low-light television - American Radio History

low-light television - American Radio History
Apri11973 25p
SURVEY: DISC CUTTERS AND TAPE COPIERS
SOUND '73 PREVIEW
LOW-LIGHT TELEVISION
1 1 1 1 1 1 1 1
I
1 1 1 1 1
1
CREATIVE SUCCESS....
Console designed for
Soundpush -CMS Studios,
Blaricum, Holland.
This console was supplied 32 into 8,
wired for up- dating to 32 into 16
considering future studio expansion.
Whatever the recording
Automatic function selection by push- button control
of the audio systems, including complete sync facilities
eliminating the need for multi- switching in order to change
over from normal recording into overdubb or re -mix.
ada
Cadac (London)
Limited
STANSTED ESSEX ENGLAND Tel: Stansted 3437 & 3132
MANUFACTURERS OF AUDIO CONTROL EQUIPMENT FOR THE SOUND RECORDING INDUSTRY
studio sound
INCORPORATING TAPE RECORDER
EDITOR
DAVID KIRK
APRIL 1973 VOLUME
ASSISTANT EDITOR JOHN DWYER
ADVERTISEMENT MANAGER TONY NEWMAN
AUDIO GROUP ADVERTISEMENT MANAGER
ROBIN WELLS
AMERICAN REPRESENTATIVE
STEPHEN H. LAMPEN
Editorial and Advertising Offices: LINK HOUSE, DINGWALL
AVENUE, CROYDON CR9 2TA. Telephone: 01 -686 2599
American Office: P.O. Box 99569, San Francisco,
California, 94109, U.S.A.
©Link House Publications Ltd 1973. All rights reserved.
CONTENTS
FEATURES
OPTU- ELECTRONIC AUDIO LEVEL DISPLAY
By
Rune Espelien
35
SOUND '73 PREVIEW
44
DISTORTION: CAUSE AND EFFECT
Part Two
By Tony Eden
50
THE dBm OR THE dB(V)?
By
Angus McKenzie
54
SURVEY: DISC CUTTERS
56
SURVEY: TAPE DUPLICATORS
60
COLUMNS
NEWS
22
NEW EQUIPMENT
24
LETTERS
28
PATENTS
By Adrian Hope
30
DIARY
By John Dwyer
36
VIDEO: MARCONI XQ1402 LOW -LIGHT TUBE
By Roderick Snell
40
15
NUMBER
4
WOULD YOU ENCOURAGE your son to enter the sound
recording industry? Probably not, since present working
conditions make it one of the least secure vocations in existence
-second only to cinematography.
The first serious step towards improving the status of recording engineers took place at Lansdowne Studios on January 31.
An inaugural meeting of the Engineers Guild was chaired by
the president of the Association of Professional Recording
Studios, Jacques Levy. One of the Guild's first acts was to bite
off their own head by declaring that they would not be involved
in trade unions, politics, conditions of work, or rates of pay.
'These things,' Mr Levy claimed, are provided elsewhere'.
Indeed? Then `elsewhere' has totally neglected its duties.
The one trade union with any interest in this industry, the
ACTT, is recognised by only a few of the larger studios and
virtually none of the many small ones. Few junior studio staff
receive any formal training, few are allocated reasonable
working hours, few receive more than token wages, and few
enjoy even the security of a used -car salesman. The majority
work in conditions tending to cause premature deafness.
Why do youngsters tolerate these limitations? Attracted by
what they consider an alternative to the commercial rat -race,
they find themselves instead in the thick of it. And since every
opening faces a queue of other keen souls to replace any
disillusioned junior, the tendency is to remain as long as sanity
and a hard -pressed love of music allow.
The Guild desire to see sound recording recognised as a
profession, a latterly devalued term defined as (1) an employment
not mechanical and requiring some degree of learning; (2) a
religious belief or pretence. Which definition they choose must
depend largely on their attitude to formal technical training.
The Tonmeister concept has not exactly been welcomed in this
country, despite capable work by the University of Surrey, so
what will the Guild suggest as an alternative? Some kind of
recognised qualification, whatever its level, would in the long
term be more profitable than the present system resting on vague
`studio experience' and actually meaning 'jobs for the boys'.
Qualifications can indeed be a disadvantage under present
conditions as one Oxford graduate in physics discovered
recently when sacked by a studio manager fearful of being
ousted by his junior. And this was no back -street studio.
Mr Levy and others are known to fear trade union involvement in the recording industry. To quote the words of the
APRS president on an earlier occasion, `eventually they'll say
it takes 14 people to operate a desk'. Admittedly many unions
have displayed the most deplorable contempt for the general
public but this is all the more reason for a presently union -free
industry to put itself in order.
REVIEWS
INFONICS 102 CASSETTE COPIER
By Hugh Ford
COVER
72
Kodalith photograph of a Neumann cutting lathe at EMI Abbey Road,
from an original by Tim Bishopp.
CORRESPONDENCE AND ARTICLES
All STUDIO SOUND correspondence should be sent to the address
SUBSCRIPTIONS
printed on this page. Technical queries should be concise and must
include a stamped addressed envelope. Matters relating to more than one
department should occupy separate sheets of paper or delay will occur
in replying.
Articles or suggestions for features on all aspects of communications
and musical engineering will be received sympathetically.
Manuscripts should be typed or clearly handwritten and submitted with rough
drawings when appropriate. We are happy to advise potential authors
on matters of style.
management to keep abreast of new technical and commercial
developments in electronic communication. The journal is available
without charge to all persons actively engaged in the sound recording,
broadcasting and cinematographic industries. It is also circulated by paid
subscription to manufacturing companies and individuals interested
in these industries. Annual subscription rates are £3 (UK)
or £3.30 ($8 or equivalent) overseas.
STUDIO SOUND is published on the 14th of the preceding month
unless that date falls on a Sunday, when it appears on the Saturday.
BINDERS
Loose-leaf binders for annual volumes of STUDIO SOUND are
available from Modern Bookbinders, Chadwick Street, Blackburn, Lancashire.
Price is 85p. Please quote the volume number or date when ordering.
STUDIO SOUND, publishedmonthly, enables engineers and studio
PAST ISSUES
A small number of certain past Issues may still
be purchased from Link
House, price 31p each including postage. Photostat copies of any STUDIO
SOUND article are available at 25p including postage.
10111/4111III
STUDIO SOUND, APRIL 1973
3
Budget priced
compact
cassettes
spendor
The "New standard in loudspeaker
design is now even better
from 26p
Low Noise
Guaranteed
Screwed
Not Welded
Library Case
Prices
1
29p
C60
POST& PACKAGE
C90
39p
1 -10 cassettes 10p
11 -100 cassettes 25p
C120 52p
Price per cassette
10
100
28p
37p
26p
35p
44p
46p
Spendor introduce the BC
VAT not included
These prices are liable to alteration without notice.
fpa
`
Fraser - Peacock Associates Ltd
94 High St. Wimbledon Village
London SW19 01.9471743,/2233
Registered Office:94 High St Wimbledon Village London SW19
PLEASE SEND ME
C60
C90
C120
Nominal impedance
Frequency response
Frequency range
Power rating
Units
8
Dimensions
Weight
Price
314"x154'x151"
I
II
ohms
22dB 50Hz -14kHz
30Hz -20kHz
watts peak programme
Spendor 12"
Spendor 8"
Celestion HF1300
Celestion HF2000
70
701b
On application
*John Shuttleworth, 'Studio Sound', September 1970
CHEQUE /PO. FOR
Spendor Audio Systems Limited
NAME
Kings Mill Kings Mill Lane South Nutfield
Redhill RH1 5NF . Phone Nutfield Ridge 2554
.
ADDRESS
II
Registration No 779084(England)
.
.
The current complexity and prohibitive
cost of multichannel recorders has
previously deterred the musician from
utilizing the full potential of a professional
recorder as a creative medium.
Direct Selling
Our policy of direct selling
together with large scale
production is obviously reflected
in our selling price of £492. To
ease any financial burden we have
negotiated with U.D.T. the
lowest terms currently available.
Nice 'n' Easy
At the touch of a button it is
now possible to produce L.P. quality
masters or demos in the relaxed
atmosphere of your own studio for
under £500.
Curtains
The end of the studio is nigh ?
Certainly not, since the introduction
of this recorder is creating a new
generation of recording studios.
Comprehensive
The Industrial Teac is so comprehensive
that such tapes may be produced with only
a pair of headphones, a microphone and
a mixing lead.
Low Multitrack Noise
The fact that we have broken the
-63dB noise and £1000 price barrier is no
coincidence. A -63dB noise level coupled
with absolute simplicity is creating a new
generation of smaller recording studios.
D
&D
-
Delivery immediate to your door
Demonstrations to studios within 150 miles of
London.
Domestic version available at £465.
Complete MINI STUDIO around £1100.
NEW LOW TAPE PRICES
We can offer Scotch 207 3600 ft. at 25% BELOW
TRADE PRICE for moderate quantities.
Sole U.K. Distributor
INDUSTRIAL TAPE APPLICATIONS
105
High Street, Eton, Windsor, Berks.
Tel: (95)
52663
STUDIO SOUND, APRIL
1973
5
NEW equipment
for the
professional soundrecording
studio from
brii..iI
DESIGNED AND MADE IN THE U.K.
MULTI -CHANNEL EQUIPMENT
We have set a new price/performance standard with our 4, 8 and 16 channel studio
recorders offering full facilities for the production of master recordings. PPM or VU
meters on each channel. Equalisation to CCIR, NAB and IEC characteristics. Remote
control for tape transport and record functions. The equipment is in full production and
studio use in both U.K. and overseas.
STUDIO RECORDERS
for 2- channel reducing, field recording and full -track mastering.
re
TAPE TRANSPORTS
We offer a widened range of 2 speed and 4 speed models from 15/16
to 60 IPS, á" to 1" tape width, with heavy duty solenoid operation and
remote control facilities.
b
11
BRENELL ENGINEERING CO LTD
231 -5
Liverpool Road, London
N1
1LY Tel.
01
-607 8271 (5 lines)
See and hear the
world's finest Audio Equipment at:
Britain's Premier Hi -Fi Audio Exhibition
0 NEM13
Sonex 73, the 4th International Exhibition sponsored by the
Federation of British Audio, 31 Soho Square, London W1V 5DG
6
Excelsior Hotel, London Airport (Heathrow)
Wednesday 28 March to Sunday 1 April inclusive from
11 am
Tickets and posters for you and your clients may be
obtained from B.A. P. Ltd, 31 Soho Square, London
Free coach service from
W1 V 5DG
Car Parking
Hounslow West Underground Special Audio Features
and technical presentations
HS77 I5-7
The high speed Revox is firmly
established as standard equipment in
the majority of London Theatres,
Local Radio Stations, and Recording
Studios
PRIDE
f230
Delivered to your door
SEL SYNC +120
IMMEDIATE DELIVERY
SOLE U.K. SUPPLIER
VHS77 30-IS
WIDE BANDWIDTH 40 Hz -40 KHz of
particular interest to research establishments
TAPE DUPLICATION The equalisation
characteristics 17.5 and 35 Sec are such
that a 1:1, 2:1 or 4:1 speed ratio will produce
a copy tape of the same recording characteristic as the master
HIGH TAPE VELOCITY of 30 ips (76
ems) is invaluable for the analysis of data
and transient information
TAPE ECHO 50 milli seconds or 100
Fs.
milli seconds
Delivered to your door
1298
LE
.T.A.
for
REVOX
REVOX HIRE
HIGH ST., ETON,
WINDSOR, BERKS.
Tel. WINDSOR (9S) S2663
IOS
Contact Barry Lambden for further information
London's most competitive rates
Finance available through UDT only 92 %
Subject to increase after 1st April '73
NEW LOW TAPE PRICES
We can
offer Scotch 207 3600 ft. at 25% BELOW TRADE
PRICE for moderate quantities
STUDIO SOUND, APRIL
1973
7
EVERY NUN NEEDS
a SYNTHI
Electronic Music Studios (London) Limited
49 Deodar Road London SW 15
01-874 2363
New York 408 East 78th Street N.Y. 10021 USA
The Synthi Range by
AUDIO CONNECTORS
A GOOD ALL ROUNDER
BROADCAST PATTERN JACKFIELDS, JACKCORDS
PLUGS & JACKS. QUICK- DISCONNECT MICROPHONE
CONNECTORS.
AMPHENOL (TUCHEL) MINIATURE
CONNECTORS WITH COUPLING NUT. HIRSCHMANN
BANANA PLUGS & TEST PROBES. XLR COMPATIBLE
IN -LINE ATTENUATORS. LOW COST SLIDER FADERS
HM80
Hybrid
Module
This
BY RUF.
approx.
actual size
FUTURE FILM DEVELOPMENTS LTD.
Wardour Street WIV 3LE
90
general purpose Hybrid AC control module. It provides a dynamic
control range of 80 db and it is capable of performing any function that lies
between the frequencies of 3 Hz and 200 KHz.
Furthermore it will operate with single supply voltage ranging from 4.5 to 24
Volts with negligible variation of all other characteristics except of course the
maximum input and output voltage swing which is mainly determined by the
supply voltage.
This miniature encapsulated 24 pin Dual -In -Line module contains also all the
necessary coupling and decoupling capacitors and therefore the external
components are limited to those necessary to perform the individual function
is a
required.
The internal pin connections have been specially arranged to make the design
of printed circuit boards very easy and the module will plug into a standard 24
pin D.I.L socket for maximum flexibility.
The outstanding quality and reliability of this module makes it ideal for use in
the professional field and along with the specification sheet comes a very
comprehensive application report dealing with all aspects of sound recording
equipment.
Furthermore we undertake to design free of charge any application required
but not listed in the application report.
01
ELECTRONICS
MILL LANE, LONDON NW6 INQ
Telephone:
01- 794 -8326
QUALITY
BRITISH
P.V.C.
MYLAR
&
POLYESTER
RECORDING TAPES WITH FITTED LEADERS,
Etc., EX 3"
Thanks to bulk purchase we can offer tensilised HI -F1 tapes, manufactured
by a British firm of world repute. All boxed individually (sealed if required) in
polythene. Our tapes are not to be confused with imported sub -standard or used
tapes. Full money refund if not delighted.
3'
APOLLO
-437 1892'3
WE SPECIALISE IN BRAND NEW
TOP
For further details write or phone:
96
EMS
4"
5"
5r
7"
This month : -"DRY SPLICE" (19p) given FREE with every order.
Std.
L.P.
D.P.
Boxed
Length ea.
3for
Length ea.
3 for
Length ea. 3 for empty spis
150' 10p 29p
3" 220' 12fp
300' 20p 50p
4" 450' 25p
600' 30p 87 }p
5" 900' 40p
900' 35p EI.02+ 5 }" 1200'52 }p
1200'45p El .27¡ 7" 1800'65p
All orders despatched by return.
35p
70p
LI.17+
0521
El 92¡
3"
4"
5"
51"
7"
400' 223p 65p
600' 34p 97 }p
1200'62 }p LI.85
1800'85p
E2.50
2400'El.05 E3.05
3"
3p
4"
5"
8p
9p
9p
5
*"
7"
lop
Postage and Packing 9p per order
STARMAN TAPES, 421 Staines Road, Bedfont, Middlesex
Amcron
FmLIpIErs
Amcron, you will recognise world- renowned Crown International
in the world. Only the
product name has been changed to avoid any possible confusion of identity.
The range shown here will meet the needs of studios, groups, theatres,
and indeed wherever power is demanded with the absolute maximum quality and
reliability.
In
amplifiers- beyond all question, the best of their kind
All quoted output powers are Root Mean Square values.
D.60
the
100
watt amplifier
Two channel extra -compact power amp. In stereo-40 watts per channel at clip
point into 8 ohms; 62 into 4 ohms; in mono, 100 watts into 8 ohms. At 30 watts
per channel into 8 ohms power response is -±-1 dB from 5 to 30,000 Hz,
THD is below 0.05, and hum and noise 106 dB below. Built -in protection against
mis -use. Input sensitivity 0.75V into 25 Kohms. Size 17in x 81in x 11in high.
D.150
the 330 watt amplifier
Two channel model. 100 watts per channel at clip point into 8 ohms. 140 watts
into 4 ohms loads. 330 watts into 8 ohms used mono. Power response
±1 dB from 5 to 20,000 Hz at 75 watts per channel into 8 ohms. THD less than
0.05°,. Damping factor greater than 200 up to kHz. Hum and noise 110 dB
below at 75 watts per channel into 8 ohms. Input sensitivity 1.19V +2% into
25 Kohms for 75 watts out. Built -in protection against mis -use. Size
16Zin x 5in deep x 8in high, less front panel (Front panel optional extra, £15).
19in rack mounting fittings also available. Price, less front panel
1
DC.300A the 1,000 watt amplifier
Power at clip point (per channel) 200 watts into 8 ohms: 350 watts into 4 ohms:
500 watts into 2.5 ohms. Used mono -greater than 650 watts into 8 or 4 ohms.
This new unit will operate into loads as low as ohm and no longer
requires protection tuses as did its predecessor the DC 300.
Power response +1 dB from zero to 20,000 Hz at 150 watts per channel
into 8 ohms. Total harmonic distortion 0.02°,ó at 300 watts
per channel into 4 ohms. Hum and noise below 110 dB at 150 watts
per channel into 8 ohms. IM distortion 0.05°,ó from 0.01 watt to 150 watts per
channel into 8 ohms. Input sensitivity 1.75V for 150 watts out per channel into
8 ohms. Size, with front panel, 19in x 7in x 9111in (suitable for standard rack
mounting).
1
M.600
'0
I
Single channel power amplifier. 600 watts into 8 ohms or 1,000 into 4 ohms with
THD less than 0.1 °;,. Frequency response f1 dB from zero to 20 kHz.
Two M.600s can be linked to give a massive 2,000 watts into 8 ohms. With built -in
automatic two -speed cooling and protection devices against mis -use. Weight
80Ibs nett. Size 19in x 81in high x 161,in (standard rack mounting).
_
w
Amcron amplifiers carry a three years' warranty on materials and
labour. Full descriptive leaflets gladly sent on application.
MACINNES LABORATORIES LTD. STONHAM, STOWMARKET. IP14 5LB.
Telephone Stonham (044 971) 486.
STUDIO SOUND, APRIL
1973
9
MYC
Pictured here, the PRO A120, one of
the three new professional PA amplifiers
Eagle have in store for you this year.
This one has an RMS output power of
120 watts behind it. And there's a 65 watt
amplifier and a 35 watt mains /mobile
model too.
All three have 100 volt balanced line
outputs as well as 4, 8, and 16 ohms.
All three have a priority page circuit
which preempts all music and other voice
transmission.
They all function as mixers too.And
there are slide controls and memory
markers on each for easy operation.
Have a look down our list of
specifications and see just how many other
features we've included.
Could be you'll find the price tag
something of an attraction too.
kC-2 PRIORITY
Amplifier
Output Power: 120 watts RMS
Frequency Range: 35- 20,000 Hz.
Inputs: Mic 1: Hi 5 mV @ 50,000 ohms or Lo
PRO A120 Professional PA
200 uV
'
200 ohms (using PPLZ).
Mic 2: 5 mV @ 50,000 ohms.
Mic 3: 5 mV @ 50,000 ohms switchable
to Magnetic Phono: 4 mV () 47,000 ohms (RIAA)
Mic 4: 5 mV @ 50,000 ohms.
Aux /Tuner: 400 mV @ 100,000 ohms.
Signal to Noise Ratio: Better than 75 dB.
Output Impedance: 4, 8 and 16 ohms and 100
volt line output.
Operating Voltage: 220 -250 volts AC.
Dimensions: 350 x 130 x 310 mm.
List Price: £125.00 (excl. VAT)
Amplifier
Output Power: 65 watts RMS
Frequency Range: 40- 20,000 Hz.
Inputs: Mic 1: Hi 5 mV @ 50,000 ohms or Lo
200 uV @ 200 ohms (using PPLZ).
PRO A65 Professional PA
...
illllll
MASTER VOLUME
Mic 2: 5 mV @ 50,000 ohms.
Mic 3: 5 mV @ 50,000 ohms switchable
to Magnetic Phono: 4 mV @ 47,000 ohms (RIAA)
Aux /Tuner: 400 mV @ 100,000 ohms.
Signal to Noise Ratio: Better than 70 dB.
Output Impedance: 4, 8 and 16 ohms and 100
volt line output.
Operating Voltage: 220 -250 volts AC.
Dimensions: 350 x 130 x 310 mm.
List Price: £95.00 (excl. VAT)
PRO A35 Mains /Mobile Professional
Amplifier
Output Power: 35 watts RMS
Output Impedance: 4, 8 and 16 ohms and 100
volt line output.
Operating Voltage: 220 -250 volts AC or 12
volts DC.
Dimensions: 350 x 130 x 310 mm.
List Price: £75.00 (excl. VAT)
Eagle International°
Eagle International Precision Centre Heather Park Drive
Wembley HAO 1SU Telephone 01 -903 0144
PA
Frequency Response: 50- 18,000 Hz.
Inputs: Mic 1: Hi 5 mV 50,000 ohms or Lo
200 uV @ 200 ohms (using PPLZ).
Mic 2: 5 mV @ 50,000 ohms.
Mic 3: 5 mV @ 50,000 ohms switchable
to Magnetic Phono: 4 mV @ 47,000 ohms (RIM)
Aux /Tuner: 400 mV @ 100,000 ohms.
Signal to Noise Ratio: Better than 70 dB.
Please send me your catalogue containing
details of the new Eagle Professional
Amplifiers and.other P.A. Equipment.
Name
Address
L_
ss?I
Altec speakers systems and stereo components are designed
to offer you finer specifications for better listening and the
latest features for better control of what you hear and the
newest innovations for professional recording studios.
And that's why we say they're built a little better.
Now
available
in the U.K. the world
renowned
ALTEC
LANSING
range.
Bolita little better
For further details
write to sole
U.K. Distributors:
ACOUSTICO
ENTERPRISES LTD.,
6-8 Union Street,
Kingston- upon- Thames,
Surrey. Tel. 01 -549 3471/3
(3;l i n e s).
3
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IttR (onrReSSOR{.nNpER
/sox
-R
THRESHOLD
RELEASE
RATIO
I
iNPVT
OUTPUT
EXPANDER
PEAK LIMIT
\
/
COMPRESSOR
o
STEREO
STEREO
INPUT
OUTPUT
s<
THRESHOLD
1,
RELEASE
RELEASE
RANO
PEAR LIMIT
F760X -RS STEREO LIMITER -COMPRESSOR -EXPANDER
It's all here -every facility you've ever required in the field of level
control- expansion, compression and limiting; stereo matched to
obviate image shift during operation. Eliminate increased noise due
to compression; reduce channel noise, studio cross -talk and ambience. Available on short delivery in both modular and rack formats.
8,
AUDIO DESIGN RECORDING
TEL: READING
(0734) 84487
ST MICHAELS
SHINFIELD ROAD
SHINFIELD GREEN
READING BERKS UK
12
A
J 1i1A
Sound design by
triad
Comprehensive facilities for multi-track recording
combined with functional design and performance
beyond reproach, add to this a price tag that will not
break any hearts, and the result is aTriad `B' series
console. Available with any number of input
channels, and normally supplied with 8 group
outputs and 16 track monitoring, two foldback, four
echo routes, full equalization and complete access at
large jackfield. If this isn't enough, theTriad Ä series
offers just about the most complete specification
available, and can now be supplied fully automated
for maximum versatility.
CREAM
TRIAD A
FOR ENGINEERS DT CNGINEERJ
Trident Audio Developments Limited 4 -10 North Road, London N7 9HG
Telephone 01 -609 0087 Telex, 27782
An example of the Midas
modular system mixers.
Medium scale chassis, with space for sixteen inputs. The input modules
shown include, sensitivity control and fader, pan and
output group switch, fold back with pre- fade /post -fade
switch, bass, treble, presence equalisation and reverb/
echo mix.
The top level has four output modules with PPM
calibrated Vu Meters and compressors.
The middle level accommodates the fold back output,
talk back and headphone facilities, acoustic compensation
filters and triple range crossover network. The lower level
also includes a send and return panel.
Specifications
Inputs 0.2 mV into 200 ohms, 10 mV into 50K ohms.
Outputs normally OdbM into 600 ohms.
Overload range 60 db, low and high Z, channel outputs 16 db above Odb,
Vu indication.
Line outputs Max level + 16 dbM
Signal to noise Ratio At maximum channel gain 66db,Typically 80db at normal
gain settings
Distortion
Less than 0.1% THD
Midas Professional Amplication. 87, North Grove, London, N.15. Telephone
01
-800 6341
ELECTROSONICDesigned and manufactured
the integrated sound, lighting
and projection system at the
HARDROCK, MANCHESTER
The Hardrock Control Console
is shown on the left.
ELECTROSONICWill be pleased to supply
a specification for any
project large or small.
ELECTROSONICHave supplied lighting and
projection systems for:
Emerson Lake and Palmer
Pink Floyd -The Who -YesThe Rolling Stones- Family
King Crimson.
-
-
ELECTROSONIC
Electrosonic Limited Electronic Control and Audio Systems
815
Woolwich Road London SE7 9LT
Cables: Multiplex London SE7
01 -855 1101
Phone:
14
all you need
is the plug
we supply the rest!
for
a
complete portable recording studio
LAMB LABORATORIES
PRESENT THEIR MINI -STUDIO
COMPRISING
A REVOX A77 high speed tape recorder with Sel Sync,
variable pitch and illuminated remote control unit.
PLUS
The LAMB 4 channel stereo mixer with in -built compressors-Full channel equalisation -Pan Pots and echo
send controls.
-
The mini -studio kit is completed by 4 Beyer microphones
and 4 stands (2 with booms) -Beyer DT100 headphones
Power Supply- Carrying cases -and ALL interconnecting
leads.
Remember, all you have to supply
DURING SONEX
is
the plug!
'73
If you're visiting Sonex, see the LAMB Mini -studio at our Hospitality
Suite. At the beautiful Skyline Hotel -where you can also readily
park, dine and be entertained. Simply take one of our scheduled
mini -buses (which will return you to the Sonex venue) 400 yards
down the road and enjoy the superb facilities of the Skyline.
March 28, 29, 30, 31 9.30 a.m. to IO p.m.
If you can't make it to Sonex, just fill in the Coupon
and we'll provide all the operating instructions and
the specifications you'll need to have your own
completely Portable Mini -studio. Post it to -day!
------------ - - ---I
Detailed information on Mini-studio/Mixer
NAME
ADDRESS
LAMBL
)
s0M ;','a y
Lamb House,Church Street Chiswick, London W4 2PB
Telephone 01 -995 4551. Telex 934047. Cables Lambex London
TELEPHONE
SS43
STUDIO SOUND, APRIL 1973
15
"The alternative to
QUAD
is not a
colour television set
but a seat
in the
concert hall"
QUAD
for the closest
approach to
the original sound
Send postcard for illustrated leaflet to Dept SS
Acoustical Manufacturing Co. Ltd., Huntingdon, Tel: (0480¡
16
QUAD is
a
Registered Trade Mark.
The ubiquitourlf1153.
The Shure SM53 professional unidirectional microphone is seen with increasing frequency in the best of company because it affords eight distinct performance advantages: (1) a wider front working angle with uniform tonal quality;
(2) effective noise rejection through a true cardioid pickup characteristic: (3)
a built -in shock mount for effective mechanical noise isolation; (4) extraordinary ruggedness for performance consistency after severe shocks; (5) a
superior hum rejection system: (6) an integral breath "pop" filter; (7) a minimized proximity effect for constant tonal quality; and (8) full field serviceability.
Interested?
Shure Electronics Limited
Blackfriars Road
London SE1 8HA. England
84
H
STUDIO SOUND, APRIL
1973
17
a LJ_lix
SOUND SYSTEMS AND ELECTRONICS
010.AR AUDIO bp
The MXT -800 series of audio mixing modules can be
supplied to form compact 2 or 4 group mixers suitable for
use in local broadcast and the smaller recording studios.
Each mixer is custom built and can incorporate P.P.M.
or V.U. metering, and additional master output group,
limiter, talkback, monitor, echo, oscillator, pan, and line
equaliser modules.
Overall mixer specification:
Frequency response:
±0.4dB 20Hz -20KHz including
input and output transformers.
Distortion:
Typically 0.02% at normal levels.
Less than 0.1% 20Hz -20KHz at
Noise:
+18d B m.
Microphone channels: noise
factor less than 2dB ref. 600 ohms.
All other inputs: -75dBm.
Gain:
Maximum system gain,
microphone 100dB.
Line 20dB.
MANUFACTURERS OF
SOUND SYSTEMS AND
ELECTRONICS
18
AUDIX BB LIMITED
STANSTED ESSEX
TELEPHONE: STANSTED 3132/3437 (STD 027 -971)
202
WHEN STUDIOS CONSIDER
A TOP QUALITY
DYNAMIC MICROPHONE ...
...
IT'S STILL THE AKG
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Demonstrations without obligation available on all
AKG professional microphones and reverberation units.
FOR FULL INFORMATION CONTACT:
AKG EQUIPMENT LTD.
182/4 Campden Hill Road
Kensington London W8 7AS
Telephone 01.229 3695.
STUDIO SOUND, APRIL
1973
19
The perfect companion to your Nagra recorder!
SELA
professional mixer
£336
write or phone for spec sheets
SOLE
UK DISTRIBUTORS
CINTRON GROUP
551 LONDON ROAD
ISLEWORTH MIDDLESEX
TEL 01/568/0131 TELEX 935054
GROVE HOUSE
COMMUNICATION ACCESSORIES &
EQUIPMENT LIMITED
77
-
AKEMAN STREET, TR1NG, HERTS, U.K.
G.P.O. Type components on short delivery
JACK PLUGS
201, 310, 316, 309, 404
JACK STRIPS
310, 320, 510, 520, 810
JACK SOCKETS
300, 500, 800, B3 and B6 mountings
PATCH PANELS
made to specifications
LAMPS & LAMP STRIPS
SWITCHBOARD No. 2 LAMP CAPS 10 way PO 17 20 way PO 19 BALLAST PO No.
HOLDER No. 12
CORDS, PATCHING & SWITCHBOARD
made to specifications
TERMINAL BLOCKS DISTRIBUTION
20 way up to 250 way
LOW PASS FILTERS
type 4B and PANELS, TELEGRAPH 71 (15 x 4B)
UNISELECTORS
various types and manufactures both PO and miniature
LINE TRANSFORMERS /RETARDATION COILS
type 48A, 48H, I49H, 3/16, 3/216, 3/48A, 3/43A, 48J, etc
FUSE & PROTECTOR MOUNTINGS
8064 A/B 4028, HI5B, H40 and individual I/
--
--
-
I I
--
-
-
--
COILS
39A, 40A and 40E, etc
PO TYPE KEYS
1000 and PLUNGER TYPES 228,279, etc
19" RACKS
VARIOUS SIZES
Telephone: Tring 3476/8 STD: 0442 -82
20
Telex: 82362
Answerback: Batelcom UK Tring
The simple case for using
Scotch MagicTransparent Tape
Ordinary transparent adhesive tape
Scotch Magic Transparent Tape
Very visible. Ordinary tape makes a very visible
join and spoils the appearance of the item.
Almost invisible. Magic Transparent Tape is
Difficult to write on. J ecause of its shiny
surface ordinary tape is difficult to write on.
Easy to write on. Magic Transparent Tape is
easy to write on- ballpoint and pencil reproduce
perfectly. You can type on it too.
"Ghost" effect on copies. Ordinary tape gives
"Ghost- free" copies.
a ghost effect on copies and photographs making
the subject underneath difficult to read.
79,4
rg
much less obvious. It tones in with the background
so the join becomes almost impossible to spot.
You get perfect copies
with Magic Transparent Tape. The taped section
is just as legible as the rest.
rg;r
2
Non -permanent. Ordinary tape shrinks and
yellows with age leaving an unsightly black line
round the edges. It also tends to crinkle and peel
off if exposed to moisture.
r
rg2
It's permanent so it won't shrink, discolour
or peel off. Magic Transparent Tape isn't
affected by sunlight. moisture or temperature
change. It stays just the way you stick it down
no matter how long you leave it.
If you would like a free sample of Scotch Magic Transparent
"rape, fill in this coupon and send it to: Commercial Trades
Marketing, 3M United Kingdom Ltd., 3M House, Wigmore
Street, London, W1A lET.
Nam,.
Company
you Kotre lhe /mpftf1efroen.
Nottke pe.
Pos-itiml
m
Address
SS'4 73
n
mark.
3M 2086
STUDIO SOUND, APRIL
1973
21
Nixon administration attack public
television
A PLAN to strip the American Public Broadcasting Service of its responsibility for program
production and scheduling was disclosed
recently by the board of the Corporation for
This presidentially
Public Broadcasting.
appointed body intended to restrict the network
to relaying programs among the 232 public
television stations. Announcing the plan, Mr
Henry Loomis (CBP president) indicated that
he had the support of the Nixon Administration whose disapproval was aroused by
discussion programs such as 'Washington Week
in Review' which the Administration consider
`too liberal'. The Administration were also
keen to see the removal of Mr William Buckley,
a strongly `right wing' broadcaster who had in
turn criticised Mr Richard Nixon's policies as
being 'too liberal'.
Mr Loomis denied that the Nixon Administration had given way to pressure from
commercial broadcasters. He admitted that,
prior to becoming president of the Corporation
Public Broadcasting last November, he had
never watched a public television program.
The chairman of the Public Broadcasting
Service, Mr Robert Schenkkan, has since
commented that the decision would not be
acceptable to the licensees. Other PBS representatives added that the dispute might
eventually have to be resolved by Congress.
IBA asked to preview sexual education
series
THE INDEPENDENT Broadcasting Authority have
been asked to preview a Granada Television
series `The Facts Are These' scheduled for
broadcast to schools during 1973. The series,
produced for children of 15 and 16, includes
education in venereal hygiene and contraception. The complainant, a Mrs Mary Whitehouse, commented: 'It would appear from
statements in the press that the producers are
starting from the assumption that premarital
sex is more or less normal'.
Attempt to bar BBC play
relatives of David Lloyd George
to obtain an injunction against a recent
television play failed to satisfy the Attorney
General. The play was produced for the BBC 2
series 'The Edwardians' and was criticised by
the former prime minister's nephew, councillor
William George. Although he had not actually
watched the play, he felt: 'The author relied on
completely inadequate sources and was historically very inaccurate. Most attention has been
concentrated on my uncle's morals, and alleged
association with women. I am surprised that
the point has not been raised which stuck most
in my gullet. This was the suggestion that Lloyd
George, with the knowledge of his wife,
ATTEMPTS BY
22
commited perjury. The records do not justify
the attribution of perjury to him.' Councillor
George said he spoke with knowledge of
family papers not shown to any outsider since
before the 1914 -18 war.
Sir Lew Grade bans ATV documentary
AN 80 MINUTE documentary film about Michael
Collins, an IRA leader killed 51 years ago, has
been banned by Sir Lew Grade from transmission in the United Kingdom. The £10,000
film was written and narrated by the Welsh
actor, Mr Kenneth Griffith, who agreed that
his film might 'inflame strong passions'. Mr
Griffith considers the British Government of
the day to have been responsible for the trend
of events in Northern Ireland. His film
were no objections from the IBA lawyers'. The
IBA had apparently stopped the program
primarily because they felt it should have given
certain people mentioned in the Poulsen
bankruptcy proceedings more opportunity to
defend themselves against statements made in
court and reported in the film. However, such
an opportunity had in fact been extended to all
those mentioned in the film (excluding Mr
Reginald Maudling and Mr John Cordle who
had already declined to make public statements). The majority had declined.
On February 5, production staff connected
with the documentary were supported by other
Granada, Thames TV and Midlands ATV
staff in a 30 minute television blackout as a
protest against the IBA ban.
criticised Lloyd George, Winston Churchill
and Eamon de Valera for their actions at the
time.
Taste and standards
`TASTE AND Standards in BBC Programs' is the
title of a pamphlet issued by the BBC to all it
producers during February. The 11 page guide
discusses cases of bad language assumed to
have given offence to viewers and listeners
selecting as examples: bl * *dy, bl* *ding and
These, the pamphlet declares, have
G *d.
different meanings for the older and younger
generations. An example of 'excessive nudity'
was given as a scene in the historical series
Elizabeth R; a naked girl leaving the bed of the
King of France. Portraying the bedroom
habits of monarchs in the Tudor period was
considered to contribute little to historical
understanding.
.
Granada abandon Poulsen documentary
AFTER HAVING their 60 minute documentary
'The Friends and Influence of J. L. Poulsen'
banned twice by the Independent Broadcasting
Authority, Granada finally withdrew the
production at the end of January and began
preparing a new and updated version. This was
to be presented to the IBA during March. Mr
Denis Forman, joint managing director of
Granada, said Granada's lawyers (Goodman
Derrick & Co) `passed the program as suitable
after the closest scrutiny that I have ever seen a
program subjected to, and we understand there
A Nigerian student training in educational
broadcasting techniques at the London
studios of the Centre for Educational
Development Overseas. A Leevers-Rich
E200 is being used to produce a tape
program for children. Most of the CEDO
students are qualified teachers and receive
instruction in script-writing, presentation, editing
and system operatic n. Courses last from
ten days to 16 weeks.
The Maple Leal -four
Value added tax
reminded that prices quoted in
this issue may become subject to Value Added
Tax from the beginning of April.
READERS ARE
76
geta bit more.
472 Functions (Gain, switch and position control)
100 Millisecond scan rate
Bi -phase digital encoding
with SMPTE time coding
compatibility.
Exclusive Leveloc updating facility
VCA resolution +
.1
dB (0 -45dB)
Dropout and splice immunity (Buffer memory)
Expandable and fully compatible function encoding
Tape machine speed variation tolerance ±15%
Compumix.
mixdown
system
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11929 Vose Street
North Hollywood. California 91605
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NEW EQUIPMENT
Variable speech rate unit
Audio modules
A NEW SERIES of audio modules is now being
manufactured by Key Electronics. They are
constructed on 89 x 64 mm glass-epoxy printed
circuit boards and are available in completed or
kit form. M1C- A /St/1 is an fet input stereo
microphone amplifier selling at a basic £15.20
completed and tested. Above ten off, the price
Massachusetts are making a device
which provides pitch-independent time control
of recorded speech and can be used to
synchronise a script in any situation. Voice
signals are recorded on a cassette and then
converted into digital signals. These are passed
through circuits which compress or expand
them, after which they are reconverted to
analogue form. The speed of speech can thus
be varied between 0.5 and 2.5 times that of the
original with a frequency range of 50 Hz to
11 kHz. The equipment measures 356 x 330 x
152 mm, weighs 8.2 kg, and will operate from
50 or 60 Hz mains at 110/230V.
Agents: F. W. O. Bauch Ltd, 49 Theobald
Street, Boreham Wood, Herts WD6 4RZ.
LEXICON OF
FIG.1
Hybrid audio module
module with a wide variety of
suggested applications is now being produced
by Apollo Electronics. The HM80 module is
compatible with a standard 24 pin DIL is
socket and operates from 4.5 to 24V negative
ground. Gain may be varied across 80 dB with
±0.5 dB linearity within the control range.
Total harmonic distortion under normal
operating conditions is specified as 0.1 per cent,
frequency response being 3 Hz to 200 kHz ±0.5
dB. Application reports (available on request)
include measuring equipment, subsonic Alfa
wave amplifiers, microphone and tape amplifiers, equalisers, telephone simulators and
voltage controlled filters. Fig. i shows a
suggested vc square wave oscillator configuration and fig. 2 a compressor /limiter giving up
to 20 dB compression.
Manufacturers: Apollo Electronics, 96 Mill
Lane, London NW6 1NQ.
VC SQUARE WAVE OSCILLATOR
AN AC CONTROL
Budget videotape
CONTROL
I
PUT
0
10+3V
OUTPUT
Multiposition slide switches
FREQUENCY
FOR
FOR
C
C
CONTROL RANGE
....110
=1000pF, 5= 1-10KHz
= 0.015F f = 100Hz -1KHz
R1....113K.R2....10N,R3._.100K
RI.
10K
LOG. OUTPUT
LEVEL CONTROL
01....2X3820 FET
FIG. 2
O TO
20dB COMPRESSOR LIMITER
basic price of 12.5 mm videotape
still around £10 per 730m, considerable interest
may be aroused by Dixons announcement of
Dixtec CCTV tape at £5.50. Quality is claimed
to be equal to the dearer brands.
Agents: Dixons Technical Ltd, 3 Soho Square,
London WL
A LARGER AND
HF2000 .Celestions.
The BC3 is expected
to cost £150.
Manufacturers: Spendor Audio Systems Ltd,
Kings Mill, Kings Mill Lane, South Nuffield,
Redhill, Surrey.
24
slide and pushbutton switches
manufactured by Jeanrenaud is now being
marketed by ITT Europe. Model CL6 offers up
to six positions as single pole two, three, four,
five or six way; two pole two or three way; or
three pole two way. The CL12 similarly offers
a maximum of 12 positions in all formats
between single pole 12 way and six pole two
way. Versions with 3 lim gold on brass contacts
are available for industrial applications, with a
specified life of 50,000 operations. For other
purposes, silver -plated brass contacts offer a
15,000 operation expectancy. Also in the
Jeanrenaud range, 19 x 19 mm switch modules
available with push and push /push actions. The
TFB module has a maximum rating of 20 mA
at 24V dc, insulating resistance being at least
10,000M ohms.
Agents: ITT GC Europe (EPD), Edinburgh
Way, Harlow, Essex.
A RANGE OF
R3
WITH THE
High power Spendor
more powerful monitor loudspeaker has been introduced by Spendor: the
BC3. Measuring 800 x 400 x 400 mm, the new
model is rated at 70W peak program and has a
nominal impedance of 8 ohms. Frequency
range is 30 Hz to 20 kHz (50 Hz to 14 kHz ±2.5
dB). Four units are incorporated, 304 and 203
mm diameter Spendor drivers plus HF1300 and
falls to £12.90, from 25 off to £11.60, and from
100 off to £10.65. The kit starts and ends at
£8.50.
Comparable price structures relate to the other
five modules. Type MIX/St /i is a 10 + 10
input unity gain stereo mixer at £7.70. Type
VU/GPA /St/i is a stereo VU drive and general
purpose amplifier at £5.40. The LDA /i is a
600 ohm line drive amplifier offering up to +19
dBm output at £8. A ppm driver to BBC
specification, the PPM.1a costs £17 excluding
movement. Lastly, TC /St/1 is a modified
Baxandall stereo tone control ( ±12 dB at 100
Hz at 10 kHz) at £11.45.
Manufacturers: Key Electronics, 16 Gainsborough Road, Queens Park, Bournemouth BH7
7BD, Hampshire.
FREQUENCY RESPONSE
20Hz
-20KHz
THRESHOLD LEVEL__- 10dBm,250mV
COMPRESSION RANGE... 20dB
GAIN BELOW THRESHOLD_.. UNITY
OUTPUT LEVEL AS LIMITER... OdBm
COMPRESSION RATIO....1:1
TO LIM.
MINIMUM OPERATING SUPPLY_ .9V DC
Rl....L7K, 82....1.55. R3....100K
01.02....2N3820 FET
TI....GARONERS MU7526 OR EQUIVALENT
01,0233,01.... TI 1544 SILICON DIODES
Al_..5K
R5..
LOG.
1M LIN
COMPRESSION
RATIO CONTROL
RELEASE O.1
-
5
SEC
Sela mixers and Advent cassette
recorders
SELA MINIATURE audio mixers, designed to
operate directly from Nagra recorders, are now
being distributed in Britain by Cintron. Manufactured in Sweden by Svenska Elektronik, the
Sela 2880 has four inputs to suit balanced
capacitor or dynamic microphones (50 to 200
ohms) and can also be switched to 0 dB line
(10k ohms). Output is two channel feeding the
Nagra (50 mV into 2.5k ohms) or program line
(3V into 600 ohms). Equalisation comprises
±10 dB at 100 Hz and 10 kHz (2 dB steps)
26
)10.
Sansui. the grandmaster of the stereo -world: jus
made three new bold moves. The EIGHT. The SEVEN.
The SIX. Moves which get Sansui once more into
the forefront of imaginative audio engineering. These
new items unite, for the first time, the outstanding
characteristics of different type components
resulting in an astonishing high level of versatility
and performance.
For detailed and free information on these new
Sansui items please contact the addresses below.
Continuous
Power
Total Harmonic
Sansui RMS
power at 8n Bandwidth( HF)
distortion
EIGHT
SEVEN
60/60 watts
47/47 watts
39/39 watts
SIX
10- 40.000
less than 0,3%
less than 0,3%
less than 0,3%
-lz
10- 50.000 -tz
10- 50.000 Hz
EIGHT
FM Sensitivity
(IHF)
Selectivity
1,7v.V
better than 60 dB
better than 60 dB
better than 60 dB
1,8!V
2
p.V
SEVEN
S(Z.IZSZLL
SIX
r
England: VERNITRON LTD., Thornhill Southampton S09 OF - Tel.: Southampton 44811
Ireland: INTERNATIONAL TRADING GROUP LTD., 5 Cope Street.
Vv,
Dame Street Dubl r. 2
COMPO HI -Fl G.M.B.H., Re
wng ris 6 Frankfurt ark Main
France: HENRI COTTE & CIE, 77 rue J -R. Thorelle. 77 92- Bourgla-Reme
Luxerkbowg LUX HI-FI, 3 rue Glesener "MI Austria: THE VIENNA HIGH FIDELITY &STEREO C °, Burggasse 114- 1070 Wien 70 Belgium: MATELECTRIC S.P.R.L.,
Boulevard Léopold II, '99 - 1080 Brussels
Netherlands: TEMPOFOON N.V., Kapitcin Halterastraat 8, Posthus 540- Tilburg C Greece: ELINA LTD., 59 & 59A Tritis Septemvriou Street Athens '03 H' Italy: GILBERTO GAUDI s.a.s., Corso Di Porta Nuova 48 - Milano LI Norway: FRIGO NORSK A.S., Eitert Sundtsgatan 40 - Oslo 3
Sweden:
MAGNETON, Sveav_gen 61 - 113.59 Stockholm
Denmark:.OUALI-FI INGENI0RFIRMA, Christiansholms Parkvej 26 - 2930 Klampenborg n Finland: AUDIOVOX OY Kornetinhe 2 Helsinki 38 L: Cyp'us: ELECTROACOUSTIC SUPPLY C° LTD., P.G. Box 625 - Limassol Ci Portugal: CENTELEC LDA, Avenida Fontes Pereira
de Melo 47,
4.odto Lisboa 1-1 Malta: R. BRIZZI, 293 Kingsway Valletta LI Switzerland: SONOVOX AG, Wallstrasse 11 - 4051 Basel Canary Islands: R. HASSARAM, Calle la Naval 87
Las Palmas
South Africa: GLENS (PTY) LTD., P.O. Box 6406 Johannesburg
SANSUI AUDIO EUROPE S.A., Diacem Bldg, Vestingstraat 53/55 - 2000 Antwerp, Belgium LI SANSUI AUDIO EUROPE S.A. FRANKFURT OFFICE, Reuterweg 93 - 6 Frankfurt am Main West Germany
SANSUI ELECTRIC C° LTD., 14.1, 2- chome, Izumi,
uçinami-ku - Tokyo 168 - Japan
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STUDIO SOUND, APRIL 1973
25
NEW EQUIPMENT
Automated cinema projector
system based on a
projector has been developed
by Clewer Audio Visual Services. Initiated
from a single pushbutton located in the
manager's office or the auditorium, the system
follows a preset sequence to dim house lights,
mask the screen, fade background music and
commence sound and picture. On completion
of a 21 -hour film, the projector rewinds the
film in 25 minutes ready for a subsequent
program.
Suppliers: Clewer Audio Visual Services Ltd,
Suwiley House, 466 Bath Road, Slough,
AN AUTOMATED PROJECTION
with low -pass filtration at 20 kHz (-5 dB) and
32 kHz (-18 dB). A speech filter provides 18 dB
per octave cut below 100 Hz. Dimensions are
360 x 320 x 550 mm. The 2880 weighs 6 kg and
costs £336.
Cintron are also handling the Advent 201
two channel cassette recorder. This employs
a Wollensak tape transport and Dolby B noise
reduction system and sells for £165.
Agents: Cintron, Grove House, 551 London
Road, Isleworth, Middlesex.
16 mm Elf--Lire
Buckinghamshire.
Visual track analyser
£8.95, the Willis Magna-See kit
comprises a tin of magnetic fluid, a developing
bath, magnifying lens, tape cleaning fluid, and
a reel of low -tack tape. After a recorded tape
has been immersed in the bath, and surplus
fluid allowed to evaporate, magnetic powder is
deposited on the recorded tracks which are
then rendered visible.
The powder may
subsequently be removed or transferred to
paper by means of the low tack tape.
Manufacturers: Willis Computer Supplies Ltd,
PO Box 10, Southmill Road, Bishop's Stortford,
Hertfordshire.
SELLING AT
Acoustic alarm
HIGHLY PENETRATING audio signal, either
frequency or amplitude modulated, is produced
by the Cybertone audible warning unit.
Equally suitable for fixed or portable applications, the 40 x 46 mm unit is entirely selfcontained and is described as highly reliable
A
Four channel headphones
FIBREGLASS PRINTED
Linear vca
dBx, the 202 voltage controlled
amplifier comes encased in a 50 x 25 x 12.5 mm
can with 3 mm gold-plated printed circuit
board pins. Gain varies from -100 to +30 dB
depending on the applied control voltage.
Excellent linearity and unit -to -unit tracking are
claimed. Input noise is specified as 6µV with
peak signal levels up to 100V, 20 kHz bandwidth and 0.07 per cent distortion.
Manufacturers: dBx Inc, 296 Newton Street,
Waltham, Massachusetts 02194, USA.
output transistors.
Manufacturers: Valradio Ltd, Browells Lane,
Feltham, Middlesex TW13 7EN.
have been appointed UK
agents for Superex, the second largest US
manufacturers of headphones. Of particular
interest in the Superex range is the model
QT-4B four channel headset incorporating four
acoustically isolated and electronically independent elements. If the principle seems open to
question, Superex are unequivocal: `True four
channel sound, with even more spatial drama
than stereophones offer'. The QT-4B, as
illustrated, employs conventional ear clamping
configuration and weighs 455 gm. Other headphones in the Superex range are the PEP77D
mains electrostatic (£56), PEP79 self-energising
electrostatic (£39.90), and a series of seven
moving -coil models.
Agents: Acoustic Research International, High
Street, Houghton Regis, Bedfordshire.
ACOUSTIC RESEARCH
Ppm boards
circuit boards for the peak
program meter circuit described by Hugh
Walker in our January 1973 issue are now
available from Surrey Electronics, 24 High
Street, Merstham, Surrey. The 70 x 65 mm
boards are fitted with gold plated eight -way
edge connectors and cost 75p. Complete kits
for the ppm driver are available at £8, including
six cermet trimpots, six 5 per cent zeners, four
BC109C and the gold edge connector. Surrey
Electronics also offer the circuit assembled and
tested at £12. Suitable meters are 600 ohm 1
mA left hand zero such as the Ernest Turner
642-PPM at £9. All prices include postage and
packing.
B12/400S raises 12V dc to 115 and 230V 50 Hz,
400W maximum. The C24/500S accepts 24V
dc and produces 500W. Each unit incorporates
a low level stable oscillator followed by an
intermediate amplification stage feeding into
since it does not employ make /break contacts.
Operating voltage is 12V dc at 20 mA and
temperature tolerance is -20° to +55 °C.
Manufacturers: A. P. Besson Ltd, St Josephs'
Close, Hove, Sussex BN3 7EZ.
NEW FROM
Filter module
NEW AUDIO frequency filter has been
announced in the USA by Spectra Sonics.
Model 506 can provide three separate outputs
from a single input signal, using external
switching. Two configurations are available,
the high pass 506H filtering below 40, 70 or
100 Hz. Model 504L passes below 10, 12.5 or
15 kHz. Quoted frequencies are -3 dB points,
rolling off at 18 dB per octave. Card dimensions
are 64 x 127 x 13 mm and the US price $69.
Manufacturers: Spectra Sonics, 770 Wall
Avenue, Ogden, Utah 84404, USA.
A
Dc /ac
transvertor
transvertors from Valradio: models
B12/400S and C24/500S. Both are to sell at
£197 and have a frequency stability better than
+0.25 Hz at 50 Hz. They are described as
suitable for industrial video recorders, film
cameras, audio recorders and small computers,
up to a loading not exceeding 500W. Model
TWO NEW
26
t.
A 3 -head, 30-20,000 Hz, 24 Watt,
4 -track stereo, semi-professional,
x95 let -down.
Specifications. Price. Performance. These are
the factors you compare before you buy audio
equipment, aren't they? But there's seldom
any way of checking reliability. Which is why too
many enthusiasts, who should know better, end up less than
enthusiastic about the 'bargain' they've made.
At Grundig we don't believe in publishing fancy
figures. We'd rather our machines lived up to their
specifications - and continued to do so.
For instance our published top
end response is i 6,000 Hz.
But i 6,000 Hz it'll stay, long after
less hard -headed machines have
worn down. Our output power
rating is continuous rms power.
And sounds it.
Grundig flywheels and capstans and motors
are built to precise tolerances. Yet we quote a best wow
and flutter figure of as much as ± o. i °,. Much better,
we think, than quoting less - and having an independent
lab. discover several 'oval' capstans in a batch
!
Grundig recorders have no gimmicks, but good
reliable mechanism, tape cleaners, and robust, positive
and accurate controls.
And sophisticated circuitry, with
minimal discrepancy between
stereo channels.
So whichever Grundig you
buy, it'll give you a lot more than
figures to impress your
friends.
Eight models to choose from.
The difference is incredible
Grundig (Great Britain) Ltd., London, SE26 SN l
STUDIO SOUND, APRIL 1973
27
LETTERS
The Ambiguous Watt
Dear Sir, I wholeheartedly agree with your
Editorial in the December issue on the
`Ambiguous Watt'.
A letter is not the place to enlarge on whether
the phrase `rms Watts' has any meaning at all
but, assuming that most people use it to mean
average Watts, one may legitimately ask
whether average Watts are an appropriate
measure of the output capabilities of an
amplifier or of the input capabilities of a loudspeaker. My own opinion is that, except for
very specialised applications (for example
using an amplifier to drive a capstan motor or
using a loudspeaker in sound insulation
measurements), one is not interested in the
maximum average performance of the device.
The really vital factor is that the amplifier
should not distort for the largest instantaneous
power outputs demanded by the signal. I
suspect that a workable measure could be built
up from consideration of the point where
perceptible (to be defined carefully in an International Document) voltage (or current) slipping occurs. Let us say that this point gives
values of output voltage (or current) swing
(peak) of U (or 1), then if the load is R we can
call the peak output U2 /R (or 12R). A similar
argument can be carried out for loudspeakers.
I am carrying out some experiments on power
amplifiers to see what sort of numbers come
out when one uses a criterion like the above,
and also to see if a long -term average (say one
hour) power rating would be necessary as well.
In the meantime let us all try to give up
using Watts -no qualifications at all', `Watts,
speech and music,' `Genuine rms Watts' (sic),
`Music power,' `Watts rms delivered to a load,'
and `Watts Programme' to list only a few
quoted in your December issue.
Yours faithfully, J. M. Bowsher, University of
Surrey, Guildford, Surrey.
[We are not responsible for advertisement copy!
-Ed.]
raggedness of response, if not in general
balance.
(See `What Price Loudspeaker
Response Curves ?' by Ralph West, Hi-Fi News
& Record Review, September 1971.) When we
eventually have a method of measurement
which is: (1) definitely repeatable; (2) may be
applied to all loudspeakers; and (3) is not open
to reasonable dispute-then we shall start
publishing frequency response curves with our
reviews.
Regarding impedance curves, I confess that
we had not assumed our readership to be so
ignorant as to confuse electrical impedance at
the terminals with frequency response in the air,
but Mr Shuttleworth's fears may apply in some
cases and we are now adding a warning note to
the curves. Our thanks for this suggestion.
Impedance curves are not, I would suggest,
quite as pointless as Mr Shuttleworth implies.
Modern speakers frequently descend to 3 ohms
or less at some frequencies, and in consequence
more than a few amplifiers are not able to give
of their best. Also, the phase-shifts in consumed
current arising from reactive loads (represented
by steep slopes on the impedance curve) can
sometimes do curious things even with highly
respected amplifiers, a fact discovered to everyone's puzzlement and distress at several audio
exhibitions. Amplifiers are not yet by any
means as perfect as is commonly imaginedunless working into a 10 ohm pure resistance!
Yours faithfully, John Crabbe, Editor, Hi -Fi
News & Record Review, Link House, Dingwall
Avenue, Croydon CR9 2TA.
Loudspeaker impedance
Dear Sir, One point John Shuttleworth failed
to mention in his December article on loudspeaker measurements: Despite the tendency
to regard DIN standards as inadequate, in the
area of speaker impedance tolerances they are
really quite tight. In fact all the speakers
mentioned-Spendor, Rogers and the Quad
ESL-would probably fail to meet it
Yours faithfully, Reginald Williamson, Bay
Cottage, 18 Unthank Road, Norwich NOR
!
Pointless Curves?
Dear Sir, As editor of a `consumer audio
magazine' whose loudspeaker reviewing policy
seems to fit the description offered by John
Shuttleworth in his article Loudspeaker
Measurement Parameters (December), I would
like to comment on his remarks. There are two
separate issues involved: the usefulness or
otherwise of electrical impedance curves, and
the extent to which a measured frequency
response may be misleading.
On the latter, I happen to believe that loudspeaker design at its best has now advanced to
the point where objective measurements of
response can correlate quite well with subjective
assessments of overall tonal balance. The
remaining doubts here concern the variety of
ways in which measurements may be made,
each `legitimate' and with its own rationale,
but all giving different results in terms of
28
28E.
Specifications
Dear Sir, Your December issue Editorial is
concerned with a subject about which I feel
fairly strongly. I am a confirmed supporter of
properly informative and accurate specifications, and a pre- requisite of these is a standardised system of methods of measurement. It is
not generally recognised in this country that
these already exist for audio equipment, at
least for amplifiers, loudspeakers and now
record playing units, as well as radio receivers
and soon radio tuners. I find it very surprising
that, in spite of the work put in by industry,
consultants and the staff of the British Standards Institution, there appears to be a positive
aversion to using these standards, which lay
down methods of measuring and expressing
the result of, among other things, manufacturers specifications. In case anyone should be
motivated to look at them, the reference
numbers are BS3860, BS2489, BS4850 and
BS4054. (Tuners will be included in a supplement to BS4054 to be published probably in
1973.)
It may be objected that these specifications
are not internationally accepted and there is
some truth in this, for, if UK engineers do not
promote their use, who will? There is no such
reticence on the part of our German counterparts. DIN standards themselves are not easy
to use for two reasons. One is that they are
rarely self-contained, making many crossreferences to other DIN standards. For a full
use of the well -known DIN 45.500, for instance,
about 120 other DIN standard documents are
required, excluding test records and tapes, and
some of these documents appear to be permanently in draft form and not generally
available. Also, many are only available in
German and anyone who has seen the mess
even quite a competent non -technical translator
can make of a technical document will understand what that implies. Anyone unconvinced,
who has access to IEC documents, might look
at 29B (Germany) 20. The translation here was
almost certainly under strict technical control
but there are things you can write in German
that are nonsense in English.
It may also be suggested that some of the
BSI standards are out of date. Again, there is
some truth in this and the reason is that the
International Electrotechnical Commission are
gradually publishing two massive Recommendations, Publications 315 (covering all
types of radio receiver) and 268 (sound system
equipment), together with corresponding documents concerning tape and disc players as units
rather than system components. When these
are published in full, or nearly so, the appropriate BSI committees will consider bringing
the corresponding British standards into line
with the IEC recommendations, as is normal
BSI policy.
Regarding `The Ambiguous dBm', the
situation was further changed at the recent
IEC SC29B meeting in Oslo, and the critical
wording in Publication 268.2 is to be changed.
The basic reason for this is that abbreviations
for units are the responsibility of IEC TC25
and it is that committee who cannot accept the
`dBm' abbreviation, quite apart from the
confusion explained so clearly by your distinguished contributors. The chairman of TC25
attended the SC29B meeting and, after much
discussion, the `V7' proposal was not accepted.
The only admissible expression was `dB
(0.775V)'. Those who support the dB(V) as a
preferred reference feel that the very clumsiness
of the expression will cause it to fall into disuse.
Yours faithfully, J. M. Woodgate, 28 Adelaide
Road, Chislehurst, Kent BR7 6BB
Response
by Audio Applications Limited
SMS SERIES MIXERS
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quality mixer, we have included
exceptional monitoring facilities, making this model a
real pleasure to use.
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to tell you all about our various
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Why not 'phone him
?
AUDIO APPLICATIONS LIMITED, Kensington Barracks, Kensington Church Street, London, W.8.
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SIX-CHANNEL STEREO DISCOTHEQUE MIXER
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Console Kits also available (2 or 3 decks)
Hear a demonstration at our showroom or send
for details.
ICElectrics Ltd.,
15 Albert Road,
ALDERSHOT (0252-28513)
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TRADE INQUIRIES WELCOME
STUDIO SOUND, APRIL 1973
2
PATENTS
THE FOLLOWING list of Complete
Specifications Accepted is quoted
December
1303808
1304533
from the December and January issues
of the Official Journal (Patents). Copies
of specifications may be purchased at
25p each from The Patent Office,
Orpington, Kent BR5 3RD.
Plessey Co Ltd
Speech analysers and synthesisers
Zenith Radio Corporation
Chroma amplifier for a colour receiver
1303867
1304554
Matsushita Electric Industrial Co Ltd
System for processing music to produce
a tremulant effect
RCA Corporation
Liquid crystal display device
vibrato signal
13, 1972
1303945
Mattel, Inc
Disc record drive
December
6, 1972
1303021
Sansui Electric Co Ltd
Sound reproduction system
1303036
Akai Electric Co Ltd
Video tape recorders
1303054
Freeman,
R J
and Freeman, H
Information reproducing system
1303119
Sony Corporation
Magnetic recording and reproducing
apparatus
1304030
Libbey- Owens -Ford Co
Antenna type windshields and methods
of producing them
1304050
Philips
Electronic á Associated
Industries Ltd
Circuit arrangement for producing a
marker in a television image
1304061
Hitachi Ltd
Chrominance signal generator having
a patterned filter
1304091
Computer Optics Inc
Display systems
Staar SA
Tape recording
apparatus
1303203
1304104
AKG Akustische
Philips Electronic &
Associated
Industries Ltd
Receiver tuning arrangements
1303181/2/3/4
U Kino -Gerate GmbH
Reverberation system
1303207
Brown Boverì & Co Ltd
Electron tube protection apparatus
1303268
Socias, A
Cassette tape recorders
and /or
playback
AKG Akustische U Kino -Gerate GmbH
Capacitor microphone
1305305
Licentia Patent -Ver- Waltungs -GmbH
Uhf communication systems
1305307
RCA Corporation
Reduction of tape stiction
1304564
S -Atlas -Werke GmbH
1305331
Magnetic tape cassette recorder
Sony Corporation
1304594
Magnetic recording and reproducing
apparatus
Western Electric Co Inc
Acoustic optic devices
1305359
GABR, S Z M
Arrangements for cancelling feedback
1304606
Western Electric Co Inc
Single sideband modulation
digital filters
using
1304613
Kolbe!, G F
System for the presentation of a visual
display with accompanying sound
1304637
Columbia Broadcasting System Inc
Scanning apparatus
1304648
1305456
Heil O
Electroacoustic
transducer
electromagnetic
1305480
Siemens AG
Stearable antenna arrays
December
29, 1972
1305506
Prall Modling Co Inc
Musical instrument
ITT Industries Inc
Differential pressure units
1305622
1304118
AKG Akustische U Kinogerate GmbH
Apparatus for producing artificial
reverberation
1304134
December
Dolby Laboratories Inc
Signal compressors and expanders
20, 1972
1304774
Palmer, W W
Tone control circuits
1305635
Sony Corporation
1304801
Video signal generating apparatus
Tesla Narodni Podnik
Electrostatic spiral transducer
1305683
Standard Telephones & Cables Ltd
Pulse regenerator equalisation
International
Standard
Electric
Corporation
Internal delay stabilisation device for
transponder
1304929
1305735
1304910
Power transmission mechanism
Nippon Electric Co Ltd
Magnetic
recording - reproducing
system
1303423
1304210
International
Corporation
Booth, B H
Aid for the teaching of music
Texas Instruments Inc
Target scanning camera
Meth ,d and apparatus for synthesising
vocal sounds
1305801/2
1303518
1304213
1304988
Sonicaid Ltd
Ultrasonic detection instruments
Handland (Photographic
tation) Ltd, John
High speed cameras
Information storage using a conductor insulator- semiconductor structure
1303277
Bell & Howell Co
1303602
Shackman, A
Loudspeaker assemblies
1303612
Brown Ltd, S G and Ibbotson, T D
Ear defender headsets
1303621
Messerschmitt- Bolkow -Blohm GmbH
Directional wireless systems
1303657
Muirhead Ltd
Facsimile apparatus
1303694
International
Business
Machines
Corporation
Magneto -optic transducing system and
method for reading superimposed
magnetic recordings
instrumen-
a
Siemens AG
Echo compensation circuits
sprocketless
motion picture projector
1304268
Standard Telephones & Cables Ltd
Image display device
1304276
Ricoh KK
Magnetic recording and reproduction
1304288
Farnell -Tandberg Ltd and Dakin A W
Production of sound tracks on cinematographic film
1304363
EMI Ltd
Recording apparatus
1305891
Borg -Warner Corporation
Recording systems
Bolkow, L
System for radio transmission
guidance commands
1305101
Bruce Diamond Corporation
Reproducing stylus
British Aircraft Corporation Ltd
Antennae for transmitting and receiving
radiation
1305148
Magnetic recording and reproducing
apparatus
Amplitude control circuits
1303720
RCA Corporation
Multiple channel display system
International
Standard
Corporation
Convergence circuits
30
Philips Electronic &
Associated
Industries Ltd
Circuit for producing an aperiodic
1306178
1305117
1305234
1304492
Nippon Hoso Kyokai
Converting equipment of standard
television broadcasting signals
Western Electric Co Inc
Visual display apparatus
RCA Corporation
Standard Telephones & Cables Ltd
Television video signal processor
1306194
AKG Akustische
Spring system
U
Kino -Gerate GmbH
1306197
Bell & Howell Co
Electric
Motion picture projector with
cartridge support assembly
film
1306366/7
1305244
Communications Patents Lyf
Wired broadcasting systems
Toho Machine Co Ltd
Mounting of tone arms for record
playing units
Thomson -CSF
Bandwidth compandor system
1305303
of
1306130
1305111
1304383
Electro acoustic transducer
1305819
1305100
Sony Corporation
1303792
Gabr, S Z M
General Electric Co
Post Office
Method and apparatus for detecting a
speech signal in the presence of noise
1303719
1304461
Multitone Electric Co Ltd
Communications systems
Mullard Ltd
Electromagnetic horns
Sony Corporation
Magnetic erasing head
Standard Telephones & Cables Ltd
Gain control circuits
Machines
1305075
1304221
Eastman Kodak Co
Film
snubber for
Business
1306376
32
10.
B EyE FR L7`NAM C
I
M 500 N
Unidirectional Studio Microphone
Dynamic Unidirectional Ribbon Microphone
The M 69 is an unusually sensitive microphone
A ribbon microphone designed for capturing the
full intensity of modern music while suppressing
undesirable side effects such as popping, breath
noise and hissing. Flat frequency response, high
sensitivity and excellent front -to -back ratio are
the distinguishing features of this new BEYER-
It
with outstanding cardioid characteristics.
makes high -quality transcription possible even
under acoustically unfavourable conditions. The
well -balanced response curve of the microphone
maintains the highest fidelity in the reproduction
of speech and music. Version SM with VOICE OFF -MUSIC switch.
DYNAMIC PRODUCT.
Specifications:
Frequency Response: 40-18000 Hz. Output Level at
kHz (0 dbm A 1 mW per 10 !Lbar) 0.13 mV/!Lbar
( -55 dbm). Polar Pattern: Hypercardioid. Output ImpeLoad Impedance: > 10000.
dance: 50052 _: 15 "Í,.
Connectors: 3-pin Tuchel T 3262,1 - 3- 50012.2 ground
2
5000, 3
Tuchel T 3007 spez.,
M 500 N (T)
50 T, 2 3
ground M 500 N (C)
Cannon XLR
50012,
ground. Dimensions: Head diameter 56 mm,
shaft diameter 28 mm, length 180 mm, weight 210 g.
Specifications:
1
Frequency Response: 50 -16000 Hz. Output Level at
kHz: (0 dbm _
mW per 10 ;Lbar) 0.24 mV / :Lbar
( -50 dbm) Polar Pattern: Cardioid Output Impedance:
3 200
200 ohms. Connections: 3 -pin plug T 32621
ohms, 2 ground. Dimensions: 6.7" x 0.9 "0, head 1.7 "0
Also available with Cannon connector XLR -3 -50T
1
1
-3 1
+
-
1
M 160
Dynamic Unidirectional
Studio Purposes
Dynamic Moving Coil Microphone
With hypercardioid characteristics and unusually
high sensitivity. Due to its very good front to
back ratio it is less subject to feedback and provides excellent discrimination against unwanted
sound. It is used by broadcasting and TV-studios,
recording artists, bands and instrumentalists.
Microphone for
principle the highest
possible reproduction quality of music and
speech is guaranteed. Non -linear distortions are
imperceptible.
By using the double ribbon
Specifications:
Specifications:
Frequency Response: 30 -20000 Hz. Output Level at
mW per 10 :Lbar) 0.25 mV rLbar
kHz: (0 dbm
( -50 dbm). Polar Pattern: Hypercardioid. Output Impe3
dance: 200 ohms. Connections 3 -pin plug T3262
200 ohms, 2 ground. Dimensions: 6.5" x 0.9 ", head
1
1
1
:
!
Frequency Response: 40 -18000 Hz. Output Level at
10 !Lbar) 0.1 mVJ!Lbar ( -57
1 mW per
kHz: (0 dbm
dbm). Polar Pattern: Hypercardioid. Output Impedance
200
200 ohms. Connections: 3-pin plug T 3262 1 - 3
ohms, 2 ground. Dimensions: 6" x 0.9`, head 1.5'0.
Also available with Cannon connector XLR- 3 -50T.
1
1.9"0.
Also available with Cannon plug XLR -30 -50 T (M
N
88
(C))
Dynamic Unidirectional Ribbon Microphone
The M 260 is especially suited for speech and
music reproduction. It has excellent transmission qualities. The dampening effect backwards
is almost constant over the whole frequency
range.
Version SM with 3 position Voice -Off -Music
switch.
To: BEYER DYNAMIC (G.B.) LTD.
CLAIR ROAD
HAYWARDS HEATH, SUSSEX
1
Please send me full particulars and illustrated
brochure of BEYER DYNAMIC Products.
Specifications:
Frequency Response: 50 -18000 Hz. Output Level at
mW per 10 :Lbar) 0.09 mV /ubar
kHz: (0 dbm
( -58 dbm). Polar Pattern: Hypercardioid. Output Impedance 200 ohms. Connections: 3-pin plug T 32621 4 3
200 ohms, 2 ground. Dimensions: 6.5" x 0.9', head
1.7 "0. Also available with Cannon connector XLR -3 50T
1
1
NAME
ADDRESS
STUDIO MICROPHONES
STUDIO SOUND, APRIL
1973
31
PATENTS
January
January
4, 1973
10, 1973
Solartron Electronic Group Ltd
Input circuits for electrical instruments
1307531
Forster Elektronik GmbH
Combination of a data processing or
writing head and an endless tape
magazine
Motion picture projectors
1307560
1306584
Vockenhuber, K and Hauser, R
System for reproducing motion pictures
Matsushita Electric Industrial Co Ltd
Apparatus for facsimile using prism shaped fibre optics
1306848
1307566
Sony Corporation
System for producing an electrical output signal in correspondence with a
International Standard Electric Corporation
Decoder for the high colour fidelity
reproduction of a PAL encoded colour
signal
1306898
Porsche KG Dr -Ing HCF
Loudspeaker arrangement in
1307587
Liquid crystal cells
International Business Machines Corporation
Multipletransducing element magnetic
heads
1306999
1307608
Pacific Plantronics Inc
Matsushita Electric Industrial Co Ltd
Multi -track dual gap magnetic head
assembly
a
vehicle
1306912
PPG Industries Inc
Headsets
1309400
Philips Electronic & Associated Industries Ltd
Cassette for a magnetic recording disc
Eastman Kodak Co
magnetic flux generating source
17, 1973
1308056
Bellis, T G
Antifade devices for aerials
1306471
January
1307480
1308079
1308082
International Business Machines Corporation
Method of making a magnetic head
assembly
Licentia Patent-Verwaltungs -GmbH
Reproduction arrangement for reproducing information stored on a disc in
a spiral groove
January
31. 1973
1309489
International Standard Electric Corporation
Snow and ice removal system for an
antenna
1309531
1308158
Bio- Dynamics Inc
Matsushita Electric Industrial Co Ltd
Tape recorders and /or players
Adaptor for use with an audio repro-
1308175
1309570
RCA Corporation
Television camera utilising
encoding filter
a
colour
ducing machine
General Electric Co Ltd
Degradation detection in a pcm system
1309632
1308192
Metro Goldwyn- Mayer-British Studios
Ltd
Mechanisms for transporting cinematograph film
Matsushita Electric Industrial Co Ltd
Tape recorder
1308629
1309818
Soc D'Applications Generales D'Electricite Et De Mecanique
International Standard Electric Corporation
Method of determining the varying
equipment delays for pulse transponder
1307146
Magnetic recording apparatus
1308636
1309951
Staar, SA
1307725
Apparatus for reading magnetic tapes
stored in cassettes
Agence Nationale De Valorisation de
Pasquali, G
Musical sound generating device
La Recherche
1307212
1307761
RCA Corporation
Waveform source
receiver
Ampex Corporation
Verifying the recording of information
on a magnetic recording medium
Electrical filters enabling independent
control of resonance frequency and of
bandpass especially for a speech
International Business Machines Corporation
Time domain equaliser and method of
measuring distortions in a data transmission system
synthesiser
1310036
1308704
LTV Electrosystems Inc
Signal synthesiser
1307059
Bosch Photokino GmbH, Robert
Device for simultaneously winding and
unwinding an endless band
for
television
1307269
Chicago Musical Instrument Co
Electronic musical instruments having
dc keying
1307270
Chicago Musical Instrument Co
Electronic musical instruments having
a unified keying circuit
1307722
1307777
EG & G Inc
Honeywell Ltd
Tape guide arrangements
Method and apparatus for producing
compressed digital representations of
a visible image
1308956
1307821/2
1308974
RCA Corporation
Web cartridge
Instrument Systems Corporation
Electronic voice annunciating device
Higher -fi from telephones
WITH THE current worldwide obsession for
broadcasting telephone calls, basically not a
bad idea but in practice often excruciatingly
boring, the proposals for a higher -fi telephone
transducer to be found in BP 1,293,670 from
Siemens AG have some relevance to the present
pages.
The operating frequency band for telephones
is approximately 100 Hz to 35 kHz. According
to Siemens, most known telephone transducers
(i.e. microphones and speakers) have a drop in
the upper limit of the transmission range. They
say this is usually fairly expensive to correct
but the frequency response can be flattened out
much more cheaply with their own proposals.
Briefly these involve mounting a metallic (e.g.
titanium) diaphragm which has a piezo -ceramic
coating glued to it and connected to an amplifier and diode in the headset itself. The means
of mounting is apparently the novel departure,
this taking the form of a ridged circle of silicone
rubber which grips the diaphragm round its
edge by two annular rings (fig. 1). By reason
of its inherent flexibility, the silicone rubber
allows the diaphragm to vibrate with resonance
peaks which correspond not only to the
fundamental of the diaphragm but also to other
harmonic frequencies. These have vibration
nodal lines in parts of the diaphragm other
32
1310165
Matsushita Electric Industrial Co Ltd
Multi- element magnetic head
than the gripped regions. The parts of the
diaphragm which are separated by the second
harmonic nodal line move in opposite directions
and it is claimed that the resulting resonant
peaks are less pronounced; thus the final
frequency response smoother and the sounds
clearer. The patent specification is itself not
the clearest of documents but presumably
Siemens get reasonable results in practice. One
thought may cross cynical minds. The public
at large are now so used to what a peaky
telephone sounds like that it may well reject an
improvement on the grounds that it sounds as
if there is something wrong with it.
Fluid bearings for tape
IN BP 1,293,205, IBM discuss the use of fluid
bearings between tape and transducer heads.
The usual fluid is, of course, air and the obvious
advantage is reduced wear on the head and the
tape. But, nothing in this world being perfect,
all manner of problems arise -especially in
maintaining the 1:1 ratio of transduced signal
characteristics for forward and backward tape
drive.
Fig. 2 shows a conventional fluid bearing
head. The head 22 has a gap 20 nominally at
the centre of a curved region 14 of a guide
surface 12. The curved region 14 merges into
Sued -Atals -Werke GmbH
Magnetictape recorder having a friction
wheel drive for the spool carrier of the
tape
Elektroakusztikai Gyar
Sound radiator
1310178
Nippon Columbia KK
Tape movement detecting devices for
tape recorders
straight regions 16 and 18 and the wrap angle
produces a separation between the tape and
surface 12 of about 2µm.
But the tape does not follow the ideal path
at 24. Where the wrap angle is about 10° or
less, there is insufficient arc length between the
points 26 and 28 to keep the tape stable and it
often rucks downstream. This rucking results
from non -symmetrical pressure distribution
between the tape and surface 12, a negative
34
FIG.
1
FIG. 2
18
A
'
r
161E
rA1P-
18
-R
J_
81
IB
.
*.
"Kee built -TO
Series
II
STAND ON
ITS
OWN
CNS Unit MAINS POWERED
follow up to our very successful
Cross -talk and Noise Suppression Module
The Series II Free Standing Unit offers all the
Functions of the Module Plus Continuously
As
a
Variable Suppression.
INPUT GAIN
Continuously Variable Rotary Control.
SUPPRESSION
Rotary Control Giving
SUPPRESSION IN 'OUT
Miniature Toggle Switch.
SUPPRESSION INDICATOR
Light Emitting Diode.
POWER
220/240V 50 60 Hz, via Cannon Mains Socket.
AUDIO TERMINATIONS
Jack Sockets, Standard
PRICE
£98.00
£121.00
Un -bal.
a
Range of 4 to
18
dB.
or Cannon Type to order.
Delivery Ex- Stock.
Bal.
/46.:Ce (STANCOIL LTD)., ALEXANDRA ROAD, WINDSOR, ENGLAND
Tel: Windsor 51056.
STUDIO SOUND, APRIL 1973
33
Fluid coupling for tape drives
PATENTS
MI
pressure region arising because the bearing
fluid (air) cannot flow into the space beneath
the tape quickly enough when the tape is
moving at high speed. So the tape gets dragged
down out of its true and ideal line of travel.
What is more, unless the gap 20 is absolutely
exactly half way between the points 26 and 28,
the tape performance will be different for
forward and backward directions of travel.
What IBM propose as a solution is to
provide slots (see figs. 3 and 4) at 44 and 46
upstream and downstream of the gap 20. These
FIG.
(Holdings) Limited in BP
1,294,178 have had claims accepted for the
fairly basic principle of using fluid transmission
between tape deck motors and the take-up and
take -off shafts which they drive. So apparently
the Patent Office Examiners regard the idea as
NORMALAIR- GARRETT
3
new.
Fig. 5 shows take -off spool 10 and take -up
spool 15 with tape 11 passing past heads 12,
and tape pinch drive 13, 14. All this is quite
conventional and driven by a motor 19 via
gear trains 16, 17. But the motor 19 also drives
a gear train 20, 21 to rotate the outer half of a
rotary vane fluid damper 22. This is a conventional fluid transmission with viscous fluid such
as oil, the internal half of the drive being
directly coupled to the take -up spool 1.5. Thus
the take-up drive is from the motor 19 but via
a viscous fluid coupling.
In another design, both the feed and take -up
spools are driven via fluid dampers of this
general type. The theory is that the tape can
never be over tensioned and there seems no
reason why this should not work well. But
surely it has already been tried?
Automatic arpeggios
1,295,994 from the Chicago Musical
Instrument Company takes a great deal of
wading through and for me the going was even
tougher because I fear the end product in terms
of sounds produced by the invention will be
pretty nasty. But duty dictates that I report it.
The patented gadget will make it possible for
musicians to incorporate musical flourishes
into their playing despite the fact that they lack
the technique to do it for themselves.
The instrument may be an organ or electronic
`piano' with a conventional keyboard having a
left-hand portion and a right -hand portion. A
series of tone producing circuits are keyed by
the right -hand keyboard in the usual way but
the organ also has an arpeggio switchrwhich
can feed voltage to a triggerable circuit. The
circuit has an output coupled to an amplifier,
itself coupled to the input of a cascade circuit.
The arpeggio switch also feeds a reset circuit.
The cascade circuit has a series of separate
stages which progressively respond to a
potential increase applied from the circuit
input, each stage being connected to a series
of signal control gates. These control gates are
BP
FIG.
4
,r
Ad
:i-n'
,e--
slots communicate with atmosphere at their
sides and so prevent the possibility of any
negative or positive pressure discrepancies
arising at either side of the gap 20. Doubtless
the exact dimensions of the slots will require
very careful calculation or a great deal of trial
and error experimentation. Will slots which
work for one type of tape work properly for
another?
FIG. 6
arranged in groups of chromatically adjacent
musical notes (e.g. F. F and G; G sharp A and
A sharp etc).
When one of the keys of the left -hand part
of the keyboard is pressed, it will produce a
normal note by conventional means and will
also close a key switch which will apply a
voltage via lines 32 to the emitter of all the
control gates for the same basic material note
(fig. 6). Each of the control gates will so far
block this potential from its collector line 38
to an associated keyer circuit 12 for a relevant
one of the series of tone producing means (fig.
7). This blocking effect can be removed for
any control gate by making its base more
negative than the applied potential on its
emitter. And obviously the gate will conduct
in the manner of a pulse if the voltage applied
to the base is in the form of a pulse. These
pulses are produced by the cascade circuit 24
mentioned above and fed along the lines 28 to
the chromatically associated groups of control
gates 29. So a first pulse passes to the gates 29
associated with the notes F to G; a second
pulse comes along the next line 28 to the gates
associated with the notes G sharp A and Asharp
and so on with the sequence continuing so that
each of the chromatically associated groups of
control gates is successively triggered with time
spaced pulses. It follows that, depending upon
what keys are depressed on the left -hand
portion of the keyboard (i.e. what chord is
being played there), the corresponding tone
producing means will momentarily be energised in sequence to provide an automatic
Adrian Hope
arpeggio.
FIG.
5
FIG.
7
n uro vecrn)
tavo
1G
IJ.
s
A
r
1A
1A
3L
34
Optoelectronic
audio
level
display
RUNE ESPELIEN*
Incremental light- emitting diode
meters offer much more than an
alternative to moving -coil units. In
addition to being resistant to
physical shock, digital displays can
be designed to store the maximum
level reached during an
unmonitored program sequence.
Perhaps more promising, remote
devices may be triggered at any
preselected program threshold.
*Digital Design, Box
1220, 7001 Trondheim. Norway
A PROGRAM LEVEL meter is part of the
monitoring hierarchy around the sound console. It may be classified as an output device
which gives a visual indication of the sound
level. For audio systems in direct connection
with radio transmitters and /or tape recorders,
it is extremely important to know the peak level
in order to avoid over-modulation.
The conventional moving -coil movement or
light-spot galvanometer can be replaced by a
string of light emitting diodes (leds). Red
diffused-lens leds give better readability, less
susceptibility to washout from high ambient
light, and are resistant to mechanical shock.
And, on the human engineering side, the
column of light leads to a faster and easier
reading without eye-strain. Such a display of
instruments may also be equipped with terminals for dimming the display, which leads to
comfortable viewing independent of ambient
light conditions.
Analogue to digital conversion eliminates the
need for logarithmic amplifiers and provides a
high degree of stability and accuracy. Digital
logic circuitry has proved its reliability in
computer circuits during the last decade and is
gaining increasing attention in sound control.
Each ppm consists of three basic parts: an
analogue to digital converter, a display, and a
memory.
The a/d converter receives the analogue voltage (i.e. the sound program level) at the input
of the instrument and converts it to a digital
code proportional to the input level. The
logarithmic characteristic timing network that
determines the integration and fallback is
included in the a/d unit. These parameters can
easily be varied within wide limits to satisfy
different requirements, simply by changing
component values in RC- networks. Fallback
time can even be altered from outside to suit
different situations.
by the operator. Due to the a/d conversion at
the input, logical operations like this can easily
be obtained at negligible extra cost.
Digital logic circuitry has become the most
widely used means of solving data handling
and sequencial control problems. While circuit
costs fall, the variety of available functions
grows. The digital code can be fed to remote
equipment, should a future need for this arise.
Program can be routed in coded form to the
producer, co- engineer, or to wherever this
information is needed. Conversely, digital
information from several ppms can be multiplexed and transmitted bit- serially on a single
line.
The monitor display unit mentioned earlier
displays a column of light but the transmitted
information might equally well be decode'd to
obtain numeric readout of the program level,
then displayed on seven segment readouts.
The design is kept simple and clean but
complex solutions may be realised, to individual
need.
+6
TEST-
Resolution
The resolution of the ppm is given by the
number of bits in the digital code. If the
instrument is to cover a range of 50 dB, which
is good enough for most applications, a six bit
code is required to give 1 dB resolution all over
the scale range. A six bit code can give 28 =64
different binary combinations while a five bit
code can only give 26 =32 combinations, which
is not sufficient to display the level in I dB steps
over a 50 dB measuring range. However, a five
bit code can be used if the operator is content
with 2 dB resolution.
The ppm display unit receives the digital
code from the a/d converter, decodes it and
displays it as a column of light (not, it should
be emphasised, as a moving spot).
The height of the light column corresponds
to the input level, and a thermometer type of
instrument like this is much more comfortable
to read than the wildly twitching pointers and
moving spots of conventional ppms. Even with
a peripheral view, the operator can easily read
the length of the light column. This is important as the operator is usually busy with a vast
number of processing controls.
The memory
12
18
2
dB
30
max
!36
set
This, the third unit of the system, consists
of a few arithmetical elements which operate
on a pure digital basis. The maximum peak
value can be stored until the memory is cleared
STUDIO SOUND, APRIL
1973
35
DIARY
THE NEWS that Bonochord had made an
offer for Neve was released towards the end of
December last year. Neve's press statement
said that they had accepted the offer and that
'the direction and Management of Rupert Neve
and Co would remain unchanged'.
Briefly the terms of the takeover were as
follows: Bonochord would first acquire 51 per
cent of Neve's shares with a payment of
£170,000 plus £4 for every £1 that Neve's profits
went over £100,000 for the 25 month period up
to the end of 1973. This payment would be
limited to £89,760.
The second part of the deal concerned buying
the remaining 49 per cent of the shares.
Bonochord would pay £5 for every £1 of the
average profits of Neve over three successive
years. It would be up to the Neve shareholders
whether that three year period would end on
December 31 of 1975, 76 or 77, but if they
had not decided by 1977 then Bonochord could
acquire the remaining shares after 1977.
Neve's fortunes have improved greatly over
the last couple of years. Up to the end of
November 1971 their profits were only £4,000
but thirteen months later Neve were predicting
that their pre-tax profits for 1972 would be
£20,000 and that in 1973 they would make
£80,000 on sales of about £1,250,000. At the
time of the takeover Neve had outstanding
orders worth about £600,000 and assets of
around £250,000.
I asked Mr Metcalf Collier, secretary of
Neve, why the firm's profits had risen so
sharply. He explained that there had been a
number of production difficulties in the past
which had now been sorted out. I also asked
him if the figures hadn't been made to look a
little better than perhaps they were, to which he
replied that this was certainly not the case.
The history of Neve's new owner has hardly
been that of one success after another. Although
Bonochord made £204,000 in the six months to
the end of June, 1972 -an increase of £79,000
on the corresponding period of 1971 -as little
ago as 1969 Bonochord were in what one
financial journalist described as 'a truly
bombed -out state'.
The firm had been founded as Allen &
Hanbury's (Acoustic Aids) Ltd in May 1939.
The market for their products, hearing aids,
was big enough but they had reckoned without
the Government's making someone else's
hearing aid free on the National Health. The
public, it seemed, needed a hearing aid you had
to pay for like the Czechoslovaks needed
Adolf Hitler.
In 1949 the name of the firm was changed to
Bonochord and the company went public ten
years later. In the decade after that the only
bright spot in Bonochord's fortunes, if you can
call it a bright spot, was the knighthood of
their chairman, Theodore Constantine, in the
1964 New Year Honours list; he had worked as
a constituency chairman for the Conservative
36
By John Dwyer
Party.
Three years later Bonochord contracted a
bad case of diversification to the head and
bought, would you believe, a group of printing
firms. They kept them, I need hardly say, for a
matter of months.
In 1969 Mr Robin Rigby became chairman
and began a ruthless but necessary campaign to
weed out the unprofitable parts of the company,
rationalise (and we all know what that means)
the rest and buy up other, more profitable,
enterprises.
In March 1970 Bonochord bought a firm
called Terminal Insulators Ltd for £115,000.
TI made electrical and electronic components
and plastic mouldings and the Investors
Chronicle of September 4, 1970 said that the
new company would enable Bonochord to
reach new profit levels. In October of the same
year, Bonochord took over Hammant &
Morgan, makers of light electrical control
equipment for the toy industry.
In December Bonochord merged with APT
Electronic Industries, makers of power supplies,
language laboratories and radar equipment.
APT were important to Bonochord because
they had collared a number of Government
contracts for radar equipment. But, although
APT had made £93,000 in 1970, compared with
£71,000 in 1969, the Investors Chronicle
remarked gloomily: 'APT faces poor demand
for electronic equipment and keen competition
for language laboratories'.
During September of 1971 Bonochord
bought Aveley Laboratories, who had exhibited
at Internavex a 'new, improved and more
comprehensive range of language laboratories
of advanced design'.
The £118,420 deal
included a firm of opticians called Boume
Optical -an area that Bonochord were to
develop later on when they bought Thompsons,
a Cardiff opticians' firm, in December of last
year.
But the most important buy of 1971 was the
acquisition of the Austrian firm of Viennatone,
with its subsidiaries, for £348,000. Viennatone
made, sold and exported hearing aids and were
very successful; ever since Bonochord took
them over, in fact, Viennatone seem to have
been propping up Bonochord's less able
subsidiaries.
Terminal Insulators did not run as planned.
In the annual report for 1971 the chairman,
Robin Rigby, was obliged to make the rather
embarrassing announcement that the forecast
had been exceeded in spite of the large loss
made by Terminal Insulators. He went on:
'Because of accounting errors, which led to
erroneous information being supplied, your
board was not aware of the high level of this
loss when the interim results for the half year
ended June 30, 1971 were announced on
October 7, 1971.'
Terminal Insulators had lost more than
£100,000 during 1971 and the losses had
continued through the first half of 1972. The
chairman was careful to point out, however,
that the losses had been `stemmed' and `with
the introduction of new management it is
considered that a return to profitability would
be received on a modest scale in the last quarter
of this year.'
Concerning APT, in the same annual report
the chairman said that it would take too much
valuable cash to put APT's power supply
business right. The power supplies, which had
once been about 80 per cent of APT's business,
had now dwindled to about ten per cent.
Accordingly Bonochord sold the power supply
division of APT to Unitech Ltd for 'between
£200,000 and £250,000'. The remainder of APT
has now become the radar division of
Bonochord and seems to be successful; at the
beginning of February they announced they
had won another contract for three automatic
tracking radars worth £100,000.
Nevertheless, if you read what Mr Rigby had
to say about some of Bonochord's subsidiaries
you realise how lucky Bonochord were to have
bought Viennatone: Hammant and Morgan
were 'a little disappointing'; Path Engineering,
a firm of precision engineers, were 'still by no
means buoyant'; Shepherd Finance Ltd
continued to show improved results' and
Jennings Electronics Industries 'had their loss
reduced'
somehow, and it is to their credit,
Bonochord just aren't in the Slater Walker
...
class.
Some other recent Bonochord takeovers are
worthy of attention. The first of these are the
acquisitions of H & E White and Fairlawn
Finance, whom Bonochord amalgamated to
form what they called 'a flourishing unit'. The
next offer to buy was sent to Livingston Hire,
the studio equipment and measuring instrument
hire firm, to whom they offered £1,400,000. At
the time of the takeover, Livingston, who
operate both here and in West Germany, were
forecasting profits of £167,000 for the year to
April 30, 1973. Cannon Street Investments,
who held just over 50 per cent of the Livingston
shares, agreed to accept the offer.
Livingston were the first Bonochord buy in
what they obviously intended would be a
series of moves into the audio equipment
market. In July the Financial Times predicted
that various factors 'could lead to further
acquisitions before long' and of course they
were right.
The reasons why Neve were so attractive
were that, first of all, they had good sales and
profit figures; secondly, that Bonochord needed
to complement the range of studio equipment
that their Aveley subsidiary are about to
market; and thirdly that Neve had had long
experience of both studio equipment and its
market. For their part, Neve were willing to
succumb to Bonochord mainly because
Bonochord had an established and successful
38
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DIARY
leading Canadian broadcasting company; and
John E. Dallas Ltd. Shareholders not on the
board include Colin Kelsey, Norman Strauss
and John Maddox.
European sales organisation- something Neve
When the names were announced, Michael
wanted badly.
Levete said that he thought the news station
There is one other interesting facet to the
would cost about £1,000,000 to set up and
takeover. As is well known, Neve are assowould lose money during the first two years.
ciated with Christian missionary work, though
Listeners would be ten minutes from a news
nobody is quite sure how. By a coincidence,
bulletin during peak listening times and never
Mr D. C. Rennie, CEng, FIEE, joint managing more than 20 minutes from one at any other
director of Bonochord, is also a director of
time.
Billy Graham Evangelistic Alliance Ltd.
It is believed that the cost to LBC of renting
The IBA have announced, rather before
the transmitter from the IBA will be £180,000
anyone thought they would, the names of the
in the first year rising to £230,000 in the third
two London commercial radio contractors; in
and final year of the contract. The correspondJanuary the IBA had said the names of the
ing figures for the General station could be as
lucky winners would be announced at the end
high as £315,000 and £380,000.
of March, but the announcement came at the
Next the IBA will allocate the contract for
beginning of February.
the Birmingham station to one of the four
The General station has been won by
groups who have applied. By far the biggest of
Capital Radio, a consortium chaired by these four are Birmingham Broadcasting. The
Richard Attenborough and comprising Bryan
IBA have made it quite clear that you won't
Forbes; Michael Flint, the former head of
get any contract if you don't have any loot.
Paramount Pictures UK; David Jacobs; Air Birmingham Broadcasting have not only the
studios' George Martin; Alan Bartlett (of loot but the backing of some of Birmingham's
Bristol Industrial Securities); Robert Stiby;
most prestigious citizens-not that that will
William Beets, Graham Binns; Ronald Denny;
have any bearing on the prestige or otherwise
John Littlejohns; and the man who started the
of the programs they would produce.
company, Weybridge dentist Barclay BarclayMarquee. The studio reopened at the
White. Apart from individuals, the group also
beginning of January after closing to have a
includes Rediffusion, the Observer newspaper
new MCI 24 track desk installed. Marquee say
and Local News of London, a newspaper
it is the first 24 track in the country. The
consortium comprising 22 local newspaper
acoustics in the control room were designed by
groups.
Ken Shearer.
The consortium which will run the News
Dave Kent -Watson of Indigo tells me that
station is London Broadcasting, headed by they have been very heavily booked lately and
Sir Charles Trinder, a former Lord Mayor of
have had some enquiries for eight track recorLondon. This is the consortium to which IBC
ding. As a result, they have now bought an
studios belong.
George Clouston, IBC's
eight track Ampex MM//00 machine which
manager, will be on the board in charge of Dave tells me were delivered in late February.
production. Another member of the consortium
'Rates for eight track recording will be very
is Sir Gordon Newton, former editor of the
competitive at £16 an hour,' he said. 'ReducFinancial Times and newly appointed chairman
tion to stereo will be £12 an hour.' Indigo's
of Vavasseur, the firm that have made a takeother rates are £12 for four track, £8 for two
over bid for John Bentley's Barclay Securities.
track and £6 an hour for mono.
Sir Gordon will be chairman of the editorial
Other big news from Indigo is that they have
committee.
signed a publishing deal with De Wolfe
The other members of the board are Michael
Publications in London.
Levete, who will be managing director,
Air. As just about everybody knows, Roxy
Canadian broadcaster Kenneth Baker (market- Music have visited AIR to produce and record
ing), Roland Freeman (local government),
a new album; Rick Wolf was produced by
Alfred Geiringer (wire services), Adrian Ball
Roger Cook; Fleetwood Mac did mixing and
(networking), Mollie Lee (women's affairs),
overdubbing; John Williams produced by
Brenda Maddox (Education), and Michael
George Martin, as was the Huggett Family;
Rapinet (company secretary).
Casuals, Shoot, Gary Moore Band, Mott the
The London Broadcasting Company was
Hoople, Wishbone Ash, Terry Stamp all did
started by Roland Freeman, once a chairman
sessions; Brenda Arnau mixed some tracks;
of the GLC's finance committee and now head
Kings Singers did a mobile in Church; proviof a firm of public relations consultants. He
sional bookings include ELO and Roy Wood's
met Michael Levete, an executive of the
Wizzard and demos are being recorded for the
Charterhouse banking group, while engaged on
new James Bond film 'Live and Let Die', for
a London building project. By the time LBC
which George Martin has composed the
makes its first broadcast Mr Levete will have
music.
resigned as chief marketing executive of
On the staff side, Geoff Emerick, who left
Charterhouse, who have a large shareholding Apple at the beginning of February, has joined
in LBC.
AIR after taking a short holiday. For those
One member of the LBC board has already
who haven't heard of Geoff Emerick-and it
resigned: Norris McWhirter, brother of Ross
seems there are one or two within mic range of
'Oh- What -A- Lovely -Warhol' McWhirter.
I
the APRS -he engineered Sergeant Pepper and
understand that Norris resigned just after the
his work on it won the first Grammy for a
Warhol fiasco `to avoid embarrassment to the
British pop ]p. Later, he and Phil McDonald
company. There was no pressure from us
of Apple won a Grammy each for Abbey Road,
w hatever'.
an album which EMI say has sold more copies
Other members of the LBC consortium are
than any other Beatles album
the last
Universal News Services, Selkirk Holdings, a
count the score was 7,600,000 copies worldwide.
-at
38
Malcolm Davies has now taken over as
studio manager of Apple.
I wish him even
more luck than Geoff Emerick.
Sound Developments. Sessions on Horlicks
commercials for J Walter Thompson and
Carling Black Label for McCann Erickson;
Sound Developments also did WEA Records'
presentation for the Midem festival at Cannes.
Other sessions have included Party Pops album
of instrumental hits, produced by Bruce Baxter
for Pickwick; Ernie Entwhistle and Carl
Simmons, whom Adrian Sear describes as a
`Jerry Lee Lewis type rock and roller', were
both produced by Hal Carter's company Dash
productions. All the above were engineered by
Adrian, as were some sound effects for Peter
Sinfield, producer for Roxy Music now doing
his own album at Command.
Impulse. This studio, way up on Tyneside,
went four track about two years ago and they
tell me that since they added a four track
Ampex to the set -up studio time has more than
doubled. Because of this they were able to
start alterations for a second, eight track
studio in September of last year. The new suite
will be ready by about April 23, after which the
original studio will be converted into a dj
studio, ready by May or June. Impulse started
about six years ago and played, I am told, a
large part in the success of the Lindisfarne folk
group. They still retain a heavy interest in the
group's publishing business. Recent Impulse
releases include a Derek Brimstone album for
Rubber Records, and an 1p called Geordierama,
for MWM Records. They also did incidental
music for Tyneside Theatre Productions' Peer
Gynt, which was played by part of the Northern
Sinfonia. At the moment they are busy recording an 1p by Hedgehog Pie.
Roger Squire. A film unit making a documentary about Radio One for Anglo EMI have
spent a whole day at Squire. The result of
their visit will be used to show the kind of setup a dj uses to prerecord his material.
Advision. Gary Martin engineered an album
for Stomu Yamash'ta. Stomu is regarded as
one of the world's leading percussionists and
writes for, produces for, and directs his own
theatre-the Red Buddha. He opened at the
Roundhouse on January 29 and finished on
March 3.
More recently, Darien Spirit have been
recording their first as yet un -named album
under the production of Steve Rowlands. The
group are Scottish and include two former
members of the Bonzo Dog Band. Martin
Rushent engineered the album, which will be
released on Charisma. Steve and Martin also
co- operated on a Philips album and single by
Rosetta High Tower, ex lead singer with the
Orlons. The single will be One More Heartache
with the Bee Gees number The Walls Fell Down
on the flip side.
Finally, I went to a press do given by Zoom
Television not long ago and I will be reporting
on them next month. Also in next month's
`Diary' will be a report on SB Independent
Radio. I've had a number of complaints that I
tend to cover the same old studios month after
month. I accept this criticism but if `Diary' is
to be compiled within the time allotted there
are only so many new studios I can visit; others
send me the information regularly and if I can I
repay this courtesy by giving them some space.
So it's up to you.
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ASSOCIATION OF PROFESSIONAL
RECORDING STUDIOS
Durante il recente incontro del corpo dirigente, é stato
deliberato che la Associazione sarà lieta di porgere il suo
benvenuto alle richieste di affiliazione da parte dei loro
amici europei.
Per addizionale imformzione contatto:
23
E. L. Masek, Secretary,
Chestnut Avenue, Chorleywood,
Herts, WD3 4HA, England
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01
-648 5106
STUDIO SOUND, APRIL
1973
39
VIDEO
By Roderick Snell
MULLARD XQ1402
FIG.1
LOW LIGHT TUBE
°
REGULAR VIEWERS of `Tomorrow's World
will be aware that cameras (sophisticated of
course) can now be made so sensitive that one
can televise scenes too dark for the eye. Readers
of the technical press might in turn believe that
flat solid -state image sensors the size and
thickness of a postage stamp are just round the
corner. Still the majority of closed-circuit
television pictures remain at best obviously
`non -broadcast' and at worst scarcely viewable.
Whether it is simple monitoring for security in
a shop, safety in a London Underground
station, or seeback in a recording studio, the
most common problem seems to be lack of
light. Most cctv users accept this as an unavoidable weakness of the camera and, if they have
the money, invest in high power lighting grids,
portable `spots', and so on.
Aside from increasing the light level (or
making better use of available light), there are
at least three other worthwhile approaches:
increasing the lens diameter, improving the
camera, and improving the pickup tube.
A wide aperture lens certainly accepts more
light but one is then left with an uncomfortably
shallow field of focus. Decreasing the focal
length (i.e. increasing the acceptance angle) is
often worthwhile; the 25 mm focal length of the
normal fixed lens can be reduced by a factor of
two and costs between £40 and £100. This wide
angle is suitable for many applications and
gives two stops improvement in sensitivity for
the same depth of focus.
There are quite large differences between
cameras of the same price range. Once bought,
there is usually little one can do other than
make sure the vidicon beam and target adjustments are optimised for the light level being
used. But, given an initial choice, testing
prospective purchases at low light levels is
worth the trouble. Testing two British-made
cameras recently, the cheaper of the two had
more than one stop of usable pictures at low
light levels. Both cameras used the same
separate mesh 25 mm vidicon tube but it was
significant that the more sensitive of the two
used a field effect transistor in the head amplifier
and worked the tube in the `high field' mode,
which is to say the maximum allowable mesh
voltage was applied to the tube. This costs
more to engineer because higher powers are
then needed to drive the scan coils.
If none of the above has given the required
sensitivity, one of the new generation of silicon
target camera tubes is worth considering.
First developed by Bell Telephone Laboratories
for their Picturephone project, these tubes use a
mosaic of over 500,000 silicon diodes in place
of the semiconducting antimony trisulphide
40
TYPICAL
F G.
I
CENTIMONY- TRISOLPHIDE VIDICON
100
`,1'
i
SPECTRAL RESPONSE
102
102
10
BO
°
60
:
a
2 MULLARD XQ1400
103
Lo
20
0
Loo
1
600
600
1000
1200
WAVELENGTH Inm1
FIG.
10
L00
600
600
WAVELENGTH
1000
1200
/1m)
3
layer of the normal vidicon target. Bells'
Picturephone requirements were long life, high
sensitivity and extreme ruggedness. Any tube
that could be damaged by direct sunlight or
focused spotlamps, like the normal vidicon,
would not do but the resolution and blemishes
could be worse than those in normal cctv. The
last three years have seen much work in this
field and silicon target tubes are currently
available in the UK from English Electric,
Mullard, Thompson CSF, RCA and Texas
Instruments. The 25 mm tubes from these
manufacturers are direct mechanical replacements for antimony trisulphide vidicons and
will work in many cctv cameras with a few
electrical changes. Industrial grades of tube
cost upwards of £170 which, although roughly
six times the cost of equivalent antimony
vidicons, may save so many lighting and lens
problems that they become the easiest and most
economical way of doing the job.
The Mullard XQ1402 was chosen for the
review because, unlike some other silicon
42
II
i
I
I
---
1
1
41INwit,
To Dixons Technical Ltd.,
:
Soho Square, London, W.1.
3
`
Please send me full details of your range
of audio -visual equipment by return of post
Name
Address
Dixons
Technical
Ltd
io SQUARE
40.?
f
Cm" --
SHORT CUT
TO SOHO SQUARE.
At Dixons Technical we have the widest
range of audio -visual equipment available in
Britain. And the expertise to match.
Which is great if you happen to be near
Soho Square.
But if you live out of town, why should you
have to travel perhaps hundreds of miles, just to
see us
?
Well, quite simply, you don't!
At Dixons Technical well see to it that
wherever you live, the equipment you require
reaches you quickly and safely. We'll give you
all the expert advice and
assistance you may require.
We'll even make arrangements
for it to be
installed.
You'll find that we have all the famous
brand names; and they're yours at the most
competitive prices imaginable.
Should you not wish to touch much needed
capital, we'll arrange a hire purchase agreement
to suit your pocket. You can lease, or if you only
require a piece of equipment for a short while
we'll rent it to you.
And wherever you are in Britain, the Dixons
Technical after -sales service is ready to carry
out any necessary servicing or repairs with
speed and efficiency.
So take the short cut to Dixons Technical,
We're just a snip away.
-
IN VIDEO
target tubes, it was capable of working at the
high voltages used in the Link 101 camera
without damage through self-induced X -rays.
Although not the cheapest, it also had better
resolution than some of its competitors and the
prospect of a long working life.
Two Link 101 cameras were set up, one with
a conventional separate mesh vidicon, the other
with an Industrial grade XQ1400. The high
impedance target bias was immobilised so that
the automatic sensitivity facility was lost; like
the lead -oxide photoconductive tube, this form
of AGC cannot be used on a silicon target type.
Making minor adjustments to match Mullards'
specified working voltages exactly gave no
improvement over Link Electronics' factory
settings for normal tubes so the original settings
were left. The silicon tube's resolution was at
first slightly worse, but the pictures were so
exceptionally noise -free that increasing the hf
response until the resolution was as good still
gave the most grain -free pictures we have seen
from this camera. Although only about five
times more sensitive to green light, in our
tungsten -lit laboratory the silicon tube appeared
over 50 times more sensitive: the reason for
this can be deduced from the spectral response
curves of figs. 1 and 2. The vidicon is panchromatic, with its sensitivity, of about 100 nA /uW
centred at a wavelength of about 550 nm,
which matches the response of the human eye.
On the other hand, the silicon tubes response,
with its greater sensitivity to infra-red, more
nearly matches the spectrum of incandescent
lamps and it is with these that the gain is so
worthwhile. This spectral response can sometimes produce peculiar visual effects, especially
outdoors in sunlight when the relative brightness of different objects is altered by their
infra -red reflectivity. Even indoors, a man
wearing a dark red shirt and blue tie may appear
from the screen to have a light grey shirt and
black tie! However, indoor shots at light
levels considered comfortable for office or a
sound studio give very good noise free and
lag -free pictures if lit with tungsten lamps.
Also the unity gamma characteristic gives an
appearance of high -key lighting which is most
effective for monochrome work.
The two Link cameras were pointed at the
'scene' of figs. 3 and 4, which was lit with a
normal 40W bulb in an Anglepoise lamp.
Directing the lamp away from the scene
reduced the light level until the normal vidicon
picture could no longer be considered usable
(fig. 3). The light level was below the reliable
range of our meter, but was in the region of
1 Lm /m2.
At this level, the silicon target tube
was overloading so the lens aperture was
reduced by four stops (ie 1/16 of the light) to
give fig. 4. To give an idea of the difference in
lag between the two tubes, the white square
visible above the glass egg was attached to a
steel piano wire spring and made to bob up and
down. As most cctv cameras (including the
101 Links used in our tests) get their auto sensitivity feature by biasing the target through
a resistor of 1000M /ohms or more, this system
cannot be used with silicon tube so an iris
control, neutral density filters, or some video
agc system must be used. We found that two
neutral density filters plus the normal lens iris
42
adjustment was sufficient wherever the changes
in illumination were not too great.
Conclusions
Where a few stops more sensitivity are
needed, particularly in tungsten light, silicon
diode tubes are worth investigating. They can
usually be fitted to existing cameras with very
little modification and, providing the light
level changes are not too wide, are satisfactory
with the lens iris adjustment of sensitivity. The
higher initial cost of the tube is partially offset
by its long life expectancy and immunity from
damage by over illumination. The Mullard
XQ1400 tested here would not take long to fit
to most cctv cameras and gives comparable
resolution to a normal separate mesh vidicon
tube but with greatly increased sensitivity and
reduced lag.
Where greater sensitivity is required, both
types of tube are available with image inten-
FIG.
sifiers which amplify an 'electronic image' of
the scene, giving an increase in optical sensitivity of between 50 and 100,000 times.
Although mechanically compatible as far as
scan and focus coils are concerned, the intensifier section itself increases the length of the tube
so either a mechanical change or a new camera
An additional eht supply of
is required.
several kilo volts is also needed, which is
available in the form of a potted transistor
invertor of only a few cubic centimetres volume.
But this supply gives a convenient form of
gain control, lacking in the straight silicon
diode tube. Intensifier tube cameras cost more
and should be given careful consideration so a
list of manufacturers together with some
further reading is given below.
Manufacturers of low light television cameras
Pye Business Communications.
Link Electronics.
J. D. Jackson Electronics.
Studio
99
Video.
Further reading
English Electric Valve Co: 'Silicon diode tubes' and 'Low
light television tubes' (reprints).
J. D. Jackson Electronics: 'Low light television' (reprints
from US journals).
Studio 99 Video: 'Development and use of
tube and camera' (factsheet no. 2).
a
4
silicon target
Be Ready for
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On EMI cassettes & reels direct from manufacturer learn
FRENCH SPANISH GERMAN ITALIAN
...its so simple, just slip cassette into machine, or reel
onto recorder. Each pre- recorded language course
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Why pay
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ONE COMPLETE COURSE OF
01 ALL FOUR
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£5.50
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MANUFACTURED
UNDER CONTRACT
BY
EMI
The complete IVC range is available from Action Video.
LOW NOISE
5 SCREW TYPE
CASSETTES
with index cards at less than half list branded prices all in plastic
presentation cases.
C60 32p, 10
for £3;
C90 45p 10
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HEAD CLEANERS 30p; C12058p,
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CASES 10p. P`P 20p
CHEAPER GRADES OF CASSETTES
BY AUDIO CERTRON & OTHERS
5
SCREW TYPE INDEX CARDS AND CASES.
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£4.25. P/P 20p
INDEX CARDS 3p PER DOZEN
C60 25p, 10
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Long Play
WALKERS ( S
35p
40p
48p
)
16 Woodthorpe Road,
The IVC range available from Action Video includes a machine
for every application. The 700 Series features models with
monochrome and /or colour playback and recording, with one
or two audio channels and assembly edit ; the 800 Series
includesunitscapableofsirnultaneousrecording and reproduction
and complete insert and assembly editing ; the IVC -900 Series 1"
helical scan recorders match broadcast standards. Soon to be
introduced is the IVC 100 series video cassette recorder which
combines full IVC interchangeability and professional quality
with the convenience of cassette tape packaging. And there is a
comprehensive range of IVC cameras and ancillary equipment.
:
J
Double Play
1200'
900'
42p
1800'
55p
1200'
2400'
70p
1800'
EMPTY SPOOLS 5" 10p, 51 11p, 7" 12p. P/P 20p.
600'
900'
1200'
Realising the vastly different applications of VTR's, and,
unlike some manufacturers, not wishing to introduce new
equipment with conflicting standards, IVC have developed an
integrated range of units for all purposes, all employing an
identical format. Every machine in the IVC family -from the
lowest priced playback unit to the broadcast specification
IVC -900 series -uses the same modulation standard. Tapes
recorded on one IVC machine can be played on any other
IVC machine.
a professional standard of service to match their
equipment, it is IVC policy to supply only through the following
accredited regional dealers
SUPERB
QUALITY
LEADERS & BOXED
POLYBASED.
ESTER PVC & MYLAR
MANUFACTURED BY LEADING
ELECTRONICS FIRMS
Why not try one and cut your recording costs?
Standard Play
the world.
To ensure
RECORDING TAPES
WITH
IVC are fast becoming accepted by professional and scientific
users as the finest 1" helical scan video tape recorders in
Cameron Limited
Giffnock, Glasgow.
E.O.S. Industrial Electronics
Llantrisant, Glamorgan.
Hudson & Carter Limited
Chilwell, Notts.
C. W.
Moland Limited
Murray Swanson & Co. Ltd.
Newcastle- upon -Tyne.
Holliday Brothers
Cheshire.
Bell and Howell A -V Ltd., Wembley
ACTION VIDEO LTD
60p
80p
98p
Ashford, Mdx. 52136
T.
Plymouth.
45 Great Marlborough St.,London W.1.
Telephone:01.734 7465/6/7
PRODUCTIONS
SALES
SERVICE
HIRE
STUDIO SOUND, APRIL 1973
43
Sound '73:
ó pé197
the1973
Association
of Public
Address
Engineers
Exnibition
FROM MARCH 13 through 15, the Bloomsbury Centre Hotel will be graced with the
presence of Sound '73 -an exhibition of sound
reinforcement equipment organised by the
Association of Public Address Engineers. The
hotel is situated in Coram Street, Russell
Square, London WC1 and exhibition opening
times are 10.00 to 18.00 closing one hour early
on the final day. Tickets are available free of
charge from the APAE Secretariat, 6 Conduit
Street, London W1R 9TG (phone: 493 5256).
A program of lectures and demonstrations
has been prepared starting on Tuesday March
13 at 14.30 with a talk on `Microphones'. This
is followed at the same time Wednesday by
`Compressors and limiters' while `Industrial
design of public address equipment' commences
at 10.30 Thursday.
A new preamplifier for the C451 fet capacitor
microphone will be seen on the AKG stand. A
three -position switch gives flat response, 75 Hz
bass roll-off, or 150 Hz bass roll-off, allowing
the microphone to be optimised for boom or
hand -held operation. Model C414 is a new
capacitor capsule incorporating a pattern
selector for cardioid, omni, figure-of-eight or
hypercardioid pickup. While this is intended
for recording studios, the D1200 and new D2000
are described as ideal for speech reinforcement.
The D2000 is directional and incorporates a
combined pattern selector and on/off switch.
Made in Britain for AKG, the LM300 microphone is designed for low budget discotheque
systems.
Exhibits on the Audix stand will include
modular power amplifiers (rated at 15, 30, 60,
120 and 200W rms continuous), limiters,
equalisers, noise sensors and loudspeakers.
These can be supplied to meet the needs of
recording, broadcasting or theatre studios. A
standard Audix audio control console is
illustrated below. Equipment similar to that
recently supplied for ITN outside broadcast
vehicles will be shown.
Among new additions to the Beyer range of
Audix audio control console
44
microphones, headphones and accessories, the
M201 dynamic microphone, ST230 floor stand
and MTF 222181 microphone base plate. The
M201 is a hypercardioid microphone designed
to look into lk ohms and measuring 155 mm by
24 mm diameter. ST230 is defined as an
`extremely portable' low price lightweight
floor stand with provision for mounting two
microphone holders without an additional
clamp. Beyer Electronics are Southern and
Scottish distributors for Calrec Audio and will
also display the Calrec range of capacitor
microphones and audio mixers.
Following confusion with the Japanese
`Crown', their American namesake have
adopted a new label: Amcron. McInnes
Laboratories will display the full range of
Amcron power amplifiers on stand 38. The
DC300 is being replaced by a DC300A operating into loads down to 1 ohm. Up to 500W rms
per channel is the specified output power;
distortion is described as greatly reduced.
Recently appointed agents for Dbx, Macinnes
will exhibit examples of their noise reduction
units including the 117 which is considered to
have background music applications. It cuts
out the music?
Mains and battery powered mixers and
amplifiers are to be exhibited by CTH Electronics. Introduced last year, the MA30 amplifier
will again be displayed together with a range of
transformers, cable drums and other public
address accessories.
Eagle are adding a sound level meter to
their wide range of audio products -the Pro
TIM. This covers 36 to 130 dBA in seven steps.
The Pro A35, A65, and A120 amplifier series
will be on display and are claimed to be a new
concept in public address equipment. Features
include slider controls with preset markers,
priority page relay and resettable safety
circuits. Respective output powers are 35, 65
and 120W rms. New Eagle electret microphones will include the Pro M5 tie-clip and
Pro M25 boom arm.
Recently developed Electro -Voice electret
microphones will be seen on the Gulton stand
together with a wide selection of loudspeakers.
The latter will comprise the SP12, SPI2B,
12TRXB and 12TRX, 30W, Musicaster 1A and
Eliminator 1.
Several newly developed items from G. H.
Garland. GM3200 is a battery /mains amplifier
module with automatic switching from mains
to a 24V dc auxiliary supply in the event of
power failure. The unit is also suitable for
powering mains equipment in the field and is
available with (optional) internal trickle
charging. GM22, a portable mono or stereo
discotheque system, incorporates two Garrard
SP25 Mkt turntables, bass, treble and gain
controls, microphone and a headphone
monitor amplifier. It is designed to feed two
free standing 100W amplifier modules and
comes complete with matching 100W loudspeaker units. Matching horn units are also
available to improve the hf response. Other
items to be exhibited by Garland include a
range of remote gain controls and a family of
loudspeaker units for 100V sound distribution
systems.
A new series of public address amplifiers in
the Toa range will be shown by the local agents
of this Japanese company, Goldring Ltd. The
900 series can be fitted with a variety of inter 46
CALREC
INlJST1líL
AIIHDSIDIS
all part of the PSP
CALREC HAVE MOVED!
Service
Calrec Audio Ltd., are pleased to
announce their move to larger and
better premises. Full details of our
complete range of microphones and
mixers are now available from the new
address :
Calrec Audio Ltd.,
Hangingroyd Lane,
Hebden Bridge, HX7 7DD
Tel. Hebden Bridge 2159
You probably know us for our technical know -how
and specialist distribution service.
But this month we're featuring something rather
unusual.
These spray -on aids include lubricants such as
MS4 grease, degreasing and cleaning solvents,
anti -static /anti- tracking sprays and a freezing
agent for the quick tracing of faults.
WOW and FLUTYEN METERS
ME 105
The latest is an electronic protective lacquer
with a very wide range of applications.
The demand was such that it had to be created
and produced at very short notice.
They're all described in our Catalogue No. P 16.
Why not send for your copy now?
And don't forget our vast stock of other products
audio, circular, rectangular panel /rack,
printed circuit and co -axial connectors .... all
kinds of test components .... cables to
-
European and USA standards .... et cetera.
is the ME 105, the very latest type of Wow
Flutter Meters manufactured by Woelke Magnet bandtechnik, Munich, Germany, and distributed
exclusively by us in the U.K. Anyone concerned with
the most accurate measurement of drift (down to
plus/minus 0.1 %) and wow and flutter (down to plus¡
minus 0.03 %) will be interested in the ME 105,
available from April onwards. Fuller, final details on
Illustrated
and
ITT Cannon Authorised Distributors
228 PRESTON ROAD, WEMBLEY,
MIDDLESEX HA9 8PB
Telephone: 01 -904 9521 (5 lines)
Cables: PSPEL Wembley
application.
LENNARD DEVELOPMENTS LTD.
206
CHASE SIDE, ENFIELD, EN2 OQX
MIDDX.
Tel.
01
-363 8238
PSP
ELECTRONICS LTD
STUDIO SOUND, APRIL
1973
45
SOUND
'73
PREVIEW
changeable octal -based plug-in modules to
match any likely source. The BS -367 loudspeaker is also being introduced and takes a
spherical form suitable for ceiling suspension.
Two eight track cartridge background music
machines, one for rack mounting, the other
complete with power amplifier, are to be
demonstrated. Goldring will be found on
stands 41 and 42.
Prolific seems the word for Millbank Electronics who plan to announce over 40 completely new products at Sound '73. These will
include a new family of integrated and power
amplifiers forsound reinforcement applications.
Cannon, DIN and CSA connections will be
offered, all models conforming fully to European electrical standards. Another amplifier
series has been designed for recording studios
while yet another is being aimed at single
applications such as paging and fire alarms.
An eight track continuous playing cartridge
machine is to be marketed as a background
music source. This will be available in single
and double transport forms.
Two electret microphones from Sennheiser
should attract interest on the Hayden Laboratories stand. Since no high voltage polarisation
is needed, the entire microphone electronics are
incorporated in the unit head. MKE201 is an
omnidirectional model priced £28.50 while
MKE401 is a £33.25 supercardioid. Hayden
recently obtained the agency for Isonetta
loudspeakers including a miniature spherical
SNS Chorale mixer/
amplifier and Strauss
loudspeakers
model of some 87 mm diameter -comparable
with a tennis ball. These might have applications in tetraphonic audio though no further
data is available beyond a price tag of £9.50.
SNS Communications are to display their
PA12/40 six input four output mixer/amplifier.
Two low impedance microphone inputs are
incorporated in addition to an input switchable
between microphones, grams or tape. Separate
gain controls are fitted to the three main
channels with master bass and treble tone
controls giving 15 dB cut of boost. Also on
show will be the Strauss range of public
address loudspeakers. Models from this range
are illustrated below together with the Chorale
entertainment mixer/amplifier.
The latter
features six inputs with individual slide faders.
Each input channel has bass, treble and
reverberation controls. Price is from £455.
Illustrated above, a largely self -contained
public address system to be shown by Trusound
Manufacturing. Model TPA20 operates from
either mains or internal batteries and has inputs
for 30/50 ohms (100 uV for full output) or 500
mV at 250k ohms microphone. Output power
is specified as 10W rms with an additional 10W
rms available from an extension loudspeaker
feed. Retail price is £85.67.
PSP Electronics, based in Wembley, plan to
show a comprehensive range of connectors and
accessories including Cannon XLR and -perhaps better known in the air than on the
ground -Hellerman-Deutsch. Also a new
range of aerosol packed cleaning and lubricating products.
On the Celestion stand, speakers from the
Ditton range, of which the largest is the 66
Studio Monitor. Frequency response is described as `substantially level' from 25 Hz to
30 kHz, power capacity being 80W into 8 ohms.
From Chymes Audio, a claimed `first': their
£117 audio mixer with integrated lighting drive
unit. Chymes recently supplied a quadraphonic
discotheque system to the Sindlesham Mill
country club, Berkshire, and examples of their
dj console systems will be on display. Power
amplifiers are available from £79 (2 x 100W)
and £147 (2 x 200W). These, Chymes consider,
offer the best performance /price ratio at the
high quality end of the discotheque market.
Among microphones and accessories on the
Keith Monks stand, a wide selection of floor
and table stands including the MSPA /B
floor and versatile SC/1 side clamp.
Last but not least, the staff of STUDIO
SourID will exhibit themselves on stand 43.
David Kirk will attend Tuesday, John Dwyer
Wednesday and Thursday.
AKG EQUIPMENT LTD, Eardley House,
182
Campden Hill Road, London W8
Phone
229 3695
:
Representative:
Stand: 11
P. J. Eardley
ASTRONIC LTD, Dalston Gardens, Stanmore,
Middlesex, HA7 1BL
Phone: 2042125
Representative:
Stand: 15
G. H. Gray
AUDAC MARKETING LTD, Trinity
Trinity Lane, Wareham, Dorset
Phone : 092 95 2977
Representative: W. E. Armstead
Stand: 12
Works,
AUDIX BB LTD, Bentfield End, Stansted, Essex
Phone: 027 971 3132
Representative: C. J. Billet
Stand: 26
BEYER DYNAMIC (GB) LTD,
Haywards Heath, Sussex
Phone : 0444 51004
Representative: S. Duer
Stand:
1
Clair Road
16
CANADIAN INSTRUMENTS AND ELECTRONICS LTD, 35 Waverley Street, Nottingham
NG7 4EB
Phone: 0602 71157
Representative: F.
Stand:9
K.
Watts
CTH ELECTRONICS, Somersham Road,
Industrial Estate, St Ives, Hunts, PE17 4LS
Phone 04806 4388
:
Representative:
Stand: 4
C. T. Heinlein
CHYMES ORGANISATION LTD,
Road, Wokingham, RG11 1BR
Phone
:
320 Barkham
0734 1970
Representative:
Stand: 31
C. Smith
S. B. DAVENPORT LTD, 113 Graham Road,
Wimbledon, London SW19
Phone
:
540 2266
Representative:
Stand :6
G. W.
Aggett
EAGLE INTERNATIONAL, Precision Centre,
Heather Park Drive, Wembley, Middlesex, HAO 1SU
Phone: 9030144
Representative: W. J. Morrow
Stand: 35
48
46
A SELECTION
FROM OUR
WIDE RANGE
OF MICROPHONE STANDS, SEE THESE AND
1973 A.P.R.S. EXHIBITION, SONEX 73, AND HANOVER FAIR
OTHERS AT THE
Banqueting Stand. 421b base. Matt
black finish. 20in max height. Stem may be
fixed upright or angled.
BSI /B
BS2/B Banqueting Stand. 71b base. Matt bla -k
finish. 29in max height. Stem may be fixed
upright or angled
MSPA /B Angle Floor Stand. Matt black finish.
80in max height.
SB /I
long.
SB'I
Stereo Bar. Matt black finish. IOin
in locking screws provided.
SC /I Side Clamp. Matt Hack finish. Adjustable for different tube diameters.
¡in
locking screw provided.
For further details write or phone_to:
BSI/B
BS2/B
MSPA
r
KEITH MONKS (AUDIO) LTD
26 -30 READING ROAD SOUTH FLEET .HANTS
Telephone: Fleet 102 514) 7316 and 3566
A
custom -built mobile 50 -way
rip
°,
`!'yTay;^!+*,.Ty.
i' á"`. i'"w 8',
iT...7pT, pTyTq,/TayT!
i"'..
f:'.
Mixer...
CTH Sound
**1.,.W1.
:1474 :.:N:V .=1,
.14;
A"
The photograph shows the
.
er_
T4-14"4.1.
50 -way
trolley -mounted console of
a
complete sound distribution and mixing system recently com-
*
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64388 (0480 64388)
STUDIO SOUND, APRIL
1973
47
SOUND '73 PREVIEW
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Phone: 427
Stand 27
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Representative: K. G. Faure
Representative:
Stand: 24
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Phone: 9851152
Representative:
Stands: 41 & 42
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Representative: D. A. Fisher
Stand: 18
Phone: 044 971 486
Representative: I. Marshall
Stand: 38
SON ET LUMIERE EQUIPMENT LTD, Ide Hill,
Kent
Phone: 073 275 454
Stand: 7
Phone: 0825 4166
Representative: A. Walker
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& CABLES LTD,
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INSTRUMENTS
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i
LAST MONTH, consideration was given to
the methods of measuring the harmonic distortion content of a sinusoidal waveform. Ultimately these methods of measurement are the only
ones which are consistent enough to be used in
comparing one tape system, amplifier or loudspeaker with another. However, such methods
leave a number of questions unanswered, the
most important of which is: What figure is
good enough for the distortion of a piece of
equipment? Without an objective function,
there is no way of determining whether a total
harmonic distortion content of, say, 0.5 per
cent is good enough. The only objective
function as yet developed for evaluating the
performance of an amplifier or loudspeaker is
an aural test and this inevitably introduces a
subjective evaluation.
While subjective
measurements are disliked by many engineers,
a vast amount of work has been performed in
acoustic measurements and some consistent
results have emerged.
Firstly, a trained listener finds higher order
harmonic distortion more objectionable than
lower order harmonics. This may in part
account for the observation that a Class A
power amplifier sometimes sounds better than
a Class B amplifier of comparable total distortion content. Class A amplifiers generate
second and fourth order harmonics whereas
Class B amplifiers generate third and fifth order
harmonics. Wigan, in an article in Electronic
Technology (April 1961) proposed using a
weighted measurement to take account of
higher order harmonics being more objectionable than lower order harmonics.
Tolerable distortion
Secondly, based on a single 1 kHz sinusoidal
waveform input, a trained listener can tolerate
a second harmonic distortion level of about
1 per cent before detection and the figure for
the third harmonic is about 0.4 per cent.
Distortion:
Cause
and
Effect
TONY EDEN
In the second of two articles,
the author attempts
an objective answer to the
question 'How much
distortion is tolerable ?'. The
usefulness of an
oscilloscope in evaluating
distortion is emphasised
and several methods of
measuring amplifier distortion
outli ned.
50
Thirdly, the trained listener can detect what
has been called the `acoustic roughness' of
complex waveforms. This appears to have a
far lower distortion content than the minimum
detectable on a single sine wave.
The last point has led to the development of
methods which attempt to evaluate complex
waveform distortion.
Fundamentally the
problem is this: a sinusoidal waveform of one
frequency, when passed through an amplifier,
will at the output contain harmonics. Another
frequency will be similarly affected and, when
both frequencies are introduced, one frequency
will amplitude modulate the other. This is of
no consequence as far as the fundamental
frequencies are concerned since normal complex
waveforms occur in this manner. However,
modulation also occurs to the harmonics producing in effect sidebands of the fundamental
frequency. These sideband frequencies occur
as the sum and differences of the fundamentals
as well as other more complex relationships.
It is the occurrence of these sideband frequencies
which produces what is known as acoustic
roughness and the magnitude of the roughness
is determined by the depth of modulation of
the carrier signal. In turn, the depth of modulation is a function of the harmonic distortion
content of each of the frequencies being considered. Thus, while harmonic distortion gives
one measure of roughness produced by an
amplifier or loudspeaker, what it does not do
is give any indication of how much harmonic
distortion can be permitted before acoustic
roughness becomes apparent. Von Bekesy, in
a large number of tests on the relative roughness measures of one frequency beating with
another, showed that roughness is at a maximum when one frequency is about 50 Hz away
from the other (see fig. 1). Furthermore, the
roughness increases to a maximum when the
frequencies are around 3 Hz, and appears to
be smaller at lower frequencies -which is in
accord with general experience. When the
difference between the two frequencies increases
or decreases from 50 Hz, the roughness appears
to diminish.
Measuring 'roughness'
The work of Von Bekesy in the mid 1950s
summarised many other workers' efforts,
particularly those who tried to measure roughness by two frequency methods.
Hilliard described a method of measuring
roughness or `intermodulation distortion' in an
article in Electronics (July 1946) which was
subsequently adopted by the Society of Motion
Picture and Television Engineers and is now
usually known as the SMPTE method. The
two frequencies used are a low frequency signal
(Q) of about 60 Hz and a high frequency signal
(P) of about 3 kHz. Q is arranged to have four
times the amplitude of P. The two signals are
combined and passed through the amplifier.
A high pass filter follows the amplifier which
rejects signal Q. The modulated high frequency
signal consists of P, plus the products (P+Q),
(P Q), (P +2Q), etc. These signals are now fed
through a detector and low pass filter so that
P is removed leaving only the modulation
products (fig. 2) which are then read on a
millivoltmeter.
It can be seen from the work of Von Bekesy
that this measurement is not evaluating what
the ear detects as roughness since the frequency
difference between the two signals is too great.
Therefore the method does not measure the
subjective impression of roughness though it
does have its uses in loudspeaker testing. One
of the most difficult aspects of loudspeaker
design is to reproduce bass cleanly and it is
here that most `tricks' are employed to give a
reasonable bass output, especially in small
enclosures. While the distortion of a single
low frequency signal may not be immediately
obvious, the distortion level may be sufficient
to intermodulate higher frequencies causing a
particular roughness effect.
The nature of this roughness differs from that
caused by an electronic process such as
amplification; instead, the distortion arises
from the fact that the low frequency is modulating the higher frequency and therefore, as the
cone moves forwards and backwards at a low
frequency, the high frequency is carried on this
cone movement. A stationary listener finds
that the higher frequency is changing in frequency; an effect first observed by Doppler. A
changing high frequency in the presence of a
lower frequency occurs as one form of roughness and is often called Doppler distortion.
This form of distortion can be minimised by
using two or three speaker units each handling
a different part of the frequency range. Also, a
totally enclosed cabinet is often used in which
the stiffness of the enclosed air at low frequencies (30 to 100 Hz) is made equal to the
mechanical stiffness of the diaphragm
suspension.
FIG.1
given rise to the general acceptance that the
harmonic distortion level in an amplifier should
lie below 0.1 per cent throughout the major
portion of the audio range (100 Hz to 10 kHz).
It was mentioned last month, and is worth
reiterating, that an oscilloscope can be extremely
useful in evaluating many forms of distortion.
Intermodulation is a good example. If the
SMPTE method is used to measure distortion,
the oscilloscope trace may well appear as shown
in fig. 4. By making use of the graticule on the
oscilloscope, a quantitative value can be placed
on the distortion level. Alternatively, if one
VARIATION OF ACOUSTIC
ROUGHNESS WITH BEAT RATE
HIGH
R.1.
MIN
`\
I
MIL
'
frequency is put directly on the vertical plate of
an oscilloscope and the other frequency on the
horizontal plate, then the various waveforms
that result are shown in fig. 5.
Two other methods are used for testing the
roughness of amplifier responses. If white
noise is applied to the input of an amplifier in
which a band of the noise is suppressed, then
the output from the amplifier can be measured
to ascertain if there is any signal present in the
suppressed region. If this is the case, then inter modulation distortion is present in the amplifier. This test is particularly useful to show the
BOOHz`320OHz
FIG. 2
LOW
D
20
L0
60
80
100
BEAT RATE
120
140
160
SMPTE METHOD OF MEASURING INTERMODULATION DISTORTION
180
IN Hz
OSCILLATOR
'P'
Hence, under conditions where the low
frequency distortion level may be high, the
SMPTE method can give useful design
information.
Scott, working at the General Radio Cornpany, described another method of measuring
roughness using two frequencies. This article
appeared in Electronics in January 1945 and
the method was later adopted by the International Telephonic Consultative Committee
(CCIF) and is now named after that organisation. Two signals of equal amplitude (P and
Q), but with a small frequency difference
(usually 50 Hz), are combined and fed into the
amplifier under test. The resultant signal then
passes through a low pass filter to reject the
P and Q signals (fig. 3). The even -order inter modulation products (P -Q), 2(P -Q), etc, are
passed by the filter and measured on a milli voltmeter. This method does not measure the
odd order harmonics 2P -Q, etc, for which a
wave analyser would be required. The method
represents a good measure of subjective roughness since the two frequencies are of equal
amplitude and both frequencies close together.
Typically the frequencies used are 3 kHz and
3.05 kHz.
As a guide, the ear would detect roughness
as being apparent using the SMPTE method
when the lower frequency has a distortion
content of about 5 per cent. However, the ear
can detect roughness using the CCIF method
when the frequencies have distortion levels of
about 0.2 per cent. The latter test has probably
FIG. 4
REJECTS
REJECTS
METER
AMPLIFIER
OR IDGE
HIGH
PASS
UNDER TEST
FILTER
FILTER
o
1
SIGNAL HERE
SIGNAL HERE CONTAINS
SIGNAL HERE
CONTAINS
+OI,IP -GI.
(P +20),(P -201 ETC.
CONTAINS ONLY
O,IP
P.O
INTERMODULATION
PRODUCTS
(60Hz1
SIGNAL AT
B
IS MEASURED AS A PERCENTAGE OF
TO GIVE INTERMODULATION
F!G. 3
A,
DISTORTION.
CCIF METHOD OF MEASURING INTERMODULATION DISTORTION
OSCILLATOR
'P'
REJECTS P,0
IP- 2O1,1P +201 ETC
ME:ER
AMPLIFIER
BRIDGE
A
TSIGNAL
OSCILLATOR
tt
'a'
ERE
LOW PASS
FILTER
UNDER TEST
SIGNAL HERE
CONTAINS
P.O
(P- 01.(F +O)
IP- 201.1P +20)
= 3KHz
MAX
RESULTANT SIGNALS AFTER PASSING THROUGH HI -PASS FILTER
_
MAX.
- MIN.
MAX.+ MIN.
x 100
SIGNAL HERE
P,O,
CONTAINS
SIGNAL AT B IS MEASURED AS A PERCENTAGE
TO GIVE INTERMODULATION DISTORTION
t
DISTORTION
B
PASS
DETECTOR
i
OSCILLATOR
= 60Hz
7.
LOW
OR
LOUDSPEAKER
USE OF OSCILLOSCOPE TO ESTIMATE DISTORTION BY THE SMPTE METHOD
F
P
13KHzI
OF
CONTAINS
IP- 01,2(P -01
ETC
ETC.
A,
distortion content of the high frequency end
of the amplifier. For example, if noise is
applied above (say) 15 kHz and the amplifier
output measurement is tuned to the 1 to 4 kHz
region (the most sensitive part of aural spectrum) then the level of output gives a good
indication of the intermodulation that has
occurred above 15 kHz.
The final method to be described for measuring distortion of amplifiers is very simple in
concept. A signal (single or complex) is applied
to the input of an amplifier and the amplifier
output is attenuated and compared with the
input signal. The object is to balance, as far as
possible, the input with the output signals
thereby (in an ideal case) resulting in zero output after the balancing network. Since phase
52
STUDIO SOUND, APRIL 1973
51
- DISTORTION
FIG. 5
GAIN DEVIATION METHOD FOR ASSESSING DISTORTION
PHASE
I00Hz
shifting occurs in the amplifier, some form of
compensating network is required (fig. 6). By
making a phase shift network that compensates
for the amplifier signal throughout the audio
range, the dynamic distortion present in an)
musical item after amplification can be tested.
SHIFT
INPUT
SUM
RRIOGE
AMPLIFIER
HIGH PASS
ONHz
UNDER
TEST
Y
INPUT
FILTER
Transient distortion
Another form of distortion which arises in a
rather different manner but results in the same
acoustic roughness is transient distortion.
Transient distortion is present in amplifiers to
a small extent but is a much more important
consideration in loudspeaker design.
The
problem here is that a large quantity of enerp
is required to make the loudspeaker cone mo
Thus there is a delay in making the cone mote.
due to its inertia, when a pulse is applied.
FIG. 6
OSCILLATOR
PROGRAMME
SOURCE
TYPES OF OSCILLOSCOPE TRACE
IiI lI II0 I111111
1
I
lIl
II l II II
1111111111111111111I111111111
(a)
NO
k)
(b)
HARMONIC DISTORTION
Und HARMONIC
3rd HARMONIC OISTORTIOH
DISTORTION
DYNAMIC METHOD OF TESTING AMPLIFIERS
OR
N
4P.'
AMPLIFIER
UNDER
TEST
OUTPUT
FINE
AMPLIFIER
ADJUST
Similarly, when that pulse stops the cone
continues vibrating. This can give rise to many
forms of 'hangover' resulting in roughness.
One method of testing loudspeakers has been
to apply bursts of tone to the loudspeaker and
observe the results on an oscilloscope. The
loudspeaker with low transient distortion will
commence vibration very quickly and likewise
will cease very quickly when the tone burst
ceases. This is a very useful method of testing
at the development stage of a loudspeaker but
does not of course give any quantitative information about the loudspeaker performance.
Considerable research has been undertaken
over the last two decades (much of it by the
BBC) to produce loudspeakers with reliably
low distortion at all power levels. It is a tribute
to the BBC Research Department that the
results of their development work are incorporated into so many loudspeakers used for
monitoring purposes. In nearly every publication on loudspeakers, the final evaluation of
the quality of a speaker is dependent upon
aural tests. The reason for this is that the
single frequency test will yield some information on the distortion level of a speaker, a two frequency test will yield rather more information, but speech and music contain very much
more complex waveforms than the first two
tests can possibly evaluate. Hence the final
assessment of the quality of a loudspeaker is
usually made by listening critically to different
types of program material.
52
ANALYSER
PHASE
NRIOGE
ADJUST
Speech (especially male) is a good test of the
low /middle frequency range, an area where
distortion (or coloration) is usually most
objectionable.
An instrument such as a
harpsichord provides a very good test for the
transient response of a loudspeaker as the
attack and decay times can be extremely fast.
A full choir provides a very useful test for the
power handling capabilities of the loudspeaker,
as well as a very good test for the 'cleanness'
of soprano voices. Finally, certain pieces of
organ music provide a very good test on the
quality of deep bass and this test will usually
reveal objectionable intermodulation distortion.
In a few more years it should be possible to
analyse the quality of a loudspeaker as it relates
to the human brain.
Distortion measurements on tape recorders
can be complicated by the effects of wow and
flutter on the figures. Wow and flutter
are. of course, a source of distortion giving an
effect on a single frequency similar to Doppler
distortion in loudspeakers. The simplest single
frequency method of measuring distortion on
tape systems is to use a distortion factor meter.
It is difficult to make accurate measurements
to much below 0.5 per cent because the
frequency is being modulated (fm) by the wow.
Hence accurate tuning of the 'notch' becomes
impossible. The problem is usually not too
bad because the notch is sufficiently wide to
allow for small variations in the fundamental.
The problem is much worse if a wave analyser
(METER
OR
AMP +SPEAKER)
to be used for tape distortion measurements.
Here the response can be 3 dB down for a
bandwidth deviation of 6 Hz (which is independent of frequency) and therefore measurements
become extremely difficult at frequencies above
about 5 kHz. One method of overcoming this
problem is to use a tuned amplifier but tuned
over a fairly wide frequency spectrum such as
one-third octave. In this way frequency variations of the fundamental can be catered for
and such a facility is fitted to the B & K
spectrum analysers. Intermodulation distortion
measurements are possible on tape systems but
are infrequently made and even less frequently
quoted. Any such tests are usually restricted
to the amplifiers only. More rigorous distortion
tests on tape machines would quickly differentiate between machines which apparently have
the same frequency response and noise level.
The most widely quoted measurement is the
maximum single frequency signal that can be
put on tape for a 2 per cent distortion level.
What happens below this level is rarely disclosed. The signal can be distorted by the tape
mechanics, the bias oscillator, the tape medium
itself, and the electronics.
It is hoped that this rather brief survey of
the methods of measuring distortion will help
to put into perspective the advantages, disadvantages and limitations of the various
techniques, as well as to indicate the necessary
interpretation if meaningful figures are to be
obtained.
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STUDIO SOUND, APRIL
1973
53
IN AN EXCELLENT article in the December
STUDIO SOUND, John Bowsher and H. A. O.
Wilms gave a most interesting history of the
use of the dBm and made some suggestions for
clarification in the use of the various dB refer-
The dBm
dB(V)?
ANGUS McKENZIE
The decibel is arguably the most
frequently misused and the
least understood 'unit' in
electronic engineering,
despite hard competition
from the Watt.
Responding to H. A. O. Wilms' and
J. M. Bowsher's theoretical
article published in our
December issue, the author
suggests practical definitions
of the dBm.
54
ence standards. While in general agreeing with
the various points raised, I feel that further
clarification might be of interest. I would also
like to propose some new standards myself.
Though agreeing that the 0 dBm reference
point was originally designed to represent a
power level of 1 mW dissipated in a 600 ohm
resistance or impedance, and that dB relative
to this originally referred to variations in power
level, I have always regarded the unit as a
convenient voltage reference of 0.775V. I
would suggest that 99 per cent of engineers
involved directly in the sound recording
industry nowadays also regard the unit in the
same way, although line communication
engineers and some film audio engineers may
well continue to use the unit as a power reference.
Provided that the output source
impedance of equipment was always 600 ohms
and the input load impedance was also 600
ohms, the unit could perfectly easily be used
for voltage references without any misunderstanding. I use the word `was' because almost
all studio audio equipment is now normally
supplied with a low output impedance and a
high bridging input impedance, although 600
ohm impedances can usually be supplied for
the diehards. Many manufacturers, however,
still completely misunderstand the 600 ohm line
theory. While supplying input termination
resistors to make up the input impedance to
600 ohms, they then frequently terminate the
output with a parallel 600 ohm resistor, rather
than building out the output source impedance
to 600 ohms by adding a series resistor allowing
a 600 ohm source.
My own experience of confusion in relation
to dB as power gain or voltage gain was in 1958
when I purchased two STC microphone amplifiers which were normally supplied with 600
ohm input and output impedances floating
balanced. The amplifiers had switched gains
with positions labelled 40, 50, 60 and 70 dB
gain. Since at the time all my mics were of 30
or 50 ohms impedance, the units were ordered
from STC to work with such mics and to feed
equipment with 600 ohm input termination
resistors. I remember being baffled for a while
because I had measured the voltage gain of the
equipment on each switched position some
8 dB higher than stated by STC. Since 8 dB
change of voltage corresponds to an impedance
change of approximately six times, the input
impedance of the STC amplifier would therefore have been approximately 100 ohms, which
would have tied in with the specification. The
necessity of loading the output with 600 ohms
in order to achieve correct working levels,
however, brought considerable complications.
The most serious of these was the necessity of
using either trap valve amplifiers to feed
various pieces of equipment, or hybrid transformers which split the output power to
different loads. It was not always economic
to allow valve equipment to give both a high
voltage clipping level and a low source
impedance since this amounted to an ability to
give considerable power.
With modem
transistor equipment, however, it is easily
possible to design all equipment to give levels
of above 7V from source impedances as low as
a few ohms, plus the dc resistance of a transformer's secondary where applicable.
With most equipment using 1:1 ratio line
output transformers, the output impedance of
a few tens of ohms is in my experience almost
entirely due to the dc resistance of the transformer windings. The input impedance of
almost all industrial equipment is now 10k
ohms or over, although frequently the manufacturers specify that the equipment should be
driven from a. source of 600 ohms or less in
order to avoid input transformer reactance
compöiients having a detrimental effect on
performance. It therefore seems quite pointless
to consider power gain of amplifiers used in
modem recording studios and it would therefore be reasonable to consider the adoption of
not only a new unit but a new voltage reference.
I therefore propose the adoption of the dB(V)
as such a reference, 0 dB(V) representing a 1V
voltage level anywhere in the system. Most
studios work to a nominal peak line level
referred to as +8 dBm which, in old terminology, should perfiaps more correctly be
referred to as 1.97V. If this same level were
referred to as 2V, i.e. +6 dB(V), the error
would only be 0.2 dB which is of no real
significance.
After considerable research I have ascertained that some studios peak approximately
6 dB above 320 nWb /m on their tapes even
when Dolby noise reduction systems are used.
For interchange purposes, therefore, it would
be extremely convenient if 0 dB(V) could be
standardised as a level equivalent to a recorded
flux of 320 nWb /m. This would in particular
tie in precisely with current BBC practice where
a peak of six on their ppms corresponds not
only to an output voltage of 1.97V but also a
recording level on BASF LR56 tape (used
frequently by them for stereo recording) of
640 nWb /m (6 dB above DIN reference level).
A standard line -up level of four on a ppm
would therefore correspond to -2 dB(V). In
such a system a ppm reading of 4.5 would
correspond to a tape flux level of 320 nWb /m
and 3.25 would then correspond to Ampex
operating level, also referred to as `Dolby level'.
Once again it is convenient that 3.25 on a ppm
happens to coincide with BBC stereo line -up
tone.
The eventual adoption of these proposed
levels would necessitate changes of gain in
many units but, under almost all circumstances,
preset gain controls will be found to have more
than enough gain in hand.
There are obviously a number of snags in
such a change, the main one being the necessity
of replacing scales on test equipment having
references to 0 dBm equalling 0.775V. Much
test equipment, however, including that made
by B & K, is scaled in dB(V). In any case,
instruments such as the Level microvoltmeter
series are, by the die-hards' standards, incorrectly scaled in dBm, since their input impedances are usually at least 1M ohm. Also, they
measure voltage rather than power. A change
of scale to dB(V) would put right this error for
all, and bring the instruments up to the same,
scaling standard as B & K.
Alternatively, as John Bowsher points out
the scale should be referred to in dB(V.7), a
unit which I strongly object to as nobody would
remember to add the `.7'. New scales would
not be expensive to produce and would be very
much easier to correlate. Amplifier input
sensitivities are often given in mV which can
be quickly referred to in dB(V), whereas rapid
mental calculations translating mV into dBm
or vice versa can easily result in 2.2 dB being
absentmindedly added or subtracted in the
wrong direction.
I discussed all the above suggestions with
John Bowsher and he agrees in principle with
them. The matter was a1s§o raised at a recent
AES meeting held at the lEE where most
people who contributed to the discussion also
agreed in principle.
One rtiêmher, `of the
audience, however, insisted that ail dBm
should always be used for power level references
and further stated that he preferred to see all
amplifier gains as power gains. I replied that
this seemed unnecessary since very few engineers now were concerned with matching
amplifier impedances. I quoted the absurdity
of specifying the power gain of an fet capacitor
mie amplifier having an input impedance of
several hundred megohms and an output
impedance of 200 ohms or so, and having a
voltage gain of unity. To avoid loading effects
I also pointed out that it would be most
convenient to agree upon an international
standard that all output source impedances of
studio equipment shall be less than 100 ohms,
and all input impedances greater than 10 k
ohms with the sole exception of microphone
preamplifier inputs. For the latter it would be
reasonable to specify internationally lk ohms,
and for microphones to be designed to work
into this impedance. In practice, normally all
professional microphones are designed for
optimum performance into 1k ohms. All
equipment could also have performances
specified with lk ohms input and output
terminations. Under these circumstances, we
would therefore have a situation where 0 dB(V)
would equal 0 dBm as originally used, a power
dissipation of 1 mW, but into lk ohms. This
nominal impedance is of course geometrically
half way between 100 and 10k ohms in terms
of loading. Input and output transformers
could be designed to work at all appropriate
impedances below or above 1k ohms respectively, with no undue problems. Many manufacturers find it necessary to load a balanced
output transformer in order to obviate high
frequency ringing or peaking. The addition of
a reasonable number of 10k ohms input
impedance amplifiers would not materially
affect output levels since the output impedance
would be less than one -tenth of lk ohm. This
would end the 600 ohm legend. It is incidentally
worth noting that, whereas 600 ohms is not a
standard value of resistance, 100 ohms, lk ohm
and 10k ohms are.
The VU meter unfortunately presents a
problem. Not only is a 0 VU reference an
awkward one but it has been normally regarded
as indicating Ampex operating level or Dolby
level. Most industrial machines have VU meter
amplifiers of variable sensitivity. It would
probably be best to consider increasing their
gain by approximately 7 dB so that 0 VU could
correspond to a voltage level of 4.8 dB(V),
having established 0 VU as 320 nWb /m. With
older equipment in which VU meters are
switched across 600 ohm source impedance
lines, most VU meters will be found to introduce distortion on to the line because of the
diodes used in the meter rectification. In such
circumstances, would it perhaps be better to
consider a metering system not having such
failings and giving a truer indication of peak
line levels?
It is fair to add the VU meters used across
lines driven from low source impedances (i.e.
100 ohms or less) do not add significant
distortion. The advantages of effectively lowering the absolute peak voltages in systems also
include the possibility of using considerably
lower ht rail voltages in equipment, with the
subsequent saving in cost of components.
Lower power levels would be involved and
emergency battery supplies such as two PP9
in series (18V) would be ample for many
purposes.
I realise that all the above suggestions are
rather controversial but feel that such standards
would be very convenient for many users. I
realise that referring a tape flux level to a line
voltage may be impracticable, partly because
of the VU meter, but I think that at least the
use of the dB(V) rather than the dBm can be
most seriously considered, leaving the dBm
where it originally belonged
the line
communications engineers.
The VU meter design is now well over 30
years old and, while in its early days it was
remarkably sensitive (having approximately
1.8V ac fsd with an impedance of 7.5k ohms),
it could be greatly improved with current
technology. It might be fairly simple to design
a meter of the same input impedance, but
using more efficient diodes, and a better
magnetic system which could allow a sensitivity
of 580 mV for 0 VU (which is also incidentally
the voltage level proportionate to most B
system Dolby levels, as well as Dolby level on
my new suggested standard of 1 V =320 nWb /m.
If the new standard reference impedance of lk
ohm could be used, this might be referred to
internationally as 0 dB(kf/), in which case the
already suggested IEC standard of dB(mA)
representing a reference of 1 mA would tally
most conveniently. If most of these recommendations could be adopted, they would
finally realise Dick Swettenham's slogan `600
ohms is dead'.
with phantom
feeding (9v /12v /48v)
FET Condenser microphones with parallel
feeding (9v /12v)
FET Condenser microphones
Capsules with single directional pattern
Capsules with several switchable direc-
tional patterns.
Changeover of the directional pattern
is effected by altering the
mechanic -acoustic elements of the
capsule. By this means the
switchable capsules need only one
diaphragm, thus avoiding
falsifying phase effects even at
the highestfrequencies, (German
and foreign patents).
Further special features include:
Great modulation range
Very low harmonic distortion
over the entire frequency
range
Optimal focusing with the
pressure gradient
microphones
-to
Late news item
going to press, we were
informed by Mr Ira Gale (Gale Electronics &
Design Ltd, 39 Upper Brook Street, London
WlY 1PE) that he is organising an exhibition
of industrial audio equipment to run concurrently with Sonex '73 at the end of March.
A bus will take visitors from the Excelsior
Hotel to Proson '73 at the Sheraton Hotel,
Heathrow, and back again. Admission will be
free but by ticket only (available from Gale).
It is understood that AKG, Amcron, Ampex
and Audio Applications equipment will be on
show in addition to a Gale loudspeaker.
Contrary to rumour, STUDIO SOUND is in no
way involved with this event though we will
be represented at Sonex.
SHORTLY
BEFORE
Degree of focusing largely
independent of frequency
For stereo recording
by X/Y or M/S
intensity principles,
the stereo microphones CMTS 301
(p) and CMTS
501
are ideal, and
practical.
In the heads of these
microphones are two
capsules, which can be
switched independently to
card ioi d- bi -omn i- directional,
one of which can be rotated
through 360° These capsules
are switched mechanically
and possess only one
diaphragm.
r
A.V. Distributors
(London) Ltd.
Park Road, Baker Street,
London, NWI 4SH
26
Telephone:
01
-935 8161
further details on Schoeps
Condenser Microphones
Please send me
Name
Address
L
SS4
-
STUDIO SOUND, APRIL 1973
-
J
55
COUNTY
County Recording Service, London Road,
Hinfield, Bracknell, Berkshire.
Tel : 0344 4935.
Disc -cutting equipment and all ancillary units and
services. A complete system could be supplied costing from £500 upwards, depending on requirements.
Individual items are priced as follows:
Disc recording heads rebuilt, repaired and serviced
-from £15 upwards. Stylus heater units -£25.
Swarf extraction systems -about £100. Disc cutting
equalisers with or without a monitor section-from
£100 upwards.
County make and supply styli for all types of cutter
head from £3 each. Heater windings are fitted to the
styli for an extra 25p each. Disc cutting styli are
relapped at from £1.75 each. County Recording
Services say they have neatly finished experiments
on a new stereo disc recording head. It is a moving
coil device which they hope to sell for about £750,
with the electronics, power amplifier, equaliser and
so on costing a further £750. They hope to be able
to convert suitable disc recorders to cut stereo for
under £2000, which will include mechanical overhaul, delivery and setting up in the client's cutting
room. In the near future they also hope to offer 18
cm recording blanks for 40p each.
Cutter head mounting: intended for the Ortofon
10 Hz
MSR series
equipmen
Turntable diameter: 40 cm.
Turntable weight: 18 kg.
Turntable vacuum: vacuum indexing for
Technical specifications
Warwickshire.
Tel : 0676 32468.
cuttin
stylus heater current switching depth of cut electrically controlled and adjustable.
Turntable speed: 16i, 45, 331, 78 rpm.
18 cm /s
recording blanks.
Leadscrew: servo controlled with varigroove.
All functions are actuated by push buttons which
are illuminated to indicate the function in operation.
Switching operations are carried out by solid state
circuitry mounted on plug -in printed circuit boards,
thus avoiding the need for unreliable relay switching.
All pushbuttons and controls required for the operation of the lathe are grouped together on a control
panel. Separate instruments on this panel indicate
groove pitch, stylus current, depth of cut and peak
programme groove modulation.
The 406 mm diameter turntable is driven direct from
a dc motor, servo controlled using a crystal
controlled clock achieving a high degree of speed
stability over a long period. The system is independent of mains frequency.
The leadscrew is driven from a servo -controlled
motor which may be adjusted manually to give a
wide range of grooves per centimetre. Varigroove
is also incorporated in the same circuitry and its
signal is derived from an advance head on the tape
replay machine. The vari- groove signal is analysed
for programme level and frequency spectrum before
overriding the groove pitch set manually for the
leadscrew motor. The vacuum line serves two purposes, namely collect swarf from a point directly
behind the cutting stylus and as a turntable vacuum
for retaining the recording blank.
The cutter head mounting and suspension is intended for the Ortofon stereo cutterhead type DSS661.
The mounting also contains the stylus heating coil,
which is cut off when the cutter head is lifted, and
electronically controlled depth of cut.
Groove pitch: continuously variable from 40 gpc
to 160 gpc for each turntable speed.
Stylus heating: variable dc current up to 1A.
Microscope: Nikon microscope 150 times magnification with calibrated graticule.
Metering: independent meters are used to monitor
groove pitch, depth of stylus cut and stylus current.
Programme Input: balanced floating 10k ohms.
Presettable in onedB steps from -6 dBm to +6 dBm.
Monitor output: 100W rms per channel into 8 ohms
impedance.
Programme metering: one ppm per channel
switchable to read programme input and other
functions.
Recorded velocity: peak cutting velocity 30 cm /s
Frequency response: measured on disc. t3 dB
MSR
MSR Electronics Ltd, Meeting House
Lane, Balsa!! Common, Near Coventry,
Survey:
Disc
Cutter head suspension : automatic lower and lift
1000
and
2000
disc cutting lathe
The MSR series 2000 and MSR series 1000 disc
cutting lathes are designed to cut stereo and mono
records respectively. The system is intended to
accommodate all standard record sizes and a range
of four turntable speeds.
A control system which has the following functions
is used to achieve semi -automatic cutting: lowering
and lifting the cutter head; scrolling in and out at
predetermined diameters; adjustable timed marker
groove; start stop of the tape replay machine and
so on.
The cutting system incorporates the Ortofon stereo
cutting amplifier type G0701 /GE 701 and the complete
unit is housed in a floor standing console accommodating recording amplifiers and control logic
circuitry.
stereo cutter head type DSS661.
25 cm /s and 30 cm /s
to 36 kHZ. ±1 dB 20 Hz to
18
kHz.
Harmonic distortion on disc:
kHz recorded at 25 cm /s peak. 2nd harmonic 0.4 ï;,
3rd harmonic 0.2 °,,
30 Hz recorded at 1 cm /s peak. 2nd harmonic 0.6 %,
3rd harmonic 0.2 ",,.
1
Intermodulation : different tones
6.6 kHz and 7 kHz 8 cm /s peak. 40 Hz = 0.07%.
0.1%.
12 2 kHz and 12.6 kHz 2.8 cm /s peak. 400 Hz
NEUMANN
Georg Neumann & Co, 71 Heilbronn
Neckar Fleinerstr. 29, Postfach 2120,
West Germany.
Tel : 8 22 75.
Agents: FWO Bauch Ltd, 49 Theobald
Street, Boreham Wood, Hertfordshire.
Tel :
01
-953 0091.
Disc recording lathe system V MS70
Components: Computer programmed automatic
groove spacing (pitch) and depth control, as
Left: Neumann cutting system.
56
a
function of program material provides optimum
utilisation of the record surface.
Relay -less control system.
Plug -in programmer; one for each record rotational
speed and diameter, all other functions such as
lead -in and end groove diameters, basic -pitch,
automatic pitch control, lead -in, spiralling and lead out pitch, concentric end groove, cutter lift delay
and so on are programmed automatically. Re -calibration is not required.
Amplifier rack
This rack houses all of the electronics required for
operation of the SX68 stereo cutterhead.
Components:
RIAA recording characteristic equaliser (switch able).
Cutterhead drive power amplifiers.
Circuit breaker: to protect the cutterhead against
thermic overload.
Feedback amplifiers.
RIAA playback amplifiers (pick -up /feed- back).
Monitor power amplifiers.
Cutterhead alignment module.
Automatic high frequency limiters.
Mounting space and all connections provided for
the tracing simulator TS 66 for reduction of tracing
distortion.
Programme controller SP 172 (48 cm version)
Programme controller SP 272 (console desk
version)
The programme controller is the heart of the tape to -disc transfer system. It is here that the program
coming from the tape playback machine is processed,
metered and monitored. All important program
parameters such as disc level, equalisation pitch/
depth control and automatic banding may be reproducibly influenced here. Tapes of greatly varying
level and quality parameters can be brought into
line to produce optimum results. The VMS 70 lathe
may be remote controlled from the program
controller.
Complement:
Metering and indicating unit comprising dual light
beam peak indicator, two VU meters and stereo
correlation meter and phase monitor scope.
Relative disc level attenuator for selection of the
recorded disc velocity without influence on meter
indication (automatic range switching).
Preview offset control :for changing control channels
separately from modulation channels to influence
record fill- factor. Both above are 0.5 dB /step amplifier /attenuators.
Four active equalisers: for low /high /mid range
boost and droop control.
Four high /low cut -off filters for limiting of frequency
band width.
Two elliptical equalisers for reduction of low frequency vertical component to provide compatibility
improvement.
Linear board -fade attenuator.
Output for tape recorder for simultaneous tape copy.
Five-frequency precision test oscillator with pushbutton injection into programme circuits.
Complete jack field (tip /ring /sleeve) provides access
to all essential circuits for rapid fault diagnosis,
insertion of external components etc.
Monitor selector buttons give access to all vital
points for both metering and listening.
Flashing push buttons as reminders of certain vital
non -standard functions. Prevent false starts and
lacquer spoilage.
Automatic banding unit provides spirals, selection
counting and lead -out from optical sensor on tape
recorder. Relay -less.
Mounting space and signal and power connections
provided for two Dolby Model 360/361 and EMT-156
PDM compressor.
Push button controls provided for: phase reverse,
channel reverse, Dolby insertion, equaliser insertion,
mono /stereo, 150/300 Hz compatibility turn -over
frequency, cutter on /off, 14 dB test record gain
increase, monitor mono control and A /Bcomparison.
Preview /playback tape console MT72
Tapes are played on the tape deck of the special
MT72 console, which is equipped with special idlers
and two stereo playback heads which provide both
hght)): VMS 500 VA
the control signals for automatic pitch /depth control
and the modulation outputs for the cutterhead.
Complement:
Speckal AEG Telefunken M -15 magnetophon with
switchable 19/38 cm /s tape speeds.
Four playback amplifiers.
Four switchable NAB /IEC (CCIR) playback equalisers.
Preview head continuously variable preview distance
to suit all tape and disc speeds.
Optical sensor sends pulses on seeing leader between selections and at the end of the tape to provide fully automatic spiralling and lead -out grooves.
Four VU meters with range switch.
Stereo disc cutterhead SX68
In combination with the amplifier rack the dynamic
feedback cutterhead SX68 cuts stereo and mono
records.
VG 400
Technical specification
Price: £11,530.
Amplifier system VG66S- mono /stereo
Turntable rotation :Ise, 22;, 33f 45 rpm switchable.
Pressing diameters: 178, 254, 305 mm switchable.
Lacquer blank diameters: 178, 254, 305, 337, 356,
,
406 mm
switchable.
Tape speeds: 19 and 38 cm /s, others available.
Recorded velocity capability: 33 cm /s lateral.
Playing time at 33 rpm: programme dependent
but
33
minutes not uncommon.
Frequency response:
1
,
at least 70 dB
(measured according to DIN 45539).
Weighted peak flutter:
"
0.03
max (measured
according to IEC, DIN 45507 and ANSI S 4 3 1971)
Programme dependent automatic low -pass (30
kHz to 7 kHz): HK66 automatic high frequency
limiters (two off).
Compatible cutting through reduction of vertical
signal: switchable 150/300 Hz, 6 dB /oct: EE70 compatilising cards (two off).
Reduction in second harmonic (tracing distortion): TS66tracing simulator at least 18 dB at groove
excursion limit.
Automatic pitch /depth control information: every
# turntable revolution.
Nominal line level: 0 VU corresponding to 4
±
Weight: VMS
350 kg; VG 130 kg: SP172 125 kg;
MT 150 kg.
Disc cutting lathe system VMS70-mono/
stereo.
With disc cutting lathe AM66, microscope Leitz
ZA36a, cutter head suspension SA66, depth of cut
control unit TE66, pick -up arm TA70 with magnetic
stereo -pick -up, lead screw drive -unit VA66with echo
device for elimination of echoes, drive control AS66,
SP272 150 kg;
power supply NG70 and three program plugs
(30 cm/33A rpm; 25 cm/33. rpm; 18 cm /45 rpm),
vacuum chuck turntable ZA3, turntable drive motor
SM8 /3 -A, lathe console ZT70 with wiring and suction installation, vacuum pump VP1 and control
amplifier SV66.
The VG66S contains one 48 cm rack SG66, one amplifier component assembly VB66S, two monitor preamplifiers WV661C,two recording equalisers SE661C,
two cutter adjustment modules CE66, two feedback
amplifiers GV66, four drive amplifiers LV66, two circuit breakers S166, one monitor control ÁR66, two
monitor amplifiers AV66, two power supply assemblies NS66 and one dummy cutterhead EW68A.
Price: £3,575.
Control console SP272- mono /stereo
disc section: 40 Hz -16 kHz :. dB.
tape section: 40 Hz -16 kHz
1.5 dB.
Channel separation : at least 35 dB.
Weighted signal-to- rumble ratio:
1400 x 620 x 1370 mm.
VA 540 x 630 x 1950 mm.
SP172 100 VA 540 x 630 x 1950 mm.
SP272 100 VA 1400 x 620 x 1080 mm.
MT 160 VA 810 x 670 x 890 mm.
dbm.
Switchable for under modulated tapes: to -10
VU corresponding to -6 dBm in 0.5 dB steps.
Switchable for high output tapes: to *10 VU corresponding to 14 dBm in 0.5 dB steps.
Tape playback equalisation: NAB /CCIR switch !
The control console SP272 contains one peak meter
unit with one double light beam instrument M±W,
two peak level indicator amplifiers PTMV and one
power supply NS66; one VU meter unit with two VU
meters (Weston), one correlation coefficient meter
U79t with instrument and two amplifiers VU70; one
cassette field with two active level controls RV72,
four equaliser amplifiers PEVb, two two -channel
high -low -pass filters HT66 and one stereo monitor
oscilloscope; one automatic spiralling device KS70
(the light barrier LS70 is to be mounted on the
'Magnetophon' M15 in MT72), one stereo flat -track
fader; one switchfield with one test oscillator PG70;
one amplifier unit with six amplifiers PV26b, two
elliptical equalisers EE70; one power supply unit
NESP with three power supplies NS66, orte power
supply 2TN15-01A and one impulse switch 1G.
Price:
£8,600.
One stereo cutterhead SX68.
Price:
£2,440.
One set interconnecting cables.
Price:
£56.
Ten *Cutting sapphires
74
kMH at £10.60.
able.
Price:
Nominal disc level (peak recorded velocity): set-
Two treble limiters HK 66 at £272.
table in 1 dB steps between -4 dB and t8 dB: producing 5 cm /s per channel corresponding to 7 cm /s
lateral at 1 kHz.
Preview offset: -6 dB switchable in 0.5 dB and
1 dB steps.
Programme equalisation, high /low equalisation:
60 or 100 Hz and 10 kHz: L 15 dB reproducible in 11
steps.
Price:
£106.
58
£544.
Presence /absence: 0.7, 1, 1.4, 2, 2.8, 4, 5.6 kHz
P8 dB reproducible in nine steps.
High /low cut off filters: 60, 125, 250, 500 Hz, 8, 10,
12,14 kHz; about 12 dB /oct
Other equalisers available on request.
Automatic banding unit: max eight spirals; relay
less.
Timing of spirals: 0.25, 0.5, 0.7, 1, 1.2, 1.5, 2 s (time
function).
Metering section : two light beam peak indicators
( -70 to ±5 dB);
Two ANSI standard VU meters; one stereo correlation meter; one stereo monitor oscilloscope.
Expansion of metering section : 14 dB for standard
alignment records.
Power consumption (dimensions (wth
Right: Neumann turntable
x
dpth
x
and microscope
STUDIO SOUND, APRIL
1973
57
DISC CUTTING EQUIPMENT
One helium reduction valve.
Price: £20.
One helium cooling system BA4.
Price: £60.
One Buchmann -Meyer light ZA21.
Price: £98.
One Strobotron ZÁ42.
Price: £58.
One microscope for stylus adjustment ZA12/68.
Price:
£114.
Total price: £27,201
Tape replay machine
Either Telefunken M15 special complete in console.
Price:
£4,000.
or Studer A80/VU- pre -listening.
Price: £2,140.
cutting rubies are available as alternatives to sapphires at £12.00 each.
ORTOFON
Ortofon, 5 Trommesalen, DK 1614, Copenhagen V, Denmark.
Tel : (01) 31 08 83.
Agents: Feldon Audio Ltd, 126 Great Portland Street, London W1N SPH.
Tel
: 01
DSS
-580 4314.
661
cutter head.
normally prevented by the rising impedance of the
cutter head. However, in this amplifier a four pole
impedance matching network is inserted between
the output stage and the cutting head. This network
converts the complex impedance at the output into
a real load, essentially resistive, throughout the
entire audible frequency range.
Since the feedback is a motional feedback sampled
in the moving parts of the cutter, it reduces non linearity in the cutting action at lower frequencies,
while throughout the operating range, it reduces
system distortion and damps the cutter. In the GP701
amplifier the entire frequency range is covered by
the feedback loop. In the low region at 40 Hz, for
example, a feedback ratio of 12 dB is typical.
When the temperature of the cutter coil exceeds a
preset value, the programme is electronically
switched off and the head is disconnected. Average
temperature is displayed on a front plate meter
additional to the conventional cutter current meter.
The equalisation in the monitor section is adjusted
according to IEC /98 playback response.
The pickup playback preamplifier allows the use of
either dynamic or magnetic pickups.
All switching in the amplifier is made electronically
with analogue switches. The only relay in the amplifier is the cutter connecting relay which is of the
mercury wetted contact type.
The amplifier is provided with push buttons for
manual switching cutter on /off and monitor feedback /pickup.
The power supply GE701 contains two identical
supply systems. They supply each amplifier with
two symmetrical voltages referred to zero.
Principle
Technical specification
Each moving coil system is connected to a separate
Power supply GE701
Mains supply: ac 50 to 60 Hz, 220V or 110V, +10 %.
Output voltage per system (idle run): +40V,
0-40V.
Maximum continuous supply current per system:
recording amplifier, the moving coil system being
part of the negative feedback loop. So the two
channels are electrically isolated from each other.
The two moving coil systems in the cutter head are
mechanically coupled to a common stylus holder In
such a way that one moving coil system will move
the stylus tip in a direction of 45° to the vertical and
the other moves the stylus tip in a direction perpendicular thereto ( -45 °).
This coupling arrangement, for which Ortofon
has taken out a patent, allows the two moving coil
systems to drive the cutting stylus in the respective
directions without mutually affecting each other.
Negative feedback reduces distortion and damps
the cutter, resulting in low crosstalk, flat frequency
response and wide frequency range.
Features
The DSS 661 has a new shape which allows a working position with a tilt of 30° maximum to the vertical.
Due to the so called 'spring -back' effect it is necessary to tiltthe cutterhead about 25° in order to obtain
an effective 'vertical' angle of 15° in the groove. In
accordance with another Ortofon patent the DSS 661
has been prepared for gas cooling to reduce the
temperature rise of the driving coils at heavy loads.
This Is particularly important when cutting frequency
test records and so on where a high driving current
must be applied for a considerable time Interval.
The gas- cooling protects the driving coils from
damage due to overheating. It is not necessary to
employ gas-cooling when cutting normal music
records, but if the facility is at hand, it may as well be
used in all cases; it will never hurt and It may save
the cutter head from damage due to errors or
accidents. The cooling gas must be either hydrogen
or helium.
Price: Stereo cutter head: £1,600. Cutting sapphire,
'superior quality': £11.70. Cutting sapphire, 'first
quality': £8.75.
G0701/GE701 stereo
cutting amplifier set
The Ortofon cutting amplifier, G0701, has been
designed with careful consideration for high power
output and minimum intermodulation distortion and
harmonic distortion. The amplifier is constructed
for a sine wave output of 500W (peak power of 1 kW)
which makes It possible to cut peak velocities of
more than 30 cm /s even at 20 kHz. The transfer of
such high power, particularly In the treble region Is
58
1 cm /s peak), 2nd harmonic 0.6 %;
3rd harmonic 0.5 %; higher harmonic 0.1 %.
30 Hz (0.65A,
Difference tones:
6.6 kHz +7 kHz (0.4A, 8 cm /s peak), 400 Hz = 0.07%
12.2 kHz +12.6 kHz (0.32A, 2.8 cm /s peak) 400 Hz
0.1 %.
Dimensions: plug in unit for 480 mm frame inser-
tion (four height units).
Frontplate: 438 x 177 mm, cabinet depth: 337 mm.
Weight: 8 kg.
Delivery: ready for rack mounting, frame included.
By special order mounted in steel casing: 505 x 195
x 400 mm.
Price:
G0701 two channel cutting amplifier, complete with GE701 dual power supply: £3,880.
Four channel cutter
The Ortofon cutter head DSS661 and the drive
amplifier have been on the market for some years.
The cutter head has now been modified to cut four
channel records, the carrier wave system, at half
speed. A head for regular speed recording is in
preparation.
LPS
691
four channel equaliser
Ortofon also produce a four channel equaliser,
LPS 691, equipped with logic circuitry for manoeuvring of the master tape machine and the monitoring
circuitry. The normal version is designed for two
programme channels plus two preview channels. A
special version for regular programme channels Is
however also available.
Price: £1,095.
New filter
A regulated low pass filter of a new design will be
available from the spring of 1973. The filter is designed for protection against the cutting of non- trackable treble signals as well as against overheating of
the cutter head. Its operation is based on pulse
width modulated mos -fet's in an active filter
configuration.
approx. 6A.
Dimensions: plug -in unit for 480 mm frame insertion (three height units).
Frontplate: 438 x 132.5 mm, cabinet depth: 337 mm.
Weight: 20 kg.
Delivery: ready for
rack -mounting frame included.
By special order mounted in steel casing: 505 x 155
x 400mm.
Cutting amplifier G0701
Programme input arrangement and impedance:
balanced, floating 5k ohms. Feedback input arrangement and impedance (at 1 kHz): unbalanced, approx-
imately 10k ohms.
Pickup input arrangement:
1
to 3 ohms dyn.
pickups balanced or unbalanced.
1 to 3 k ohms magn. pickups, unbalanced.
Drive coil output arrangement, assumed coil
impedance: symmetrical to zero, 9 ohms.
Monitor output arrangement, recommended load:
balanced,floating: 1 to 10 k ohms.
Programme input sensitivity: (presettable) -6
dBm, 0 dBm, +6 dBm.
Feedback input sensitivity: approx 6 mV /cm /s.
Pickup input sensitivity: (1 kHz): Dyn. approx
20p.V /cm /s. Magn. approx 0.6 mV /cm /s.
Monitor output level (adjustable): programme
input level.
Maximum monitor output level (into approx
1k ohms) approx: +20 dBm.
Power available at all frequencies direct from
power unit into external ohmic resistor (using +40V
as supply voltage): 500W,
Output connected to cutting head (DSS661):
Available power raising with frequency to 500W at
20 kHz.
Peak output current: 16 kHz, approximately 8A.
Peak output voltage: 16 kHz, approximately 150V.
Corresponding to cutting velocity peak: 30 cm /s.
Typical data with DSS661. Measured on moni-
tor output terminal:
Frequency response: +1 dB 20
Harmonic distortion:
Hz
to
18 kHz.
1 kHz (0.4A, 25 cm /s peak), 2nd harmonic 0.4 %;
3rd harmonic 0.2%; higher harmonic 0.05 %.
WESTREX
Westrex Company Ltd, 152 Coles Green
Road, London NW2 7HE.
Tel : 01 -452 5401.
3D11
Stereodisc recorder
Dynamic, negative feedback stabilised stereophonic
recorder compatible with all Westrex stereo disc
systems. Makers say 'it retains the original advantages of a quick- change positive self -aligning stylus
holder with large diameter stylus, low spurious
resonances and high sensitivity, and special high
temperature coil wire and insulation with quick
change stylus heater wire clips
[It has] greater
mid and high frequency sensitivity, higher recording
level capability and a new stylus mounting holder.
'Cooling is not required to consistently record very
high levels without fear of distortion or recorder
damage. Long term stability is assured with the use
of 29 dB of negative feedback. Negative feedback is
adjusted for an ample margin of safety from the
tendency to self- resonate. Negative feedback monitoring over the entire frequency range provides a
metered and audible confirmation of performance'.
...
Technical specification
Type: 45 ° -45° stereodisc.
Damping : stabilised negative feedback
(29 dB at
resonance).
Coils: two drive, two feedback, one each per coil
form.
Drive coil impedance: 10 ohms nominal.
Recording frequency range: 30 Hz to 20 kHz.
Feedback voltage: 27 dBm (.035V) at resonance
(approximately 1 kHz) at 3.5 cm /s recording velocity.
Crosstalk: approximately 35 dB, 50 Hz to 10 kHz.
Stylus: P98438 red sapphire, self -aligning.
Stylus heater wire: quick-change, spring -loaded,
wire clip terminals.
Vertical stabilisation : advance ball.
Weight: 2.5 kg.
Dimensions: 8.3
x 10.8 x 24 cm.
MSR2000.
The Series 2000 disc- cutting lathe is
designed to cut stereo records with
outstanding quality. (An identical Series 1000
lathe is also available for cutting records
in Mono)
All MSR Series 2000 lathes are fitted with
a 16 inch turntable, with a direct driven
DC motor, independent of mains frequency
disc.cuttïng
he
seeing is
and servo controlled for maximum speed
stability
believing.
MEETING HOUSE LANE
'Varigroove' is provided on all MSR
Series 2000 lathes. This is controlled from
an advanced head on the tape replay
machine
The MSR Series 2000 lathe is equipped with
stylus heating and swarf collection systems
and is built into a high quality
floor standing console
MSR Electronics Limited
.
BALSALL COMMON
WARWICKSHIRE . ENGLAND
Telephone (0676) 32468
"D.S\\
Des'gn Engineers to the Recording Industry
IraserPeacoek
BIAS ELECTRONICS
B,E.1000 PROFESSIONAL
*Wow
and Flutter RMS Total
*Frequency Response Overall
±2 dB.
*Noise Overall
-60dB
*Plug
38
unweighted below
*Separate Sensitivity
in Electronics
RECORDER
0.06;
Cm /Sec 40 Hz to
38 Cm /Sec
EQ and Bias
32 mM
18 kHz
/mm Full Track
Adjustment for each speed
*Plug
in Head Block.
*Precision Cast Tape Deck *Electronic Tape Tension.
Illustrated: STEREO TRANSPORTABLE
£534.00
Associates ltd
are the tape and
cassette
copying people
We specialize in small and large
runs,write today for a rate card
BIAS ELECTRONICS LTD
Distributor to Studios
Coombe Trading Est.,
of KEITH MONKS AUDIO
Coombe Lane,
Microphone Stands, Etc.
London SW20 01 -947 3121
Fraser. Peacock Associates Limited
Unit
8,
112-120
fpa
94 High Street Wimbledon Village London SW19
01.947 2233
sole UK
distributors of Infonics
STUDIO SOUND, APRIL 1973
59
AEG TELEFUNKEN
AEG Telefunken, AEG House, Chichester
Rents, Chancery Lane, London WC2.
Tel
:
M1528
01 -242
9944.
duplicátiñe
systemg
3
Ampex AD -15
Technical specification
Master tape reproducer M15
Speed of master reproducer: 304 /152 cm /s.
Wow and flutter: approx 0.6'',.
Starting time: approx. 0.8s.
Slave tape recorders M28
Speed of slave recorders: 76/38 cm /s.
Wow and flutter: approx 0.8
Starting time: 1s.
Speed of first slave recorder if set
Frequency response -playback:
In preparing master tapes, 30 Hz to 15 kHz t3 dE.
In duplicating musicassette tapes: 30 Hz to
10 kHz
tape duplicator
A master console including:
Two professional -type M15 tape reproducers
modified for tape speeds of 304/152 cm /s. One
program panel subdivided into a crossbar distributor, eight attenuators of L12 dB, eight pushbutton controls for automatic operations and one
switch for the choice of either the musicassette or
sterec -eight cartridge system. Four or eight VU
meters for measuring program levels on each
channel can be furnished on request. Eight V797
plug -in replay amplifiers with their respective
interchangeable plug -in adjustment boards (eight
boards for the musicassette system, eight for the
stereo -8 system and four for the preparing of master
tapes). Eight V696 recording amplifiers with their
respective E696 basic equaliser. One logical modular device for the automatic control of the duplicator.
One power pack.
2. Slave consoles, each of which contains:
Three professional M28 tape recorders adapted to
76/38 cm /s speeds and to 3.81 mm tape. Interchangeable plug -in AE 696 adjustment boards
(three boards for the musicassette system, six for
the stereo eight system, one for preparing master
tapes.) The first slave console contains the central
oscillator, the separator amplifiers, and the power
amplifiers for the premagnetisation of the relative
slave recorders, while the other slaves contain only
the power amplifier. A master console can drive up
to four slave consoles for a total of 12 slave recorders
1.
Survey:
preparation of master tapes: 152/76 cm /s.
In
3
dB.
duplicating stereo eight tapes:
3
30 Hz to 15 kHz
aB.
Frequency response- recording:
In preparing master tapes: 30 Hz to 15 kHz ±3 dB.
In duplicating musicassette tapes: 30 Hz to 10 kHz
i3
dB.
duplicating stereo eight tapes: 30 Hz to 15 kHz
3dB.
All frequency response figures have been measured
with DIN reference tape 45513.
Signal to noise ratio: with reference to a one to
one duplicating speed, signal to noise ratio loss is
In
no greater than
1
to 1.5 dB.
Distortion: with reference to
a one to one duplicating speed, the distortion factor does not increase
(the percentage of distortion depends on the type of
tape and on the level of signal used).
Crosstalk at kHz: between the two tracks of the
master tape reproducer: greater than or equal to
50 dB. Between tracks one and two of musicassette
tapes: greater than or equal to 28 dB. Between
tracks two and three of musicassette tapes: greater
than or equal to 50 dB. Between adjacent tracks of
tapes or stereo eight cartridges: greater than or
equal to 50 dB.
Mains voltage: 220V, 50 Hz (60 Hz on request).
1
Current consumption:
Master console: 2.8A
for each slave recorder:
1.4A.
Production: (the number of musicassettes or
stereo eight cartridges depends, of course, on the
length of the programs). For example, musicassette
with two programs lasting 20 minutes each: about
50 pieces an hour for each slave recorder.
The V797 playback amplifier:
Frequency range (depending on the multiplication
factor of the speed): 120 Hz to 260 kHz.
Input: balanced, floating.
Input impedance: suitable for connexion to replay
heads for high speed.
up for the
Output: unbalanced.
Output level: 1.55V ( +6 dBm) across 200 ohms.
Maximum output level: 5.5V ( +17 dBm).
Output impedance: 40 ohms.
Sensitivity : with a signal on 320 nWb /m tape
running at
19 cm /s, the output level can be increased
up to 3V (12 ,-dBm).
Possible playback equalisations (by substituting
plug -in adjustment boards): 38 DIN or NAB x 8,
38 DIN or NAB x 4, 19 DIN S or H x 16, 19 DIN S or
H s 8, 9.5 DIN or NAB s 16.
Signal to noise ratio with adjustment
in position
for an output level of +6 dBm and with DIN 19H
equalisation: unweighted at least 42 dB, weighted
(1) at least 56 dB.
It should be pointed out here that when the duplicated tape is played back at its nominal speed
(4.75 cm /s for musicassettes and 9.5 cm /s for
stereo eight) the effective noise voltage is practically
reduced to the square root of the ratio one gets
between the duplicating speed and the nominal
playback speed mentioned above.
Distortion: Load resistance 300 ohms output level
+6 dBm: THD 0.07 per cent max. Output level +12
dBm: THD 0.05 per cent max.
Supply voltage: 20V dc.
Current consumption
:
30
mA.
Attenuation of 50 Hz frequency: at least 80 dB.
Dimensions: double plug -in printed circuit 100
x
Total depth with plug: 160 mm.
(1) The weighted noise is measured through a
filter with the same curve as the filter indicated in
the DIN 45405 standard (psophometric filter), the
single frequencies of which, however, are multiplied
16 times (e.g. 1 kHz x 16 =16 kHz).
160 mm.
The E696 Basic amplifier- equaliser
Frequency range (depending on the multiplication
factor of the speed): 120 Hz to 260 kHz.
Inputs: two unbalanced, electronically switchable
inputs.
Input impedance: at least 2 k ohms.
Output: one, unbalanced.
Output impedance: at most 20 ohms.
Output load: at least 2 k ohms.
Output level: 0.5V at 16 kHz.
Maximum output level: 2V at 16 kHz.
Equalisation: Input one (corresponding to
16 times
speed): low frequencies: fixed (according to standard characteristic corresponding to 1590 us at
nominal speed). High frequencies: may be regulated from 5 dB to 20 dB at 240 kHz corresponding
to 15 kHz at nominal speed. Input two (corresponding to eight times nominal speed): low frequencies:
fixed (according to standard characteristic corresponding to 3180 us at nominal speed). High frequencies: may be regulated from +4 to +30 dB at 120
kHz corresponding to 15 kHz at nominal speed.
Equalisation at low frequencies can be fitted by
means of bridges on the connecting plugs.
Amplification: max 6 dB to 16 kHz and respectively to 8 kHz.
Distortion: load resistance 2 k ohms output level
(nominal): THD 0.07 per cent max. Maximum output
level: THD 0.4 per cent max.
Signal to noise ratio with 16 x set -up: unweighted
at least 60 dB weighted at least 76 dB (1).
With 8 x set -up: unweighted at least 62 dB, weighted
at least 76 dB (1).
Supply voltage: 20V dc.
Current consumption: 16 mA.
Dimensions: 160 x 100 x 167 mm (including plugs).
The V696 recording amplifier
Frequency range:
90 Hz to 540 kHz.
Input: one, unbalanced.
Input impedance: at least
Input level: 0.5V.
Input sensitivity : 02V.
4k ohms.
Output: one, unbalanced.
Output impedance: 12 ohms maximum.
Output load: at least 200 ohms.
Nominal output level corresponding to maximum
recording level: 4V.
10V.
200 ohms load resistance, with 4V
level: THD 0.09 per cent max., with 10V
level: THD 0.9 per cent max.
Distortion: with
output
output
Signal to noise ratio: unweighted:
weighted: at least
at least 72 dB,
94 dB.
Adjustment: level.
Supply voltage: 40V dc.
Current consumption
:
45
slave console: approx 195 kg.
Dimensions: master console: 1.78m wide, 0.925m
high, 0.610m deep. Each slave console: 1.78 x
0.925 x 0.61m
(whd).
Prices: available
Features:
on application.
AMPEX
Ampex (GB) Ltd, Acre Road, Reading
RG1 6HZ.
Tel:
formats. Each slave can be equipped with a tailoring
device to deliver a completed product. All transports
accept reels as small as 13 cm and reels or pancakes
as large as 38 cm. Each master drives up to three
slaves, with three slaves, a system produces 168
365m copies in one eight hour shift. An internal
reference oscillator protects tape speed from line
power shifts.
The through the reel timing accuracy for any duplicator is x:0.08 per cent. Copies all major 3.8 mm and
6.25 mm formats. Automatic system stop /master
rewind. Accepts reels or pancakes from 13 to 38
cm diameter. Cassette /cartridge tailoring available.
Servo -controlled tape tension. Internal reference
oscillator for accurate tape speed. One master
drives up to three slaves. Attractive console design;
convenient control bridge.
0734 84411.
CD200 automatic cassette copier
A high speed automatic tabletop copier. Vacuum
columns completely isolate tape from the cassette
Professional duplicator heads are
mechanism.
The CD200 can turn out 375 C30 cassette
used.
copies per hour; a loader option makes it fully
automatic. CD200 also rewinds cassettes to the
start before copying, and senses and ejects defective cassettes. Two -track mono and four -track
stereo /two -track mono versions available. Features:
Copies 375 C30, 225 C60 or 120 C120 cassettes per
hour. Automatic loader option holds 100 cassettes;
can be loaded in 7s. Duplicates all tracks at one pass.
Automatically rewinds to start before copying;
senses defective cassettes and ejects them separately. One master controls up to five slaves.
Technical specification
Crosstalk rejection
:
50 dB or
better except between
stereo pairs.
Bias oscillator: nominal bias frequency: 500 kHz.
38 cm /s: 0.07`,'0,
76 cm /s: 0.05
19 cm /s: 0.1 ",,.
Signal -to -noise ratio : will not introduce more than
3 dB noise on duplicate.
Wow and flutter:
Direct record input: 50 ohms unbalanced, accepts
line level from 0.3V rms for recommended operating
level.
Fast speed: fast speed for rewind or search functions manually adjustable. Approximately three
minutes for 1,520m, 36 cm reel.
Start time: 3s to normal flutter specifications.
Stop time : 38 cm /s at 38 cm reel tape moves 76 mm.
from
Tape speed accuracy: within +,0.08
beginning to end of reel. With internal bridge
oscillator, tape speed unaffected by line voltage or
frequency fluctuations.
Power requirements: 105 to 125V ac, 50 to 60 Hz.
Controls: system control selects number of slaves
to be controlled. By main 'start' and 'stop' buttons.
Local control overrides system control and does not
affect other transports.
"
_+
(1) the weighted noise is measured through a filter
with the same curve as the filter indicated in the DIN
45405 standard (psophometric filter), the single
frequencies of which, however, are multiplied 16
times (e g 1,000 Hz x 16= 16,000 Hz).
Maximum output level:
Supply voltage: 20V dc.
Current consumption : 1.8A.
Dimensions: 160 x 100 x 167 mm (including plugs).
Weight: Master console: approx. 290 kg. Each
mA.
160 x 100 x 167 mm (including plugs).
(1) The weighted noise is measured through a filter
with the same curve as the filter indicated in the
DIN 45405 standard (psophometric filter), the
single frequencies of which, however, are multiplied
16 times (e.g. 1,000 Hz x 16 16,000 Hz).
The OS 696 Bias Oscillator
Nominal frequency : 560 kHz.
Dimensions:
Output: balanced, floating.
Output level : 6V.
Distortion : 0.06 per cent max.
Supply voltage: 20V dc.
Current consumption: 125 mA.
Dimensions: 160 x 100 x 167 mm (including plugs).
The HF 696 bias separator amplifier
Input: balanced, floating.
Amplification: 3 dB.
Distortion: 0.08 per cent max.
Outputs: two balanced, floating.
Supply voltage: 20V dc.
Current consumption: 1.1 A.
Dimensions: 160 x 100 x 167 mm (including plugs).
The LHF 696 bias power amplifier
Input: balanced, floating.
Amplification: approx. 6 dB.
Outputs: two balanced outputs, floating.
Output level: 15V.
Distortion: 0.2 per cent max.
Admissible load: at least 40 ohms.
Technical specification
Tape speed:
190
('_0.2%) cm /s throughout length
of C60 cassette.
Rewind speed: internally adjustable from 254 to
i60 cm /s (factory set at 380 cm/s).
Start time: with 76 cm of unrecorded tape: 0.4s at
190 cm/s from true end of tape to beginning of
program. 16s at 4.75 cm /s from true end of tape
(start time-time to reach 90 ",, of spec speed).
Overall cycletime : at C30 cassettes, approximately
40s plus load time (75 per hour per slave) C60
cassettes, approximately 75s plus load time (45 per
hour per slave).
Tape tension: constant at 93.3 (±15)g.
Frequency response: (referenced to 4.75 cm /s
playback speed).
System: 30 Hz to 12 kHz, =2 dB.
Typical copy: 50 Hz to 8 kHz, 1-2 dB, using Ampex
361 cassette, biased for maximum long wavelength
sensitivity.
Flutter: less than 0.05" rms NAB weighted.
Overall signal -to -noise ratio: 3 dB maximum
degradation in 30 Hz to 10 kHz band.
Crosstalk rejection: 20 dB (min) at kHz playback
between adjacent tracks of stereo pair. 50 dB (min)
between programs.
Power: 105 to 125V ac 58 to 62 Hz 6A (48 to 52 Hz
operation optional).
1
Operating temperatures:
65
C
10 °C
to 35`C
(-40
C to
storage).
Humidity: 5"ó to 95°;; non -condensing.
Weight: 16 kg.
Dimensions: 560 x 533 x 273 mm (wdh).
Format tailoring : 76 cm of unrecorded tape
(including leader). Program 76 cm of unrecorded
tape at end (including leader).
Track formats: four -track stereo two -track mono.
End of tape sensing : true end of tape sensed
independent of leaders, splices, sensing tape, or
tones.
Automatic slave loading: 100 cassettes (may be
replenished manually while CD200 is operating).
Load time: approximately 72.
Price: Available on application.
AD15 duplicator system
The AD15 offers a wide range of formats. Additional
heads and guides permit changes from reel -to -reel
formats to eight track cartridge formats to cassette
Tape formats:
Full and two track mono, full and two track stereo,
quarter track stereo, four track stereo cartridge,
eight track stereo cartridge: 6.25 mm tape 25
or 38 um.
Four track stereo cassette, two track mono
cassette, 3,800 um tape. 12.7 um base. Tensilised
polyester.
Number of slaves: one to three slaves can
attached to
Reel size:
a master reproducer.
13 cm to 38 cm reel diameter.
be
NAB or
EIA Std.
Tape speeds: 19, 38 and 76 cm /s.
Frequency response (1 :1 duplication):
Master tape 19 cm /s NAB, Copies 19 cm /s NAB.
Master speed 76 cm /s, Slave speed 76 cm /s:
4 dB, 50 Hz to 15 kHz.
Master tape 9.5 cm /s NAB, Copies 9.5 cm /s NAB,
Master speed: 38 cm /s, Slave speed: 38 cm /s:
+2 to 4 dB 50 Hz to 12 kHz.
Master tape: 9.5 cm /s NAB, Copies 9.5 cm /s NAB,
Master speed 76 cm /s, Slave speed 76 cm/s:
2 to 4 dB 50 Hz to 7.5 kHz.
Master Tape cassette, Copies cassette, Master
speed 19 cm /s, Slave speed 19 cm /s: -2 to 4 dB
50 Hz to 10 kHz.
Master Tape cassette, Copies cassette, Master
speed 38 cm /s, Slave speed 38 cm /s: -2 to 4 dB
50 Hz to 5 kHz.
+2 to
duplication)
Master tape 19 cm /s NAB, Copies 9.5 cm /s NAB.
Master speed 76 cm /s, Slave speed 38 cm /s:
+2 to 4 dB 50 Hz to 12 kHz.
(4:1 duplication)
Master tape 19 cm /s NAB, Copies cassette,
Master speed 76 cm /s, Slave speed 19 cm /s:
+2 to 4 dB 50 Hz to 10 kHz.
Direct recording from auxiliary source (up to
three copies per run) Recording speed: 19 cm /s
NAB equalisation 6.25 mm tape: +2 to 4 dB
(2:1
50
62,
Hzto15kHz.
STUDIO SOUND, APRIL
1973
61
TAPE DUPLICATORS
19
cm/s open reel:
System noise:
.
3.8mmtape: +2 to4dB50Hzto
Price: available
RR200
10
kHz.
on application.
duplicator system
The system consists of an RR200 master reproducer and up to ten 3400 slaves. The RR2008 plays
back eight- track, 25 mm masters to produce high quality track cartridge tapes. One version of the
RR2004 uses 12.5 mm masters to duplicate four
track stereo or four channel stereo formats; a
change of plug -in head assemblies and turn -around
tape guides, and it becomes a 6.25 mm machine in
either two or four channel format, depending upon
the head assembly used. The RR200 can be concerted from 152/304 cm /s to 76/152 cm /s by a change
of capstan idlers (provided) and removal of acapstan
sleeve. Five different plug -In head assemblies are
available for the 3400 slave, each with its own bias
and record level adjustments: tape tensioning
adjusts automatically with each head change. Uses
6.25 mm and 3.8 mm.
Technical specification
Tape speeds: 152/304 cm /s selectable (changeable
to 76/152 cm /s selectable).
Master tape formats:
RR2008: eight tracks on 25 mm wide tape.
RR2004: four tracks (staggered) on 12.5 mm wide
tape, four track (in line) on 12.5 mm wide tape.
RR2004: full track two track (in line) four track
(staggered) or four track (in line) on 6.25 mm wide
tape.
Maximum reel size:
356 mm
outside diameter: 6.25 mm and 12.5 mm
tape.
outside diameter 25 mm tape.
1 % peak to peak from
0.5 Hz to 10 kHz (unweighted). Will not introduce
more than 0.15% rms (ASA 'A' weighted) In copy.
Electronics Bandwidth : exclusive of equalisers,
+1 dB 300 Hz to 300 kHz.
Equalisation switching : independent switching is
provided for both master and copy equalisation.
266 mm
Wow and flutter: less than
Frequency response of reproducer:
19 cm /s NAB master, 304 cm /s, 800 Hz to 160 kHz,
±2 dB, (50 Hz to 10 kHz at 19 cm /s).
19 cm /s NAB master, 152 cm /s, 400 Hz to 120 kHz,
±2 dB, (50 Hz to 15 kHz at 19 cm /s).
38 cm /s NAB master, 304 cm /s 400 Hz to 160 kHz,
±2 dB, (50 Hz to 20 kHz at 38 cm /s).
Typical frequency response of copies (tape
limited)
4.75 cm/s cassette 50 Hz to 8 kHz +2 dB.
9.5 cm /s cartridge or open reel: 50 Hz to 10 kHz
+2 dB.
50 Hz
to
15
kHz, ±2 dB.
original recording. Provisions in the master assembly allow increasing the number of slaves to twenty
by adding bias amplifiers.
The transport is equipped with its own loading/
unloading motor assembly to transfer tape directly
from a reel to the storage bin. A photocell assembly
mounted in the tape path automatically counts the
number of master passes and injects a 120 Hz or
320 Hz tone on the opies for cutting points.
A new head produces a higher output at midfrequencies and greater efficiency at high frequencies.
Preamplifiers are mounted on the head
assembly. This arrangement avoids rf interference.
and redi.ces signal -to-noise ratio by reducing
capacitive shunting of the head cables.
ystem set up for to cm's master at 3u4 cm /s dU
below blank, biased Ampex 404 series tape ASA
'A' weighted at least 10 dB.
2.1 kHz bandwidth, 16 kHz (1 kHz at real speed) at
least 5 dB.
2.1 Hz bandwidth, 64 kHz (4 kHz at real speed) at
least 12 dB.
2.1 Hz bandwidth, 160 kHz (10 kHz et .eal speed) at
least 8 dB.
Total harmonic distortion:
System exclusive of tape, 0.2% at operating level.
Overload margin: reproducing amplifier: up to
level control 20 dB above operating level, after level
control 17 dB operating level.
Recording amplifier: 20 dB above operating level.
Bias supply: 1 MHz, adjustable to 60V rms at
0.5A rms.
Power requirements: 117V (±10% ac, single
phase, 50 of 60 Hz; 4A approx.
Dimensions: RR2004 660 x 762 x 1550 mm, RR2008
660 x 762 x 1550 mm (wdh) Metal cabinet with all
electronics mounted in overhead bridge.
Price: available on application.
BLM200 duplicator system
Automatic high speed duplication of multichannel
cassette and cartridge tapes is now offered by the
Ampex BLM200 duplicator system.
Rewinding.
stopping, and rethreading of the tape is eliminated
by use of an endless loop tape in the master transport. All solid -state electronics are used throughout, The system consists of the BLM200 Bin Loop
Master and up to 20 slave units of the 3400 series.
Constructed on a building block principle to provide
for future expansion, the basic BLM200 mister will
drive up to ten slaves and an optional configuration
is offered to drive twenty slaves.
BLM masters are available In two models, the
8LM2008 and the 8LM2004. The BLM2008 is an eight channel version for cartridge duplication. However,
the eight -channel BLM2008 system will also duplicate
four channel cassette tapes by rotating the slave
tape guides and replacing the plug in slave head
assembl ies.
The BLM2004 is a four channel version for cassette
duplication. If a four channel cassette master unit is
purchased first, it can be field converted to an
eight-channel cartridge version by adding a bias
amplifier, a power supply, and four more channels of
electronics. Conversion of the slave units is possible
in the field because all 3400 series slave units are
already equipped with dual-width guides and use
plug -in head assemblies. Installing the eight -track
head assemblies automatically programs the
correct tape tension.
Working master tapes for both formats are recorded
on wide tape with 38µm polyester backing, recorded
at NAB equalisation. Recordings are made in fourto- eight-track formats on eight -track recorders such
as Ampex Model MM10008 or Model ÁG4408. A
working master tape for the eight track duplicator
system follows the same track configuration as that
of the eight track cartridge format: tracks one and
five, tracks two and six etc as stereo pairs, all in
forward direction. For the four track duplicator
system, tracks three and seven make up the stereo
pair in the forward direction, and tracks six and two
in the reverse direction. (When making the master
tape, recording is done on tracks, three and seven
in both directions.)
BLM200 Master reproducer
The BLM200 master reproducer is a s =1f- contained
bin -loop system. It consists of a bin -loop tape transport, a reproduce head and preamplifier assembly,
reproduce amplifiers, record amplifiers and a bias
oscillator /amplifier. The BLM200 drives up to ten
slaves assemblies at up to 32 times the speed of the
3400
series slave assembly
The 3400 series slave assemblies are newly adapted
versions of the Ampex Model 3200 slave assemblies.
The 3400 series slave transports have turn -around
guides with 3.8 and 6.25 mm guides for tape width
conversion. Automatic tape tension programming
is also provided to reduce the possibility of tape
stretch or breakage.
Plug -in head assemblies for both four track cassette
and eight track cartridge systems are ferrite core
type and are equipped with their own individual bias
and record level controls for each track. The controls are on top of each head assembly, Insuring
interchangeability without resetting controls. No
wiring changes are required when changing from
four track cassette to eight track cartridge head
assemblies.
The 3400 series slave head assemblies for all
standard open -reel formats are also available.
Technical specification
BLM200 Master assembly
Tape speeds: 152/304 cm /s or
304/608 cm /s.
25 mm wide
Recorded at 19 cm /s NAB
Master tape format: eight tracks on
tape 38 µm polyester.
equalised.
Maximum tape capacity: 380m (about
45
minutes
of playing time per program track at 19 cm /s).
Wow and flutter: less than 1 % peak-to -peak from
0.5 Hz to 10 kHz (unweighted). Will not introduce
more than 0.1 % rms (NAB weighted) in final copy.
Frequency response:
Reproduce chain from 19 cm /s NAB equalised
master: +1 dB 500 Hz to 160 kHz at 304 cm /s.
+1 dB 1 kHz to 320 kHz at 608 cm /s (30 Hz to 10 kHz
at final copy speed).
Duplicated copies: ±2 dB, 50 Hz to 10 kHz, 9.5
cm /s eight track cartridge. +2 dB, 50 Hz to 8 kHz
at 4.75, cassette.
Tailoring tone: switchable 120 Hz or 320 Hz,
actuated by photocell, applied at saturation level to
input of record amplifiers.
Crosstalk rejection : between the tracks or between
the adjacent even or odd track pairs; greater than
50 dB from 30 Hz to 10 kHz (at final copy speed).
System noise: better than 10 dB below a blank,
biased, Ampex 404 series low noise tape; 30 Hz to
5 kHz at final copy speed. Better than 6 dB up to
10 kHz.
Total harmonic distortion: system, exclusive of
tape; 0.3% at Ampex operating level.
Overload margin: up to reproduce level control
and record electronics: 20 dB above Ampex operating level. Reproduce electronics after the level
control: 17 dB.
Environmental conditions: temperature: 16 to
41
°C.
Relative humidity: 50 to 90 %.
Power requirements: 115V (+10 %) ac single
phase, 50 or 60 Hz: 7A (BLM2004) and 9A (BLM2008)
at 115V.
Dimensions: 155 x 107 x 69 cm
Weight: 225 kg.
Price: available on application.
Left: Ampex BLM
62
200
duplicator
64
highest attainable technical
performance
quick
and easy
No major repair facilities available?
This professional tape recording equipment needs none
and can be used with confidence anywhere in the world.
In the past a fault in sophisticated equipment could mean
expensive down time, but in the E200 any fault can be
quickly isolated and the part or circuit replaced.
All major mechanical components and sub -assemblies are
quickly and easily changed. Many circuits simply plug -in.
Contact Nick Nichols at our
London office, telephone
01 -874
9054
LEEVERS-RICH
NEUMANN SX68
EQUIPMENT LIMITED
F.W.O. Bauch Limited
49 Theobald Street
Boreham Wood Herts.
Tel: 01-953 0091
A Member of the MCP Group
LEEVERS -RICH EQUIPMENT LIMITED
319 TRINITY ROAD, WANDSWORTH,
ENGLAND
LONDON SW18
STUDIO SOUND, APRIL
1973
63
TAPE DUPLICATORS
Auxiliary cassette to cassette unit
If both 6.25 mm tape and cassettes are to be used as
masters, then
series slave assembly
Tape speed: 76/152 cm /s or 152/304 cm /s.
Slave tape format: eight tracks on 6.25 mm tape
3400
m or 25:1m polyester or acetate (Ampex 681 tape
or equivalent). Four tracks on 3.8 mm wide tape,
12.5 ;a.m polyester (Ampex 9219 tape or equivalent).
Other formats available.
Maximum reel size: 36 cm in diameter. A hub
diameter smallerthan 11.5 cm (NAB size) not recommended for 3.8mm wide tape.
Wow and flutter: less than 1". peak-to -peak from
0.5 Hz to 10 kHz (unweighted).Will introduce less than
0.1
rms (NAB weighted) in copy.
38
Power requirements: 115V
(zr_10 %)
ac single
phase, 50 or 60 Hz 2A per slave ässembly.
Dimensions: 79 x 66 x 66 cm.
Weight: 68 kg with metal cabinet.
Price: available on application.
a
separate high speed cassette replay
unit may be plugged into the standard master
Cassette rewind unit.
Cassette to cassette copier
Up to four cassettes may be loaded independently
into the fast wind unit. Half- hour-per -side (C60)
cassettes are rewound in approximately 20s and are
ejected automatically at the end of the process.
Operation
The machines demand little or no skill to operate
and with electro- mechanical interlocks, monitor
speaker and indicator lamps their operation is
simple and foolproof and unskilled personnel can
be trained in a few minutes.
Head and track configurations
The standard master unit contains two record and
two replay channels, and standard heads are
supplied to transfer any two tracks simultaneously
within the normal 6.25 mm tape and 'Philips' cassette
standards. Extra channels and non -standard track
configurations can be supplied to order.
Durability
B
All tape heads
&A
Branch and Appleby Ltd, 42 High Street,
Harrow -on- the -Hill, Middlesex.
Tel:
01
-864 1577.
The B & A Systems Division of Branch and Appleby
manufacture head electronics and high speed
copying equipment for tape and cassettes. The
equipment is variably custom built to satisfy specific
requirements and is designed around modular units.
Vaiiety of in cassette' dubbing machines has
evolved during the past three years which can
satisfy most small to medium production requirements in the educational and entertainment fields.
A typical technical specification follows. Complementary high speed rewind units and demagnetisers
are also offered.
Master reel to cassette copier
This unit uses a reel -to -reel playback deck to transfer master recordings made at9.5 cm /s at a speed of
3.8 cm /s on to eight cassettes running at 19 cm /s for
eventual playback at the standard speed of 4.75
cm /s. The master reel -to-reel deck and the cassette
decks are all electronically interlocked during the
dubbing process but the system allows the stopping
or removal of any cassette during dubbing without
disturbing the remaining cassettes. The system
run -up time is less than 2s.
Master cassette to cassette copier
This is similar to the master dubber, but with a high
speed cassette playback deck substituted for the
reel -to-reel deck.
Slave copier
The eight cassette slave unit is connected to the
master unit by a single multicore cable and is
remotely controlled via the mastercontrol panel. Any
number of slave units may be added to increase
output; for example with ten slave units over 5,000
dubbed cassettes can be produced in an eight hour
day.
in B & A systems equipment are
manufactured by Branch and Appleby Limited, and
are fully guaranteed subject only to fair wear and
tear, for six months. Frequency response remains
constant throughout head life, which is not less
than 1,000 hours for the reel -to -reel deck and not
less than 2,000 hours for the cassette desks.
In the event of mechanical or electronic failure:
1. the cassette decks (which are factory set for
immediate use) unplug on the removal of the cover
and one screw,
2. the electronic circuit boards slide into edge
connectors -no technical knowledge is required to
replace them.
3. the above and all other parts are available by return
of post from B &A Systems on an exchange replacement basis.
Master Copier Technical specification
Standard machine frequency response: 40 Hz to
11
kHz rh2 dB.
Cassette to
50 Hz to 8 kHz
cassette
f3
frequency
response:
dB.
Signal to noise ratio : within 2 dB of master tape.
Crosstalk rejection, standard model: better than
46 dB.
Distortion: no degradation of master tape.
Wow and flutter: less than 0.25% rms.
Equalisation, standard model: to DIN 45513.
Level indicators: true peak reading meters.
Bias supply: crystal controlled master oscillator,
push -pull power stages.
Monitor speaker: switchable to either channel
volume adjustable.
Master deck rewind speed : 20 minutes tape in 35s.
Auxiliary input: three pole GPO jack low impedance 1.5 k ohms for additional master deck.
Duplicating rate without slave units: up to 60 type
C60 cassettes per hour.
Transfer speed: four times normal playing speed.
Power requirements: 210 to 250V 50 Hz 2A.
Console dimensions:
floor standing 1,200 x
desk type: 580
540
x
(HWD).
(HWD).
570 mm
x 540 x 570 mm
Weight:
floor standing: 37 kg.
desk type: 33 kg.
INFONICS
Agents: Fraser -Peacock Associates Ltd,
High Street,
SW19.
Tel
:
01
Wimbledon
94
Village, London
-947 2233/1734.
Infonics fast speedwinder
The Infonics speedwinder will rewind or advance up
to six cassettes at high speed. Any combination of
cassettes can be loaded and unloaded while others
are still rewinding. Cassettes can wind forward or
backward simply by reversing the cassette position.
The speedwinder has individual cassette shutoff at
the end of each tape so that cassettes of any length
can be wound simultaneously.
Dimensions: 356
Weight: 5 kg.
x
212 x 121 mm.
Capacity : six cassettes.
Power: model SWE 220V ac, 0.75A.
Warranty: one year.
Price:
£100.
Infonics reel to reel duplicator model RR4
(stereo)
Duplication of tapes recorded at any speed from
performed at 63.5 cm /s, with all
tracks being duplicated simultaneously. The reel to
reel duplicator produces three 365m reels of magnetic tape from a master reel in ten minutes. Plug-in
slaves extend the duplicator's capacity by an additional four duplicate tapes so that a system consisting of a duplicator and two slaves produces 11
tapes every ten minutes.
Duplicating time (30 minute tapes): four minutes.
Master duplicating speed: 63.5 cm /s.
Copy duplicating speed: 63.5 cm /s.
Master recording speed: 4.75 to 38 cm /s.
Frequency response: 20 Hz to 15 kHz, ±3 dB.
Signal to noise ratio: 50 dB.
Wow and flutter: 0.2 % rms.
4.75 to 38 cm /s is
Timing accuracy: 0.2 %.
Dimensions: 406 x 406 x 420
Weight: 22.2 kg.
Price: £1575.
mm.
Infonics reel to cassette duplicators (Super
RC-2 or Super RC-4, mono or stereo available).
The Super RC line of reel to cassette duplicators
features a 152/76 cm /s master tape transport with a
dual speed hysteresis- synchronous capstan motor
and two torque motors.
Duplicating time (30 minute tapes): 2.3 minutes.
Master duplicating speed: 152 or 76 cm /s.
Copy duplicating speed: 38 cm /s.
Master recording speed: 19 or 9.5 cm /s.
Frequency response: 20 Hz to 10 kHz +3 dB.
Signal to noise ratio: 45 dB.
Wow and flutter: 0.3% rms.
Timing accuracy: 0.2 %.
Dimensions: 572 x 610 x 380
Weight: 4.1 kg.
Price:
mm.
Super RC -2 £1743.
Super RC -4 £2415.
Infonics reel to reel duplicator model RR2
(mono)
Duplication of tapes recorded at any speed from
4.75 cm /s
to 38 cm /s is performed at 63.5 cm /s with
all tracks being duplicated simultaneously. The reel
to reel duplicator produces three 365m reels of
magnetic tape from a master reel in ten minutes.
Plug-in slaves extend the duplicator's capacity by an
additional four duplicate tapes so that a system
consisting of a duplicator and two slaves produces
11 tapes every ten minutes.
Duplicating time (30 minute tapes): four minutes.
Master duplicating speed: 63.5 cm /s.
Copy duplicating speed: 63.5 cm /s.
Master recording speed : 4.75 to 38 cm /s.
Frequency response: 20 Hz to 15 kHz, ±3 dB.
Signal to noise ratio: 50 dB.
Wow and flutter: 0.2% rms.
Timing accuracy: 0.2 %.
Dimensions: 406 x 406 x 420
Weight: 22.2 kg.
Price: £1102.
Infonics cassette copier
mm.
102
The model 102 makes two cassette copies from an
original cassette at 63.5 cm /s or approximately 14
64
times the normal cassette playing speed. Two C30
cassette copies are produced every minute. Both
tracks are duplicated in one run. Cassettes of any
length can be run in the copier up to C90s.
Duplicating speed: 76 cm /s.
Duplicating time: (C30s): minute.
Rewind time (C30s): 30s.
1
Frequency response: 40
Bias oscillator: 500 kHz.
Dimensions: 445
Weight: 15.9 kg.
Price: £900
x
Hz to 10 kHz
+3 dB.
305 x 260 mm.
Infonics reel to cassette slave duplicators
(CS -2 and CS-4 mono or stereo available).
To expand the duplicating capacity of all Infonics
duplicators up to three cassette slaves (CS) may be
electrically connected to the duplicator. Each slave
makes an additional eight cassettes in complete
synchronism with the master tape.
With a system consisting of one duplicator and one
slave, therefore a total of 12 C-30 cassettes can be
This provides a
duplicated every 23 minutes.
duplicating capacity of 1,400 cassettes every eight
hours.
CS -2 £1575. CS
Price:
-4 £2100.
BRENELL
Brenell Engineering Co Ltd,
Liverpool Road, London N1.
Tel 607 8271.
231 235
Tape speed:
38 and 19 cm /s standard; 19 and
cm/s to order; 76 and 38 cm /s to order.
Tape speed stability: better than +0.2%from end
to end of reel with reference to absolute.
Rewind speed: 730m in 90s continuously variable.
Start time: 0.9s to rated wow and flutter condition.
Spool capacity : 29 cm European, 26.7 cm NAB,
21 cm cine.
Wow and flutter: (measured over bandwidth of
200 Hz) 0.06° rms total at 76 cm /s, 0.06% rms total
rms
at 38 cm /s, 0.08% rms total at 19 cm /s, 0.1
total at 9.5 cm /s.
Frequency response: (overall response within +2
dB between) 40 Hz and 25 kHz at 76 cm /s, 40 Hz and
18 kHz at 38 cm/s, 40 Hz and 14 kHz at 19 cm /s,
40 Hz and 10 kHz at 9.5 cm /s. Noise level: measured
unweighted at 38 cm /s. Full track 62 dB below peak
level. Stereo 60 dB below peak level. Twin track
58 dB below peak level.
Cross talk: Twintrack 45 dB minimum at 1 kHz.
Distortion: total amplifier distortion at peak level
9.5
0.2% between 40 Hz and 15 kHz.
Input: -14 dB for peak recording level with preset
sensitivity adjustment. 10 k ohms bridging.
Output: maximum output before clipping +22 dBm
into 600 ohms. Source impedance approximately
50 ohms.
Metering : VU meter standard ppm to order. Switched to read 'line in' and 'line out' and'reccrd'.
Monitor: Switched to read 'line in' and 'line out'.
Terminations: Cannon XLR3.
Duplicating system price: from £1945.
:
Tape duplicating equipment made to customer's
specifications.
LIBERTY/UA
Agents: Avcom
Systems Ltd, Newton
Works, Stanlake Mews, London W12 7HA.
Tel:
KLARK TEKNIK
Klark Teknik Ltd, MOS Industrial site,
Summerfield, Kidderminster, Worcestershire.
Tel
:
0562 64027.
Teknik 2000 tape transport
A range of tape recorders and reproducers from
38 mm to 50 mm tape widths.
Type
2000S
Slow speed, multi -track for cassette and cartridge
quality control.
Features: wow and flutter 0.6% at 9.5 cm /s; dc
servo-controlled capstan; digital electronic tape
measurement; complete logic control; all solid
state relays; low s/n ratio 60 dB (weighted); can
operate with pancake spools to 43 cm diameter;
constant tension in all modes for storage of duplicated tape.
Type 2000N -25 mm
Variable speed 19 cm /s-38 cm /s for preparing
masters. Available as reproducer only or as a
complete recorder.
Features:less than 0.05ió wow and flutter; extremely
high audio and mechanical performance.
winding
April-Cartridge /cassette
Available
machines-comprehensive range of automatic
high -speed logic controlled winders /splicers. Klark
Teknik specialise in complete installations including
interface mixers, and so on.
LEE VERS -RICH
Leevers -Rich Equipment Ltd, 319 Trinity
Road, Wandsworth, London SW19.
Tel: 874
9054.
Systems built to customers specific requirements
based on the E200 open reel tape duplicating
machine.
E200
Tracks: full, twin
01
749 2201.
Liberty tape duplicator
The Liberty tape duplicator is designed primarily to
mass reproduce cartridge and cassette tapes on a
reel to reel basis, to be broken down after duplication. This method of duplication provides a more
consistent and higher quality finished product than
can be achieved within cartridge duplication.
The duplicator consists of one cabinet rack containing the head preamps, slave driver electronics, bias
supply, master tape deck and tape bin. The master
unit will drive one to ten slaves.
A special 6.25 mm tape loop bin system is available
for cassette duplication where it is not desirable to
go to 25 mm or 12.5 mm masters with accompanying
added mastering expenses and equipment.
Necessary associated equipment would be a breakdown winder such as the Liberty Winder CW15
with 20 Hz sensing amplifier.
Liberty Tape Duplicator LT1600 series
Duplicating ratio:
16:1.
Master speed and system: real time of master is
cm /s recommended. Loop bin system 304 cm /s.
152 or 76 cm /s.
Capstan Drive: Flywheel and belt drive to hysteresis synchronous motors. Slave capstans ceramic
coated for less wear and tape slippage problems.
Wow and flutter: will not add more than 0.15".,
duplicates measuring components to 400 Hz.
Frequency response: 9.5 cm /s duplicates +2 dB,
-3 dB 40 to 10 kHz 4.75 cm /s duplicates 4 2, -3 dB,
40 to 10 kHz.
Crosstalk rejection: greater than 50 dB except,
19
Slave speed:
between cassette stereo pairs.
Master tape and reel sizes: 25 mm or 12.5 mm for
eight channel. 12.5 or 6.25 min for four and two
channel. Up 25 mm reel on master.
Slave tape and reel sizes: 6.25 mm and 3.8 mm
cassette up to 36 cm reels on slaves.
Electronics: amplifiers and equalisers on plug -in
cards. All solid state.
Heads: Ferrite for maximum head life and minimum
maintenance on slaves. Heads on plugs for easy
change of duplication formats and maintenance
Mumetal on master.
Bias frequency : 1 MHz crystal controlled.
Tape guides: except in head assemblies are roller
type for minimum tape stress.
Tape wipers: on all units built -in wipers to reduce
head clogging and wear.
Production capabilities: Capacity based on program content is about 32 minutes total all sides,
production should be approximately 640 to 840 eight
track cartridges per one slave during an eight hour
shift. About 320 to 420 cassettes per slave during an
eight hour shift. (This of course, depends on operator skill and down time of duplicator.)
Programmed operation: manual slave start and
stop at master cabinet or automatic start from
master tape leader through photocell logic. Manual
stop at master or predetermined stop after desired
number of runs through predetermined counter in
master cabinet.
Power requirements:
Master 720W; per slave: 180W
120V. 60 Hz, (220V 50 Hz operation available).
Shipping weight: about 726 kg.
Prices: from £7920 (with 6.25 mm loop bin master
transport, quarter track electronics for stereo
cassettes and one 'slave' position). Note: This
equipment can be ordered for cassette or eight
track cartridge use, with a number of slaves, and
with 25, 12.5 or 6.25 mm loop bin master options, and
a Mumetal or ferrite head option.
PENTAGON
Agents: Afcom
Systems Ltd, Newton
Works, Stanlake Mews, London W12 7HA.
Tel:
01
749 2201.
Pentagon make a number of units which can be
combined in a variety of ways. Systems can be reel
to reel, reel to cassette, cassette to cassette or
cassette to reel; two track or four track; eight or 12
times copying speed ratio; various speed and
widths of tape. A few typical designs are described
below.
RM1200 /RM1400 reel to reel, two or four track
master
Master tape deck:
Designed for high speed duplicating. Direct drive
capstan from dual speed synchronous motor. Two
direct drive inducation spooling motors. Failsafe
Interlock
differential mechanical brake system.
motion control circuitry employing relay and solid
state switching logic. Automatic tape lifter in fast
winding modes, defeatable for cueing purposes.
Master operating speeds: 76 cm /s and 152 cm /s
master.
Rewind time: approximately 45s for
Power: 115V, 60 Hz single phase.
18
cm reel.
and stereo dimensions to BS
66
1568 -1970.
STUDIO SOUND, APRIL
1973
65
I
TAPE DUPLICATORS
operated push- buttons with defeatable tape lifter
(for cueing purposes). Cassette transports have
synchronous drive capstan motors. Both reel and
cassette transports are designed for continuous
operation. Bias readout, individual channel selector
switches. 'Accutrack metering' and pull out circuit
boards. Will accept NAB hubs.
C1323 Tri -Master 'Editor' duplicator
Reel to cassette, cassette to cassette, cassette to
reel (for 9.5 and 19 cm /s reel masters 4.75 cm /s
cassette masters).
This system permits the duplication of either reel to
reel or cassette masters on to three cassette slave
positions. In addition, this system can convert the
reel play transport into a record deck. Through use
of the cassette master position, it is then possible
to transfer cassette program information on to the
reel to reel transport for editing purposes. The reel
to reel transport is a two speed 27 cm deck with
relay operated push- buttons. The tape lifter can be
released for cueing purposes. The tape deck uses
direct drive dual speed synchronous capstan motor
and two direct drive spooling motors. The cassette
transports have synchronous drive capstan motors.
Both reel and cassette transports are designed for
continuous operation.
Bias readout, channel
selectors test switch. 'Accutrack Metering' and pull
out circuit boards. Will accept NAB hubs.
C5400 Reel to cassette (for 12.5 mm, 9.5 and 19
cm /s reel masters)
A stereo duplicator system that provides four
cassette copies from 12.5 mm reel tape masters.
The tape transport will accept 27 cm reels and
utilises a direct drive dual speed synchronous
capstan drive motor and two direct drive spooling
motors. The push buttons are relay operated and
the tape lifter is defeatable (for cueing purposes).
The cassette transports have synchronous drive
capstan motors. Both reel and cassette transports
are designed for heavy duty operation. All cassette
positions have individual audio /bias level controls
to permit precise and accurate level adjustments on
all cassette record channels. Premium stereo (four
track) cassette heads are included in this system.
Bias read -out, individual channel selector switches,
'Accutrack Metering', mono /stereo switch and pull
out circuit boards are all standard on this duplicator.
C -340 Cassette to cassette (for 4.75 cm /s cassette
masters)
Duplicating system consisting of one cassette
master with three cassette slave positions. Unit
includes features such as 'Accutrack Metering' bias
read -out, individual channel selector switches, test
position switch and pull out circuit boards. Transports are driven by synchronous capstan drive
motors. Each cassette position has precision capstan and slider assemblies.
Note: Models are available in both eight and 12
times normal play speeds and in two and four track
formats.
C -140 Cassette copier
This model offers a cassette master and cassette
slave position. One push- button starts and completes each duplicating run. Uses integrated circuits has built in rewind capabilities for both master
and slave positions as well as channel selector
switches. Duplicating speed is 38 cm/s and has
add -on capability of recording from reel masters.
RME -2410 Reel Master (For use with most Pentagon
slave models). Uses 9.5 and 19 cm /s reel masters.
Two speed 27 cm reel to reel master transport
complete with control electronics. VU meters and
level controls. This reel master works directly into
most of Pentagon's slave models. The transport has
direct drive dual speed synchronous capstan motor
66
and two direct drive spooling motors. Uses relay
operated push- buttons with defeatable automatic
tape lifter (for cueing purposes). Will accept NAB
hubs. Bias readout, individual channel selector
switches. 'Accutrack Metering' and pull -out circuit
cards.
CM -1400 Cassette Master (For 4.75 cm /s cassette
masters)
Plug in module adaptable to Pentagon master
systems that do not already possess cassette
master capabilities.
capstan drive motors for greater speed accuracies.
Has precision capstan and slider assemblies and
channel selector switches for greater flexibility and
reliability. These slave modules are designed for
use with the cassette copier series of duplicators
(C120- C140). A total of three additional slaves
modules (six slave positions) can be added to the
C120 duplicator without additional electronics. A
total of two additional slave modules (four slaves)
can be added to a C140 duplicator unit without
additional electronics. The slaves are housed in
solid walnut cabinets to complement the C120/C140
duplicator line. Additional electronics may be
purchased to increase system size.
RS2410 Reel to reel slave (6.25 mm tape)
Two speed 27 cm reel to reel slave transport for
reproduction of 6.25 mm reel copies of programmed
materials.
The transport has two direct drive
spooling motors. The capstan motor is a direct
drive dual speed heavy duty synchronous motor.
Transport is designed for continuous operation and
is housed in walnut veneer cabinet. System will
accept 27 cm pancake reels with conventional
NAB hubs. This reel slave can provide 38, 19 and
9.5 cm /s reel copies from 38, 19 and 9.5 cm /s reel
masters.
RS -1410 Reel to reel slave (38 µm tape)
27 cm reel to reel slave transport with direct drive
spooling motors. Capstan motor is a direct drive
heavy duty synchronous motor.
Transport is
ruggedly designed for continuous duty operation
and is mounted in a functional walnut veneer
cabinet. System will accept 27 cm pancake reel
with standard NAB hubs. Slave provides 4.75 cm /s
cassette programs for loading into cassette shells.
S -140 Two station cassette slave
Two position slave module utilising synchronous
PHILIPS
Pye TVT Ltd, PO Box41, Coldhams Lane,
Cambridge CBI 3JU.
Tel : 0223 45115.
Philips STD
Philips STD tape duplicators consist of one master
reproducer and any number of slave recorders, up
to twenty. The machines are solid -state and self contained which implies that a simple installation
consisting of one master and two slaves can be
extended just by adding a number of slaves. The
equipment complies with the most severe demands
of studio transcription services.
Master Reproducer
The master reproducer comprises a steel console,
containing a tape deck and three 480 mm panel units.
These units are: a container for the plug -in amplifiers, a filter unit, and a 24V dc power supply.
Tape deck
The master reproducer is equipped with a heavy duty tape deck being specially adapted for tape
duplicating. A hysteresis synchronous motor for
1500 and 3000 rpm gives tape speeds of 76 and 152
cm /s. The tape deck is provided with an automatic
tape lifter which comes into operation on rewinding.
Tape tension is controlled electronically and kept
at 80g.
Controls
The tape deck of the master reproducer is provided
with push- buttons for start, stop and fast rewind.
These buttons also control the operation modes of
the slave recorders. In addition, there is a continuous control to adjust the fast -winding speed.
An end -stop switch employing a light- dependent
resistor (LDR) unit automatically stops the master
reproducer if the tape should break, or when the end
of the tape is reached, after playback or rewinding.
The use of transparent leaders of sufficient length
at both tape ends prevents it from running off the
CS -440 Four station cassette slave
Four position slave module utilising synchronous
capstan drive motors for greater efficiency and
accuracy.
System design enables hook -up of
unlimited number of slave modules to master
console due to slaves unique design. Cassette
transports are ruggedly designed for continuous use
application and have precision capstan and slider
assemblies. Also pullout circuit boards for serviceability.
S-1400 Eight station cassette slave
Same as above CS 420 /CS 440 slave system specifications except for number of slave positions. This
system contains eight slave positions in one module.
Note: available in two or four track formats and in
eight or 12 times copying speed.
Price: master and twc slaves; either eight or 12
times copying speed ratio; for reel to reel, reel to
cassette, or reel to reel with a 6.25 cm master and
38 um cassette tape open reel slaves, for subsequent
reel breakdown and cassette loading, sells for
£2,100.
reels. After rewinding it stops at the beginning,
ready for the next duplication run.
Head assembly
A plug -in head assembly is mounted on the tape
deck. The assembly is provided with two Ferroxcube
playback heads for full -track mono and twin-track
stereo use. In this way the system is suitable for
both mono and stereo application. The changing
from one to the other is effected by simply turning a
switch on the reproducer, re- plugging the connection cables underneath the slave tape decks, and
adding a few electronic units. If required, a head
assembly equipped with two half-track playback
heads can also be supplied. Exchanging of the head
assemblies is easily effected because of the plug -in
type fixation.
Because of the high electrical resistance of the
cores, Ferroxcube heads give only low electric
losses. As a result the intrinsic head noise is very
low, which favourably influences the signal -to -noise
ratio. In fact the cverall signal -to -noise ratio of the
copy tape is better than 60 dB, with the appropriate
setting of frequency response and bias. Moreover,
the low losses at high frequencies means that low
bias currents are required for recording. This is
especially important for high -speed tape duplication
where bias frequencies of 700 kHz are employed.
Ferroxcube heads are highly wear resistant, as a
result of which the electrical performance during
total operation life is practically constant. Consequently electronic adjustments to compensate for
the head wear effect are only necessary after long
intervals. The life of the heads is 5000 operation
hours on an average.
Overall specification
Frequency response (with optimum bias adjustment) for 38 cm /s duplicates from 38 cm /s master
tape: ±1.5 dB from 40 Hz 16 kHz ')19 cm /s duplicates
70
-
The newest product from ORTOFON
The ORTOFON cutting amplifier GO 701,
has been designed with careful
consideration for high power output
and minimum IM and harmonic
distortion. The amplifier is constructed
for a sine wave output of 500 watts
(peak power of kW) which makes
it possible to cut peak velocities of more
than 30 cm /s even at 20 kHz.
The transfer of such high power,
particularly in the treble region is normally
prevented by the rising impedance of
the cutter head. However, in this
amplifier a special four pole impedance
matching network is inserted between
the output stage and the Cutting Head.
This network converts the complex
impedance at the output into a real load,
essentially resistive, throughout the
entire audible frequency range.
I
ORTOFON
CUTTING EQUIPMENT FOR
THE ULTIMATE IN TRANSFER
FROM TAPE TO DISC
vax
Li
Cutting amplifier GO 701 works in
conjunction with
Correction Amplifier CPS 691
Monitoring Power Amplifier GKS 681
Logarithmic Converter SSj 701
Cutting Head DSS 661
Cutting Amplifier LV 701
('l
i
i
Exclusive UK distribution
FELDON AUDIO LTD
GREAT PORTLAND STREET,
126
LONDON WI
01
-580 4314
for hire.
* Dolby A36I Revox High
Recorders from
* Revox Industrial High
makes supplied including Ferrograph,
* All leading
Quad, Tannoy, Spendor, Uher
Speed A77
and
£210.
Speed
4000/4200/4400,
Teac,
Report IC Recorders.
BAILEYS
131
The Parade, High Street, Watford WDI
Tel. Watford
INA
34644
-IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII'L-
HIGH SPEED COMPACT CASSETTE
COPYING SERVICES
*
*
*
*
-
Central London
Cassette copies in minutes
Io to IO,000
Write today for rate card
MAGNEGRAPH-EUROTEL
Hanway Place, London WI (Jnct Oxford St/
Tott Ct Rd) Tel o1 -637 1225 or of -58o 2156
4 to 20 cassettes
every 4.5 minutes
every 9 minutes
FraserPeacock Associates Limited
I
IIIIIIIIIIIIIIIIIIIIIIIIIIIIdIiIIJIIIIiIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIr
3toll duplicates
fpa
94 High Street Wimbledon Village London SW19
01.947 2233
sols UK
distributors of !Monies
STUDIO SOUND, APRIL
1973
67
3M announce a double.side.c
in the quality of
professional recording
New Scotch 206.
A new oxide coating that gives
a 3 db increase in signal -to -noise
1.
ratio,
,.<..
i
CalWTII-11
C°a 1CM DJ
EXCL.USII E
ILI"
BqCK TQEÁTME nil T
MUCaAa aM !M{b9
ia[
mprovement
¡ape.
3M have been at the forefront of recording
tape development for many years. Now they
offer a new dimension in recording perfection
with their new Scotch 206 professional tape.
This remarkable product is the result of
technological breakthroughs in the coatings
on the recording and backing surfaces.
1. A new oxide recording surface
After several years of laboratory research
JI have developed a proprietary oxide which
makes possible a 3 db increase in signal -to -noise
ratio. This means you have the latitude to
capture the extremes of frequency and output
without sacrificing any pure sound quality.
+10-
No206
{
Premium Low Noise Tape
:\ new matt back coating
which ensures better handling
and reduces head wear.
2.
Premium Low Noise
Tape
1 -'f-r
No.206
No 206 and
Premium Low Noise
Tape
-
_
Bias ed Noise Out put
by ya Octaves
1
100
1
1
1
300 500
1
I
1
1
1K
1
3K
5K
1
I
I
10K15K
FREOUENCY,Hr
DYNAMIC RANGE; Recording
at 15 ps.
í
Scotch 206 tape also considerably reduces
accumulated noise on multitrack recordings a major problem up to now.
It is also very tough, resists scratching and
prevents drop outs caused by tape debris.
2. A new matt back coating
The new back coating improves the tape's
handling characteristics, prevents slipping and
ensures more uniform winding.
It also helps to guide the tape more
accurately across the recording heads, reducing
expensive head wear.
'The backing is tougher, more scratch resistant than its rivals. And since it is
electrically conductive, dust and dirt are not
attracted and held to it.
Scotch 206 tape is compatible with any
professional recording system and is available
in ", I" 1" and 2" widths.
For further details fill in the coupon below.
1
,
To: Mr. R. Haworth, Magnetic Products, SS/4/73
:;NI United Iíingdom limited,
3M House, Wigmore Street, London, w1A lET.
Please send me further details about Scotch 206
professional recording tape.
Thm unique back coating gives
Scotch 206 tape a more even wind.
Compare it yourself with the
ordinary tape on the right, abovt_.
Name
Position
Address
Tel. No
3M 2040
Scotch is
a
tradomark of 3M Company
TAPE DUPLICATORS
(from 38 cm /s master tape): d 1.5 dB from 40 Hz
14 kHz') 19 cm /s for 9.5 cm /s duplicates (from 19
cm /s or 38 cm /s master tape): f2 dB from 60 Hz
to 12 kHz').
Signal to noise ratio: for 38 cm /s duplicates,
60 dB (full track); for 19 cm /s duplicates, 57 dB
(full track); for 9.5 cm /s duplicates, 50 dB (half track).
Permissible ambient temperature: (for specified
performance): up to 40 °C.
Power supply: 220V,
Notes
(1) measured
50 Hz
or 110V, 60 Hz.
with wow and flutter meter type
Gaumont Kalee 740.
measured with wow and flutter meter type
(2)
EMT 420.
measured with BASF tape LGR for tape speed
of 38 cm /s and 19 cm /s and with BASF tape LGS 35
for tape speed of 9.5 cm /s.
(4) output voltage with respect to a tape flux of
2u.Wb.
(3)
TELEX
Agents:
Avcom Systems Ltd, Newton
Works, Stanlake Mews, London W12 7HA.
Tel
:
01
749 2201.
Telex tape duplicating systems consist of the open reel series 300 -1 and the reel -to- cassette series
300 CS -1.
A variety of track and channel configurations are
available which may be intermixed within a system.
Openreel and cassette slaves may be interfaced
within a system. To expand a basic system, open
reel or cassette slaves can be added for a total
complement of ten slaves without additional electronics or modifications.
The systems are solenoid controlled and are operated by push- buttons from the master console.
Hysteresis synchronous capstan drive motors are
operative when the ac power is switched on so that
tapes are always duplicated at true speed from
beginning to end. All tracks of a master tape can be
simultaneously copied in one pass. Automatic
features stop the system at the end of a duplication
run or if the master tape should break. However,
should a tape on a slave unit break, only this slave
becomes inoperative, allowing the duplication
process to continue uninterrupted on all other
slaves. A photo electric sensor allows for programming and captive tape operation on the master
transport. By adding transparent windows and
leaders to the master tape, this tape may be programmed for duplicating and it becomes necessary
to reload the master for a repeat run.
Telex duplicating systems can be virtually custom used with standard components. It is possible, for
example, to make quarter track copies from a half
track master tape. Or, tape speeds can be changed;
a 4.75 cm /s master can yield 38, 19 or 9.5 cm /s open reel copies or4.75 cm /s cassette copies. Or a system
may incorporate both cassette and open -reel slaves.
All tape motions are controlled by push- buttons.
The playback heads, without pressure pads, are
protected by tape lifters during fast forward or
rewind modes. The transport panel is standard
480 mm rack -mount size.
Master transports are
fitted with playback heads of the desired track and
channel configuration.
The open -reel slave transport is identical to the
master transport except no digital counter is provided and the unit is fitted with special duplicating
record heads of the desired track and channel
configuration. A hinged rear -panel match box
contains individual channel audio record level
adjustments, bias current adjustments and bias trap
adjustments.
The cassette slave module contains three cassette
transports with a common, two -speed hysteresis
synchronous motor. Cassette transports operate
at 19 and 9.5 cm /s. Positive braking in the stop
70
mode
Special
assure
skew.
prevents tape creeping during loading.
tape guides and supply spindle torque
accurate tape tracking and minimise tape
An over -sized capstan and self -aligning
pressure roller provide positive, smooth tape drive.
A three -cassette slave module panel is standard
480 mm rack -mount size. The module is fitted with
premium duplicator record heads of the desired
track and channel configurations.
The hinged
rear -panel match box contains the same adjustments
as the open -reel slave.
Head configurations are available in half -track
single -channel and two -channel, and in quarter-track
two -channel and four -channel. In addition, full t, ack head configurations are available for open -reel
duplicators. Any configuration is always duplicated
in a single pass.
Open -reel slaves with 6.25 mm four -channel configurations can be used to reproduce four -channel
monoaural tapes. However, due to the narrow width
of cassette tape, four -channel monoaural programming on cassettes is not recommended.
Consoles
Telex duplicators come in consoles for table or
bench height placement. Console panels are slanted. Louvred top panels provide air circulation for
the equipment. Side panels contain ports with
removable covers for connecting cables.
Each
console accepts two transports and one amplifier
chassis. Thus, a basic system of one master and
one slave transport and all associated electronics
are contained within a single, table tep console.
When slaves are added to a system, consoles may
be purchased as required.
Technical specification
Frequency response: meet or exceed ±3 dB 80 Hz
40 kHz at 38 cm /s; f3 dB 40 Hz to 20 kHz at 19
cm /s; 9.5 cm /s copies 40 Hz 10 kHz ±3 dB; 4.75
cm /s copies 40 Hz to 50 kHz ±3 dB.
to
impedance.
500 mV, 50 k
ohms
Monitor output: 1V into 25k ohms minimum load.
Crosstalk rejection : Better than 50 dB at all
frequencies.
Signal to noise ratio: less than
from master tapes;
38 cm /s.
55
standard VU meters for each program channel.
Equalisation : front panel switching. Standard
NAB and EIA.
Distortion : less than 1 % THD at 1 kHz at 0 VU at
19 or 38 cm /s.
Heads: Laminated, hyperbolic ground, no pressure
pads required.
Bias frequency: 300 kHz.
Long term speed regulation : 0.5%.
Capstan Drive: flutter -filter multiple belt drive.
Capstan Flywheel: dynamically balanced.
Capstan and reel bearing: oil impregnated bronze,
no lubrication required.
Capstan drive motor: two speeds hysteresis
synchronous.
Spooling motors: standard shaded four pole
torque motors.
Wow and flutter: 0.17% rms at 38 cm /s 0.2% rms
at 19 cm /s.
Brake: differential balanced braking, self energising
in the event of power failure.
Control circuits: 24V dc.
Transport controls: push- button relay. Rewind,
stop, play, fast forward.
Reel size: 18 cm maximum.
Fast forward rewind: 365m reel, 60s.
Counter: three digit decimal, reset-table. On
master transport only.
Power requirements: 340W maximum for basic
system at 105 to 130V ac 50/60 Hz. Each additional
slave 150W maximum. Also available for 210 to
240V ac 50 /60 Hz.
457 mm deep at base.
86835 -07 six slaves £2,660.
86835 -08 nine slaves £3,110.
Portable rewind for three cassettes £76.
Series 300 CS -1 reel to cassette duplicating
system
Frequency response: 30 Hz to 10 kHz ±3 dB at
4.75 cm /s.
Auxiliary input sensitivity:
impedance.
813 mm high, 533 wide,
Front panel base 240 mm
500 mV, 50k
ohms
Monitor output: 1V to 25k ohms minimum load.
Crosstalk rejection : half track, two channel,
50 dB at
1
kHz; quarter track two channel, 30 dB
stereo channel separation at 1 kHz *; quarter track,
four channel 30 dB stereo channel separation at
1
kHz, 45 dB adjacent stereo program crosstalk
rejection at
kHz *.
*not recommended
1
for individual monophonic
Signal to noise ratio: within 3 dB of master tapes.
Illuminated meters: One for bias adjustment.
ASA standard VU meters for each program channel.
Equalisation : front panel switching. Standard
NAB and EIA.
Distortion : less than one per cent at
1
at 19 cm /s.
kHz at 0 VU
Bias frequency : 300 kHz.
Tape speed : 19, 38 and 76 cm /s (master transport),
19
and 9.5 cm /s (cassette).
Long term speed regulation: 0.5% (master),
0.8 %
degradation
dB peak S/N ratio at 19 or
3 dB
Illuminated meters: one for bias adjustment ASA
Console dimensions:
Price:
Track two channel system
86476 -10 three slaves £1,660.
86476 -11 six slaves £2,015.
86476 -12 nine slaves £2,235.
Quarter track four channel system
86835 -06 three slaves £2,155.
recordings.
Series 300 1 open reel duplicating system
Auxiliary input sensitivity:
high, accepts TDC. Two transports mounted at
67° angle for operating convenience.
Finish: Stainless steel front panel. Console -black
anodized aluminium, vented top and side panels,
removable back.
Note: The Telex 300 series replaces an earlier
series, the 235. The 300 series is identical to its
predecessor but with 76 cm /s master transport
speed.
(cassette).
Capstan and drive bearing: oil impregnated
bronze, no lubrication required.
Capstan drive motor: two speed hysteresis
synchronous.
Wow and flutter: 0.25% rms.
Control circuits: 24V dc.
Master fast forward/rewind: 365m reel, 60s.
Counter: three digit decimal reset -table. On
master transport only.
Power requirements: 265W maximum for basic
system at 105 to 130V ac 50/60 Hz. Each additional
slave 75W maximum. Also available for 210 tc 240V
ac 50/60 Hz.
Console dimensions:
813 x 533 x 240 mm (hwd).
Equipment mounted at 67° angle for operating
convenience.
Finish: Stainless steel front panel. Console
black anodized aluminium, vented top and side
-
panels, removable back.
Note: The Telex 300 series replaces an earlier
series, the 235. The 300 series is identical to its
predecessor but with 76 cm /s master transport
speed.
Price:
Half track two channel system
86781 -21 one slave £1,680.
86781 -23 three slaves £2,178.
86781 -25 five slaves £2,840.
86781 -27 seven slaves £3,522.
86781 -29 nine slaves £4,200.
Quarter track four channel system
86783 -21 one slave £2,150.
86783 -23 three slave £2,725.
86783 -25 five slave £3,460.
86783 -27 seven slave £4,180.
86783 -29 nine slave £4,910.
Special head track configurations
prices on rapt est.
available;
The Telex copier
This is a desk top unit designed to be operated by
non -technical personnel in business, industry,
education, libraries and the office. It is so simple to
operate it can be used by anyone without special
instructions. Small size and compact styling suit the
copier to the constantly growing applications where
cassettes are used fot communication or information
storage.
The copier is available in two configurations. The
cassette copier one (master) provides all controls
and makes one cassette copy from the original. It
has add -on capabilities for two cassette copier two
(slave) modules. Each cassette copier two makes
two copies but relies on the cassette copier one for
all power and control. The cassette copier two is
equipped with a single emergency stop button.
Both units are identical in size and styling.
The cassette copier one features two button operation. Illuminated rewind and copy buttons and a
track selector provide complete control. The unit
is automatically switched on when the original
(master) cassette is inserted. The operator sets the
track selector to copy channel one or two or both
and then activates the rewind button to assure that
cassettes are copied from the beginning of the
tape. Indicator lights now tell the operator to push
the copy button. Old material on the selected
channels is automatically erased as the cassettes
are copied, but existing material on other tracks is
preserved. This eliminated the need for a bulk
eraser. When copying is completed, cassettes are
automatically erased as the cassettes are copied,
but existing material on other tracks is preserved.
This eliminated the need for a bulk eraser. When
copying is completed, cassettes are automatically
rewound to start. The unit returns to stand -by or
automatically shuts -off when the original cassette is
removed. A manual emergency stop, which stops all
tape motion, is activated by pushing both the copy
and rewind buttons simultaneously.
The cassette copier features all solid state circuitry
and all electronics are on modular plug -in boards
for easy serviceability. Removing the case bottom
screws provides complete accessibility to all
electronics and any board can be replaced in the
field in minutes. The Telex copier is colour coordinated in ivory, blue and charcoal.
duplicating just track one or track two or both). Red
motion light for each transport to indicate stoppage
of tape travel.
Equalisation: RIAA and DIN standard.
Weight: less than 13.5 kg.
Dimension : 40 cm x 45.5 cm x 19 cm (wdh).
Warranty: one yea..
TRD
Tape Recorder Developments, Hall Lane,
Walsall Wood, Staffordshire, WS9 9AU.
Tel : 054 33 5351 -3
TRD have for sometime been supplying equipment
for use in tape copying, especially to universities and
colleges. In all cases these systems have been
designed and built from standard modules and
parts used in the normal production of TRD's
professional tape machines.
Current enquiries are being quoted using components from the Series 700 tape machine. A recent
quote to a UK University is typical and is summarised
below.
One master tape machine with half track mono
record /replay facility allowing the customer to use
it as a separate machine or in the copying bank.
Two slave machines with half track mono record
facility only.
A remote control unit allowing simultaneous
operation of all machines. A ppm and record level
control to the slaves being included.
Price: Ex works for the complete unit £950.
Late entry
BIAS
Bias Electronics, Unit
Estate,
SW20.
Tel:
01
1121120
0.05% at 152, 76 and 38 cm /s, better than 0.1 % at
Coombe Trading
Coombe Lane, London
8,
cm/s.
Spool capacity:
29 cm
pean and Cine centres.
Will accept, NAB, Euro-
Tape tension : Electronic servo tape tension system
controlling the feed spool. Tension held within
±10g throughout the length of a NAB spool. Ten-
947 3121.
Description
Bias Electronics, the manufacturers of the 13E1000
tape recorder, also market the 8E1000 tape deck as
a separate unit with high speed versions for use in
tape duplicating systems available to order.
Technical specification
tape transport
Power requirements: 110, 120, 200,
19
BE1000 6.25 mm
220, 240V, 50 Hz
(60 Hz to order).
Speeds: 19/38, 38/76, 76/152 cm /s.
Speed stability: better than +0.2%.
Wow and Flutter (peak weighted): better than
sion normally adjusted to 80g for 38 cm /s operation.
Can be adjusted from 0 to 120g as required.
Rewind time: 100s for 730m of tape maximum.
Start time: to rated speed better than 0.1s to 0.1%
wow and flutter better than 1s (both measured at
38 cm /s).
Mounting : standard 480 mm racks mounting or can
be supplied in console if required.
Formats: 6.25 mm as above but 12.5 and 25 mm
versions are also available.
Prices: from £376 for a 19/38 cm /s deck.
Available: ex works London, or from local agents
abroad.
Technical specifications
Duplicating speed: 76 cm /s.
Rewind speed: 152 cm /s.
Frequency response: 30 -10 kHz.
Automatic erase: track selectable.
S/N ratio: 45 dB below record level (3 per cent thd).
Crosstalk rejection : 50 dB minimum at kHz.
Head configuration: half track two channel.
Controls:lighted amber rewind button, lighted blue
1
copy button.
Three position track selector (for
CHILTON 10/2 MARK
Value -added tax
Readers, particularly those not registered under
VAT, are reminded that all prices in the foregoing
surveys are exclusive of value -added tax.
2
BASIC FACILITIES:
Prefade listen and auxiliary send on all 10 input channels. Break jacks on all
inputs and output groups. HF and LF equalisers, talkback and switchable
(line or monitor) ppms. Line -up oscillator: 40 Hz, 100 Hz. 1 kHz, 10 kHz
and 15 kHz ±0.5 dB. Illuminated red /green cue pushbuttons.
External stabilised 24V supply with auto overload cutout.
Low noise: -122 dBm ref 600 ohm source over 20 kHz bandwidth.
Low distortion : 0.05;á at +10 dBm out, 1 kHz.
Low crosstalk : -55 dB, 1 kHz.
Bandwidth : 30 Hz to 18 kHz +1 dB.
Dimensions: 570 x 466 x 233 mm.
Weight:
9 kg.
PRICE: From
£275.
MANUFACTURER: MAGNETIC TAPES LTD., CHILTON WORKS,
(Tel: 01 -876
GARDEN ROAD, RICHMOND, SURREY, ENGLAND.
7957)
STUDIO SOUND, APRIL
1973
71
REVIEWS
INFONICS 102
CASSETTE COPIER
BEFORE PROCEEDING with the details of
the Infonics cassette copier, it should be mentioned that the quoted specification is taken
from the instruction and service manual for
the copier, and is not a sales specification. The
agents for the copier were at pains to point out
that the unit is sold for the purpose of copying
cassettes containing speech recordings and that
it has been sold to many religious organisations
and similar bodies for this purpose.
No doubt, many engineers will regard a
cassette-to- cassette copier as an instrument of
doubtful virtue but it does provide a quick and
simple means of copying recorded cassettes for
such needs as sales promotion, language
laboratories, personnel training and similar
applications where only speech quality is of
importance. While I would have preferred to
have reviewed a reel -to- cassette machine,
Fraser -Peacock felt that there was little point
in reviewing their current machine because it
is about to be replaced by a new model. I look
forward to the opportunity of reviewing the
new version when a sample is available.
The Infonics 102 is a half -track copier which
produces two copies per run of the 4.75 cm/s
master tape at a nominal tape speed of 76
cm /s. As will be seen, the operation of the
copier is extremely simple so that anyone who
is capable of operating an office duplicator
will have no trouble at all in producing copies
of cassettes.
There are only four operational controls,
all of which are in the form of pushbutton
switches mounted on the top of the unit. The
first control is the mains on /off switch, the
correct operation of which is shown by a sensibly bright indicator light. The remaining
three operational controls effect the tape movement and are the simple functions of 'stop',
'duplicate' and 'rewind'. While there is no
mechanical interlock between these controls,
the operator has to be really stupid to do
things wrong and no disaster could result from
going out of the fast rewind function into stop.
On the UK model of the copier there is one
further external control in the form of a toggle
switch located at the bottom rear of the copier.
This switch selects the mains power for either
220 or 240V. The type of switch and its location
are most unsatisfactory because it would be
all too easy to operate the switch by accident
when, for instance, cleaning around the copier.
In practical operation, the mastef cassette
is loaded into the (clearly labelled) left hand
transport. Rewound and bulk erased cassettes
are loaded into the remaining two transports
and the rewind button is pressed, which
rewinds all three cassettes until the master
transport stops. Finally 'stop' and 'duplicate'
72
MANUFACTURER'S SPECIFICATION.
Cassette playing speed: 4.75 cm /s.
Duplicating speed: 76 cm /s.
Duplicating time (C30): minute.
Rewind time: 30s.
Frequency range: 40 Hz to 10 kHz.
Wow and flutter: 0.21 ;' rms per station (within
1
NAB specification).
Equalisation: DIN 4.75 cm /s.
Bias frequency : 500 kHz.
Power consumption: 150W
(600W surge) at 110
to 125V ac, 50 or 60 Hz. 230V ac input available on
special order.
Fusing: 5A (electronics); 5A (motors); both on
230V ac.
Dimensions: 446 x 305 x 261 mm.
Weight: 15.9 kg.
Price: £900 (recommended retail).
Manufacturers: Infonics Inc, 1723 Cloverfield
Boulevard, Santa Monica, California 90404, USA.
Agents: Fraser -Peacock Associates, 94 High
Street, Wimbledon Village, London SW19.
buttons are pressed and operation commences.
The copier then continues operations until
the master tape has stopped, from which point
all cassettes automatically rewind. All this
works well and only one possible snag was
found. This was that, while the copier always
rewinds the master fully, the copies were not
Wow and flutter across 65
necessarily fully rewound. This happens
because the copier decides to stop the transports a short time after the right hand hub of
the master cassette stops at the end of tape.
Because the capstan drive is not used in the
rewind function, the rewind speed depends
upon internal friction in the cassettes with the
result that the copies may take potentially
longer to rewind than the master and therefore
not be fully rewound when the master stops.
Insertion and withdrawal of the cassettes
was positive and simple and the location of
the cassettes in the copier was satisfactory.
There was, however, no lockout facility for
sensing the presence of the record interlock
tabs in cassettes. It was therefore possible to
record inadvertently on already recorded
cassettes. While the copier is not fitted with
erase heads, it would still ruin a recording.
The overall mechanical construction of the
copier was to a high standard, and it should
be mentioned that the unit employs one massive motor to drive each cassette transport.
All the electronics are mounted on good
quality printed boards and are readily accessible once the cabinet has been removed,
which is a simple operation once a large
number of screws have been undone. Access
to the transports and heads for cleaning is
really excellent as the complete top cover of
the copier just pulls off.
Rather surprisingly, the quality of the tape
wind was found to be good with a variety of
tape makes and types, ranging from C30 to
C90. While it is possible to copy CI20, this is
really asking rather much.
Although the duplicating speed was not
measured with precision, it was certainly very
close to the specified 76 cm /s, and the rewind
speed was about double this, depending upon
the internal friction of the cassette being
rewound. Of much more importance is the difference in duplicating speed between the slaves,
and this was measured by copying a cassette
which was pre- recorded with an accurately
known frequency. The first slave was found to
run between 0.2 and 0.3 per cent fast, and the
second slave between 0.15 and 0.3 per cent
slow, representing a timing error of less than
6s across 30 minutes in the worst case.
Wow and flutter was determined by copying
prerecorded cassettes containing 3.15 or 3 kHz
tone of known low wow and flutter, and then
replaying the copies on a replay machine
having a well defined and low wow and flutter
performance. The measured wow and flutter
of the copies was virtually identical for both
slaves, and in both cases was better at the
beginning of the copy than at the end of the
copy.
The DIN (peak weighted) wow and flutter
was measured as 0.45 per cent at the start of
copies, increasing to 0.55 per cent at the end of
copies. As can be seen from the photograph of
74
0
THE TAPE DUPLICATING CO.
(G.B.) LTD.
the largest
INDEPENDENT
CUSTOM
DUPLICATOR
in Europe
DUPLICATORS FOR THE MAJORITY
OF BRITAIN'S MAJOR RECORD
COMPANIES AND INDEPENDENT
PRODUCERS IN EUROPE
WHY NOT FOR YOU ?
The Tape Duplicating Co., Audio Works,
Cartersfield Road, Waltham Abbey, Essex EN9 1JF
ENGLAND
(A Division of Metrosound Audio Products Ltd.)
Telephone:- Waltham Cross 31933
telex:- 25166
STUDIO SOUND, APRIL
1973
73
INFONICS
102
REVIEW
FIG. I
the weighted wow and flutter waveform, by
far the largest component is at about 4 Hz. By
stretching the imagination a little, the rms wow
and flutter could just be within the specified
0.21 per cent but none of these figures is very
good. Remembering that in practice the wow
and flutter from the master is added to these
figures it is quite clear that any attempts to
copy music will be hopeless and that copies of
speech will be of marginal quality.
Uniformity of reproduction was investigated
by recording a full C90 cassette with 1 kHz
tone in the half track monophonic format, and
then copying this entire cassette. All three
cassettes were then replayed on a quarter track
stereo recorder, the output of which was
monitored with a Bruel & Kjaer level recorder
with the pen speed set to 1 m /s. The resulting
plot (fig. 1) shows very considerable deterioration of uniformity at the beginning of both
copies, reasonable performance at the middle
of the copies, but a further deterioration at the
ends.
FIG. 2
INFONICS 102
REPRODUCTION UNIFORMITY (SEE TEXT)
BEGINNING
MIDDLE
ENO
MASTER
r
COPY
1
5dB
COPY 2
30s
INFONICS 102
FREQUENCY RESPONSE
(
-25dB
COPY
REF.
25pWb /mm)
1
TRACK
1
MASTER
COPY
1
TRACK 2
20
50
100
200
500
1000
2K
50
10K
20k
FREQUENCY IN Hz
The frequency response performance shown
in fig. 2 at a recorded level of -25 dB with
reference to 250 pWb /mm with a pen speeds
of 100 mm /s and paper speed of 3 mm /s also
reveals a cyclic lack of uniformity, but the
actual frequency response is quite good, with
3 dB points at 60 Hz and 9.5 kHz, compared
with the master which had 3 dB points at 40
Hz and 13 kHz. The comparison between the
master and copies in fact improves as the
recorded level is raised, showing the biasing
of the copies and the overload margins of the
copier's amplifiers are satisfactory.
Reference to fig. 3 shows the third harmonic
distortion introduced by the copier at various
record levels of 315 Hz tone and demonstrates
the effectiveness of the internal auto gain control
in the copier. It is in fact quite remarkable how
little distortion is introduced by the copying
74
process and this result was considered to be
excellent.
Copied tape noise
Copied tape noise was also found to be satisfactory at a level of -53 dB(A) with respect to
a 250 pWb /mm with half track (mono) replay
(50 dB unweighted). However, a very serious
snag was discovered during the exercise of
measuring noise performance. It was found
that the copies contained very serious static
discharge clicks (similar to car ignition noise)
when the copier was operated in low humidity
conditions. This fault appeared when the relative humidity was between 40 and 50 per cent
and was found to be present with C60 and
C90 tape of BASF, EMI and 3M manufacture
when they were used as masters. It has been
suggested, and is likely, that back coated tapes
may alleviate this problem but, so far as I am
aware at the time of writing, only one or two
makes of cassette tape are available with a
back coating and they suffer from other tape
problems.
A further point also observed during the
measurement of noise performance was that
the copier was to a limited extent microphonic.
While this problem is to no extent serious, and
not in the same category as the static discharge,
it is necessary to ensure that the copier is not
subject to excessive vibration and is not
handled during copying.
Finally, the matter of electrical safety was
considered in terms of British Standard 3861:
Part 1:1965 which is concerned with the electrical safety of office machines. While the stan76
EAROPENER
Power Handling: 100 Watts
x 104 inches, 1.7 cubic feet
57 x 32 x 26 centimetres, 47.4 litres
Guarantee: unconditional,for 7 years
Origin: designed and made in Great Britain
Launch: Sonex 73, rooms 4029 -4031
Enquiries about the Gale GS401 Loudspeaker:
D Gale, Gale Electronics & Design Limited
39 Upper Brook Street London W1Y 1PE
Dimensions: 222 x 124
I
INFONICS
REVIEW
ever, testing with speech provided perfectly
are concerned, the performance was perfectly
acceptable.
My feelings towards Infonics 102 cassette
copier were to treat it in much the same terms
as a regularly used office duplicator and the
comments made in this review are related to
this type of performance requirement. The
construction of the copier is good but I doubt
if the mechanics are sufficiently sound to stand
up to full time use, five days a week, as a
copying machine. That is without considerable
degradation in performance.
Against all this one must balance the cost.
At a recommended retail price of £900, this is
no cheap toy. But, if one balances this against
some 30 off £30 cassette recorders which would
match the Infonics in copying speed and be
probably not so good in performance, it
becomes more realistic, particularly in view of
the labour costs involved in loading and
unloading cassettes. If your application is
appropriate the Infonics 102 may be a best
buy but it is definitely not recommended for
copying any form of music recordings.
adequate results and, so far as copies of speech
Hugh Ford
102
dard's requirements were not investigated in
any detail, one or two matters were found to
require attention on the part of the manufacturers. Probably the most serious matter is
that the colour coding of the mains lead is
green, white and black, which is non -standard
for Europe and also contrary to the UK 'Electrical Appliances (Colour Code) Regulations
1969'.
It was also noted that the previously mentioned toggle switch for changing mains voltage
was mounted such that its metal dolly was not
earthed to the chassis of the copier, and also
that various metal ventilation panels were
not earthed.
Subjective testing of the unit confirmed that
its performance on music was far from good
from the aspects of wow and flutter and lack
of uniformity of output, also the signal -tonoise ratio left quite a bit to be desired. How-
FIG. 3
INFONICS 102
"P"'"-V-1
THIRD HARMONIC
Postscript
During the course of this review, I contacted
Messrs Fraser-Peacock Associates to enquire
if the problem of static 'ignition noise' had been
experienced with the Infonics duplicator.
It turned out that this was a known problem
and, some time after writing my review, I was
contacted by Messrs Fraser-Peacock Associates
requesting me to examine a modified version of
the Infonics cassette duplicator which had an
electrically conductive strip inserted across the
original plastic moulded dummy erase head
on the `master' transport.
This modification did effect a considerable
improvement in the original static problem,
such that the problem may not be noticed in
loud speech recordings. However, the defect
still exists and will without doubt remain a
cause for complaint at its modified level of
severity.
DISTORTION
4.1.,.--°
PJ`
INPUT/OUTPUT
LEVEL
250pWb/mm
COPY
MASTER
20
50
100
200
500
1000
2K
5K
10K
20K
FREQUENCY IN Hz
SYNTHESISER?
PATCHING?
Build your own using Dewtron Professional Modules: Voltage -control system, Discount offers on
quantity. NEW "MODUMATRIX" INSTANT MODULAR ROUTING System to replace patching
VOLTAGE -CONTROLLED OSCILLATOR. New VCO -2 gives SINE, SQUARE and TRIANGULAR
symmetrical outputs simultaneously. Supplied singly or MATCHED and TRACKED! 1v /Octave.
All modules obtainable separately, including ring modulator, VC filters, VC amps, Keyboards, contacts,
envelope shapers, sample /hold /envelope circuit, VC phaser, white noise, reverb. etc. Modules guaranteed
2 years. OTHER MANUFACTURERS USE Dewtron Professional Modules in their equipment ... that's
sound reasoning! ALSO COMPLETE SYNTHESISERS CUSTOM BUILT TO YOUR REQUIREMENTS.
Standard models "Gipsy" and "Apollo"
!
Full catalogue I5p from:
76
D.E.W. LTD.
RINGWOOD ROAD,
FERNDOWN, DORSET
254
Classified Advertisements
4 -TRACK STUDIO
Advertisements for this section must be pre -paid. The rate is 7p per word, minimum 70p. Box Nos. 20p
extra. Semi -display rates on application. Copy and remittance for advertisements in MAY 1973 issue
must reach these offices by 16th MARCH 1973 addressed to: The Advertisement Manager, Studio
Sound, Link House, Dingwall Avenue, Croydon CR9 2TA.
NOTE: Advertisement copy must be clearly printed in block capitals or typewritten.
Replies to Box Nos. should be addressed to the Advertisement Manager, Studio Sound, Link House, Dingwall
Avenue, Croydon CR9 2TA, and the Box No. quoted on the outside of the envelope. The district after Box
No. indicates its locality.
SITUATIONS VACANT
SOUND RECORDIST
Required by the Overseas Press and Radio Division of
the CENTRAL OFFICE OF INFORMATION to join a
small and busy group of sound engineers servicing
both programme and news output. The Division
produces programmes and news items for transmission by Radio stations overseas and in the United
Kingdom. The successful candidate should be versatile
and capable of operating all types of studio and
location recording equipment. He /she will also be
required to edit tapes and to operate circuit transmission equipment to overseas radio stations. The
ability to work quickly and accurately under pressure
is essential. Some late night and weekend working is
involved. Salary according to experience and qualifications on a range £1674 to £2139 per annum. Please
send postcard for application form to:
CENTRAL OFFICE OF INFORMATION
Room 53, Floor 'I', Atlantic House, Holborn
Viaduct, London ECI
quoting reference number PE1290131 VY.
date for completed forms 30 March 1973.
Closing
*Chateau d'Herouville, 95- Herouville, France
el. 466 48 26 or 28, are seeking for their studios
English sound engineer-must be well qualified.
Telephone or call immediately.
*Small but rapidly expanding company requires
Audio Electronics Desigrer to work on
development of professional recording equipment for Motion Picture and TV industry in a
young and enthusiastic team.
Salary by
negotiation plus monthly profit sharing.
Knowledge of studio and film industry techniques an advantage. Box 650.
SOUND ENGINEER
Rapidly expanding studio requires an editing dubbing
engineer. Must be experienced and able to work to
high standards of quality in both music and voice
recording. Knowledge of audiovisual field also an
asset. Salary negotiable. Please write to:
IAN HIGHLEY
Fraser -Peacock Associates Ltd., 94 High
Street, Wimbledon Village, London,
SWl9
Technical audio sales to
*Audio- Sales.
professional studios. FM and TV broadcasters.
Several full time regional openings available in
the USA and Europe. Send resume to RC
Desmarais, Burwen Laboratories, 209 Middlesex Turnpike, Berlington, Mass. 01803.
*Enthusiastic young man (18 -21) w;th A levels
or ONC in electronics to woi k in recording
studio. Interest in and know :edge of recording
essential. Phone Jerry on 01 -499 7173 for
appointment.
INDIVIDUAL
To take an active part in expanding my small London
based outfit. This is an excellent opportunity for a
person who has a thorough technical background in
audio. Must be willing to contribute in accordance
with the demands of an exciting and challenging
business manufacturing professional quality high power
sound systems. Substantial remuneration offered to the
right person.
Write giving full background to Box No.
651.
*Technician for Electronics Section concerned
with medical educational television and audio
tape recording. Starting salary up to £1300
depending on qualifications and experience.
Day release towards ONC can be arranged.
Duties include operation and maintenance of
Further
equipment and tape duplicating.
details write or phone J. Cooper, Audio Visual
Communication Dept., British Medical Association, Tavistock Square, London WC1 H 9JP.
Tel. 01- 387 4499.
£4.50 HOUR
Free use of Hammond Organ, Fender
Amps, Hayman Drums
Fender, RMI, Wurlitzer Electric Pianos
Fender, Gibson, Martin Guitars, Synthesiser also available.
T. W. STUDIOS
400
Lillie Road, Fulham, London, S.W.6
Tel.
01
-385 4630/0393
*J & B Recordings.
Tape to disc -latest high
evel disc cutting, all speeds. Mastering press'rigs, studio, mobile. 14 Willows Avenue,
Morden, Surrey. MITcham 9952.
mjb
recording and
transcription service
*County Recording Service. Stereo and Mono
Vinyl pressings and acetate demodiscs.
Limiting,
compression and equalisation facilities; high undistorted cutting levels with feedback cutter heads.
Booklet available.
ST. MICHAEL'S, SHINFIELD ROAD,
SHINFIELD GREEN, READING, BERKS.
Reading (0734) 84487
Member A.P.R.S.
Roger squire
*County Recording Service. Top quality,
reasonable price, quick delivery. Tel. Bracknell
4935. London Road, Binfie!d, Bracknell, Berks
STUDIO FACILITIES
masters, 12" vinyl pressings.
Di
RGI2 5BS.
*Mobile recording van. Live sessions. Stereo.
Studios
Anywhere. Mobitrack,
HI-FI "RUMBLECURE"
The best facilities in town for
making Audition Tapes, Jingles,
Programmes and Sound Commercials. For further information
(Patent 28949169)
These Patents expose the inability of the trade, and
its advisor's, to solve the complicated phenomena of
telephone
vibration. WE DEAL DIRECT ONLY.
Tel. 061-330-2836 (anytime)
Black Knight, Ashton -u -Lyne, Lancs. OL6 6TA
01-7228111
*County Recording Service. 7" vinyl discs
pressed on our own plant.
Tape - disc pressings,
*Fanfare Records.
demo's, masters, any quantity. Studio/mobile.
Neumann disc cutter. S.A.E. brochure.
Broomfield Close, Rydes Hill, Guildford.
Telephone 0483 61684.
1
FOR SALE-TRADE
*Professional tape only 45p. 1200ft. Agfa on
hubs, no joins (p. and p. one box 25p, each
additional box 10p). We handle 99% of all
s/h professional recording equipment. Send for
list. Jackson Studios, Rickmansworth, Herts.
FOR SALE
YOUR TAPES TO DISC
-7"
from LI.50, 12" from L4.00.
Records made to order
4 -day postal service. Vinyl pressings, sleeves, labels.
Tax -free for schools, etc. We cut records for many
Recording Studios, etc, and use the same equipment
for you: NEUMANN Disc Cutting Lathes -Mono and
Professional tape machines with
Stereo systems.
Ferrite playback heads, Dolby A and B systems, 200W
Amplifiers, Lockwood monitors, Teletronix /Ortofon
Limiters. Send SAE for photo leaflet.
DEROY STUDIOS (1948)
Hawk Street, CARNFORTH, Lancs. Tel. 2273
*County Recording Service. Stereo and Mono
discs from your tape.
*Graham Clark Records. Tape to disc press'rigs. 124A Station Road, Addlestone, Weybridge, Surrey. Tel. Weybridge 43367.
COMPACT CASSETTES
PROFESSIONAL HIGH -SPEED DUPLICATION
-
Dolby B- compression and equalisation available
competitive prices on small runs -full productions
undertaken-music and language specialists.
Contact Chris Sands
AUDIO EDUCATION COMPANY
01 -723
6635
01 -892 9599.
LEEVERS -RICH
8
1"
TRACK MACHINE
PRICE
-
£3,000
O.N.O.
Contact
TONY LEATHER
01
-499 7173
*Sennheiser MD112 Microphone, new /boxed.
Normal price £44. Special offer £32. AKG K50
Phones 75 ohms £5.90. Perfectone EPGA
(Pulse) £95. Special Microphone Offers: AKG
D109 £11.00. AKG D202E1 £32.00. AKG
D190C £15.00. Sennheiser MD211 £32.00.
Sennheiser MD413 £25.00, p.p. 50p. Sennheiser
HD414 Dynamic Headphones £8.25, p.p. 30p.
J. J. Francis (Wood Green) Ltd.,123 Alexandra
Road, Hornsey, London, N.8. Tel. 01-888 1662.
77
STUDIO SOUND, APRIL 1973
RAC MIXERS
WE HAVE MOVED
RA NK -KALEE
Wow and Flutter Meters
Excellent condition
One or two available at E85.00 each
Burgess Lane & Co. Ltd., Thornton Works,
!
Demand for our products has meant larger
premises! Our new address:
19
Thornton Avenue,
Chiswick,
01 -994
Freemantle Road, Bilton, Rugby
Tel: 0788-810877
London
W.4
5752/5953
...
*Tame
those dB's
Plug in professional
quality FET compressor module £15.50. For
the `slick operator'
`Voice over' module
£15.50. S.A.E. details. Cathedral Sound SS,
"Fourways," Morris Lane, Halsall, Lancs.
Custom Built RAC Mixers for Groups, PA,
Hospital Broadcasting, Recording, Discos,
etc
RAC Audio Modules for building your own
mixers. Shure, AKG, Calrec Mikes, Stands,
etc in stock. Write, phone or visit us.
...
L39 8SX.
*Lancashire. Tandberg, Ferrograph, Tape
Recorders, etc. Plus over 10,000 high fidelity
systems. After-sales service. Holdings, Photo Audio Centre, 39 -41 Mincing Lane, Blackburn
BBA 2AF. Tel. 59595/6.
SOWTER TRANSFORMERS
for all purposes in
SOUND RECORDING AND REPRODUCING EQUIPMENT
We are suppliers to many well -known companies,
studios and broadcasting authorities and were established in 1941. Early deliveries. Competitive prices.
Large or small quantities. Let us quote.
E. A. SOWTER LTD.
Transformer Manufacturers and Designers
7 Dedham Place, Fore Street, Ipswich IP4 IJP
Telephone 0473 52794
KEY Electronics
-announce their new
Integrated circuit Peak Programme Meters, Microphone Amplifiers, Mixers, Line Drive Amplifiers, etc.,
(and also Ernest Turner 642 PPM movements).
FOR SALE-PRIVATE
Full details from:
*Vortexion C.B.L. 6H. Mint £118. Kibble,
232 Westrow Drive, Barking, Essex. Tel. 01-
Dept. ST, P.O. Box 7, Bournemouth, BH7 7BS
594 1749.
*If quality
matters consult first our 105 -page
illustrated Hi -fi catalogue with technical specifications (60p). Members enjoy unbiased advisory service, preferential terms. Membership
(40p) p.a. Our associates also manufacture
records from your own tapes or record the
Master at our studios (Steinway Grand). Bulk
terms for choirs, fund -raising, slim- discs. Please
specify requirements. Audio Supply Association, 18 Blenheim Road, London, W.4. Tel.
01 -995 1661.
UNIMIXER STUDIO 4 and 6 MIXERS
Each channel can be switched to accept 5 different
inputs, choice of DIN, Cannon, jack -sockets, slider
faders, tone controls, PPM. Overall noise is better
than -127 dBv with a 200 ohm source (using 20 kHz
band with filter). Mains or battery powered. Prices
from £87 (as with the successful 45 range, supplied
directly to users) only from:
SOUNDEX LTD
18
Blenheim Road, London W4 IES
01
-995 1661
*All must go. Offers invited please. Good
homes required Leevers -Rich fin.-4 track,
E.M.I. Mono Plate, Elcom 8 in 2 out mixer.
Other smaller items. Inspection welcome. No
reasonable offers refused. Domino Records,
High Street, Albrighton, Nr. Wolverhampton.
Tel. Albrighton 2384.
*Professional system consisting pair of I.M.F.
Reference Monitors 200 watts, high speed
quality Teac 7030 deck, F600 -RS stereo limiter/
compressor by Audio & Design, two Alice
(Stancoil) crosstalk /noise suppressors with
power supply, studio quality pre -amp with
Graphic equalisers and Peak reading output
meters, also transcriptors reference turntable,
sweep arm, stylus brush, arm fitted with Empire
1000ZEX cartridge. Everything latest models.
Complete system cost £1,600, must sell £1,000.
Offers for separate items entertained. 01 -980
7683 (evenings).
*Uher 4000L with leather case. Excellent
condition. List £172. Accept £110. Runcorn
66180.
*din. recording tape.
Ilford brand standard
play. £2 per N.A.B. roll. Phone 01 -567 2746,
01 -734 0072. Box No. 649.
*Custom-built 4 track tin. recorder, also 8
channel stereo-mixer.
Best offer secures.
Further details phone Carlisle 0228 29486.
*Brand new tin. s.p. professional tape. Agfa
per VO 1200ft. on Tin. spools, factory -fresh
and boxed at £1 per reel. 6 -10 reels at 95p each,
11 and over at 90p each (p. and p. 1 box 15p,
2 boxes 25p, each additional box 5p). Jackson
Studios, Rickmansworth, Herts. ' Telephone
Rickmansworth 72351.
*Allen & Heath 10 channel stereo mixer. Fold
back, echo send, panning on all channels.
V.U's and P.P.M's. Effects equaliser. Space
for extra channels. £320 o.n.o. 2 AKG P20
£30 each. 01 -437 8184 daytime.
WANTED
*Lee
Electronics. The Tape Recorder and
Hi -Fi Specialists wish to purchase good quality
Tape and Hi -Fi equipment for cash. 400
Edgware Road, W.2. Phone PAD 5521.
*Replay Amplifier for E.M.I. TR52 Tape
Machine. 061 -436 1381.
TAPE EXCHANGES
*32 -page illustrated booklet: "Hints for Tape talkers, International Message Making," avail-
able to non -members: 15p. Worldwide Tape talk, 35 The Gardens, Harrow.
MISCELLANEOUS
*Repairs.
Our modern service department
equipped with the latest test equipment including a wow and flutter meter and multiplex
stereo signal generator is able to repair hi -fi
and tape recording equipment to manufacturer's standards. Telesconic Ltd., 92 Tottenham Court Rd., London W.1. Tel. 01 -636 8177.
*Tape and Cassette Recorder Repairs
by
Specialists. The Tape Recorder Centre, 82
High Holborn, London W.C.1.
*Tape -Heads reconditioned.
Guaranteed
satisfaction. Send worn head enclosing £2 to
Sara Electronics, Fawkham Avenue, Longfield,
Kent.
INDEX TO ADVERTISERS
Acoustical Mfg Co. Ltd. ..
Acoustico Enterprises Ltd.
Action Video Ltd. ..
..
A.K.G. Equipment Ltd. ..
Alice (Stancoil Ltd.)
..
Allen & Heath Ltd.
..
Apollo Electronics Ltd. ..
A.P.R.S.
..
..
Audio Applications Ltd. ..
Audio Design (Recording)
Audix, B. B., Ltd. ..
..
..
..
..
..
..
..
..
..
..
..
Automated Processes Inc.
.
AVDistributors Ltd. (Schoeps microphones)
Baileys
..
Bauch, F. W. O., Ltd.
.
..
Beyer Dynamic (GB) Ltd.
..
Bias Electronics Ltd.
..
Brenell Engineering Co. Ltd.
..
16
12
43
19
33
39
8
39
29
12
18
49
55
67
63
31
59
6
2
45
Cadac (London) Ltd.
..
..
Calrec Audio Ltd. ..
..
..
..
Cintron Group
..
..
20
Communication Access. & Equipment Ltd. 20
.
C.T.H. Electronics ..
..
D.E.W. Ltd.
..
..
Dixons Technical Ltd.
Eagle International
10,
Electronic Music Studios (London) Ltd...
Electrosonic Ltd. ..
..
..
..
47
76
41
11
8
14
Feldon Audio Ltd...
..
67
Fraser -Peacock Associates Ltd. ..
4, 59, 67
Future Film Developments Ltd. ..
8
Gale Electronics & Design Ltd. ..
37, 75
Grampian Reproducers Ltd.
.. 53
Grundig (GB) Ltd.
..
.. 27
ICElectrics Ltd.
..
.. 29
Industrial Tape Applications
.. 5, 7
Lamb Electronics
..
15
Leevers-Rich Equipment Ltd.
63
Lennard Developments Ltd.
..
45
Macinnes Labs Ltd.
..
..
.. 9
Magnegraph -Eurotel Recording Co. Ltd. 67
Magnetic Tapes Ltd.
..
..
.. 71
Metrosound Audio Products Ltd.
.. 73
Published by the Proprietors, Link House Publications Limited,
.
10 -12
.
Midas Amplification
.
.. 14
Millbank Electronics
..
.
.. 79
Miniflux Electronics Ltd.
53
Minnesota Mining & Mfg. Co. Ltd. 21,68,69
Monks, Keith, Audio Ltd.
.. 47
MSR Electronics Ltd.
..
.. 59
Neve, Rupert, & Co. Ltd.
.. 80
PSP Electronics Ltd.
.. 45
Quad /Eight Electronics
.. 23
Rola Celestion Ltd.
.. 53
Rumble, C. H., Ltd.
.. 39
Sansui Electric Co. Ltd.
.. 25
Shure Electronics Ltd.
.. 17
Sonex 73
..
..
..
6
Sound Audio Electronic & Video
Techniques
..
53
Spendor Audio Systems Ltd.
4
Starman Tapes
..
8
T.B. Technical Ltd.
..
.
39
Trident Audio Developments Ltd.
13
Walkers, N.
43
.
.
.
.
.
South Crescent, Store Street, London WC1E 7I3G, and Printed by Arthurs Press Limited, Woodchester,
Stroud, Glos. GL5 5P13.
First we looked at the works.
Then we worked on the looks.
It's amazing the number of good -looking
amplifiers there are about these days.
But that's the easy bit.
It's what's underneath that counts.
So we decided to make sure of the works
before we did anything else.
And we came up with our 'C' series.
A new range of three monitor or
entertainmenLpower amplifiers.
With the following features.
600 ohm bridging, floating, input.
8 ohm output.
Unique fully protective circuitry.
Distortion better than 0.2 %.
Available in 19" rack or free standing form.
Peak reading meter is switchable between
output and input.
Signal and mains inputs by XLR sockets.
M EX 301C: 30 watts, M EX 501C: 50 watts,
and MEX 1001C: 100 watts.
Quite some amplifiers.
And we finished them in stylish Havana
with anodised alloy handles.
After all that, they deserve to look good.
And they do.
Milibank
It's got to be good.
Millbank Electronics Group, Uckfield, Sussex, England. Tel: UCK (0825) 4166. From Europe: 892 -96 -4166.
Manufacturers of specialist audio equipment for industrial and entertainment applications.
Sound mixers, tuners, sound systems, loudspeakers, tuner amplifiers, audio modules and amplifiers.
ITE
MILLBANK
Neve
at
Covent Garden
Neve is wherever you find the world's
finest sound - in recording studios,
in radio and TV, in theatres, concert
halls and film studios.
It's the performance of the consoles
that makes the sound of Neve.
Look at the figures achieved on this
console now in the Royal Opera
House, Covent Garden.
11000111
MVO
Distortion At +20dBm
Highest recorded figure 0.058%
Median figure 0.035%
Neve specification claim 0.075%
Noise 20Hz to 20kHz
Output stage - maximum
Neve specification claim
One channel selected maximum
Neve specification claim
-99.0 dBm
-80.0 dBm
-81.5 dBm
-77.0 dBm
Equivalent input noise maximum -125.5 dBm
Neve specification claim -125.0 dBm
For the best performance
figures in the world
choose Neve.
Write now for further
information.
Rupert Neve
Er
Company Ltd.,
Cambridge House,
Melbourn, Roystòn,
Hertfordshire SG8 6AU,
England.
Tel: Royston (0763) 60776
telex 81381
cables Neve Cambridge
Rupert Neve of Canada Ltd.,
7528 Bath Road,
Malten,
Toronto,
Ontario,
Canada.
Tel: 416 677 6611
telex 0621 7652
Rupert Neve Incorporated,
Berkshire Industrial Park,
Bethel,
Connecticut 06801,
U.S.A.
Tel: (203) 744 6230 telex 969638.
Hollywood Office,
Tel: (213) 465 4822
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