitches, 3
motor drive. Call (201) 767 -7874.
CONSOLE:
SPECTRASONICS
Model
1020 -8/16... 14 buss, 20 input, 16 -track
monitor, quad, all factory wired, mint condition. We paid $34,600; sell for $19,000
or best offer. Phone for information:
Brian (213) 461 -3717.
SCULLY 280 -4 TRACK, in console,
$2,500.00 Ampex 350 mono, Lang Electronics, console, $800.00. (213) 462 -4966.
-
THESE UNITS MUST GO: Scully 280
8-tk/w sync. master and remote, $5,000:
Scully 280 mono /w heads and remote,
$1,500; Ampex 440- 1/2-tk /w 1/2-tk playback and all new heads, $2,000; Fairchild 16 x 8 console w /8 -tk mon., $500;
and Revox A77- ':4k -w remote, $500.
Studio 2000, Suite 104, 515 28th St., Des
Moines, Iowa. (515) 282 -8306.
FOR SALE 2 MATCHED ELA M251 E Telefunken mikes with p.s.. mint condition
$800.00. each, also
RCA 77D, 2 E -V
666R,best offer. (212) 575 -0295.
1
SOUNDCRAFT STUDIO CONSOLE 24/
16, 23- PPM's, P &G faders, sweep EQ,
260 position patching (mint) $19,500
U.S.; Ampex MM -1100 16 track, 500
hours, like new, $17,500 U.S.; 3M M79
16 track with selectake, $15,900 U.S.;
Ampex ATR -100 2 track, mint! $6,800
U.S.; Phone 1- 902 -469 -3243. Canada.
BGW: FOR IMMEDIATE DELIVERY. UAR
Professional Systems, 8535 Fairhaven.
San Antonio, TX 78229. 512 -690 -8888.
CATALOG
FREE
&
AUDIO APPLICATIONS
CONSOLES
KITS & WIRED
AMPLIFIERS
MIC., EC), ACN,LINE,
TAPE, DISC, POWER
OSCILLATORS
AUDIO, TAPE BIAS
POWER
®OP:1.1 P
I
SII, N
1
LOS
ANGE
SUPPLIES
ESS,,OCA
(2131934-3566
90038
MICROPHONES WANTED for broadcast
historical archive; Early RCA and Western Electric models. Contact: James
Steele, National Association of Broadcasters, 477 Madison Avenue, New York
10022. (212) 759 -7020.
TASCAM, TEAC, Sound Workshop,
Technics Pro. Otani, dbx, MXR, Eventide, E -V, Shure, Maxell, Ampex.
UREI, Stax, Sennheiser, Orban, Spec tro Acoustics. DeltaLab, NAD, IVIEand
more! Send for price quotes.
ZIMET PRO AUDIO, Dept. DB
1038 Northern Blvd.
Roslyn, NY 11576
SERVICES
BOOK SALE
A very limited number of cosmetically -
damaged Microphones: Design and
Application by Lou Burroughs are
available in paperback. Price $7.95
($1.00 additional, outside the U.S.). All
checks must be in U.S. funds, drawn on
a U.S. bank.
db Magazine
1120 Old Country Road
Plainview, NY 11803
JBL PROFESSIONAL STUDIO MONITORS. Electro -Voice Sentry and Interface
speaker systems. E -V raw speakers and
Pro-Music products. BGW amps and
preamps; HME wireless microphones;
Otani recorders; Tapco mixers: dbx products; Shure Pro- Master; Altec monitors;
and Sennheiser microphones. Strong discounts- prompt delivery to all U.S.A. and
foreign destinations. For specific product
quotes call: (305) 462 -1976.
Teac & Tascam Multitrack: FOR IMMEDIATE DELIVERY. UAR Professional Systems, 8535 Fairhaven, San Antonio, TX
78229. 512- 690 -8888.
SCOTCH 209 and 207 1/2-inch recording
tape. Used only once. 900 -ft. reels: $1.50
each; 1800 -ft. reels: $2.50 each. Will sell
in quantities of 50 reels or more. Call
(201) 540 -8811.
FOR SALE: IMPECCABLE MCI 428 console, 28 -in/24 -out (upgrading to Neve/
Necam). Also Scully 280 2 -track (all new
heads, 14" reel capacity). Revox A77 '/."
track, Eventide's 1745 DDL, 901 Harmonizer (fully loaded), Dynaco Graphic EQ.
New RMI Rocksichord Keyboard, large
Buchla synthesizer in futuristic cabinet,
Arp Odyssey, Digital Sequencer; also
brand new Commodore computer system:
Pet 2001 w /32K memory, dual floppy -disk,
centronics 779 printer. Contact RPM
Sound, 12 East 12th Street, NYC 10003
(212) 242 -2100.
Lexicon Prime Time: FOR IMMEDIATE
DELIVERY. UAR Professional Systems.
8535 Fairhaven, San Antonio, TX 78229.
CUTTERHEAD REPAIR SERVICE for all
models Westrex, HAECO, Grampian.
Modifications done on Westrex. Avoid
costly down time; 3 -day turnaround upon
receipt. Send for free brochure: International Cutterhead Repair, 194 Kings Ct.,
Teaneck, N.J. 07666. (201) 837 -1289.
MAGNETIC HEAD relapping -24 hour
service. Replacement heads for professional recorders. IEM, 350 N. Eric Drive,
Palatine, IL 60067. (312) 358 -4622.
JBL AND GAUSS SPEAKER WARRANTY
CENTER. Full lines stocked. Instant recone service, compression driver diaphragms for immediate shipment. New come Sound, 4684 Indianola Ave., Columbus, Ohio 43214 (614) 268 -5605.
ACOUSTIC CONSULTATION- Specalizing in studios, control rooms, discos.
Qualified personnel, reasonable rates.
Acoustilog, Bruel & Kjaer, HP, Tektronix,
Ivie; equipment calibrated on premises.
Reverberation timer and RTA rentals.
Acoustilog, 19 Mercer Street, New York,
NY 10013 (212) 925 -1365.
AMPEX SERVICE COMPANY: Complete
factory service and parts for Ampex
equipment; professional audio; one -inch
helical scan video systems; video closed
circuit cameras; instrumentation consumer audio; professional audio motor
and head assembly rebuilding. 2201 Lunt
Ave., Elk Grove Village, IL 60007; 500
Rodler Dr., Glendale, CA 91201; 75 Commerce Way, Hackensack, NJ 07601.
MULTI -TRACK RECORDING specialists
-1-2- 4- 8 -16 -24 tracks, authorized dealer
for Tascam, Otani, Ampex, Teac, Technics, AKG, AB Systems, Crest, SAE Pro,
dbx, Orban, Tapco C12, Audioarts, Loft,
Lexicon, Ashly Audio, Altec, PAS, PSL.
Shure, and many more. Single items or
complete studio packages. Studio design
and construction. Phone or write for a
prompt written quotation. Professional
Sound Labs, Inc., 42 North Franklin St.,
Hempstead, NY 11550. (516) 486 -5813.
512- 690 -8888.
WANTED
BUSINESS OPPORTUNITIES
WANTED: USED RECORDING equipment
of any kind. Expanding studio will pay
cash. Dennis Reed, Box 50022. Palo
Alto, CA 94303 (415) 494 -9344.
MIDTOWN COMMERCIAL PRODUCTION /DEMO studio forced to move. Will
consider partnership with existing studio
contemplating expansion, or freelance
engineer looking for permanent location.
(212) 575 -0295.
WANTED: SONY TC770 or TC772. Contact; Jack Friend, 4125 Huntley Avenue,
Culver City, CA 90230.
-
WANTED: RECORDING EQUIPMENT
mikes, recorders, consoles, outboard
gear. Greg Field, Box 243, San Mateo, CA
94401 (415) 343 -1353.
INVESTOR WANTED -Exclusive 24 -track
recording studio on 4,000 acre ranch in
Texas Hill Country nearing completion.
Tremendous potential. For details, call
(512) 278 -5802 or (512) 278 -7343.
EMPLOYMENT
e
Ot c<eatve
WANTED: FULL TIME maintenance assistant for major Long Island recording
studio. Experience a must! Send resume
to: P.O. Box 192, East Norwich. NY 11732.
ro
tr9°pp°vt
e5 ate-
ENGINEERS/TECHNICIANS-Expanding
NYC re- recording facility has opportunities for experienced maintenance engineers/technicians and recording engi-
dn9
etxre a0
/N
te
bseq60e9evsto
Loudspeakers
rg
neers. Dept. 101. db Magazine, 1120 Old
Country Road, Plainview, NY 11803.
POSITION WANTED. Experience in studio recording, live reinforcement, video
work, and audio installations. Seeking
position as recording engineer soundman
with a good sound company or with a professional equipment company. Good,
hard, efficient worker. Eddie (205) 263-
Microphones
Phonograph Cartridges
Work with the leaders in the field of consumer and
professional audio products. known for excellence in
quality and reliability.
We offer excellent opportunities for individuals with a
BSEE or BSME and experience in electromechanica
and 'or electroacoustical transducer design.
We are expanding and seeking to fill highly visible
positions in the areas of speaker. microphone and
phonograph cartridge design and development.
We offer an excellent starting salary and company
benefits as well as an ideal location in a Chicago North
Shore suburb known for its superb educational and
cultural environment.
Send your resume in confidence or call:
Jack Shea (312) 866 -2236
6353.
AUDIO SYSTEMS ENGINEER -Altel
Sound Systems Inc., a leading audio systems company, furnishing audio systems
nationwide, has openings for experienced
audio systems engineers. The ideal candidate should have a B.S. in Electrical Engineering with a minimum of five years
experience in design, administration, and
site implementation of large audio sound
systems installed in stadiums, amphitheatres, corporate buildings, cathedrals,
racetracks, airline terminals, etc. Positions
also available for recent B.S. graduates
and electronic draftsman. Please send
resume in strict confidence to: Dept. 121,
db Magazine, 1120 Old Country Rd., Plainview, NY 11803.
Shure Brothers Inc.. 222 Hartrey Avenue. Evanston, Illinois 60204
SI-1UFiE
Index 1979
INDEX BY TITLE
An Automatic Broadcast Console.
Irving Joel. Sept. 1979. p. 40.
An Improved Audio Pipeline
NPR's Satellite System. Wayne L.
Hetrich. March 1979. p. 30.
Anatomy Of a Loudspeaker. Stephen
-
o)
rn
Boak. Feb. 1979. p. 26.
Audio Problem Solving With
a
Home Computer. John M. Woram.
July 1979. p. 50.
Audio Problem Solving With a
Programmable Calculator. Dr.
Albert Hayes, Jr. Jan. 1979, p.42.
Audio Tests and Measurements
Part I. Wayne Jones. April 1979.
p.41.
-
v
-
Audio Tests and Measurements
Part II. Wayne Jones. May 1979.
p. 48.
Audio Tests and Measurements
Part
III.
Wayne Jones. June 1979.
p. 46.
Automation: Its Evolution. Dave
Purple. Aug. 1979. p. 17.
Build a Heater For a Condenser
Microphone. Bob Katz. Dec. 1979,
p. 20.
CAMEO (Creative Audio and Musical Electronics Organization).
July 1979, p. 38.
Choosing a Console -Is a Picture
Really Worth a Thousand Words?
Carl Yanchar. Aug. 1979. p. 22.
CMOS Microphone Cable Tester.
Kirk Elliott. Dec. 1979. p. 26.
Convention Report: 63rd Audio
Engineering Society Convention.
Irwin J. Diehl. Aug. 1979. p. 40.
Convention Report: APRS 1979.
John Borwick. Sept. 1979. p. 50.
Convention Report: The 11th Ton -
meistertagung (or TonmeisterSoftware and Equipment -Hard
ware). Jeff Nieckau. March 1979.
p. 52.
Cross Reference Guide to Magnetic
Tape Specs. Jan. 1979. p. 37.
db Application Note: Speaker Protection. Feb. 1979. p. 44.
db Application Note: Tape Speed vs.
Biasing..lan. 1979, p. 34.
db Reviews...The Incredible Secret
Money Machine. Irwin J. Diehl.
Oct. 1979, p. 26.
db Speaker Spotlight. Feb. 1979.
p. 49.
db Special Report: The A ES, SPA RS.
"PROSOt'ND INTERNATIONAL," and IEE. John M. Woram.
Oct. 1979, p. 40.
db Special Report: Education and
Audio. John M. Woram. Nov.
1979. p. 43.
db Special Report: On the Future of
Radio and Recording. John M.
Woram. J une 1979. p. 44.
db Test Report: Leader LFR -5600.
Larry Zide. April 1979, p. 57.
Designing a Notch Filter With a
Programmable Calculator. Albert
F. lla es. Jr. May 1979, p. 73.
Digitizing Audio With Delta Modulation. Sidney I.. Silver. April
Magnetic Tape Reproducer Calibrator. Robert K. Morrison. April
1979. p. 54.
MCI JH-556C Console, The. Diane
Wendt. Aug. 1979. p. 25.
Metal Particle Tapes: Upgrading
Analog Performance. Kevin .1.
Byrne. Jan. 1979. p. 35.
Mini -Survey of Graphic Recorders, A.
John M. Woram. July 1979, p. 48.
Murphey's Theorem Applied to P.A.
Work. Michael P. Rogalski. Feb.
1979. p. 52.
Directory of Microphone Manufact risers. Dec. 1979, p. 33.
Directory of Tape Manufacturers.
Jan. 1979. p. 38.
Directory of Test Equipment Manufacturers. April 1979, p. 58.
Directory of Signal Processing
Manufacturers. May 1979,
p. 76.
Directory of "Super Consoles."
p. 34.
New Digital Delay System, A.
David L. Haynes & John M.
Brennan. Nov. 1979. p. 50.
New World Of "Creative Audio,"
The. Kenneth B. Sacks. July 1979,
p. 36.
On the Intricacies Of Tape PerJan. 1979, p. 28.
On the Technical Administration Of
a Studio. I nein J. Diehl. Oct. 1979,
One Man's Choice. Sam Zambuto.
July 1979.
p. 42.
Precision Dynamic Range Controller, A. Burgess Macneal. May
1979. p. 52.
Dilley.July 1979, p. 26.
Rebirth Of Quality F.M. Radio,
Construction Project. Michael
S.
The. I.en Feldman. Sept. 1979,
p. 29.
Professional
Re-
cording Applications. Richard
Orhan. May 1979.
p. 68.
Experiments With Binaural Recording. Fred G. Geil. June 1979,
Fibonacci Numbers, the "Golden
Mean," and Audio Engineering.
Barry Hulker. June 1979. p. 41.
FR AP Point- Source- Microphone,
The. Arnie Lazarus. Dec. 1979.
p. 47.
-
High Fidelity In the Control Room
Why Not? Floyd F. 'Toole. Feb.
1979. p. 30.
Impedance Matching. Daniel Queen.
Feb. 1979. p. 46.
Inside the Aphex. Vladimir Nikanorov. June 1979. p. 36.
It's About Time. Almon Clegg.
Feb. 1979, p. 38.
Recording Studio Equipment Financing. Hamilton H. Brosious.
Oct. 1979. p. 35.
Report From Japan; CBS/SONY
Recording Studios In Tokyo.
p. 30.
Spectrum Analysis On a Personal
Computer. Richard Factor. Nov.
Stereo Microphone Technique.
Bruce Bartlett. Dec. 1979. p.34.
Test Equipment Without Tears.
Richard Lerner. July 1979, p. 45.
Three -dimensional Analysis: It's
About Space. Almon H. Clegg.
April 1979. p. 46.
Time -Aligned Loudspeaker Systems. Dean Austin. March 1979.
Understanding Magnetic Tape Specifications -Part I. Dave Ruhenstein. Oct. 1979. p. 42.
p. 38.
Larry Maguire. April 1979. p. 50.
Doohickii Digitali. Anthony Agnello
& Richard Factor. May 1979,
For
-
p. 58.
Producers Studio: A Do- It- Yourself
Equalizers
In Audio Applications.
Michael Tapes. May 1979. p. 42.
Solid State Logic Studio System
Part I, The. Douglas F. Dickey.
Aug. 1979, p. 32.
Solid State Logic Studio System
Part II, The. Douglas F. Dickey.
essing
1979. p. 46.
Aug. 1979. p. 39.
Distortion and How It Is Measured.
p. 62.
-A
Sept. 1979. p. 44.
New Cartridge Tape Recorder, A.
Vladimir Nikanorov. Sept. 1979.
formance. Peter Vogelgesang.
1979. p. 60.
Shape Of Things To Come: Psycho Acoustic Space Control Technology, The. Almon H. Clegg.
June 1979, p. 27.
New
Shared Access Memory
Concept For Digital Signal Proc-
Kent R. Duncan.
March 1979.
p. 56.
Report From Mexico City: El
Centro de Grabacion. John M.
Woram. March 1979. p. 37.
Report From New York: Sound mixers Recording Studios. John
M. Woram. March 1979, p. 42.
Report From Paris: IRCAM
Unique ('enter For Research.
John Borwick. March 1979. p.47.
Requirements For Studio Monitoring. John Eargle. Feb. 1979, p. 34.
School Days At MCI. Irwin J. Diehl.
Nov. 1979, p. 44.
-A
www.americanradiohistory.com
Understanding Magnetic Tape Specifications -Part II. Dave Rubenstein. Nov. 1979, p. 54.
Of Ferrofluid In Moving -Coil
Loudspeakers, The. D. B. Hathaway. Feb. 1979. p. 42.
Use
Using Induction Loops. Robert K.
Morrison..lan. 1979. p. 39.
Visit To AKC, A. John M. Woram.
Oct. 1979, p. 48.
XY Response Plotters For the
Studio. Brad Plunkett. May 1979.
p. 56.
INDEX BY AUTHOR
Agnello, Anthony. Doohickii Digitali. May 1979, p. 62.
Austin, Dean. Time -Aligned Loudspeaker Systems. March 1979. p. 58.
Bartlett, Bruce. Stereo Microphone
Technique. Dec. 1979, p. 34.
Boak, Stephen. Anatomy Of a Loudspeaker. Feb. 1979, p. 26.
Borwick, John. Report From Paris:
IRCAM
Unique Center For
Research. March 1979, p. 47.
Borwick, John. Convention Report:
APRS 1979. Sept. 1979, p. 50.
Brennan, John M. A New Digital
-A
Delay System. Nov. 1979,
p. 50.
cn
Brosious, Hamilton H. Recording
Studio Equipment Financing.
Oct. 1979, p. 35.
Byrne, Kevin J. Metal Particle
Tapes: Upgrading Analog Performance. Jan. 1979, p. 35.
Clegg, Almon H. It's About Time.
Feb. 1979, p. 38.
Clegg, Almon H. Three-dimensional
Analysis: It's About Space. April
1979, p. 46.
Clegg, Almon H. The Shape Of
Things To Come: Psycho- Acoustic Space Control Technology.
June 1979, p. 27.
Dickey, Douglas F. The Solid State
Logic Studio System -Part I.
Aug. 1979, p. 32.
Dickey, Douglas F. The Solid State
Logic Studio System -Part II.
Sept. 1979, p. 44.
Diehl, Irwin J. Convention Report:
63rd Audio Engineering Society
Convention. Aug. 1979. p. 40.
Diehl, Irwin J. db Reviews...The
Incredible Secret Money Machine.
Oct. 1979, p. 26.
Diehl, Irwin J. On the Technical
Administration Of a Studio.
Oct. 1979. p. 38.
Diehl, Irwin J. School Days at MCI.
Nov. 1979, p. 44.
Dilley, Michael S. Producers Studio:
A Do -It- Yourself Construction
Project. July 1979. p. 26.
Duncan, Kent R. Report From
Japan: CBS /SONY Recording
Studios In Tokyo. March 1979.
p. 56.
Eargle, John. Requirements For
Studio Monitoring. Feb. 1979.
p. 34.
p. 73.
Haynes, David L. A New Digital
Delay System, Nov. 1979, p. 50.
Hetrich, Wayne L. An Improved
Audio Pipeline -NPR's Satellite
System. March 1979, p. 30.
Hufker, Barry. Fibonacci Numbers,
the "Golden Mean," and Audio
Engineering. June 1979, p. 41.
Joel, Irving. An Automatic Broadcast Console. Sept. 1979, p. 40.
Jones, Wayne. Audio Tests and
Measurements -Part I. April
1979. p. 41.
Jones, Wayne. Audio Tests and
Measurements -Part II. May
1979, p. 48.
Jones, Wayne. Audio Tests and
Measurements-Part Ill. June
1979, p. 46.
Katz, Bob. Build a Heater For a
Condenser Microphone. Dec.
1979, p. 20.
Lazarus, Arnie. The FRAP Point Source- Microphone. Dec. 1979,
p. 47.
Lerner, Richard. Test Equipment
Without Tears. July 1979, p. 45.
Macneal, Burgess.
A
Precision
Dynamic Range Controller. May
1979. p. 52.
Maguire, Larry. Distortion and How
It Is Measured. April 1979, p. 50.
Morrison, Robert K. Using Induction Loops. Jan. 1979. p. 39.
Morrison, Robert K. Magnetic Tape
Reproducer Calibrator. April
1979. p. 54.
Elliott, Kirk. CMOS Microphone
Cable Tester. Dec. 1979. p. 26.
Factor, Richard. Doohickii Digitali.
May 1979. p. 62.
Nieckau, Jeff. Convention Report:
The I I th Tonmeistertagung (or
Tonmeister- Software and Equipment- Hardware). March 1979,
Factor, Richard. Spectrum Analysis
On a Personal Computer. Nov.
Nikanorov, Vladimir. Inside the
Aphex. June 1979, p. 36.
Nikanorov, Vladimir. A New Cartridge Tape Recorder. Sept. 1979.
1979. p. 46.
Feldman, Len. The Rebirth Of
Quality F.M. Radio. Sept. 1979,
p. 29.
Geil, Fred G. Experiments With
Binaural Recording. June 1979,
p. 30.
Hathaway, D. B. The Use Of Ferro fluid In Moving -Coil Loudspeakers. Feb. 1979, p. 42.
m
Hayes, Jr., Albert Dr. Designing a
Notch Filter With a Programmable Calculator. May 1979,
Hayes, Jr., Albert Dr. Audio Problem Solving With a Programmable
Calculator. Jan. 1979, p. 42.
p. 52.
p. 34.
Orban, Richard. Equalizers For
Professional Recording Applications. May 1979, p. 68.
Plunkett, Brad. XY Response Plotters For the Studio. May 1979,
p. 56.
Purple, Dave. Automation: It's
Evolution. Aug. 1979. p. 17.
Queen, Daniel. Impedance Matching.
Feb. 1979, p. 46.
www.americanradiohistory.com
Rogalski, Michael P. Murphey's
Theorem Applied To P.A. Work.
Feb. 1979, p. 52.
Rubenstein, Dave. Understanding
Magnetic Tape SpecificationsPart 1. Oct. 1979, p. 42.
Rubenstein, Dave. Understanding
Magnetic Tape Specification
Part II. Nov. 1979, p. 54.
Sacks, Kenneth B. The New World
Of "Creative Audio." July 1979,
-
p. 36.
Silver, Sidney L. Digitizing Audio
With Delta Modulation. April
1979, p. 60.
Tapes, Michael. Shared Access
Memory-A New Concept For
Digital Signal Processing In
Audio Applications. May 1979,
p. 42.
Toole, Floyd E. High Fidelity In
The Control Room -Why Not?
Feb. 1979, p. 30.
Vogelgesang, Peter. On the Intricacies Of Tape Performance.
Jan. 1979. p. 28.
Wendt, Diane. The MCI JH -556C
Console. Aug. 1979, p. 25.
Woram, John M. Report From
Mexico City: El Centro de Grabacion. March 1979. p. 37.
Woram, John M. Report From New
York: Soundmixers Recording
Studios. March 1979. p. 42.
Woram, John M. db Special Report:
On the Future Of Radio and
Recording..) une 1979. p. 44.
Woram, John M. A Mini -Survey Of
Graphic Recorders. July 1979.
p. 48.
Woram, John M. Audio Problem
Solving With a Home Computer.
July 1979. p. 50.
Woram, John M. db Special Report:
The AES, SPARS, "PROSOUND
INTERNATIONAL," and IEE.
Oct. 1979, p. 40.
Woram, John M. A Visit To AKG.
Oct. 1979, p. 48.
Woram, John M. db Special Report:
Education and Audio. Nov. 1979.
p. 43.
Yanchar, Carl. Choosing a Con sole-Is a Picture Really Worth a
Thousand Words? Aug. 1979,
p. 22.
Zambuto, Sam. One Man's Choice.
July 1979. p. 42.
Zide, Larry. db Test Report: Leader
LFR -5600. April 1979. p. 57.
Ron started as a singer in Philadelphia.
He worked the board at several major
festivals during the late '60s before entering
the studio in England during the early
'70s. Along the way, he began producing.
As a producer and /or engineer, Ron has
worked with The Who, Led Zeppelin, Bad
Company, Dave Mason, The Babys, UFO
and many others. His most recent project
was with The Jefferson Starship.
ON MULTI -TRACKING
'I go for the whole thing. I would
rather not do anything for two days than
have to take the band down to three
pieces and have to build it back up again.
I'd rather piece the tracks together than
piece the band together. I mean, there'll
still be overdubs and things like that,
but rock'n roll is so much a feel situation,
you know ?"
ON DIPLOMACY
'A lot of times, people will stand
around and everybody will think the other
guy likes it. Nobody will say 'Well, I don't
like it.' It won't be till after a while that they
find out that nobody ever liked it. They
just never wanted to say anything. Now,
I'm the guy who goes in there and gets
it all out of them -what they like and what
they don't like -so there's none of that.
41111441 /
can be the bad guy, sometimes. I'm just
real frank and rough. If somebody's not
doing something, I like to say it right then
and there, so one of the band members
doesn't have to say it. It might be a shock,
but none of it is taken out of the studio"
I
ON MUSICAL STYLES
"You know, hard rock stuff is the
hardest thing to record. People whacking
the hell out of the drums. Guitars turned
up to ten. Everything is distortion. People
screaming down microphones. The harder
the rock, the harder it is to record."
ON TAPE
"Consistency. That's the most important
thing. You know, you can work all day for
that one thing and you put that tape on and
it drops out or it does something. You
stay with it until it cracks up. Then you use
somebody else's. And I did that a lot.
I've used everybody's tape. I've been using
3M tape for five or six years, exclusively.
They happen to use the same tape I do, here
at The Record Plant. But :f they didn't,
I would have my own tape in in a second."
SCOTCH 250
WHEN YOU LISTEN FOR A LIVING.
on Reader Service Card
www.americanradiohistory.com
3M
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We designed our Pitch Transposer as a practical
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