Page 1 ISSN0011-7145 THE SOUND ENGINEERING OCTOBER
THE SOUND ENGINEERING
AL f, r
Yes. But, one The heart of our
Travel carry-on- flight luggage.
A rear interface circuit board in the TM 515 Traveler that can save you and your clients Lab is our600
St low distortion audio
Mainframe lets you interconnect the many dollars. oscillator, which generates square or
Consider this: plug
-in instruments to make gain, loss or response measurements
at the touch of a pushbutton.
You're recording an exciting, new spot for a new client.
The musicians and low
500 distortion sine waves from
Hz to kHz (0.035% THD
For general to
50 kHz). troubleshooting combine vocalists are set.
You're getting noise on the tape and you can't find it this compact oscillator with a full function
Multimeter with ac. dc. current, temperature and resistance readings as well as dB capabilities.
Add anywhere. Testing with a
TM 500 audio test set before recording could have saved time and money. one of our
Counters (measuring capability to
GHz) with a
Or; does this sound familiar?
You're midway through an important
MHz varieties), you've got a complete. portable
500 audio test set. broadcast. You've sold every commercial minute allowable, when your audio fuzzes out. During a
Or if you're in need of a signal source, try our 40 MHz function generator capable of commercial minute a make good is in order.
A quick check through your basic frequency /response levels with a
/dB reading meter combination could have saved that minute. tone bursts, 20 Hz to 20 kHz log or linear sweep, and amplitude modulation.
TM 500 even has a tunable bandpass filter which selects narrow bands for
Configurability selective frequency tests and a hi
-gain differential amplifier with hi or to filter
For additional information on TM
You're engineering a big theatre production. It's opening night with a full house attending. The curtain goes up while your audio stays down.
Troubleshooting with a
TM 500 test set before the show could have found the problem.
In this world of sound. time is money.
TM 500 is a collection of modular test and measurement instruments from
Tektronix that can save you plenty of capabilities.
These versatile plug
-ins can be mixed. matched and packed in any one of
6 portable, benchtop, or rackmount
Mainframes to make a test set that suits your measurement needs.
The Traveler Mainframe is on the move with you.
When you're in and out of a lot of studios our TM 515 Traveler Mainframe is your
Audio Labs, call Tektronix' answering service
(toll free) at
Channel Islands. automatic residents call col- lect on 644 -9051. For even faster service, call your local Tektronix Field Office.
Europe write: Tektronix Limited,
Box 36, St. Peter Port, Guernsey,
COMMITTED TO EXCELLENCE both. number. The
TM 515 carries up to five
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Reader Service Card www.americanradiohistory.com
The subject for this next issue is
There will be a story from Ampex on digital recording standards
sub- ject that gets more important to dis- cuss with each passing day.
John Woram is assembling a story based on visits to a new automated re- cording studio in San
Francisco aptly named the Automatt.
Digitally operated automatic loca- tion of a tape will be
A another subject. number of present day systems will be
A detailed. sophisticated digital syncronizer from
BTX is the subject of another article. Learn all about the SMPTE time code and what it can do for you.
The world's first digital tape re- corder directory will appear in this issue.
And there will be articles on micro- processors now available that can do almost everything in your studio and yet cost good almost little more than typewriter. a
All this digitally coming in
No- vember in db, The Sound Engineering
This month's cover shows what one of the first direct -to
-disc sessions looked like.
The illustration is taken from an early issue of Scientific Amer- ican.
For a look at the complete cover see pages
56/57. And don't forget to read our reprint of their cover story, simply titled The appearing on pages
SOUND ENGINEERING MAGAZINE
Irwin J. Diehl
RECORD CLEANING MACHINE
BRING YOUR OWN
THE RECORD -PLATING
SOUND WITH IMAGES
NEW PRODUCTS AND SERVICES
4-' is listed in
Current Contents: Engineering and Technology
Crescent Art Service GRAPHICS AND LAYOUT db. the Sound contents
Engineering Magazine is published monthly by Saga more Publishing Company. Inc. Entire copyright ©
1978 by Sagamore Publishing Co., Inc..
433 6530. db is published for those individuals and firms in
(514.00 per year outside U.S. Possessions. Canada and
Controlled circulation paid at
Mexico) professional audio
- recording, broadcast, audio -visual, sound reinforcement. consultants. video recording, film sound. etc. cation should be made on the subscription form in the rear of each issue.
Subscriptions are $7.00 per year
1120 in U.S. funds. Single copies are 51.00 each.
Old Country Road, Plainview, L.1.,
Country Road, Plainview,
Postmaster: Form 3579 should be sent to above address.
. tn is
U V O
U o y d o
w da) y
Cia Letters grgers
O n a) O)
Herewith a few thoughts prompted
Marshall King's two -part article,
The Technician and His Union. He mentions the decline of the big old movie studios and the rise of the in- dependents. Popular opinion has it that unions were in part responsible for this, and that unions do not pro- mote excellence; that seniority lists eliminate competition between engi- neers and shelter incompetents.
As we all know, the recording field has undergone meteoric growth over the past ten years Along with this, the role of recording engineer has also evolved. Whereas new equipment has kept the maintenance engineer on his toes, his work has remained es- sentially the same. But the recording engineer has had to become increas- ingly involved, creatively, in the use of multi -track techniques, and of the studio itself as a giant musical instru- ment.
In general, the unions have re- sisted this trend, or responded in pure- ly reactionary fashion
To the extent that it is democratic, the union is bound to speak for the majority, that which all workers have in common rather than the attributes which make each man unique.
Not all workers are equally good at all tasks, and this fact must be reconciled with the democratic principle of equal pay for equal work. The controversy sur- rounding "job classification" is im- plicit recognition of the problem, but the paradox remains, within any cate- gory there will always be important differences between individuals, with regard to both ability and motivation.
The unions are also seen, especially by artists and producers, as being op- posed to all new technological devel- opment, resisting with featherbedding and sabotage. Once a shop gets a reputation for such activities, it may suffer loss of jobs or even extinction.
Thus, while acting to support the idea of fair treatment for workers, the union may, ironically, sacrifice the very jobs it intends to protect.
Additionally, there is a growing feel- ing that bigness is itself an enemy.
As they have gotten bigecr, the unions have begun to resemble the giant corporations they are supposed to
Audio -Technica U.S.
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J & R
Pro -Audio Specialties
Standard Tape Lab
Tandberg of America
TEAC Corp. of America
is all new.
Except the shape.
If the new
-75 professional power am-
looks familiar, it's because the shape, which we created years ago, is
But, until now, you have never seen any
of this size, including Crown, that performs like the
-75 is a powerful ampli- fier.
35 watts continuous average power per
8 ohms, 20Hz to 20KHz
45 watts into
In mono, the
95 watts continuous aver- age power into
-free. Fre- quency response
100KHz. Hum and noise 106dB below rated output. THD less than .001% from 20Hz to
20KHz. IMD less than .01% from
36 watts (less than .05% from
Signal- presence LED's indicate peak output greater than l/a watt into
Active bal- anced XLR connectors, as well as unbal-
/4" phone plugs, are standard on the
an switch. Gain
includes the Crown
Input- Output Comparator
(IOC) which re- ports non
-linear behavior in the amp: over- load, TIM or
addition, separate signal
grounds are provided to minimize ground loops.
-75 is a
Crown amplifier, so you can
it to be
Compare it with any
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American innovation and technology...since
an Equalizer that
now, whether you tried
a concert hall, the end result was an increase in
Klark -Teknik equalizers are
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using yesterday's equipment,
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$815 counterpose- unresponsive to local needs, and resistant to change of any kind (bureaucracy breeds more bu- reaucracy). And, like big business. some unions are seen as come dient, crime. having be- immoral, dealing, when expe- with elements of organized
Finally, there are those
(admittedly, very few) who have deep concern about the
Constitutional question posed by sentation compulsory union repre- of all workers in a closed shop.
(A recent Supreme
Court ruling on this matter affirms freedom individual.) of the
Educated people know of the great good done by the unions in this country, over the years. Whatever problems the unions have today, the solutions can cone only from the members themselves.
Mr. King is right in saving those who criticize a union should also he actively trying to do something about it.
INPUT IMPEDANCE: Unbalanced, 10K ohms nominal. OUTPUT IMPEDANCE:
Unbalanced, less than 10 ohms,_ short
-20 dBm to +24 dBm; input
PONSE at +4
%. protection circuit
60V protected. OPERATING
POINT: +22 dBm Into 600 ohms load.
20Hz to dB.
20kHz. OUTPUT CLIPPING
Less than 0.01%
... 1kHz dBm into a
600 ohms load; less than 0.05% ... 20Hz to 20kHz at +18 dBm into a
600 ohm load.
-90 dBm unweighted,
20Hz to 20kHz.
A Member of the Hammond
The Sound of
I really find it quite disappointing. and a little hard to believe, that the error in
1978 piece was lute claimed as the abso- truth in the June issue.
Finnegan's answer, he does peak bias at
1 refer to kHz as the common guideline it is.
In the original article. however, he stated level at 10 correctly that the kHz is much more sensi- tive to the exact bias setting.
He erred. and
Gordon Carter, in his letter. picked him up on this, when he stated that the bias is set for the
"peak audio output" with the high frequency signal.
The range of
10 kHz drop with correct bias is at least as wide as given by
Carter. I have seen the best performance obtained with drops anywhere from
12 dB at 10 kHz.
Within that great spread levels, the great for
10 kHz majority of tapes were very close to peak bias for
In the last two years of using a I%3- octave rta (real -time ana- lyzer) with a pink noise source for tape and tape recorder testing.
I have become convinced of such a display of the essentialty if the goal is widest and flattest response.
The levels of the highest frequen- cies and the shape so of the curve change rapidly with small changes in bias that it is close to impossible to match the possible a scheme, performance using such
just 1,000 Hz peak bias is used.
Anyone who has not seen the
Reader Service Card www.americanradiohistory.com
... five years ago, I've done all of Shaun Cassidy and
Leif Garrett on it, most of
Donny and Marie. plus Al Martino, Sammy Davis. Debby Boone. the Supremes and others."
"After 20 singles and
12 albums on this console.
25 of them gold and platinum,
I guess you could say my
501 (serial number 0002) is a real money- maker.
It does what
I want as well as when it was new, and i m still cutting on it today."
Lloyd is one of over 300 satis- fied
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Auditronics console quality and reliability, circle reader service number or write to
3750 Old Getwell Rood, Memphis,
38118 (901) 362
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. . .
MI IM IM MI
'13- octave rta being used to set up a recorder is urged to do so.
If nothing else, on you will find it very instructive the interrelationships of relative frequency, bias. eq.. tape type. and head alignment. Finally. and perhaps not so incidentally. the pink-noise /rta approach is very fast:
30 seconds is the most time needed to see what the record /playback response is.
Well, frankly, we didn't think much of the marginal perfor- mance of the we digital delay lines we'd seen to date. We vowed wouldn't get into the
DDL ballgame until we could field an entry we'd be really proud to see in a
But now, our time has come! The
Delay Line! The proud result of over two years of intensive research and development, now available at a very com- petitive price to set new standards of performance and reliability.
Are you tired of gain pumping and transient overload that is typical of companding
A/D converters? Tired of whistles at the high end?
Tired of pre -emphasis /de- emphasis filters tak- ing 12dB of high end headroom just to meet the
90 dB spec?
And are you tired of not being able to believe what you read about digital delay line specs? Well, you should be! The technology is here to eliminate that nonsense in digital audio systems.
927 uses a unique
A/D system we call
"instan- taneous floating point conversion" to take care of those prob- lems without any of the annoying side effects inherent in other floating point and delta modulation systems, and without resorting to companding and
/or high end pre
- emphasis to achieve
dB dynamic range. Ultra -sharp
6 zero Cauer filters put an end to the whistles and beats. The result?
92 dB dynamic range with power bandwidth to 12kHz at all delay typically
0.07% at full rated output). full
- settings (distortion
As a bonus, you get FOUR separate, isolated outputs, each thumbwheel switch -adjustable to
127 milliseconds in
write us or ask your
UREI dealer for a
927 data sheet. You can
Get one believe the honest and complete specs it lists. for your next delay job and prove to yourself that
"our time has come!"
I have read with great interest
Marshall King's recent articles in db.
I have found them to be a very factual and informative description of the cur- rent status in the film and video tape industry.
I would, however, like to point out two things which need further clarifica- tion. can
First, the freelance sound mixer put together. with extreme con- fidence, a total audio package for a producer by contacting one of the several rental houses who specialize in this area. The freelance mixer has the freedom that the staff mixer does not have, to call upon one of these audio one- stops, thereby providing the producer with a state
-art audio package which is maintained to high standards, dictated by the fact that these companies make their profit by providing this equipment on an on- going basis.
Secondly, the area of rf microphones has given the audio mixer greater flexibility when they are plied, thereby giving the properly mixer ap- new found freedom along with the camera- man, lighting directors, etc.
I appreciate the opportunity
King has given everyone to have a greater understanding of the union situation in our industry.
Copies of db
Copies of all issues of db
Engineering Magazine start- with the November
1967 issue are now film. For available on 35 mm. micro- further information or to place your order please write di- rectly to
North Zeeb Road
Arbor, Michigan 48106
Fernando Road, Sun Valley, California 91352 (213) 767 -1000
Exclusive export agent: Gotham Export
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creative new start toward better sound.
"live" recording has an excitement all its own. You capture sound that will never be heard exactly the same again. And in some cases the recording is literally a once -in -a- lifetime chance. With no opportunity to remake the tape or disc.
Your creativity, your knowledge and experience are on the line. Now is when you appreciate the precision of
Audio -Technica microphones. Performance is consistent.
With results that help you extend your personal standards.
Audio -Technica gives you a choice of superb new electret condenser or moving coil dynamic microphones.
A choice of omnidirectional or cardioid (unidirectional) pickup pat- terns. With smooth, extended response that the complements finest recorders. Audio -Technica microphones look, sound, and act very, very professional.
Add more than a little creative excitement in your life, with
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We're Audio Consultants.
We solve problems; and there
no greater problem than that of high quality at low cost.
our industry, that's the
certain sound, we respond with more than just equipment.
We respond with
system that's a problem -solver. And, our equipment must do the same.
That's why everything we produce functions within an area greater than its own
within the total system, the total solution to the problem.
our systems, our equipment must solve problems at the bottom line, delivering excellence at low cost.
One of our problem -solvers
The standard of quality for the industry, the
Starbird reduces costly
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Its design permits quick and precise "spotting
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The counter- weight balances the microphone properly; and ball bearing, rubber
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simply the best. Ask the countless studios where
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Sound Comes From
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-26 Society of Broadcast Engineers
State of the
Kentucky Chapter. Ramada Inn
Bluegrass Convention Center,
R. J. Klein
ETV, 600 Cooper Dr., Lexing- ton, Ky. 40502. (606)
Institute of High Fidelity Top
Management Seminar. Doral
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10017. (212) 682 -5131.
29- Society of Motion Picture
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(914) 472 -6606.
10/31- World Energy Engineering
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Here's everything you need for one
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Broadcasting is an aural medium: end product is audio at the receiv- ing set. The program audio is created in the studios and then delivered to the listening audience by an rf transmis- sion system. The rf system has short- comings that place limitations upon the audio it can carry. Aside from these limitations, faulty components and op- eration can put back into the recov- ered audio many of the distortions we worked so hard to eliminate from the original audio signal. This month
I will touch upon some of the ways the transmission can degrade the audio signal.
The audio signal is placed on the rf carrier by a modulation process. Once on the carrier, it is no longer audio per se: it is rf. Although now an rf signal. it must still retain its internal relation- ships as well as those to the rf carrier.
(A) Modulation creates bandwidth to the wave.
All circuits which follow must have an adequate bandpass.
(B) shows the circuit with a good bandpass for a typical wideband signal. while (C) is a very poor bandpass for that signal.
Should any of these relationships he altered, the recovered audio will he affected in some manner. Once im- pressed on the carrier, the entire entity becomes a modulated wave.
A modu- lated wave requires far more spectrum space than an unmodulated carrier
how much space depends upon the type of modulation and the character- istics of the wave. The f.m. wave re- quires considerably more space than the a.m. wave.
In a.m., there are two equal sidehands spaced from the car- rier according to the frequency of the audio signal
In f.m., the amplitude of the audio directly modulates the mas- ter oscillator and causes the carrier to deviate above and below its normal resting space in the spectrum. At the same time, many sidehands are cre- ated. The space taken up in the spec- trum by the modulated wave is the wave's bandwidth.
Since the audio, through the modu- lation process, creates the widening of the spectrum space, it becomes an in- tegral part of that wave. Every circuit through which this modulated wave must pass on its way to the detector in the receiver must have a flat response curve across a bandpass at least equal to the bandwidth of the wave.
Faulty components. mistuning, or anything else which can restrict or distort the system bandpass, will limit and de- grade the modulated wave
the recovered audio in some manner.
%7) a new and valuable
The Standard Tape Manual is not a text book. but rather a practical and much -needed source for sophisticated users of magnetic recording equipment.
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We can have a perfect audio system the studio and a perfect rf transmis- sion system, yet end up with degraded audio from the receiver. This can hap- pen if there is a mismatch between the rf and the audio systems.
Transmitter inputs are designed around standard impedance values: for audio only, 600 ohms balanced. For stereo composite and
SCA. these are high impedance. unbalanced circuits.
Mismatch at this junction is purely an audio problem, even though one side of the circuit is the transmitter.
And the same ensue audio problems can
response curve, phase shifts, poor signal level transfer. Match- ing is not ordinarily an operational factor, but one of set
-up or test pro- cedures. Making measurements and feeding the audio generator directly into the transmitter can result in erro- neous indications and adjustments if the generator is not properly matched to the transmitter. Mismatching could occur if the limiting amplifier or unit which normally drives the transmitter has failed and the substitute unit used as a replacement has been set up dif- ferently, in another application, in the station.
Reader Service Card www.americanradiohistory.com
The new one -inch
NEW unique. There is
it with your favorite
get a frequency response
Hz. So one speaker does the sam job
used to take
a tweeter and super- tweeter
The secret is the
The diaphragm is the heart
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achieve a standard
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both parts and workman-
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reproduce fre- quencies up
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Audio inputs of the exciter are designed for standard audio impedance.
Others are high impedance.
When you delay
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Perhaps the most common cause of transmission distortions result from overmodulation of the carrier. The modulator requires a given level of input audio to produce the
100 per cent FCC limit on modulation. This is the design objective, and if the audio input exceeds this amount, distortions can be created right here at the modu- lator as well as down along the rf transmission system. Besides standard input impedances, the transmitter is designed around a standard input sig- nal level.
The transmitter does not have op- erational input controls. Those which are provided are intended for set -up, and trimming controls. The opera- tional control of the input audio levels must be done by external audio limit- ers or similar devices.
The modulator in the a.m. trans- mitter requires considerably more audio signal level for full modulation than does the f.m. modulator. There will be several audio amplifier stages within the a.m. transmitter besides the modulator itself, which is an audio power amplifier. High input signal levels to the transmitter can overload these audio stages.
The most common results of overload are peak clipping and intermodulation distortion.
The audio stages may be able to handle the high input audio level with- out distortion, but it will be applied to the rf modulated stage.
With more than enough audio to fully modulate the carrier on negative going peaks. the carrier will be cut off during the peak portion of that signal. Cutting the carrier with high level audio peaks in this manner creates clipped audio negative peaks and in other distortions the recovered audio at the receiver. the severity depending upon the amount of overmodulation.
The best sound equipment there
Because from conception
completion we make no compromises.
e start with a job, not a market.
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we can't do it correctly the first time around we work until we find a way.
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Overmodulation of the a.m. carrier on the negative peaks will cause the be audio peak in recovered audio to clipped.
The Garner 1056
You'll get perrect dubs time after time with Garner's common capstan drive.
It drives the master and
5 slaves at consistently the same speed. And Garner uses only glass bonded ferrite recording heads
-which outwear ordinary metal heads
In addition to quality and accuracy, the 1056 is fast
minute tape loading and
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-year mechanical and a
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Look to Garner for quality electronic audio and video products.
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4300 ACTIVE EQUALIZERS
A new standard
40 Hz through tween
I.S.O. centers octave bands from
894 Hz on and be- one -third octave
-third octave bands from
Hz centers. through
16 kHz on I.S.O.
10 dB boost or cut on continuous, calibrated,
Mil -Spec controls both boost and cut
Equal Q in conditions
Precision inductors in mag- netically shielded enclosures for maximum hum rejection
Noise guaranteed better
90 dBv or
Accessory socket to permit inser- tion of
12 dB/octave or
18 dBloc- tave low -level crossover networks for bi- amping or tri
Mid and high frequency output trimmers accessible from front panel
Input attenuation control variable to
20 dB of attenuation accessible from front panel
Variable high -pass filter
20 Hz through
ONE SIXTH OCTAVE REAL TIME
P.O. BOX 698
53 on Reader Service Card www.americanradiohistory.com
During a maintenance period when measurements are being made on the a.m. transmitter, higher than usual dis- tortion figures may he indicated, in spite of the fact that the modulation and input levels are correct. The modu- lators and the modulated stage can age so that they become somewhat non
-linear. a condition which creates distortion. Balancing the modulators for minimum distortion ordinarily re- quires adjustment of the bias on each of these stages.
Changing the bias can increase the gain of the modulator so less input level to the transmitter is now required.
the input, for ex- ample, now requires r/2 dB less than previously for
100 per cent modula- tion, the limiter or other driving ampli- fier at the input of the transmitter must also he reduced by the sanie amount.
this is not done, that in- creased t/2 dB can cause
5 per cent overmodulation during programming.
Consequently, the peak will be clipped and distortion result. perhaps far more distortion than the adjustment in the was first removed by place.
Many a.m. stations are required by
Rules to cut back transmitter output power at sunset every day.
This reduction can be considerable. for example
5 kW day to
1 kW night.
It requires a correspondingly smaller amount lower of audio to fully modulate the rf power level.
This is usually accomplished within the transmitter by switching in an audio pad. or a trimming potentiometer for accurate balance. Any fault in this circuit could cause severe overmodulation at the lower power level.
Components will age after a time, so it is necessary to check for correct balance and then trim the audio when necessary to ac- complish this.
Most f.m. transmitters use direct modulation. A pair of solid state.
when cost is more important than price
Value conscious recording engineers specify the
Studer B67 because it outperforms its competitors on the criteria that matter most to the discriminating recordist:
Studer stateof- the
Long service life with low failure rate
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If you've ever had to scrub a session because of a faulty recorder, you'll understand why we talk about total cost rather than price. Write to us for complete information on the superiority of
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44 on Reader Service Card
Studer Revox America, Inc., 1819 Broadway, Nashville, Tenn. 37203
(615) 329 -9576
Revea Canada, Ltd.
AKG is a research, development and manu- facturing organization specializing in electro- acoustic technology. Our designs have been awarded over 600 transducer related pa- tents, and our products have earned the highest degree of user respect for quality and dependability.
The AKG line of various microphone models is considered to be the most sophis- ticated available for applications ranging through the spectrum of professional uses.
From studio, to in- concert recording and re- inforcement, to location film sound...our products can be called on to solve the most difficult situations you may en- counter. AKG has developed a broad range of products to meet your varying creative re- quirements and, as new audio frontiers evolve, our engineers will lead pioneering. the technological
We set our goals rather high and turn every stone to live up to, and im- prove upon, self
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MM faders mean more mixing in less space
-inch thin -line conductive plastic faders you can cram 24 channels into an 18 -inch mix boy for high density recording studio applications, sound reinforcement and location mixers, and lighting control consoles.
MM faders retain oll the superior accepted
LM series including choice of quality of our
-inch or 4 -inch travel; b00 ohm or
10 k impedance; linear, audio or true log characteristic; and our famed trouble
-free long service life. For more mixing in less space circle render service number or call Don
617- 358 -2777 for more information about thin -line faders.
Circle 30 on Reader Service Card www.americanradiohistory.com
Typical arrangement to reduce the audio when the ri power is cut back in a.m. voltage variable capacitor diodes are placed across the frequency- determin- ing tuned circuit of the transmitter's master oscillator. Any change in ca- pacity in this circuit will directly change the amplitude carrier's frequency. This of the audio input signal is applied across these diodes; this change will their capacity a correspond- ing in amount. Changing the capacity, turn, changes the carrier frequency a corresponding amount. The FCC specifies
75 kHz on each side of the carrier resting position as
100 per cent modulation.
The modulator is de- signed for linear operation on standard input levels within this range.
When the audio input levels are too high, the modulator can be driven into non
-linear regions and distortion re- sults in the recovered the audio. Should diodes become non -linear in the normal range. distortion will result with normal input levels and modula- tion. More than one input can modu- late the the carrier at the same time.
If modulation was set for
100 per cent with the composite only, for ex- ample, when the SCA channel comes on, the transmitter will he overmodu- lated by
10 per cent.
Another factor is in the
75 microsecond pre -emphasis the audio input.
the audio has considerable high frequency energy. the boost by this pre -emphasis can severely overmodulate the transmitter or move into non -linear regions the modulator. Aside from of distortion in the modulator, a restricted band
- pass cause along the system is a common of distortion. The fully modu- lated f.m. carrier is a very wideband wave. The system should have a band
- pass of at least 200 kHz or better.
Besides audio and accurately adjusting the rf system for correct modu- lation levels, program modulation must be continuously monitored so the op- erator knows the station is within
FCC limits in addition to listening to
From now on your store or plant needs these
Changes in distortion standards
Expect some from new types of questions your customers soon about dis- tortion measurements.
Because you will find that the Insti- tute of High Fidelity recently introduced a change in the type to be used in of measuring circuit distortion measurements on amplifiers.
For example, current
IHF standards require an rms- responding meter circuit for measuring amplifier distortion, but an average responding meter for mea- suring receiver distortion.
What's more, when making total har- monic distortion measurements with either type of circuit, it can be impor- tant to know what the distortion peaks measure. Because peaks can be large even though rms or average values are small.
You can measure with an average, rms or peak button. circuit.
Just push the desired
Measure lower distortion, too
Sound Tech distortion analyzers have become the industry standards. When they were ment in introduced four years ago, they gave nearly a
-times improve- distortion range and a
100 - times increase in ease of use.
Now our new
1701A improves the distortion range even more
10 Hz to
10 kHz. Overall distortion measuring capability continues superior over the full
110 kHz range.
There's lots more features, too, in- cluding our automatic set level and in- termodulation distortion options, bal- anced input
for measuring bridged amplifiers, and lower distortion tracked signal source.
It technical leadership in your area.
And in receiver the will give your store the prestige of
/tuner production, only such instrument that will it's give the various types tion you need. of distortion informa-
Call for data
Be prepared for customer questions.
Get the details now on the
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Or send in the coupon. Now.
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1400 Dell Ave.
Your choice of three responses
So in the new Sound Tech 1701A Dis- tortion
System, we now give you three metering sponses. circuit re-
Demos and clinics
The 1701A is just what's needed to demo receivers, amplifiers, and other audio
For equipment to your clinics, too. customers.
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Circle 23 on
Reader Service Card www.americanradiohistory.com
S ac e
s f e
9 ao o,
More than one input can modulate the t.m. transmitter at the same time.
3600 oor ad
Reader Service Card www.americanradiohistory.com
what is on the air. Set -up adjustments and operations require some accurate standard of measurement. The moni- tor can do this, but it must be cali- brated properly if it is to indicate accurately.
An oscilloscope and tone modula- tion can be used to calibrate the a.m. monitor.
Set the peak flasher adjust- ments and the meter adjustments for accurate
100 per cent negative modu- lation.
During programming, however. use the peak flasher as the more ac- curate indication of overmodulation.
The meter circuit will not provide true peak indications on program material.
The f.m. monitor can he calibrated with a spectrum analyzer if one is available. or the method as old as f.m. can be the used: tone modulation of carrier, a communications receiver and the
Zeroes, or nulls. With
100 per cent tone modulation of the carrier, operate the positive and nega- tive switches to note if both peaks are equal.
If they are not. there can he some non -linearity of the signal in the rf system.
The equipment at the receiving end of the transmission system can do much to degrade the recovered audio. hut we can do nothing about it.
Poor receiver design. limited and distorted bandpass, poor design in the audio stages, the speakers, plus faulty com- ponents, mistuning, multi
-path recep- tion, antenna and so forth can all have a definite bearing on what the listener hears. Yet another factor in the design of the receiver is the lack of filtering to sort out the various signals into their own channels. This enters the picture when the f.m. sta- tion is in stereo, or mono, and in
SCA in either mode. Unless there is actual cross -talk among these various chan- nels occurring at the transmitter, they can show up whistle, etc. here as birdies.
10 kHz without proper filtering in the receiver.
The rf transmission system can dis- tort the recovered audio signal.
We have touched on only a few of th_ areas in the rf system where dis- tortions can arise.
There are many other possibilities. From the opera- tional view, overmodulation and im- properly calibrated monitors can be a common area of distortions. Modu- lated carriers have greater bandwidth and require a comparable bandpass of all circuits through which they must pass. At the end of the system. a cheap receiver can undo just about everything we have tried to accom- plish with the audio.
Soundmixers enjoys noise with
New York City. d
Newton, MA 02195
20 on Reader Service
The Space Camera and Related
But they come cheaper. only
Boilermaker gives you all these top quality fea- tures:
6061 aluminum alloy.
choice of five show
- stopping colors to choose from.
If you can tolerate only the best in your act, act now and call us for all the details.
Can you recall how far back the first space camera was used in a space vehicle? We're not going to tell you.
You can do your own research.
What is interesting, though, is that a new camera is being developed by under contract to the
Center. ones used
It will be similar to the in the
Apollo lunar surface adventure. Those were also developed by RCA.
This camera system contract will be up around
$10.5 million and will trans- mit live color and black and white t.v. pictures during the manned orbital
Shuttle flights. The Space Shut- tle is a recoverable launch vehicle that can he reused to place multiple pay- loads into orbit.
It is launched like a rocket, orbits the earth as a satellite. and returns to the ground as an un- powered aircraft.
That portion of the
Shuttle which flies into space is called the
The closed circuit system will be installed on the
Shuttle for earth orbital missions starting in 1979 and subsequent
RCA flights scheduled will provide up to for
1980. fifty cameras for approximately 500 shuttle flights planned over the next ten years. Each
Orbiter can carry up to six t.v. cameras as part of the closed circuit system.
The camera system is intended to assist the crew
Shuttle in of the performing the complex tasks of deploying. retrieving and ser- vicing spacecraft in orbit.
The system on each flight will con- sist of several t.v. cameras, a video control unit, pan and and tilt mechanisms. monitors. The system will use the standard 525 lines of the US
NTSC broadcast system. Cameras will he in- stalled in the crew the compartment. in cargo hay. and on a remote manip- ulator arm.
Within the cargo bay. camera positions will he located at the forward and aft bulkheads and in the
A space shuttle closed circuit t.v. system.
72as io _J1l'o_+
Circle 33 on Reader Service Card
TV CAMERA www.americanradiohistory.com
Birth of track
Otani two -track machine is de- signed for discriminating recordists.
Built with inside -out improvements over our long succession of compact profes- sional recorders. ease and
-in operation better serviceability.
With fidelity, reliability and professional func- tions indispensable for every critical ap- plication you have in mind.
DC -servo direct drive for minimum wow/ flutter and speed deviation.
With ± 7% pitch control and foolproof
- sensing control logic. Optional remote control for all transport and mode func- tions.
30dBm input and 600 ohm +
-over output with
XLR connectors. Front
- panel edit and cue, test oscillator, stepless bias and
IEC equaliza- tion.
Full professional four heads with extra quarter
-track playback. And it's designed for both vertical and horizontal operation.
Resultant performance: smooth punch
-out mastering at
55dB crosstalk and 70dB erase
It's the latest and wisest choice for your quality
-3/4 ips masters. For the full story about the new generation recorder /reproducer, contact your near- est
Otani dealer and see why we call it the masterpiece.
Circle 40 on Reader Service
Road. San Carlos. California 94070. non at
Japan: Otar Electric Co
'N óbna.m OgikuoO Suginamrku. Tokyo 167.
The Orban 516EC Dynamic
de- essing specialist. It
from voice while retaining brilliance
and crispness. Sibilants are
that sound natural
optical film or
Your Orban dealer
show you how
quickly and effectively.
Street, San Francisco,
94107 (415) 957 -1067
The camera in the crew compart- ment will be portable and capable of beaming
"live" telecasts in color to earth monitoring stations. This porta- ble unit could also be used by an astro- naut in any extra- vehicular activity
The astronaut could leave the crew compartment with the hand -held unit and investigate areas of the vehi- cle that arc not adequately covered by the mounted cameras.
be with its own viewfinder to enable the astronaut to focus accurately on an object in space, such as the moon any or a free -flying satellite, or on part of the vehicle. The fixed cam- eras will be black and white units with full pan and tilt movement. These cameras can be controlled remotely by either the crew or by the ground con- trol personnel at
Johnson units will he sup- plied lenses. with multiple focal length zoom
The cameras will weigh about
14 pounds and measure
151 inches long by
5 inches high by 5' inches wide. They will contain a silicon -in- tensified- target
(SIT) vidicon tube.
This tube is relatively immune from damage by high brightness and pro- vides high sensitivity to low light level conditions. The cameras will have in- terchangeable lens assemblies for color and black and white pictures.
Speaking and of space video equipment delivery systems reminds me that the S.M.P.T.E.
120th will be holding its
Technical Conference in
2. One of the subjects that will be cov- ered in the sessions relates to the space shuttle, including discussions of
Satellite Communica- tions, Transmission of
Simulta- neous Television
Programs via a Sin- gle
Satellite Channel, Remote Control of Earth Systems, and more.
Other subjects to be covered at the conference are
Sound Technology in two separate sessions, Video
Production, and topics related to film production, film
-to -tape and tape -to
-film transfers, and video- disc special effects, plications. editing. and ap-
In addition to the technical sessions. the conference will have an exhibition of professional motion picture and television equipment. More than
100 companies have signed up and there will be more than 200 booths.
Among the exhibitors planning to he there will be Belden, Bell &
Bosch Corp., Chyron Telesystems.
Circle 52 on
Country, too! is
Kitty Puckett checks out
45 rpm stamper, while auditioning one at 33'/3 rpm.
Scanning Electron Beam Microscope photo of
- hedron® stylus, 2000 times magnification; brackets point out wider contact area. c STANTON 197P
Nashvi..le Record Production,
Stanton exclu- sively are throughout its
Disc Cutting Studios. Naturally, they mostly involved with Country Music, but they also get into
Pop and Rock.
John Eberle states that they use the
cutting system calibration, including level and frequency response ",
.. and they use the
-E in their Disc Cutting operation
plans to soon move up to the new Professional Calibration Standard,
681 series and 881S cartridge, is guaran- teed to meet its each one specifications within exacting limits, and boasts the most meaningful warranty... an indi- vidually calibrated test result is packed with each unit.
Whether your usage involves recording, broadcasting, or home entertainment, your choice should be the the choice of
Terminal Drive, Plainview,
45 on Reader Service Card
Visit us at the AES Convention
N tronix, TeleMation.
Thomson -CSF, and more than a from
England. half dozen companies
Last year more than 6,000 people attended.
This year expectations are for even more.
Speaking ferences, of conventions and con-
Industry Publica- tions of White
N.Y. is again running its
Video Expo. In May, they had the conference in
Chicago. The next meeting will take place in
-17th. In December. from
The space shuttle television camera.
NEW FROM LEADER
25dB, 50dB or
Linear Span Range.
Low As lmV.
Level Voltage Meter.
(also use independently).
Auto or Manual Sweep.
Variable Chart Speed.
Audio System Performance
Flutter and drift.
Tape recorder frequency response.
Audio amplifier and receiver frequency response and signal
-to- noise ratio.
Cartridge frequency response.
See your distributor or write for details.
Dupont Street, Plainview, N.V.
Quality Counts ..
5th to the
7th, the shops and exhibits
VideoWork- will move, for the first time, to the Southwest. The
Houston in Texas will he the conference site.
Then. the whole affair moves to the West Coast.
Feb- ruary 20th to the 22nd. all the exhib- itors and video experts will get to- gether at the
Tar Hotel in San
Each of these
Expo locations will give those the involved or interested in video field to get the latest infor- mation on what's happening in hard- ware and software. The workshops and seminars phases will provide experts in all of the industry to instruct and direct hands
-on sessions. In the
York meeting. over
0 exhibitors have signed up for space.
The others will also have the hest in exhibit equip- ment and software, as well as related services.
First, there will be a seminar on the
Electronic Editing. in- tended to be a review of where we are and where we're going in editing. Then. there vtr /vcr will be a seminar on
Methods and Techniques.
This will include discussions on prac- tical approaches to choosing. using. and expanding your audio system with emphasis on microphone selection. placement. set
-ups, and niques other tech- for studio and location produc- tions. (This session is intended for those in video who want to improve the audio of their video productions.
Old hat to you guys. right
Then. there'll be a session on
Skills. another on
Learning to Read
Video (video meter, wave- form monitor, vectorscope, and other specialized devices to read and inter- pret a video signal). Other topics will include Advanced Electronic Editing.
Interactive Television Methods and
Techniques. Media Center
VCR Problem Analysis and Diagnosis.
Portable Video Production Techniques and Guidelines,
Evaluating Color eras and VCRs, and more.
In the exhibit area
(which you can attend without going to even one semi- nar), you'll be able to discover what's new and coming in cameras, tape re- corders. video projectors, tape ment, cassettes, editing equip- systems, ac- cessories, etc. there
Among the exhibitors. will be
Echo Science Corp., BJA
Hi- tachi, Ikegami, Image
Sharp, Sony, Tele
Vue Optics. Video
Components, and many, many more.
No kidding. This is one show you really should go to. East Coast, West
.. no excuses.
not supposed to
enhance, add to, subtract
supposed to do
what's on tape. Because
to know everything
And everything that
isn't. Before it's
thousands of recording
broadcast studios around the world.
a national survey by Billboard
JBL's are in
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less. If that sounds
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-way monitor. Com- pact and efficient. for small broadcast control rooms and home studios.
The most popular monitor going.
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As might be expected, my column matching, damping factor and such, in the July issue, brought some re- sponses. Most of them concerned theory in much the same way as the question had come
more or less
"overall" thing. But one of them in- troduced the question of load lines, and how things have changed since the days of tubes, when load lines were critical, to now, when switching devices, such as transistors, with lots of feedback, are the order of the day.
Of course, a lot has changed. But basic principles have not. Perhaps negative feedback was a bigger new thing than transistors or other solid state devices were. son,
And for that rea- perhaps it is still less understood.
Load lines are just as relevant, if less often used, with switching devices, as they were with tubes; maybe they're not as critical, but even that may be a matter of viewpoint.
The first tubes used for amplifica-
whether just with voltage am- plification to provide gain or with power amplification to provide power
triodes. Choosing an operating point, by laying a load line on these characteristics, enabled the right re- sistance load and supply circuit to be provided to get maximum output. whether voltage or power. the
Because with a triode the slope of characteristics represented a lower resistance value than the load into which the voltage or power was fed. triodes had what later became known as damping factor, greater than
an internal resistance smaller than their load resistance.
TETRODE AND PENTODE
Advent of the tetrode and later, the pentode, produced a quite different family of plate characteristics. The slope of these characteristics is quite different from that of the triode and represents a high internal resistance. compared to any load that is used with them. The choice of the load line was more critical to getting maximum volt- age or power.
The spacing between the character- istic lines was also less linear for the pentode than for the triode so that. until the advent of feedback, pentode outputs, while far more efficient, en- abling bigger output from smaller power supplies, produced more distor- tion than triodes. In view of today's low distortion figures, we should put some figures in here.
Typical distortion, at maximum out- put level, for a triode was
5 per cent, mostly second harmonic. Typical dis- tortion for a pentode at maximum out- put was
10 per cent, consisting of second, third, and even higher orders of harmonic.
That was not all, these were measured into their ideal resist- ance load. As anyone knows, loud- speaker impedances spend a lot of their time being reactive, which makes an elliptical load line, increasing the contrast several fold.
Then came feedback, to "straighten things up." Unfortunately, it was more difficult to apply lots of feedback to a circuit using pentodes than to one using triodes because of their more complicated supply circuits; you had to decouple the screen voltage, and all that.
This led our old friend, Dave Hafler, to come up with something that seemed www.americanradiohistory.com
Drive a drill with a
125 -watt audio amplifier?
Of course you wouldn't.
But we did...to prove a point.
-125 professional amplifier drove the drill for a solid week, continuously, even though we repeatedly clamped the chuck to overload ìt. Feeding an induction motor like that is one of the toughest torture tests you can give an amplifier, yet it drove the drill through a
2x4 again and again...thanks to our current limiting circuit which protected it from harm even under adverse overload. Crazy? Not if this unusual test convinces you that at
Bogen, RELIABILITY is NUMBER ONE.
If it can handle a drill, you can be positive that a
-craft amplifier can handle any speaker load under virtually any conditions... beautifully.
The performance specs include frequency response within
±.1 db from
20 to 20,000
Hz at rated output power...and total harmonic distortion less than
Hz, also at rated power. dual channel power amplifiers, mixer -power amplifiers, graphic equalizers, a compressoriline amplifier, and a wide range of accessories.
They are designed with unsurpassed features and specifications for today's sophisticated requirements, highest reliability and total system compatibility.
We believe they offer the finest values in professional sound equipment.
Availability? Who but
Bogen delivers a line like this from stock?
One last point. The drill we drove was made by another
LSI division, National Twist Drill and Tool. They're tops in their field, too, and we mention it to emphasize the vast technological resources that stand behind us as part of a
S1 billion corporation.
PRODUCTS ARE G.S.A.- LISTED.
For more information, please write or phone us.
What does it take to produce a line like Tech -craft?
A company like Bogen.
Professional Series incorporates all the knowledge and skill we've acquired during 45 years in sound.
Yet it isn't encumbered by any earlier design concepts. We developed the entire series at the same time, using the latest state
It includes active mixers and mixer -extenders, single and
16 on Reader Service
OF LEAR SIEGLER. INC
Box 500. Paramus. NJ
to get the best of both worlds: using a he special kind of output transformer, made a pentode tube work as some- thing in between a triode and pentode, an effect known as ultra linear.
To explain this
pentode can be run as a triode by strapping its electrodes together so the screen voltage moves with the plate voltage.
That produced an operation that was no more efficient than a triode, since in effect it was a triode; connect- ing it as a pentode got much more power, but with much bigger distor- tion too. The ultra linear connection got much more
almost as much as pentode connection
much less distortion. It also made the application of larger lumps of feed- back easier than it was wtih pentode connection.
Finally came transistors. The first thing that engineers noticed was the collector that current
-voltage character- istics, working grounded emitter, are very like the pentode characteristics of a tube. But the circuit is much simpler than that in a tube because the tran- sistor is a triode, not a pentode. Its load impedance, if not its internal impedance, is much lower than that of a pentode, which make larger amounts of feedback possible too.
Further, it can be operated as a grounded collector, instead of as a grounded emitter, which makes it like the cathode follower used during tube days. When complementary pairs are employed they do not even need an output transformer to get push
So the transistor eliminates a whole lot of problems that came with the pentode tube, in spite of their similarities.
When the transistor is used as a grounded collector, it functions more like a tube than in any other mode.
In the more conventional grounded emit- ter mode
is the mode in which characteristics are usually taken
characteristic lines represent incre- ments in input base the lines current, where for a pentode tube represent increments in input grid voltage.
But when you change to a grounded collector operation, which merely means the that the collector, instead of emitter, stays at a constant voltage. what the base needs more than a cur- rent swing is a voltage swing, just like its tube counterpart. the cathode fol- lower. It's true there is a current swing input which the tube cathode follower does not have, the but in other respects operation is identical.
In fact, the grounded collector tran- sistor amplifier makes a more perfect impedance multiplier or divider (ac- cording to which way you view it) than the tube ever did.
The voltage at the base and emitter, just like the volt- age at the grid and cathode in the case of a tube, are close to identical (much closer than for the able current tube) while avail-
multiplied at the emitter, as compared with the base, by the the transistor. current gain of
But getting back to transistor char- acteristics and their similarity to the pentode tube characteristics; load lines are determined in essentially the same way. Both a tube and a transistor have a maximum dissipation line, in the form of a hyperbola (shown dashed in the figures). Both have a maximum voltage which, when operated in Class
B so the unit is cut off when it gets its maximum voltage, is close to double the operating voltage.
This means age that needs to be the operating volt- about half the maxi- mum voltage in each case.
For maxi- mum current, the limitations are little different but, operationally, their ef- fect is similar.
For the tube, maximum current depends on the point where the grid voltage crosses from negative to zero, because at that point the grid
m fuuauritE things
Lee De Carlo*
Compex- Limiter for well overa year
- always with the same gratifying results.
It's capacity for effects seems endless while its reliability in its performance as a
Expander /Gate is only surpassed by its flexibility in these same modes.
it is one
there is a fire in -the studio and a
Compex-timiter is destroyed, it is probably better to buy a new one."
Lee De Carlo is Chief Engineer ,or 'Record Plant
Studios' working with such artists as
Rolling Stones, Angel, and
760X -RS COMPEX- LIMITER
Separate Peak Level
-Ratio Variable Threshold Compressor
option integral Power Supply
Ft design recording inc.
Hawaii 96822 Tel: (808) 845 7226
Box 902, Marina, Calif.93933
34 on Reader Service Card www.americanradiohistory.com
MODEL 2710 ONE
Gives Professional Sound Man More
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Display Sensitivity Control
Line -in, Line -out Jacks on Rear Panel
REAL TIME ANALYZER model 2709
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belongs in your next system
Just the duo you need for ultimate sound control.
Gives super fine adjustment and up
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A demo from your favorite pro sound dealer will be the convincer.
Or write for our promo sheets.
For sound that makes the stars shine
Neptune Electronics Incorporated
934 N.E. 25th Avenue
(503) 232 -4445
Circle 39 on
Reader Service Card www.americanradiohistory.com
current starts, complicating things.
For the transistor, the current rating of the transistor sets the limit.
Inherently, the linearity of transis- tors and pentode tubes is not very different. The advantage of the tran- sistor is that it is easily possible to lay on enormous amounts of feedback, so its effective linearity is much better than that of the tube. Also, since it is a triode. it is possible to reduce the number of reactive coupling elements which, as well as allowing much more feedback, also makes it much more stable, against being thrown off its op- erating point, when the maximum level is accidentally exceeded.
Every transformer or coupling ca- pacitor in a feedback loop introduces the possibility of the operating point shifting as the instant maximum level is reached, after which it takes the amplifier a time to return to normal. depending on the time constant of that circuit. This may happen in the case of a tube because the grid starts to conduct, upsetting the operating grid voltage.
In the case of a tran- sistor, when the base -emitter junction ceases to conduct, a similar thing can happen because base -emitter voltage is normally small and nearly constant, where when it ceases to conduct, it suddenly rises in the opposite direction.
So, while the superficialities may seem different, transistors and pent- odes have more similarities than most people realize. With both, the effect of large amounts of voltage- derived feed- back is to make the output voltage al- most independent of the load value connected, which represents a high damping factor.
McINTOSH AMPLIFIER unity coupling
a cathode swung equally and opposite to the plate its
the first to apply large amounts of was feedback. But the tubes were operat- ing as pentodes, because the screens were kept at a constant voltage differ- ence from the cathodes. In Dave
Haf- ler's ultra linear circuit, the cathodes stayed at constant voltage and the screens swung at a specified fraction of the plate voltage swing, so the tubes operated in a condition between that of triode and pentode.
Transistors are triodes, but have characteristics more like pentode tubes, bringing to bear the best potential for high output
high efficiency output
low distortion, yet.
The basic principles, or theory, do not change.
The practical ramifications do. sales offices
THE SOUND ENGINEERING
11803 516- 433 -6530
Stemmons Tower West.
Dallas, Texas 75207 214 -637 -2444
Denver, Colo. 80237 303 -758 -3325
Houston, Tex. 77006 713- 529 -6711
Los Angeles, Cal. 90020
503 -292 -8521
Suite 265, 5801
415 -653 -2122
We have achieved a degree of excellence recognized
Wide in the field of intercom systems.
Exceptional sound quality is contoured frequency response
Hz) and new headsets. Noise audiometric cancelling achieved with our type
II microphones and high output
(112 dB) noise attenuating headphones insure communications under the most demanding conditions.
Our Stainless Steel Belt
Pack with, State of the
Art encapsulated electronics assures long life and reliability. Our belt withstand a 60 foot drop to concrete. pack will
& 8- channel stage manager control stations.
Over 200 remote station capability with
8- channel switchboard.
Visual signaling between stations.
Interconnects with standard
2- conductor shielded microphone other telco lines .. cable and adaptable to communication systems including
Catalogue with complete specifications available upon request.
-Corn® intercom systems
CA 94107 (415)
Theatre. Larkspur, Calif.
Circle 50 on Reader Service
switches with goldplated
available, the best.
Interchangeable with other professional models, more Series
Faders can be positioned in
smaller space because
%" width. them ideal
Designed for high performance, the
ductive plastic element
remarkably durable, has
characteristics and enjoys an eight
Other unique features include
linear and audio outputs, single or dual channel
high- impact cases are solvent- resistant plastic with built
ture and dust
Terminals accept quick -connect receptacles. Temperature range:
as a complete drop
module with knob and escutcheon, they are also available
stroke lengths with 2%" and
Custom knobs include our
new low- profile,
round and square designs
choice of six colors.
it your best shot. Write or call today for complete information. the same size package. Internal
T R O N +
2865 FAIRVIEW ROAD
COSTA MESA, CALIFORNIA 92626
Designed for driving headphones,
-10 amplifier's rear mounted toggle switch selects mono or stereo outputs.
Four watts rms on each side of four stereo channels go into four ohms. Claimed flat frequency response is
20 to 20,000 Hz. The unit includes individual and master gain controls.
Complexities usually found only in studio mixers are present in Series
1S portable stereo sound mixer. The unit can be had with either an aluminum flight case for on the road or in walnut for permanent installation. It comes in
20- channel formats.
-in high pass filter combines with a to variable gain microphone amplifier attenuate high level low frequencies and to avoid distortion through the input channels. A four -band active equalizer on each input channel per- mits a sweepable frequency of the two mid -bands between 130 Hz and
2.5 kHz, and 750 Hz and
15 kHz; four independent equalizer amplifiers avoid interaction between bands. The stereo mix can be overridden on monitor headphones by an auto -solo pushbut- ton on any input or output channel, which also switches two -volume unit meters to read the solor level.
Three auxiliary mices are provided, two for prefade monitor and one for post
- fade echo and other effects.
Mfr: Soundcraft North America
Circle 82 on
I I cdw
PL.. er w
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1aN It 5962
Ma.IO UP 35.180360011.
..Your son, EwrlChrw11.
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$59.95 DA.7 d
HOW TO order or
For shipment within
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I.ase add 5350 per order for shipping
& handling. (S5.50 for orders outside U.S.). N.V.S. residents add tax. No
100% guaranteed. brand new
6 factory fresh. jiliMgc\
Row, New York City, 10038 (212) 732-8600
WRITE FOR FREE
Circle 28 on Reader Service Card
BROADCAST DELAY LINE
A maximum delay of up to
6.4 seconds is possible with BD955 broad- cast delay line, used to blip objec- tional material from live broadcasts.
When an announcer hears the ob- cenity or other unsavory noises, he presses the DUMP button. The pro- gram continues immediately in real time while the BD955 extends the safety delay margin to maximum. De- lays ranging from
6.5 milliseconds to maximum can also be used to fake
"doubling," create echo effects, and provide delay for echo chamber feed.
In t.v. applications, landline trans- mission of audio can be delayed to match satellite video signals.
The de- vice is rack mountable, has a frequency response of either
15 or 7.5 kHz; the lower frequency is suitable for "talk only" use while the
15 kHz response model can handle any program material.
Mfr: Eventide Clockworks, Inc.
Circle 83 on
FM sound is good
nniv station equipment
Dolby Laboratories Mud needed for Dolby
FM listeners these days are sensitive to
If you have any
just take a
at the sales of
quality home and automotive stereo equipment.
signal quality could
well be a
the run of the mill.
is what Dolby
FM is all about. The Dolby
75 to 25 µs. along with
-type Dolby you
dB more headroom
at 10 kHz
just the thing
that are rich in high
originally designed for
rather than filtering out
of the time.
Listeners with receivers have the
reception* opportunity. for
the first time. to
signal in virtually the same signal can
it left the studio. Your FM
as the high
listeners play at home.
time. listeners with
receivers aren't penalized. because
emphasis subjectively complements
new listeners to
FM station is one thing: keeping today's another. That's
quality and Dolby
like to find out
more about how
FM can be
good for your
us at the
"There are now more than 80 consumer product models equipped for Dolby FM reception, including several new car stereo systems.
'Dolby and the double -D symbol are trademarks of
25 on Reader Service Card www.americanradiohistory.com
346 Clapham Road
Cable Dolbylabs London
Sharp contemporary design, all black plexiglass and brushed matte finish aluminum, make the Audiofile
Lowboy a showoff piece. The unit has a plexiglass top and heavy casters, can handle in excess of
400 lbs. of equip- ment with a rack mount capability.
Optional shelving is available. Dimen- sions arc
Reader Service Card
Conveniently situated barrier strip connections, on the rear of the con- sole, simplify wiring and patching from SP610 I0
/8-out stereo console. Input modules include a
in. conductive plastic slide fader,
-band parametric equalization.
TK assignment buttons, post echo sends, monitor send control,
2 cue sends, solo button which allows stereo panning when engaged, a mic
/line switch, program
/sync switch, and an attenuation switch of
Output includes cue
1 and cue
2 level controls, each of which can be soloed, and
2 echo returns. Mic input impedance is
150 ohms balanced, line input impedance
10k ohms, dB, output level vu. output level
dBm above zero
Circle 85 on Reader Service Card
Shipped from STOCK! c
Ask for Our
DES PLAINES. ILLINOIS 60018
PHONE (312) 827 -8388
Reader Service Card
REAL -TIME SPECTRUM
Covering the frequency range from
20 millihertz to 25.6 kHz, Model
3582A spectrum analyzer is useful for electrical and physical measurements which have significant spectral in- formation in the audio and sub
-audio range. Amplitude and phase are dis- played alphanumerically on a large crt display. Two independent meas- urements (amplitude, phase, or both, as well as coherence) can be displayed simultaneously or digitally stored and recalled later for visual comparisons.
The unit has a zoom feature (band selectable analysis) which makes it possible to locate frequency spans of
25 kHz down to
Hz anywhere with- in the frequency range of the instru- ment. A microprocessor executes the
Fast Fourier Transform to measure signals that have long measurement times. An exponential form of power averaging is used for measurements where the spectral information is not stable but varies slowly, continually reducing older spectra importance to prevent old data from obscuring new data. Because of it's built -in noise source, the unit can be used to pro- vide a drive signal, which functions like a tracking generator, or low -fre- quency network analyzer with real
- time measurement speed.
Circle 86 on Reader Service Card
At TDK, we know that your test cassette is a vital element of your laboratory or service procedure.
So when we created a series of test tapes, we approached them as integral com- ponents, with both tape and housing engi- neered as precisely as your test instruments.
You'd expect that from the high bias reference the makers of TDK SA, standard for many manu- facturers' cassette decks.
TDK test cassettes don't jam and they're dropout
free. They're built to last under unceasing use.
If you're a store service manager, assembly line quality control inspector, or highly discerning audiophile, you need that kind of precision and reliability.
To make abso- lutely sure you get it,
we custom quality
-control each and every one.
No matter what data you need, TDK has 'a test cassette to help you find it out: bias/EQ alignment;- playback level calibration;
Dolby calibration; head azimuth alignment; wow and flutter and tape speed and
11, five and three
-point frequency characteristics checks.
Check out the complete line of TDK test cassettes by writing, or calling
(516) 746 -0880.
When you do, find out about our bulk duplication cassettes, bulk duplication pan- cake tape, audio visual, leaderless, data and endless cassettes, too.
Yóu'll find that the same TDK reliability quality and that goes into our test tapes applies all the way down the line.
ST TAPE FREQUENCY
World leader in recording tape technology.
TDK Electronics Corp.. 755 Eastgate Blvd.. Garden City, NY 11530
Chicago, IL 60645; 2041
Rosecrans Ave.. Suite 365,
21 on Reader Service
.Q designed for
rnrnerc ¡al a
tough or and is
heavy sive the the
switch the roo for most
ATR 7O duty,
for the cop n
t sting that
A continuous of
The recorder reel dim, al keeps trips Nowthere's
I is a betty
an d ationruns sty on the e4
All switches deepr,d types, moving excuse
s than for reel the arts less from align ns
¡cation nad even
ofe turn out. on the
Ampex d city. every mal
field. audio portable situation i itself full rang And
a areas actors rigid,
Mas- hundreds the s for
most uattAmpex audio the fin and it's
9 ap63, 415
-inch rack mountable Model
10 x 3 microphone splitter is con- structed for sound reinforcement as well as recording and broadcasting.
Working from ten female XLR con- can go three ways from each input
direct output for phantom powering from the main console for condenser microphones or splitter outputs con- sisting of two bridged outputs with ground lift switches on each. The transformers are dual
Faraday shielded. to eliminate hum and buzz.
Mfr: Uni -Sync Inc.
Circle 87 on Reader Service Card
Three -head, three -motor, two -speed
/sec.) Model A -3440 four channel open reel deck with Simul-
-inch reels, can be monitored through monophonic head- phones, each channel switch -selectable.
Features include professional micro
- switch, manual cue level, four vu level meters, mic
/line input selectors, four front -panel mic jacks and independent output level controls for each chan- nel.
Remote control is available. Spe- cifications include 0.04 per cent wow and flutter, 65 dB
ratio, and 35 to 22.000 Hz frequency response at
In the same series, the manufacturer is also offering two new reversing decks taking a seven -inch reel, and another
-inch reel model.
Circle 88 on Reader Service
"By its nature, the
Vocorder is absolutely multi -para- poly -phonic" is a quote from a fascinating booklet on the
Vocorder Sound Effects device, which, among other sounds, is able to replicate human speech. Source: Senn
- heiser Electronic Corp.,
St., New York, N.Y. 10018.
Son of Ampzilla and his entire family tree of amplifiers are described in a sort of amp Roots, an
-page brochure. Source: The Great Ameri- can
Sound Co., 20940 Lassen St.,
Chatsworth, Ca. 91311.
Dual and single trace oscilloscopes are the subject of a full
-color catalog from
Leader Instruments. Source:
Leader Instruments Corp.,
St., Plainview, N.Y. 11803.
WORLD VIDEO STANDARDS
4 x 9 in. trifold card lists 150 countries alphabetically, along with their standard plus scan fre- quencies and their line voltage and frequency rates. Source: Devlin Pro- ductions, Inc., 150 W.
York, N.Y. 10019.
REEL TO 1 EEL
On reels or hubs.
With Agfa. Ampex.
LEADER & SPLICING TAPE
EMPTY REELS & BOXES
All widths, sizes.
. all or write:
Div. or 1233
(10 lbs.) CW
-3 cas- winder will rewind three c -60 cassettes in 55 seconds. Individual cassettes can be loaded or removed without affecting the operation of the other stations. Precision set torque evenly winds the cassettes.
20 -page catalog lists capacitors, resistors, switches, cable assemblies, accessories, etc. Source: World
16 mm 300 de- gree potentiometers for consumer and commercial applications are covered in a data sheet. Source:
Cor- poration of America,
Marietta, Ga. 30067.
still at it.
We started in
Audio Development Company producing
jacks and jack panels
the broadcast and telephone industries.
has produced such
printed circuit board
doing for you
impedance audio connectors. We have six models
they're available soon- er.
about making a sound con- nection
W 78th St
Telex 29 -0321
Sales offices in
Atlanta GA (404 i
766 -9595 Dallas.
-6783 Denver. CO (303)
CT (2031 255 -0644
Lafayette. IN (3171474-0814 Melbourne
(305) 724 -8874 Menlo Park. CA (4151323-1386 Minneapolis. MN (6121835 -6800
Washington. DC 1202) 452 -1043 Montreal. Quebec
47 on Reader Service Card www.americanradiohistory.com
THE TAPE -TO
-DISC transfer session the last step in record production, or the first step in record manu- facturing? It depends on whom you ask. Some disc mastering facilities (notably abroad) are located at the pressing plant, far, far away from the influence of anxiety- ridden producers
given half a chance spend hours trying to "fix it after the mix."
Other facilities are found right at the recording studio, where the recording engineer and producer can directly supervise
(or interfere with) the transfer from tape to disc. others are found at "halfway houses," specializing just in disc mastering, and usually not affiliated with a particu- lar record company or studio.
So, perhaps we should view disc mastering as a little bit of both the production and the manufacturing process.
And maybe we should also spend a little more time learn- ing something about it.
After all, how many people hear your priceless master tapes?
Iry Diehl helps us get started, with a look at Basic Groove
On tape, the recorded level has no influence whatever on playing time.
Not so on disc, where every extra dB means a bit less playing time.
On tape, a
101/2 in. reel will record for about thirty minutes (at
How long is a
Well, it depends. Depends on what? Check with Iry for the answers.
When was the last time you saw a new disc cutting lathe?
We saw one at the recent Audio Engineering Society con- vention, and sent Suzette Fiveash (our new Associate Ed- itor, no less) out to find out something more about it, and report back.
She did, as you'll read in her story,
Cybersonics: A New Disc Mastering Lathe.
Given the time vs. level constraints of disc recording, wouldn't it be nice to figure out a way to squeeze a few more dB onto your next record? The folks at the CBS
Technology Center thought so too, and have spent the past five years developing a way to do just that. Charlie
Repka reports on their progress in his feature on the
DISComputer Mastering System.
-to -disc recording has been attracting a lot of notice these days. And, whenever versation turns to "d -d,"
(or wherever) the con- you're sure to hear the name of
Bert has been very active in this challenging area, and in between sessions, we asked him to tell us a little something about The Logistics of Direct
- to -Disc Recording.
Never one to take the easy way out, Bert does most of his d -d work on location. And that means he's got to beg, borrow or steal a few cutting lathes for every session.
And that means talking a few disc mastering engineers into coming along, and not just for the ride. Well, since Ms.
Fiveash made the mistake of sending her Cybersonics story in early, we sent her out again
time to talk to
Stan Ricker at the JVC Cutting Center, about what it's like to Bring
Own Lathe: The Logistics of Cutting
This issue of db was really inspired by a letter from
James Shelton, president of Europadisk Plating Company.
Mr. Shelton took us gently to task for not saying much about the lesser -known aspects of audio
as the rec- ord plating process. We cheerfully admit to ignoring record plating for years. And for good reason: we don't know much about it at all. And that placed the ball back in
Shelton's court, where he quickly obliged by serving us A
Look At the Record Plating Process.
And that brings us to the end of this issue. We know a little more about disc cutting now, and promise never to take it for granted again. What about you?
you can choose your microphone to enhance your sound system.
Like microphones musical instruments, for every each imaginable different type of use.
Shure microphone has a distinctive "sound," or physical characteristic that optimizes it for particular applications, voices, or effects.
Take, for example, the Shure SM58 and SM59 microphones:
Mellow, smooth, silent...
The SM59 is a relatively new, dynamic cardioid microphone.
Yet it is already widely accepted as a standard for distinguished studio productions.
In fact, you'll often see it on TV
especially on mus- ical shows where perfection of sound quality is a major considera- tion. This revolutionary cardioid microphone has an exceptionally flat frequency response and neu- tral sound that reproduces exactly what it hears. It's response when miking markably designed to give good bass rugged
at it's a distance. built to
Re- shrug off rough handling. And, it is superb in reject- ing mechanical stand noise such as floor and desk vibrations because of a unique, patented built
-in shock mount.
It also fea- tures a special hum
-bucking coil for superior noise reduction!
Some like it essentially
IN HERTZ s a
Probably the most widely used on- stage, hand -held cardioid dynamic microphone. The
SM58 dynamic microphone is preferred for its punch in live vocal applications
espe- cially where close -up miking is important.
It is THE world
- standard professional stage mi- crophone with the distinctive Shure upper mid -range presence peak for an intelligible, lively sound. World
- renowned for its ability to withstand the kind of abuse that would destroy many other microphones. Designed to minimize the boominess you'd ex- pect from close miking. Rugged, effi- cient spherical windscreen eliminates pops. Lightweight (15 ounces!) hand -sized. The first choice rock, pop,
B. country, among gospel, and jazz vocalists.
...some like a
iREOUENCY W HERr:
Inc.. 222 Hartrey Ave..
Manufacturers of high fidelity components, microphones, sound systems and related circuitry.
Circle 26 on
Reader Service Card www.americanradiohistory.com
The mathematics góverning the spiral trip from the perimeter to the center
a recording disc.
DESPITE ALL THE RECENT
ADVANCES in all audio technology, the recorded disc remains the fav- orite mass
-market medium for music recordings.
Yet, at times disc recording appears to be a sort of step -child to the recording industry. Often misunder- stood, the disc recording art is considered by some to be a
Of course, there have been impressive advances in disc recording technology too, but, the basic principles em- ployed in cutting discs have remained unchanged for decades.
Simply stated, the disc record comprises a spiral groove, engraved or embossed on the surface of the disc.
Con- ventionally, the groove is engraved from the outside to the center of the disc, while the signal to be recorded modulates the groove. Other than for the sake of stand- ardization, there is no reason why the process could not be reversed with the record beginning near the label and then spiralling its way outwards, towards the record's outer diameter.
One first principle that may be obtained from this simple description is the relationship between the time it takes the groove to spiral from the outside to the center of the disc, and the duration of the program to be re- corded. The spiral rate, or pitch, depends upon the dimen- sions of the disc (7
"), and determines how many lines there will be from the start of the recording to the end. The number of lines will therefore be related to the dimensions of the disc and the program length. This relationship is expressed by the formula:
Pitch, measured in lines -per -inch
Rotational velocity of the disc.
Dimension available for recording.
Typically, a twenty minute program, to be recorded on a
LP record at 33.3 rpm, will begin at an outer diameter of
11.5 inches, and should end at an inner diameter of about
The outer diameter con- forms to the
Record Industry Association of America
(RIAA) standard for the Outermost Groove at Recording
Pitch. The standard also specifies a
Minimum Inside Di- ameter of
Recording, which is 43/a inches. However, if the program length is not excessive, most disc mastering engi- neers prefer to end the recording well before this minimum dimension in order to minimize inner -groove distortion.
The dimension over which the program is recorded is equal to the outer diameter minus the inner diameter, divided by two. (11.5
3 inches). This is the radial distance across which the groove spirals while the program is recorded onto the disc.
Using the above for- mula, we find the required pitch to be:
(20 min.) (33.3 rpm)
Once the recording pitch has been determined, other parameters can be ascertained.
For example, the spacing between the lines is the reciprocal of pitch.
(For our pur- poses, we are assuming the groove is spiralling inwards at a constant rate.) If the pitch is
222 lines- per -inch, then the line spacing is
1/222, or 0.0045 inches -per -line.
Typically, this dimension is expressed in mils
(thou- sandths of an inch), which in this case would be 4.5 mils. www.americanradiohistory.com
This space between lines must be apportioned between the width of the groove, the modulation displacement, and any headroom that may be required. The basic groove width is generally equal to, or greater than,
2 mils. The space remaining after subtracting the width of the groove is that available for modulation.
DISPLACEMENT AND VELOCITY
When we inspect the modulated groove under a micro- scope, one parameter observed directly is the amplitude of displacement. However, there is no direct relationship be- tween the applied electrical signal level and the resulting mechanical displacement. The quantity that is directly proportional to the applied electrical signal is stylus velocity.
As the applied signal voltage is increased to twice its origi- nal value, stylus velocity increases by the same proportion.
Displacement of the groove, on the other hand
dependent on the magnitude of the applied signal
in- versely proportional to the frequency of the applied signal.
As the recorded frequency decreases, displacement in- creases, and vice
Due to the direct relationship be- tween the the applied electrical signal and the stylus velocity,
RIAA pre- emphasis and de- emphasis characteristics are tabulated in terms of velocity, as are recording levels.
(These RIAA characteristics arc analogous to the NAB pm- and post
-emphasis found in tape recorders. Ed.)
The relationship between stylus velocity and groove displace- ment is expressed as:
Amplitude of displacement.
Peak stylus velocity.
Given a line -to -line spacing of 4.5 mils, and assuming a groove width of
2 mils, 2.5 mils of space remains to ac- commodate modulation. A common record velocity refer- ence level used in disc recording is 7 cm.
/second (peak) at
1 kHz. Note that this reference is a peak, or maximum, velocity, thus implying that other velocities are involved as well.
Unlike an automobile travelling at a fixed speed along a winding road, on an LP record it is the
(that is, the groove) that is doing the travelling, while the
"car" (the stylus) is pushed from side -to -side by the undu- lations of the groove.
If the groove is a sine wave, at each of its amplitude peaks the stylus comes to a halt and then reverses direction, pretty much like a pendulum.
It then picks up speed, until it reaches its peak velocity
(at the zero crossing point) and then it begins slowing down again as it approaches the next amplitude peak in the sine wave.
7 cm./second reference level represents the maxi- mum velocity at which the stylus travels, as it traces
(or engraves) the groove. The displacement that would result if
1 kHz was recorded at a reference velocity of
7 second is calculated below: cm./
0.439 mils peak displacement
Doubling this value gives us a peak
-to -peak displace- ment of 0.878 mils. Since the next adjacent inner and outer lines (grooves) are also modulated, the total space required between adjacent lines is equal to the peak
-to- peak displacement (A
In our example, more than ample space is available for signal modulation at
On the other hand, if a frequency of
Hz was re- corded at the same velocity, we would find that our groove displacement is excessive, and the adjacent grooves will run into each other, causing overcut.
In this example, we have included a conversion factor, 103/2.54, to provide an an- swer directly in mils.
Since groove displacement is inversely proportional to the frequency of the modulation signal, the standard RIAA
Recording Characteristic provides for a low frequency at- tenuation to conserve disc space (some
Hz), as well as a high frequency boost. When referenced to
/second peak velocity at l kHz, the peak velocity and resultant displacement at some other frequency (after
RIAA pre -emphasis) will be;
Peak velocity as some specified frequency. cm.
(taken from the
Amount of pre -emphasis at the specified frequency standards).
Reference velocity at
For a frequency of
100 Hz, we find that the peak velocity is
/second. There- fore, since earlier we found plify matters, A
/27rF (or, to sim- we can now calculate the displacement of a
Hz input signal, with our system calibrated to a 7 cm.
/second reference at
1 kHz. Once again, we include the conversion factor for mils:
1.864 mils, peak -to
It is evident from the last example that if the applied electrical signal at the input to the disc recording system was constant at all frequencies, the resulting groove dis- placement would not be constant, but would increase as frequency decreases, even with the compensation provided by the RIAA standard.
We have looked at just one point in the low frequency range, namely
Hz. What of the displacement at say,
Why not try these yourself, to get some in- sight into disc level constraints at low frequencies?
RIAA RECORDING CHARACTERISTICS
Frequency Pre -emphasis
Note that most modern disc cutting systems provide a variable pitch function. This automatically adjusts the pitch, as the disc is being cut, to provide the optimum spacing between grooves.
Typically, during a quiet passage. when not much space is required between lines, the pitch will be tightened. Before a very loud signal, the pitch will
"open up," to provide ample space for the increased groove dipslacement. www.americanradiohistory.com
this is what you are
If you demand nothing less than true hi -fi performance, you'll understand the advantages and flexibility that resulted when
Technics separated the basic amplifier /control /tuner functions into the five units we call the Flat
The automatically switchable dual
FM tuner. The
-9010 stereo para- metric
/graphic frequency equalizer.
-9020 peak/peak-hold/average metering system.
DC power amplifier.
You'll also understand why the
Series challenges the performance of the most expensive professional equipment in the world. And very often
Inpu Waveform to ST9030 FM
1 surpasses it.
Look at the graphs.
The repro- duced waveform is virtually true to the original. All types of distortion
-some measurable, some not
And the linear frequency response is
Output Waveform from Technics Fiat Series.
8f2 Both ch driven
- extremely wide.
Were confident that the truly dis- criminating critic will recognize the magnitude
Espe- cially when that achievement is offered at prices that are unprecedented for equipment of this caliber.
And with the flexibility to incorporate one or more, or all five units into your system.
Depending on your needs or budget.
To see how
Technics achieved the incredible performance shown in the graphs; you have to see and compare the incredi-
+120 ble specifications that are typical of the
Series on the facing page.
Output power (W)
'low car off
Output. Power in
Gain, Phase vs.
-9060 A np
-2.0 dB. IMAGE and
73 dB. FREQ.
REJECTION, SPURIOUS RESPONSE
58 dB. STEREO SEPARATION
(19 kHz). Fixed
(19 kHz, 38 kHz).
-9060. POWER OUT-
70 watts per channel (stereo), 180 watts
8 ohms from
20 Hz to 20 kHz with no more than 0.02% THD. INTERMODULATION
-1- dB. POWER BANDWIDTH:
120 dB (IHF A).
& NOISE: 100
All the specifications of
Flat Series are too numerous and corn
- plex to list here. But their performance is too good to miss. So don't.
Series is now available for demon- stration at selected audio dealers. For very selective ears.
And for very selec- tive eyes there's Technics
-999. A movable
19" custom rack with rosewood veneer side panels.
A rare combination of audio technology. A new stand- ard of audio excellence.
This is what
Smaller size and cost -trimming simplicity might bring this lathe into the more modest studio operation.
The Cybersonics DM 2002 Disc Mastering
DEVELOPMENT of the
Cybersonics DM 2002 Disc
Mastering Lathe began about five years ago. At the time, there were all sorts of new ideas and products around. Consoles were becoming auto- mated, digital delays had made their appearance; there were parametric equalizers, new expanders and com- pressors, noise reduction systems
list goes on and on.
Most of these newly -developed devices were brought about through the application of an ever -expanding variety of digital and analog integrated circuits, many using the new computer technology, which was fast becoming ac- cessible to audio design engineers. Designers had a seem- ingly endless number of options from which to choose in developing newer, smaller, more compact devices. It seemed as though everyone was improving everything.
Yet, disc mastering remained more -or
-less invisible. Im- provements in this area were known only to those few with an intimate knowledge of the medium. It occurred
Susette Fiveash is db's
West Coast associate editor. to
Cybersonics president Tom
Lippe] that here was an area of professional audio that could also benefit from some of the new technology. He noted that a very small percentage of recording studios were directly involved in disc a mastering. Possibly, the complexity and expense were deterrent, limiting the field to a comparatively few specialists
Thus, the newly- formed Cybersonics.
Inc. directed its
R &D towards coming up with a mastering system that would be far less formidable than those presently available.
In doing so, they hoped to make disc mastering more attractive to the small studio, by keeping the price tag down and offering a lathe that would be simple to operate and maintain.
In fact, simplicity became the primary goal. not only because it would allow a precision machine to be manufactured at a reasonable cost, but it would also permit the non -specialist user to easily gain competence in disc cutting.
Cybersonics is located in
Southern California, which is not only a focal point in the recording industry, but also supports the bulk of the aerospace design companies in www.americanradiohistory.com
The head mount assembly.
Prototypes of electronics cards, accessed by sliding the front panel out on drawer slides. the USA. The accessibility of technical information from both industries was a great asset in the development of the lathe.
After reviewing the various technologies, and research- ing several methods of generating controlled linear motion, digital positioning systems, and other electro- mechanical systems, it appeared that it would be possible to design a complete mechanical system
using any belts, pulleys, gears, or hydraulic devices.
What emerged after five years of development was a self
- contained disc mastering lathe bearing little resemblance to its predecessors. When first encountering the
Disc Mastering Lathe, one notes its compact- ness of design.
In fact, it could almost be mistaken for a large record playing device of some ultra -modern design.
Not only is it compact, but its designers seem to have paid some attention to aesthetic detail as well.
In other words. it doesn't exactly look like a traditional lathe. This may distract some, who arc accustomed to the behemoths seen in the modern tape
-to -disc transfer facility, hut there is certainly some rhyme and reason hehind the DM 2002's diminutive size, 351/2-inches wide,
271/2-inches deep and
16- inches high (including microscope).
It weighs in at about
250 pounds. and this should make it especially at- tractive for those remote direct
-to -disc sessions, where a lathe must he transported to an often -hostile environment. and set up very quickly.
Mechanically, the concept is: simple, direct, small. The lead screw carriage, microscope drive system and turntable assembly are all mounted on a single platen, which is
'fl- inch thick. 33- inches wide and 24- inches deep. is
The platen constructed of special -grade aluminum, ground and fin- ished to a flatness within a weight
I mil tolerance. The platen's
extreme damping. stability, and linearity to all moving mechanical functions.
The actual lead screw and head -mount carriage assem- bly consists of two end blocks
precision -ground, and pinned to the underside of the platen. Between the end blocks are two stainless steel parallel rods, on which the carriage assembly glides, and these arc mounted on super
- precision low- friction linear bearings. The head -mount carriage itself is driven by a
screw, captured by a half -nut follower made from a special "oil
-homogenized" plastic material.
The microscope drive system is a smaller replica of the carriage assembly, and is also fitted to the platen. as is the turntable drive system.
A good measure of design simplicity was made possible by a new d.c. torque motor, one of many components "bor- rowed" from the aerospace industry.
It is a permanent
- magnet d.c. servo motor, with enough commutator seg- ments to virtually eliminate any "togging."
The motor's speed
/torque relationship is linear, and it satisfies
Cyber- sonics' precision -design requirements for all mechanical sub -assemblies.
For its size, the motor has extremely high torque. very low inertia, and is easily controlled with rela- tively simple electronics. Consequently. Mr. Lippe! feels that its speed control is considerably superior to that of other types of motors.
Four of these torque motors are used in the
The motors directly drive the lead screw. the turntable, the cutter suspension, and the microscope.
In the lead screw carriage sub- system, the motor con- trols the linear speed (lines -per -inch. or LPI) of the car- riage.
It is able to follow a complex velocity profile quite accurately, thus assuring precise control of the groove spacing on the disc's surface. Since the motor is direct
- coupled to the lead screw. all complicated systems
(such as clutches, gears, belts and pulleys) are eliminated, along with their associated problems. The motor's slow speed reduces the possibility of mechanical vibration transmis- sion, and its design simplicity reduces the necessity of many routine adjustments.
In the turntable sub -system the torque motor is used as a constant
-speed device. It has sufficient torque to accelerate the ten pound platter to 45 rpm in about one quarter of a revolution. Once up to speed, it is held constant by a crystal -controlled phase lock loop. Long term speed sta- bility is as good as the crystal, 0.001 per cent. Wow and flutter are negligible because the motor's torque is always in control. The lathe also has an automatic disc hold -down vacuum system, which utilizes a hollow drive shaft through the motor housing to the underside of the platter.
(No more forgotten vacuum chucks!)
In the microscope -drive sub- system, slow speed and easy control are the requirements, so the motor is pulse -width driven. Speed and direction are controlled from a single knob on the operator's panel. This allows the engineer to inspect the disc being cut comfortably. and therefore do a more thorough job inspecting the lacquer for groove imperfections.
The precision ground lead screw and carriage ways viewed from below.
The trol. fourth torque motor is for cutter- suspension con-
It is only rotated through a few degrees in total: while the disc is being cut, it moves through seconds of an arc. Its primary function is to control cutting stylus pressure and thereby the depth and width
Electronic damping of the groove.
a feedback circuit in conjunc- tion wtih the cutter head suspension-eliminates levers. strings, knobs, cams, and hydraulic dampers.
Again, there's not much to adjust or change: therefore, not much margin for error.
The motor is also used to raise and to lower the cutter head, at the start and finish of the transfer.
FRONT PANEL CONTROLS
Deliberately, the ease front panel than been kept simple, for of operation. Microscope control knobs and switches are at the extreme left. Next, two large analog meters indicate pitch and depth information.
At the center of the panel, a recangular l.e.d. display reads out the precise diameter at which the stylus is cutting. This is accom- plished by means screw. of a shaft encoder coupled to the lead
The encoder also eliminates the need for mechanical switching relating to automatic mode functions, such as head drop, lead -in spiral, automatic tape- start, lock -out concentric groove diameter, head tract-to- rest position. lift, and automatic re-
Within the I.e.d. display area, two additional readouts indicate stylus heater current and turntable speed.
The speed indication is actually a digital strobe. and reads the precise speed at which the platter is rotating.
Motion and mode control buttons are located to the right of the front panel. Below the front panel. there is a sub
- panel with pre
-set controls for heater current, band -time switch, half
-speed selector. etc.
Contemporary electronic devices arc used within the
2002: random access memories, twelve -bit analog -to- digital and digital
-to- analog converters with an accruracy of one part in 4.096 (213), or ±0.025 per cent, precision sample- and
-hold circuits with f.e.t. op
-amps and low power
Schottky logic. These circuits control the pitch /depth com- puter as well as the basic lathe functions, such as turntable speed, mode control, etc.
Additional logic circuits provide safety against an accidental head
-drop when the lathe is functioning in a mode that would be dangerous.
Tape recorders can no longer be looked upon as independent units in today's ex- tremely sophisticated sound systems, but rather as components within a total system with performance capability as advanced as all other components of that system.
Drawing upon its unequalled
30 year tradition in magnetic recording technology,
Tandberg has met this challenge by developing a completely new concept known as
ACTILINEAR Recording (Patent pending).
In conventional recording systems, the summation of record
& bias currents in the recording head is done through passive components, leading to inherent com- promise solutions. The new ACTILINEAR
System is free of these compromises, as the passive components have been re- placed with an active Transconductance amplifier developed by Tandberg. Just a couple of its benefits are: up to
20 dB more headroom over any recording system cur- rently available, and the ability to handle the new high coercivity tapes.
In fact, Tandberg's new ACTILINEAR
Recording System, when used in conjunc- tion with the soon- to -be- available metal particle tapes now under intense de- velopment in the U.S.. Japan and Ger- many, offers performance parameters approaching those of experimental Pulse
Code Modulation (PCM) technology, yet is fully compatible for playback on all existing tape recorders.
It is literally a recording system for the future, with no obsoles- cence factor, as it can be used with any tape, available now or in years to come.
Tandberg engineers have mated this advanced recording system with the finest cassette deck making their transport available new TCD 340
A a today, worthy suc- cessor to the world- famous TCD 330 cas- sette deck. When used with the better brands of recording tape currently availa- ble, the TCD 340 As ACTILINEAR Record- ing System permits an extremely linear frequency response, a significant increase in headroom, as well as a reduction of high frequency
IM distortion and the cancella- tion of Slew Rate limitations.
And when metal particle cassette tapes become available, the TCD 340 A can be adjusted to take full advantage of their increased signal capacity. At that time,
Tandberg will also sette deck offer the ultimate cas-
-the remarkable TCD 340 AM, complete with front panel switching for the new metal particle tape.
Both these remarkable cassette decks excel in more than just their circuitry. Like their famous predecessor, the TCD 340 series offers
-1 three separate heads (not a sandwich" head compromise) for professional recording
& monitoring, as well as
Tandberg's renowned three -motor, dua' capstan closed loop transport, coupled with complete logic- controlled solenoid operation. Plus exclusive fea- tures such as adjustable azimuth
10 kHz tone generator, allowing the user to select the perfect alignment for each cas- sette, as well as to spot dropouts and inferior quality tape.
And the TCD
A boasts a
70 dB signal
-noise ratio, plus very low 0.12% WRM wow
And there's more: Automatic take -up of tape loops when the cassette is inserted.
Frequency -equalized, peak- reading met- ers.
Servo -controlled high speed winding.
Plus vertical or horizontal operation, op- tiona, remote control
& rack mounting.
330 was the deck that delivered cassette performance exceeded only by the finest reel -to -reel machines.
Now, the 340 series with
Recording narrows the gap even more.
For your nearest dealer, write: Tandberg of
Labriola Court, Armonk,
Available in Canada.
The microscope carriage viewed from below. ample, automatic head
is initiated if the operator stops or changes turntable speed, or moves the carriage in the fast
-out mode while cutting.
When the front panel is pulled out, all electronics are exposed, for easy trouble
-shooting. l.c.'s are mounted in computer -grade sockets to allow quick replacement if and when the need should arise.
COMPUTER PITCH CONTROL
All control signals are taken from the standard preview head on the tape playback system to allow the circuits to anticipate what is going to happen to the groove when it is cut. The preview signal is also stored for one revolution in the computer, where a comparison is made between what the previous groove loked like and what the uncom- ing groove will look like. This information is converted into pitch and depth control signals. is
The computer receives new capable information constantly and of up- dating pitch and depth information from two to eighteen times per turntable revolution. A program- mable delay time in the computer's logic compensates for preview head -to- playback head distances, disc speed, and tape speed, thereby eliminating the need for complicated tape paths on the master tape machine.
All control signals are formed into eight
-bit words. in order to facilitate automated disc recording, in conjunc- tion with presently available computer mixdown systems. or with future microprocessor
-based systems. The feature also makes it possible to tronically. for high link several lathes production or direct together elec-
-to -disc recording.
Because of its small size and ease of operation, there is doubt that the Cybersonics lathe could open the door to versatility in disc mastering a bit wider. Two or three lathes might be placed in the amount of space formerly required for just one. Since the lathe is not much bigger than a typical tape recorder, it is conceivable that it could be placed in the recording studio control room. This would allow the engineer to cut a reference lacquer in the same environment in which the multi -track recording and mixdown were done.
And more important perhaps, if the Cybersonics
2002 Disc Mastering Lathe lives up to its promise ducing the cost and complexity of re- of disc mastering, it should make this important aspect of recording services more accessible to the small and medium
-size studio operation.
27 on Reader Service
A micro processor based unit controls consistent production in disc
-cutting operations at
CBS' fariung installations.
CONSIDER the following problem. You are a major record company producing records on a world wide basis and you have to manufacture enough records album, along to meet the demand for your latest hit with all your normal production demands.
Design and build a state
-art variable pitch and depth computer and install around the world. Now it in all your cutting lathes
these first two sentences don't seem related to each other, perhaps a few more facts will clear things up a bit.
The production of a million or copies of the same record requires that a large number of identical metal stampers also be produced.
And this in turn requires that a large number of identical lacquer masters be made. In a large company like
CBS, and variety of with its large staff mastering equipment, of cutting engineers the chances of the same engineer, using the same necessary lacquers equipment, cutting all the for that million dollar seller is very small indeed.
At the same time, there is an excellent chance that a tape mastered by engineer
A, using a
Neumann cutting system using a
(for example) cannot be duplicated by engineer
Westrex system, or vice versa. In addition.
you consider that some records
(usually classical) will remain in production for many years and that
CBS has divisions all over the world producing what are theoreti- cally identical discs, you can see that what appeared to he a relatively simple problem is in reality a very complex one.
The awareness of this problem led
CBS Records to ask
CBS Laboratories (now known as the CBS
Center) to find a way to improve lacquer mastering stand- ards. The research team began by ting system existing at the time investigating every cut- with the hope that one system could be chosen as a standard. This idea was quickly rejected when it was discovered that all the cutting systems were either inadequate wtih respect to repeatability or were too conservative in design to meet the demands of modern studio recording technique
(as well as that ever lurking nemesis, the modern record producer!).
It would also have been away all prohibitively expensive for
CBS to throw of its existing lathes and replace them with any one manufacturer's system.
It was then decided that the best approach would he to design a variable pitch and depth computer that could be interfaced with any lathe used by any division of
The result, after five years of research and devel- opment, was the CBS
The start of the
DISComputer is a microprocessor unit which allows the very complex pitch and depth command
A close -up of the recording lathe.
Charles Repka is a freelance
in Oakland, N.J. recording engineer based www.americanradiohistory.com
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The entire disc
-mastering system. signals. needed repeatable to a during the cutting of an
LP side. to be high degree of accuracy. The analog signals from the preview head are continuously examined for maximum waveform levels. The maximum level is sam- pled 200 times on each disc and then stored in the revolution, converted to computer. Next. the digital. computer uses the previous revolution's stored signal and the present sig- nal to generate proper pitch and depth control signals that not only meet the demands of the program material, but also the constraints (level, pitch and groove width) re- quired by the cutting engineer as well as several pre- programmed constraints. (The circuit details regarding the manner in which the command signals are generated within the computer are considered proprietary by
CBS and can- not be discussed until proper patent protection has been secured.)
The high sample rate (about
25 times higher than used in previous systems) allows a more efficient use of the available recording space. The pitch computer can expand the for a loud signal and then close the pitch again very quickly, while remembering to avoid those groove excur- sions on the next revolution.
Since more "decisions" are made in each cent revolution, the net result is a
20 to 40 per improvement in space utilization. This means the engineer can space either cut a record using
25 -40 per cent less than before (sometimes desirable due to distortion considerations) or use the same space and put a
-3 dB higher level on the disc.
-in constraints control the rate at which the pitch and depth can change to keep the control signals well below the point of audibility, yet make efficient use of record space. Studies by CBS
Technology Center revealed that these changes should be smoothed to yield a well de- fined path of cutter head motion, which has virtually all of its energy resonance concentrated at frequencies below the tone arm of the playback system.
This ensures maximum utilization of record "real estate" with no disturbance to the listener. The computer also has a built
-linear function (again based on extensive studies in the lab which corrects for pre- and post -echo that can take place during cutting and plating).
The use of a microprocessor has resulted in several unique features not usually found in professional audio equipment. The ates each time the checked and. unit is turned on. 800 test points are
a malfunction is found, the problem area is computer has a self -test function that oper- indicated on the front panel. The test function can also be initiated at any time by the operator.
The computer make a will not permit the cutting engineer to
Say the engineer tells the com- puter to cut at 800 lines per inch with a
4 mil groove width.
The computer will ignore the
LPI command and will in- stead set
4 mil itself to 250
(the maximum allowable at a width) and indicate the proper
LPI on the readout display.
The computer can also be used by the engineer to deter- mine the optimum level
When cutting a tape for for the any given first time, program material. the engineer looks at the running time and the nature of the program material and makes an educated guess as to the proper pitch and level settings. side, the
The lacquer is then cut and at the end computer displays the amount of the of level
(in dB) that should be added or subtracted (assuming no change in the basic pitch setting) to give an optimum cut utilizing all the available space.
Or, more simply put,
the chosen pitch and level has not used up all the available space, the computer tells the engineer how many dB he can raise the level. using the same pitch setting, to fill the disc.
If, on the other hand, the engineer had guessed wrong and run out of space. the display would show how many dB the level must be lowered to fit the program onto the www.americanradiohistory.com
This process can also take place lacquer by without ever cutting simply playing through the computer and observing the display at the end of the tape.
Of course. the engineer always has the option of trying a different pitch setting and going through the process again.
As part of the research for this article,
I went to the
CBS mastering facility in
NYC to observe the
DISComputer in operation.
I brought with me a tape that
I had cut on another system (no names please, but it was the best money could buy, about one year ago) with which
I had experi- enced some difficulty. The tape was of a symphony orches- tra recorded in a large reverberant hall, contained no unusual levels or dynamics and was only
23 minutes long.
However, the recording had been made using spaced omni microphones and, as a result, contained a great deal of out
-phase low frequency information that cause the sys- tem
The to overexpand and run out of space on the initial cut.
DISComputer cut the same tape at the same level, with room to spare. and told us at the end additional
11/2 dB of the tape that an of level could have been used.
A second cut was then made at the higher level with no problems.
During both cuts, mastering engineer Stew Romain used a much coarser than
I had used pitch (300
LPI at 2.6 mils groove width)
LPI at 2 mils). Using my pitch set- tings, several tained. additional dB of level could have been ob-
To achieve a satisfactory cut with the other system.
I had to resort to a
Hz mono combine network as well as a slight reduction in level.
Installation of the
DISComputer involved the removal of the existing pitch and depth computer as well as the lead screw drive mechanism and replacing them with the
CBS -designed units. Typical installations
Neumann lathe and an older Scully with system are a modern shown in the accompanying photographs. Units are currently in ser- vice in CBS cutting facilities in New and Canada. and
York City. Nashville modifications are taking place at
CBS divisions in
Australia, Mexico, Holland. Germany, and
Japan. Since installation has been completed in the
CBS has experienced a master related significant reduction of lacquer
- quality control problems in its plating and pressing plants. to overcuts,
This means there are fewer rejections due lifts (too narrow a groove), and fewer recuts due to mastering related problems in the plating process.
In summation, the new CBS
DISComputer has brought the following improvements to the recordmakers' art:
Increased the average level of a typical disc by
Made possible longer sides improved repeatability with no sacrifice in level. for lacquer recuts.
Improved product uniformity in all CBS divisions.
Reduced costs by reducing the number of recuts caused by cutting errors.
Improved disc quality achieved by improved s/n ratio and reduced pre- and post -echo.
That's quite an impressive list and before any of you accuse me of being paid off by the CBS
Publicity depart- ment, you may be surprised to discover that CBS has no plans whatsoever to market the
DISComputer: only enough computers will be made to equip the various
CBS record divisions. CBS is not and does not want to he in the disc computer manufacturing business.
The DISComputer will pay for itself at
CBS by means of reduced manufacturing costs and hopefully. through increased sales as a result of improved product quality.
I find that to be a refreshing thought!
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If a machine talks, we are apt to regard it as almost human; if it sings, we look upon it as being artistic.
EITHER permanent or transient records of sounds, as exemplified by Scott's phonauto- graph or Koenig's monometric flames, is no longer a novelty, but recording and repro- ducing musical sounds and speech are recent. Sound re- producing machines are no less wonderful than sound transmitting apparatus, and although the talking machine may not find as wide a field of application as the tele- phone, it is perhaps more interesting and instructive, and has the additional peculiar charm possessed by anything mechanical that faithfully reproduces any of life's actions.
If a machine talks, we are apt to regard it as almost human; if it sings, we look upon it as being artistic.
The versatility of the gramophone enables it to embrace almost any sound; military bands, instrumental solos, piano, cornet, clarionet, banjo, etc., songs, recitations. whistling, imitations. Educational features of the instrument are lessons in elocution, lessons on the correct pronuncia- tion of different languages and the memorizing of verses, songs, and music.
Some years ago we gave an account of the earlier work of the inventor, Mr. Emile Berliner, in this direction, and our present first page engraving illustrates the gramophone in its latest form. It is presented as a popular instrument for the use of everybody. It affords amusement to people of all ages and also presents a means of preserving records of various kinds.
1 is shown a gramophone provided with the reproducing apparatus only, it being designed for use in connection with records made by the
Gramophone Com- pany or the dealers. The instrument is provided with a turntable mounted on a pivot, as shown in
FIGURE 8. which is revolved by frictional contact with a rubber wheel on the shaft of the fly wheel.
The latter is provided with a pulley and is driven by a belt extending around
This is a reprint of an article which appeared in the May
1896 issue of Scientific American. the larger pulley on the crank shaft.
On the placed the turntable is rubber disk bearing the record. The sound box is mounted on a swinging arm, which also supports the conical tube or resonator.
FIGURE 2 represents the recording instrument operated by a simple electric motor.
The essential parts of the recording instrument are the turntable, the worm screw which guides the carriage hold- ing the recording diaphragm, and the recording diaphragm.
The action of the mechanism is to so guide the recording diaphragm, while recording the sound, as to make it trace a to continuous spiral line from the the center. outer edge of the table
The method of making a sound record is to place upon the turntable a highly polished disk of zinc, previously prepared with a film of fat, exceedingly delicate to the touch of a lightly bearing stylus, but dense enough to re- sist an etching bath.
As the machine is set in motion, a delicately pointed finger or stylus pivoted at its center transfers the wave vibrations from the diaphragm to the zinc surface. The finger moves laterally. and literally writes the sound through the thin film which covers the zinc disk.
During the operation the plate is kept soaked with alcohol from the glass reservoir seen in the cut. The object of this is to soften the film and to prevent the particles of film or dust from collecting around the point of the stylus or finger; by this recorded. method a true and exact sound wave is
The record made, the zinc disk is taken from the turn- table and the alcohol is rinsed off: the disk is then placed in an etching bath of chromic acid. The length of time consumed in the etching depends solely upon the ampli- tude of the wave vibrations. Recorded waves of small amplitude receive short etching and those of large ampli- tude long etching. When taken from the etching bath the disk is cleaned and ready for the first reproduction.
Since the first reproduction consists mainly in cleaning out the groove, the sound is at first slightly harsh and grating. Two or three reproductions make the record smooth and quick. www.americanradiohistory.com
The record is now ready to go through the duplicating process.
A copper matrix is first made by a method of careful electrotyping.
From the matrix hard rubber dupli- cates are pressed in the manner in which castings are made. in
The rubber duplicates are superior to the zinc records several ways.
They will hear rough handling and an indefinite number of reproductions, whereas the zinc would burnish and soon wear away. They are louder and smoother than the zinc. The rubber records will stand over 1,000 reproductions, the zinc from 50 to 300, according to their delicacy. A first class matrix can press out
1,000 perfect duplicates.
A peculiarity of the gramophone record is that it has almost the penetration of the original sound, although not the he broadness of tone, so that if 1,000 gramophones could worked simultaneously, it would be possible for an orator to fill a hall 1,000 times larger than his voice ordinarily would fill.
Gramophone recording agencies have been established in
Philadelphia and Washington, New
York and Boston, and similar ones will be established in every city of importance, where the voices of those dear to us may he permanently recorded.
FIGURE 4 is the record of a shown the cornet solo. arrangement for producing
The reproducing sound box, which is shown in
FIGURE 5, is provided with a diaphragm connected with a spring arm fixed to one side of the diaphragm cell and carrying a point like an ordinary darning needle point. This point, when the instrument is arranged as shown in FIGURE
1, rests in the groove in the record plate and follows the groove as the turntable is re- volved. in the
The engagement of the needle point with the groove record disk causes the spring arm to vibrate and produce vibrations in the diaphragm, which are the same as those of the recording instrument: as a consequence, the original sounds arc reproduced in the resonator of the gramophone with a loudness and clearness which are surprising. The reproducing sound box is provided with a curved damping spring for reducing the vibration of the spring arm when it is desired to connect the sound box with ear tubes to be held in the ear.
A cross section of the reproducing sound box is shown in FIGURE 6.
The manner of holding the sound box in the position of use is shown in FIGURE
9 is given a much en- larged view of a section of a record, showing the sinuous nature of the grooves. An electric motor has been applied to the gramophone, as shown in FIGURE 10, by means of which the table is rotated at a uniform speed. and in
11 is shown the adaptation of spring clockwork to rotate the turntable.
The type of reproducing machine which seems to find most favor is turned by hand, and as the groove in the record itself guides the sound box, thereby eliminating the necessity of a costly worm screw and intricate gear- ing, it moves so easily that with five minutes' practice a child can operate it so as to reproduce a hand selection or a song in perfect tune. Those who object to manipula- ting will the crank can have a simple motor gramophone that reproduce the selections by merely turning a switch.
The modest plant first started by the Berliner Gramo- phone Company, 1032 to 1036
Filbert Street. Philadelphia. has been increased to four times its original size.
Dupli- cates are pressed out by the thousands, showing the rapid growth of this fascinating little machine.
Overleaf, the reproduced Scientific
- that illustrates this article.
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The Keith Monks Record Cleaning Machine. co
YOU have seen one of these units at a distance, you may be believing that it is the invention of the late
As it comes out of its carton it is a turntable system that clearly will not play records.
What it is, however, is a turntable that will superbly clean records.
It may seem, based on the following description, that this machine is a kind of cleaning overkill. It probably is, if you have but a few records to clean on occasion. But if you maintain a record station library, retail shop. etc., where discs flow through regularly, this unit will prove extremely effective and efficient to use.
To begin, then. The Record Cleaning Machine is a turn- table that revolves at high speed (80
?), washes down the grooves of the disc to be cleaned via a brush www.americanradiohistory.com
that is swung over the disc, and then proceeds to remove the wash water and dirt by use of another arm that vac- uums up the material.
Underneath the deck, there are three bottles. One is filled with a cleaning liquid of 50 per cent distilled water and 50 per cent industrial methylated spirits.
A second bottle is not to be filled; it contains merely air.
A third bottle is where the vacuumed
-up glop is deposited.
All three bottles are connected to a vacuum pump
system which serves all the action.
To use, the disc to be cleaned is placed on the platter. and an electric switch moved to
WET. The brush (adjust- able) is placed across the grooves and a front panel plunger depressed. This releases a controlled amount of cleaning fluid through the brush onto the grooves and, after a few revolutions the disc has been thoroughly cleaned, but is
The cleaning machine will not help these discs.
We thank Fred Calero for his art. Fred is chief recording engineer at the
Automatt in San
The vacuum head.
A nylon thread acts as a buffer between the disc and the head.
It is slowly sucked off a below -deck reel into the bottle wtih the dirty fluid.
The cleaning brush is fully adjustable.
co also thoroughly wet.
Now you swine the brush off the disc and throw the aforementioned front panel switch to
This starts the vacuum action. Then if you place the vacuum arm at the center of the disc. it will slowly move outward, slurping up the liquid and dirt into its innards, to he deposited in the appropriate bottle.
Does it really work?
I took some new
CBS -100 test rec- ords, measured their response, then cleaned them several times through the cycles of the machine. and measured them again.
No change. But were they quieter sounding!
Even a new disc can be reduced) by a pass further cleaned (and thus noise through this system. It's quite effective and, once mastered, easy to use.
A cleaning machine sells for
It will prove a valuable investment.
A close view of the front panel.
It's slow, slow race
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The a search
-disc pristine sound winds through labyrinth of frightening possibilities.
SAID that making a direct -to- disc
-recording is an exquisitely refined form of masochism. Cer- tainly it is an exhausting, tension
-filled experience for artists and engineers alike. The direct -to -disc re- cording process is unquestionably the most demanding and unforgiving of all present recording techniques.
In spite of this, more and more d
-d recordings are helm; made: it is claimed that more than
60 companies are pro- ducing them. Needless to say. the quality of a d
-d record- ing can vary as much as it does in conventional recordings.
The mere fact that a recording has been made with the d -d process does not automatically confer on it some extra- ordinary degree of fidelity to the original sound. In point of fact, the number of d
-d recordings that fully exploit the capabilities of this medium is comparatively limited. In consideration of the difficulties in working with the d -d medium, the obvious question is, this field
"Why all the activity in of course, is that
the stringent requirements of the d
-d process are scrupulously observed. this system is the highest medium in use today. quality, most accurate recording
WIDE RANGE ACCURACY
Few engineers, or the audiophiles who are the principal buyers of d
-d recordings, arc aware tication or the technical capabilities of the degree of sophis- of modern disc cutting systems such as those made by
Neumann or Ortofon.
Neumann SX74 and heads,
732 are moving -coil cutter
- employing motional feedback. They differ in a number of important respects. but their overall specifica- tions are similar.
I happen to have the
Neumann specs at hand,
I'll describe this system. The SX74 is a remarkable device. an exceptionally linear, very low distortion trans- ducer. Its frequency response surpasses that of the very hest tape recorders, being a rather astonishing
25 kHz. plus or minus
3 dB. Even more impressive is that in the critical range from
16 kHz, the deviation from flatness is a miniscule plus or minus a half dB! In a
Fox organ recording
I engineered for Crystal Clear
Bert Whyte's as career as a recording engineer is almost legendary as some of the conductors he has worked with.
11esupervised and engineered the great Stokow- ski interpretations, as well as many others, while with the original Everest Records, and earlier made some of the first stereo while with or binaural orchestral recordings
Records. the particular
SX74 cutterhead in the system we used was down only
3 dB at 4
Hz! Obviously. the
16 cycle fundamental recorded of the 32 foot pedal stops could he with a cutter with such an extended low fre- quency response.
The harmonic and intermodulation dis- tortion of the cutterhead is less than one percent.
Unlike tape recorders. there is no modulation noise in this
Neu- mann disc cutting system. wow and flutter are exceptionally low, and the
So dB. dynamic range /signal -to -noise ratio is about without the use of any noise reduction systems.
This truly is
"state -of- the
-art." and permits recording of the highest known quality.
People not familiar with the d
-d recording process have commented adversely on the hack time per side. In comparatively normal tape -to -disc restricted play transfer. an
- ad- vance head on the tape playback machine is positioned a certain distance before the standard playback head on the machine. The special output of this advance head feeds into a computer on the lathe and controls a number of automated control functions. Principal among these is automatic of the pitch and depth of the record groove that is being cut. The actual pitch (lines -per -inch) cut on the lacquer disc is continuously variable. as a function of the amplitude and dynamics of the program material.
In low level passages of music, the automatic variable pitch me- chanism makes the groove width narrower, and spaces the grooves closer together. In loud passages. the combination of variable pitch and variable depth control makes the grooves wider, deeper and spaced further apart.
With this variable cutting technique, space on the record can he saved (as compared to cutting at a fixed pitch). and there- fore more recording time per side is possible.
When we record direct -to -disc, there is no tape and ob- variously no advance head, and therefore no possibility automated control of of groove pitch and depth.
Now we must depend on a really savvy cutting engineer (preferably one who can read scores, and thus to a certain degree anticipate the dynamics of the music) who must manually control the pitch and depth mechanisms. Even the most skilled cutting engineer simply cannot compete with the speed of the computer as used in the normal tape -to -disc transfer. With the limitations of manual control, and de- pending on the dynamics of the program material, the playback time per side on a d
-d recording can rarely ex- ceed 18
-19 minutes, at
331 rpm, and about
-13 minutes per side at 45
the restrictions of manual cutting control were not enough of a handicap in d -d recording, the really conscien- tious d -d companies who strive for maximum quality make rn
Author Bert Whyte with conductor Arthur Fiedler and the equipment used for the recently released Boston
Pops album (Crystal Clear Records). life for the cutting engineer still more difficult by eschewing the use of any kind of limiters or compressors in the re- cording chain. Some do not even use the stylus accelera- tion limiter in the Neumann electronics. m
As mentioned earlier, the use of the d
-d process is no guarantee of high quality. medium. which
It is a mercilessly revealing will expose the bad just as easily as the good. The
"prime directive" of computer technology
equally applicable to d -d
recording. Thus, the signal fed into the cutting head elec- tronics must be as sonically pure as possible, if the high quality of the d -d process is to be fully realized. In the
Fox and Boston Pops recordings
I have engineered for the
I had the advantage of using highly refined custom
-built recording equipment. especially designed to interface with the d
-d cutting elec- tronics.
Thus special attention was directed to the suppres- sion of transient intermodulation distortion in the micro- phone pre- amplifiers. Similarly, in the recording console. all input transformers were eliminated, and sophisticated discrete circuitry employed for ultra -fast transient re- sponse, the lowest noise and gain stages and all minimum tid. other
The active devices amplifiers are in character- ized by ultra
-times and high slew rates, resulting in little or no time -delay distortion or tid. The console is extremely simple and straightforward
are no echo send or return facilities, and no equalization is available, nor is any used throughout the entire recording chain. You might he amused by the fact that the engineers who made simultaneous digital recordings along with the d -d record- ing on the
Pops sessions wanted to make sure that the signal coming out of this fancy console was a
"clean enough" for their digital recorder.
They were hit nonplussed when they used the highly accurate Sound www.americanradiohistory.com
Technology distortion analyzer and couldn't get because the console distortion was below the a reading residual level of the instrument!
BLANK LACQUER DISC
In d -d recording, it goes without saying that the lacquer recording blank disc is a vitally important part of the process. There are only four manufacturers of lacquer re- cording discs in the western world. and naturally, every cutting engineer is partial to a particular brand. The lacquer disc is. in every respect, a precision product. which must be made under the most tions. The carefully controlled condi- aluminum base discs must be ground and pol- ished to near -optical flatness. The lacquer coating is a mixture of cellulose nitrate in a very volatile solvent, plus plasticizers, lubricants, dyes, and various other ingredients.
Lacquer disc manufacturers have special proprietary methods of coating or "flowing" the lacquer onto the aluminum bases to ensure as flat and uniform a coating as possible.
After coating, the discs are passed through
"curing" tunnels. where the solvent is driven off at a con- trolled rate to insure minimum deformation of the coating.
In spite of this care in fabrication. the discs have minute deviations and undulations on their surfaces.
- heads cope with this by being mounted in a special suspen- sion with a controlled amount of flexure. A top quality lacquer recording disc has a dynamic range
-to- noise ratio of about
80 dB. which is better than that of tape, even with Dolby A noise reduction.
Even though the lacquers have been
"cured" in the manufacturing process, many cutting engineers like to maintain a stock of lacquers which are
"aged" by allowing them to "out
-gas" for five or six weeks.
This is felt to he of particular inportance in d
-d recording. Cutting engineers also seem to be in general agreement that, ideally, when a lacquer has been cut, it should be put into the electro' plating tank at once. (But, sec
Ricker's opinion, in
Fiveash's in August companion article. Ed.) Which is why of
1977, you would have found
4 a.m., of Crystal Clear
Records, on the freeway at rushing lacquers of the
-d sessions from
Garden Grove, 60 miles
North to the
AFM plating plant in Los
-d recording session in a studio is fraught with peril (and it is), the problems
d recording "on loca- tion," can be positively nightmarish. First thing is the mat- ter of the lathe itself. Whether it is a
Neumann or a
Scully. it is at one and the same time, delicate, big, ungainly, and very, very heavy! on a solid
Among other things. it should he placed foundation, with as little vibration as possible.
Needless to say, finding such a location at the recording site can be a matter frustrating experience. There is also the of the recording console, monitor speakers, perhaps an analog or digital back -up tape machine. and other para- phernalia fitting into the same location as the lathe.
Now it is obvious that a recording lathe can cut but one lacquer disc at a time.
you want to
"generate" enough lacquers so as to ensure a specific number of pressings. you can have the artists repeat their performance as many times as their stamina and union recording rules will per- mit. Or you can record on more than one lathe. Or, you can do both.
you opt for more- than -one -lathe, you com- pound the misery of handling these beasts.
Fox sessions two lathes were used. and on the
Pops recording, there were three lathes. heaven help us!
Of course, we recorded multiple performances as well. The organ used for the
Fox recordings was a magnificant Rufatti instrument from Italy, ensconced in
Garden Grove Community Church. in
California, some sixty miles south of
Los Angeles. The church is a modern structure, far removed from. traditional concepts of religious architecture. and by its nature, not suitable we for housing assorted recording equipment. Thus wound up in the immediately adjacent administration building. using a second floor room normally used as a choir dressing room.
I won't go into the harrowing details of set
-up and communications this entailed.
The sessions began at IO not to o'clock in the evening, so as interfere with church functions
Fox is a
"night person." Four nights produced two record- ings which have been very well received, hut oh, the prob- lems! As you can readily understand, when you are making a d
-d recording, once the recording begins, the artist must perform the particular work completely, for a duration some
IS minutes. of
If he makes an obvious mistake early in the recording. we must stop, put on a fresh lac- quer blank, and start all over again.
If the mistake is made only a few seconds before the end of the recording, it's still back to "square sanie token, one" again, with another lacquer.
the performance is note
-perfect. but there is a technical problem, again it's back to the beginning.
Among things we had to contend with on the
Fox ses- sions was the some police breaking in people 600 feet away during a fine take because complained we were making too much noise. (How's that for an appreciation of music from the great unwashed
Another take was low
-flying helicopter. And at the conclusion of ruined a by bravura performance broke of the
Toccata, some kids outside into loud and lusty cheers before the revcrb had fully decayed. lacquers.
Maestro Fiedler was delighted with what he heard from test lacquers and digital tape playback, and joined us in a champagne toast at the conclusion of the sessions.
Whether it be an organ recording church, or the Pops with
Fox in a with
Fiedler, the choice of micro- phones depends on the philosophies does of the engineer. as their placement. There is essentially but one differ- ence in mie placement between a normal tape
-to -disc re- cording session, and a direct -to
While one tries the to exercise his judgment to ensure the best possible balances under any recording circumstances, it is still par- tially truc in the normal tape
"fix it in mix," but obviously this is not possible in the d -d process.
It can be seen that many things can go wrong on a direct
-to -disc recording session, but even assuming that everything goes like superb lacquers clockwork, and you have made some
-you are not "home free" just yet.
For yet more perils are lurking in the electroplating baths.
For all their generally careful work, the plating companies can, and do, lose lacquers to a would be possible number of technical grem- lins. In most cases, this means a reduction in the number of pressings that can be produced. In an extreme case, it for all the lacquers to be ruined, and the entire recording effort a total loss.
So, direct -to -disc recording is not for the faint of heart.
The obvious question, is it commitment worth the effort, depends on the of the recording company to the production of really high quality recordings. When they arc done properly, I think the direct disc recordings are the truest reflections of the original sound.
Pops sessions had their own share of prob- lems.
First off, when my wife and
I arrived at
Long Island to fly up to
Boston on the
Friday before the sessions on
Monday, we were blithely informed that the is that flight was cancelled.
Now, out in the hoonies. that
there is only one flight per day.
So it was either grind back into New York, or do what we did
was to drive to
Point at the tip
World War Two, of
"Landing Craft, Tank,"
Island, and take which they a now call a ferry, to New London,
Conn. and thence wend our way to Boston.
Our logistics engineer,
Frank Dickinson. was already in
Boston desperately trying, late on a
Friday afternoon, to find tanks heads and of helium and nitrogen for cooling the cutter
- blowing off lacquers, respectively. In Boston we used three lathes. Symphony
Hall is a magnificent room. but it wasn't designed with direct
-to -disc recordings in mind. The the was
Room, which to the only place we could set up the lathes was in
guessed front, and the left of the second balcony.
it hadn't been for the wonderful help and co- operation of the great Boston stagehands, the been a disaster.
The ancient recording would instrument room is have not large. and true to its name, contains glass
-fronted cases cient musical instruments, may of them three of an- or four hundred years old. Fascinating yes, the cases but the reflections from would make our monitoring just awful.
So there was
Frank, out getting
Fibreglas 703. and covering the front of every case.
In this room was crammed two Neumanns and one
Scully lathe, the recording console, two of the big new
"time aligned" monitor speakers, an
104. and, spilling over into the adjacent lavatory, was
Stockham and his
Soundstrcam digital recording equipment. Actually, once didn't have too many problems, and a minimum set up. we of "blown"
"FISH SCALE" WAS DESIGNED
The Tentel tape tension gage is designed to diagnose problems in your magnetic tape equipment. Throw away your fish scales (or put them in your tackle box where they belong).
The TENTELOMETER will measure tape tension while your transport is in operation, so you can
"see" how your transport is handling your tape
. smooth, proper tension for quality recording? or oscillating high or low tensions causing pitch problems, wow and flutter?
"See" what your heads
"See" and HEAR the difference.
Campbell CA 95008
Circle 38 on
B. engineers, who feel
INSURANCE COMPANY that re- mote than recording sessions are just more trouble they're worth, will find little cause to envy to go the disc mastering engineer who is rash enough
"on location" with his lathe. Consider the adventures of
Simpson. As two of the west coast's finest disc cutting engineers, one would think that by now they had picked up enough smarts not to venture out of doors with their lathes.
But not only have they done just that
have transported their lathes across the country to work with
Bert Whyte (and others) on re- mote direct
-to -disc sessions.
Ricker described it to me, it's not quite the thing as wheeling a tape recorder down the hall to
Still back home in Los Angeles, as the cutting system comes apart for shipping, so does the insurance policy.
For once outside the cutting room door, all bets are off.
#1 is to get a marine insurance policy, one that will cover about $100,000 worth of very fancy hardware.
you can convince the insurance company that you're really sane, it's safe to begin the disassembly and packing.
The lathe must be
(carefully!) broken down into its many component parts, and these must be packed with great care.
an electronic component runs afoul of the shipping company, usually a little solder will take care of things. But there's not much that can be done for a lathe carriage assembly that arrives on -site with a dent in it.
Fox session, two Neumann lathes were used. Stan and
Ricker brought along a
Simpson supplied his
Both are quite heavy, so Stan and
Richard become an assembly team. once the equipment arrives on location.
Unlike a tape recorder
can probably be placed just about anywhere
-choosing the wrong spot for a lathe can be a disaster. about a
Stan looks for a likely spot foot or so away from a wall, since the wall adds some mize wall rigidity to the floor in that area and this helps to mini- building vibration. Hopefully, it's not an outside with a super- highway on the other side, but even that's better than a arc also a lot railroad.
Subways under the of fun. Even building
you can't hear the roar, the lathe ing may feel the vibrations transmitted through the build- structure, and an otherwise- perfect lacquer master may be destroyed.
Once the lathes are re- assembled, the dure begins, using an alignment proce-
NAB test record. When the play- back electronics arc properly aligned, the test record is replaced with a blank lacquer, and a test cut is made.
With a reference tone applied to the drive level is adjusted while cutter head amplifier, the monitoring the playback of the test cut. In general principle, it's about the same procedure as aligning a tape recorder. However, since the playback stylus is located about three -quarters of a revo- m
Suzette Fiveash is the new associate editor of db
Magazine and is based in
Los Angeles, California. lution beyond the cutting stylus, there is a lag time than one second of more until the record level adjustments show up at the playback electronics.
As with test tapes, test records come with a variety of reference levels available.
For example, test records from the
Japan use a reference level of
3.54 cm. /second, while the
NAB standard is
7 cm./ second.
(For more on this subject, see
Diehl's article on
Groove Geometry in this issue-Ed.)
DON'T FORGET THE REFRIGERATOR
Temperature plays a very important role in getting a quality master disc plated and pressed.
Ten minutes of direct sunlight or prolonged exposure to warm tempera- tures can virtually destroy a lacquer.
Therefore, it must be stored in a cool place. Stan keeps his in a insure their quality. After cutting, a refrigerator, to common problem is getting the lacquers being exposed quickly packaged to keep them from to heat on the way to the plating plant.
Stan packages his finished lacquers in lined styrofoam cartons, with
Aluminum is then wrapped around the styrofoam, and the cartons are placed in a crate filled with those
"plastic peanuts" that we all know and love.
OF THE OOZE
The lacquer that is used to cut discs has a melting point of
130 degrees Fahrenheit, but, since it is vinyl, it isn't a very well
-defined type of melting.
When this happens, high frequencies deteriorate. Transients suffer first, creating a loss
On one of crispness on the final product. direct
-to -disc session, several masters were cut.
These were sent to
Canada, plating plants in
Germany and Japan.
California, New York,
All were carefully packaged, but later, one set of test pressings betrayed a tell -tale loss of highs.
The only conclusion that
Stan and the pressing plant engineers could make was that somehow the lac- quers had been exposed to heat in transit. The exposure must have been long enough to cause the damage.
On playback, the effect of heat exposure sounds some- what like a medium
-thin blanket draped over the speakers.
It doesn't cut the highs completely. but rather, subdues them.
A general conception in the plating business is that a lacquer must be put in a plating bath fifteen minutes after completion of within cutting. the first
Stan feels this isn't really necessary, so long as the lacquer itself is protected against the elements. Back in Los Angeles. his cutting room is kept quite cool, and the lacquers cut beautifully. and may be stored for quite some time with- out degradation. Under such controlled conditions, the disc might be preserved indefinitely. but of course
Law clearly states that "On a remote session, the optimum location for a lathe will also be the hottest spot in the house, once the session gets under way."
MICROPHONES AND DISC CUTTING
Although the microphone choice and placement is left up to the recording engineer, the disc mastering engineer should check for possible phase problems with an
oscilloscope to make sure the disc input signal going to the will present no problems later on.
Ideally, the ratio of lateral -to- vertical modulation should be about 2:1. The www.americanradiohistory.com
playback stylus doesn't really care too much modulation and
Stan neatly puts it for vertical
a lot of nasty problems associated with it." may be
With lateral modulation, the playback stylus is driven to the left and right by the groove walls.
With vertical modulation, the stylus is driven up the groove wall by a positive -going waveform, but literally falls back down through natural gravitational forces and the vertical com- pliance there of the cartridge /stylus design.
Nothing else is to drive the stylus back down, so
the groove falls away faster than the stylus can tact with the groove drop, the stylus loses con-
-an acute symptom on loud vertical modulation. Although it's no problem to cut such heavy vertical modulation, the difficulties during playback of will the test pressings. show up
And later the test on, press- ings don't show up until long after the session is over.
So it's best to keep a close watch on the 'scope at all times!
AND CIRCUIT BREAKERS
On any direct
-to -disc session, the fine art of gain riding can make cussion or break the disc, particularly on brass or instruments.
One example might be that per- of a trumpet soloist using a
Although the trumpet may not seem to be very loud, the upper har- monic structure is quite intense. When this type of signal is vent the is cutter head also cooled from burning up, although the head with helium to help keep the heat away from the sent to the disc, the circuit breakers may trip to pre- drive coils. But, because of that fine line between the head doing its work well and protective
"going up in smoke," this circuitry is still required. It also means that an overly -enthusiastic musician may wind up blowing more than his own horn!
Or, one nice transient peak from the kick
although it may not pop the breakers
easily overcut the previous groove and then become the overcut itself with following groove, because of the unexpected displace- ment. (Remember, there are no preview heads around on direct
-to -disc sessions to prevent such little surprises.)
This type of overcut may not be easily seen while the record is being cut, so it can get awfully sweaty
the disc mastering engineer guesses wrong and stops the session needlessly.
But it's just as bad to discover the trouble later on, after the recording is over.
Either way. you lose.
To keep the disaster rate within reason, and ulcers at a minimum, there must be much pre -session planning.
The recording engineer, producer, musicians and disc mastering engineer must review any musical passages piece itself. In fact, the most that may have phase correct them or level problems, and work together to without violating the musical value of the important word on any di- rect -to -disc session is organization. And on a remote ses- sion, the word is spelled with a capitol
There's a whole series
"O." of finely
to create a successful direct -to -disc recording. The end result depends heavily upon coordina- tion between musicians and engineers. The cutting equip- ment must be in first class shape.
The disc mastering engineer should he able to follow the score, and act as his own
"preview head," anticipating fortissimos and pianissimos, in order to properly adjust pitch and depth controls. The musicians must be up playing a complete side to the pressure of without interruption.
There must be no airplanes, subways, door wrong notes. missed cues, and so on. slams, chair squeaks.
Aside from that, there's nothing to it!
Ricker or Richard
Simpson. But don't tell them
I sent you.
Sound Workshop will introduce the
Memory System at the
4th, 5th, and
It will change all your present concepts about digital delay, pitch shifting, and digital reverberation.
bringing the technology within everyone's reach.
Professional Audio Products,
11787 (516) 582 -6210 www.americanradiohistory.com
A Look at the
The need for controlled conditions and expertise could trigger a whole new industry.
YEARS AGO, the introduction of tape cassettes and
-track cartridges once again prompted pre- dictions of the imminent demise of phonograph records. Such predictions have been made num- erous times in the past, yet the record industry has pros- pered. Even now, some say the video disc is again ringing the death knell for records.
However, no other medium for sound reproduction has such wide tolerance in all phases of its manufacturing and playback technology. The records themselves cover a range from floppy Evatone discs cheap enough for mass direct mail promotions, to the latest direct
-to -disc releases costing upwards of
Record player quality spans the spectrum from a $20 children's machine to elaborate systems cost- ing thousands of dollars.
The remarkable simplicity and wide tolerance of the record medium is likely to stand it in good stead before such potential competitors as the video disc, which is a comparatively critical, high technology medium. For the foreseeable future, it appears that records will continue to be the preferred medium for the reproduction of music.
The continuing popularity of records seems to be as much a surprise to some industry leaders as to anyone else.
How else does one account for the serious lag in the devel- opment of improved technology for record plating in this country? Significant improvements have been made in master tape and disc master technology, especially with regard to dynamic range and signal -to -noise ratios. Yet the m
P. Shelton is the president of the Europadisk
Plating Company, of New York City.
U.S. record industry has made virtually no efforts to im- prove what is now the weakest link in the record making
American plating is still largely being done with the same primitive methods and equipment employed for the past twenty years.
There is another and equally destructive problem here and that is the notion that there is some close relationship between the plating and pressing operations. The molding of vinyl under high temperature and pressure is definitely heavy industry, involving equipment such as steam boilers and hydraulic presses, the same technique used to make a vast array of plastic products from toys to plumbing pipe.
Record plating could hardly be further removed in terms of equipment, environmental and operational considera- tions. The electroforming of record production parts is a highly complex process, demanding extremely tight control of all operational parameters as well as the maintenance of a contaminant
-free environment. Such high standards of cleanliness, control, and handling do not lend themselves to an industrial environment, but are better suited to a laboratory. The operational considerations for operating a record press are quite different from those required to oversee a complex electro- chemical operation consisting of a number of completely different processes, each requiring constant monitoring and adjustment. There is, in fact, no more correlation between plating and pressing operations than between the disc mastering and pressing operations.
Electroforming is an entirely unique part of the record making process and, as such, should he a separate industry as distant from the pressing plant as is the recording studio.
More and more these days, one reads record reviews and hears talk among record collectors of the superior quality of European pressings. When questioned closely. most people mention surface www.americanradiohistory.com
noise as the most obvious quality difference between American and European press-
pops, ticks, swishes. ocean roars, crackles. tearing, and ripping sounds. Perhaps the most annoying noise of all is the pre- and post -echo sound, or "ghosting."
Undoubtedly, some lems in the pressing of this noise can he traced to plant, such as contamination prob- of the vinyl material or perhaps non
-fill of the record stamper due to incorrect temperature, pressure. or timing in the press in cycle.
However, it is the conviction of many people cutting, plating, and pressing operations that the great majority of noise and echo problems are generated in the plate making process. The basis for this conviction is that this process is tolerant of a surprisingly wide range of errors while still producing a part which is deemed
Most U.S. plating is mired in mediocrity more through ignorance than conspiracy. "We've always done it this way," is the answer one receives most often when question- ing practices that invite unnecessary noise and other prob- lems. parts ters as
The nickel sulfamate plating process used to produce will tolerate a considerable latitude of such parame- boric acid concentration, plating bath temperature,
Ph levels, and nickel concentration. But experience in state
-the -art operations indicate that all these parameters have to significant effects and the more closely they are kept their optimum levels, the better and more consistant are the results. One can tell by a glance at a typical matrix that things aren't wavy and looks as is the result right in the plating plant; the part is
it wants to curl up. This curly look of plating bath contamination with metals other than nickel which causes stress to he
"built into" the part as it is formed and results in early failure of the part by cracking or splitting. A grainy, rough finish on the back of the matrix instead of a smooth, grainless surface is further indication of a poorly controlled plating process.
The obvious consideration of cleanliness to exclude po- tential contaminants short from the plant environment gets shrift in most operations.
All it takes is a single mote of dust in the right place at the right time to produce an audible pop or plants are tick on the finished pressing.
Yet most vertible pig stys, with accumulations of dirt, spilled chemicals, dust, etc. on the floor, equipment and work surfaces.
Most make no attempt to control the clean- liness of the air; dust laden outside air flows freely over all operations. Metal part polishing stations that produce metal dust arc not sufficiently separated from critical sil- vering and plating areas.
Rough handling is another major problem in an industrial environment. There is no time at which the record making process is more vulnerable than when the lacquer master is first unpacked in the plating plant. Handling at this point and during the silvering and pre
-plating require delicacy and precision, hardly the qualities one would expect from the industrial workers found in a pressing plant. Even the metal parts, though tougher than lacquer masters, arc highly subject to damage
Coming in contact with from a rough or hard surface careless can handling. permanently imbed a particle into the groove or collapse a groove wall.
The U.S. record market is presently dominated by rock music and this has served to encourage mediocre plating.
Since much rock music has a essentially steady state level limited dynamic range, the of the program will cover vir- tually all noise and echo problems. As a result, the atti-
Talking about automation is one thing.
Showing a working system is another.
Sound Workshop will demonstrate the
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ARMS automation at the
A.E.S. Show in
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co tudes of many plating plants has been to allow these low quality requirements to become the standard of their work.
WIDE DYNAMIC RANGE
More mature levels of rock music, as opposed to so- called "bubble gum" rock, as well as all classical music, are characterized by a wide dynamic range.
This type of pro- gram will expose any surface noise during low level pas- sages and echo problems become percussive attacks are painfully obvious when either preceded or followed by silence. Echo is often heard on piano solo records be- cause of the percussive nature of the instrument.
These problems are typical of poor plating.
There is already a shortage of plating facilities good enough to do this critical work. and as the demand for quality plating grows. the shortage will become acute. The premise for this growth is based on the fact that the median age of the record buying public is increasing along with that of the population in general.
This increase in maturity translates into a growing market for classical and other serious music with a wide dynamic range.
The trend is already in evidence and there is a growing demand for records of the highest technical quality as exemplified by the recent interest in direct -to -disc records. which exploit the wide dynamic range capabilities of lacquer masters.
With good plating and pressing. these efforts represent the highest state of the art in the record medium. There are actually record producers, some of the direct
-to -disc people among them, taking their business to
Germany because they cannot get adequate plating and pressing quality in the
U.S.! Such evidence cannot be taken lightly. since it means that the producer is willing to pay roughly double the U.S. cost and is still able to find a market for the result.
Of course. most producers cannot afford to double their pressing costs by going to
Europe and simply have to take their lumps (pops and ticks) and live with their frustrations.
Superior playback equipment is also contributing to de- mand for better records. Even a moderately priced stereo system costing $500 to
$600 boasts a good magnetic cart- ridge and speakers capable of reproducing all the noise. just as clearly as they do the program. The really expensive equipment is a proliferation of further indication of the interest in achieving the highest quality in sound repro- duction.
Such systems have the capability of reproducing quality far beyond that offered by commercial tape for- mats.
-art records can provide a program source consistent with such superior equipment and there arc precious few domestic records in that category.
One of the most important factors in preventing the in- troduction of surface noise in the plating process is matrix cleaning. When two matrices are separated at the comple- tion of a plating step, some particles from the matrix being plated are transferred to the surface of the new plate.
Any such particles must be completely cleaned off before the next plating step, or they will be reproduced on the following matrix. This also applies to any contamination. such as airborne particles, reaching the surface of the new matrix after separation.
In order to remove the so- called horns which have been transferred from the lacquer master to the mother matrix, the mother matrix is polished, which contaminates the surface with polishing compound. This contamination must also be completely removed before the final plating step to produce the stamper.
These two cleaning steps are extremely critical in that they must be thorough and yet not damage the matrix sur- face.
Europadisk. we are using a new technique devel- www.americanradiohistory.com
oped at Teldec which, so far as we know, is not in use elsewhere in the U.S. The process is and is the most electrolytic in nature thorough and safe technology yet developed for this critical application. In most U.S. plants, this clean- ing is accomplished by using a stiff brush and solvents.
Perhaps even more important than equipment and tech- nique is the basic approach, the philosophy
you will, of the plant owner /operator.
This consists principally of a firm commitment to achieving the highest quality obtain- able in every aspect of the plating operation. In any such endeavor there are the interest constant temptations to compromise in of expediency or cost. By making a commit- ment to quality above all at the outset. the pitfalls of mediocrity that are endemic in the U.S. plating industry may be avoided. such
It must also he realized that to make high standards practical will require operating per- sonnel of the highest caliber and this will make personnel as well as equipment costs higher, relative to other U.S. plating operations.
CAREFUL PLANT LAYOUT
The layout of a high quality plating plant is such that different types of operations minimize contamination from arc physically one to the separated other. to
Packing/ unpacking is done in a room separate from silvering and plating operations to keep cardboard and paper particles out of these critical areas.
The stamper hack- polishing and mother face -polishing, which generate metal dust are in their own room.
Special consideration must he given to surfaces such as floors and walls to help minimize airborne particles. Special and electronic air treatment, including both mechanical filtration is also required.
Because of higher equipment and personnel costs. rates will be higher than at most other plating plants.
However. when this age press higher cost is amortized per pressing over aver- runs, the increase is negligible: typically, less than one cent per pressing. Certainly this small premium will not present an obstacle to quality
-conscious producers since plating costs are a very small part of overall produc- tion costs.
As important goal is to make record producers more aware of the importance of good plating and to encourage them to specify the plating plant to be used for their work. it is, some producers are not familiar with the vital role plating plays in the quality of the finished pressing.
This can best be accomplished in cooperation with a reli- able disc -mastering studio.
The quality operation, pro- ducers generally have a close association who cuts with the engineer their masters and a healthy respect for his opinion. majority of these engineers are already aware that many defects in the finished pressing are caused in the plating process and, because task is simplified. of that professionalism. the
Of course it is in the interest of the cutting studios to have their lacquer masters receive the best plating possible, since that will mean fewer problems as well as better results for their clients.
As quality plating work becomes better known in the industry, we hope that new interest in its role will be generated.
This awareness can stimulate the growth new industry. The series of a of events that has led to the birth of disc mastering as a separate industry may prove to be a a parallel for the same sort of phenomenon in plating. Only few years ago, mastering was exclusively associated with pressing plants, operations recording studios, or were the in -house of major record companies.
With the introduc- tion of new
European cutting technology and a philosophy of excellence, a whole new industry came into being. We hope to generate a similar transformation in the plating industry and, at the same time, make a commercial success of our own
Europadisk Plating Company.
Closing date is the fifteenth of the second month preceding the date of issue.
Send copies db to: Classified Ad Dept.
Road, Plainview, New
Minimum order accepted $10.00.
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FREQUENCY DISCOUNT ADVERTISEMENTS ARE TO
PREPAID IN ADVANCE.
THE RESONATOR is more than a reverb.
Designed for use with any console, in- cluding
Tascam. $359.00. Dyma, Box
1697, Taos, N.M. 87571.
AMPEX, SCULLY, OTARI, all major pro- fessional audio lines. Top dollar trade
15 minutes George Washington
Bridge. Professional Audio Video Cor- poration.
07505. (201) 523 -3333.
$2,599, using package systems from pro- recording equipment from Revox, Otari, Lamb Labs, Trident.
Write for full details of offers to
Sound Services, Inc.,
(516) 538 -2220.
USED RECORDING equipment for sale.
Professional mics, speakers, miscel- laneous gear. Dan (415) 232 -7933.
TEST RECORD for equalizing systems. Helps you sell stereo equalizers and installation services. Pink noise in
1/3 octave bands, type QR-
Used with precision sound level meter or
&K 2219S. B &K
FREE CATALOG 3
TAPE, DISC, POWER
NEW PROFESSIONAL LINE of pre -as- sembled mic and patch cables in seven colors, two thicknesses; not a me -too copy of existing cables. Further info,
N.Y. 10549. (914) 241
SEMI -PRO MULTITRACK RECORD-
TASCAM, Soundcraft, Sennheiser,
BGW, Altec, Lexicon, dbx,
Beyer, R.S.D., Tapco, and more.
(514) 487 -9911
FOR SALE, large
Moog synthesizer. All components,
2 keyboards, ribbon con- troller,
2 sequential controllers. Excellent condition. Scott -Textor Productions,
54th St., New
N.Y. 10022. (212)
IVIE SOUND ANALYZERS, all stock. Theatre Technology, models
37 W. in
York City 10011. (212)
AUDIO and VIDEO
Labs specializes in equip- ment sales, systems and installation engineering,
service and demonstration facilities in- house.
We represent over 200 manufac- turers of professional and semi- professional equipment for record- ing, broadcast, sound reinforce- ment, and
Call or pricing. for commercial sound. write for information and
(Boston) Mass. 02134
Master, mint condition; Accurate
8 mixing con- sole; best offer over $6,000.00 takes both. Le Mans Sound. (201)
CSG -2 compatible stereo gen- erator, new condition,
Westrex 1574D cutter amps, $400 each.
MH -4 mixer, $125. HAECO LX
670 stereo limiter,
Frankford /Wayne Record- ing,
134 N. 12th St.,
FLANGES. We manu- facture
", 101/2", and
Also large flanges and special reels to order. Stock delivery of assembly screws
& most aluminum audio, video,
& com- puter reels. For pricing, call or write
Records Reserve Corp., 56
Batavia, N.Y. 14020. (716) 343 -2600.
-KUT drive belts.
Specify model. delivered.
Prod- ucts, 1568
Sierra Vista, Fresno,
-out, acces- sories; Sony TC8
-54 4- channel; asso- ciated equipment.
Mi. 49002. (616)
CUTTERHEAD REPAIR SERVICE for all models Westrex, HAECO, Grampian.
Modifications done on
Westrex. Avoid costly down time;
-day turnaround upon receipt.
Send for free brochure: Interna- tional
Cutterhead Repair, 194 Kings
Ct., Teaneck, N.J.
AMPEX SPARE PARTS; port; technical sup- updating kits. for discontinued pro- fessional audio models; available from
94042. (408) 739 -9740.
STAGE / STUDIO /
BROADCAST audio systems: AKG. Allison Research, Amber,
Amco., A.P.I., Audiotronics,
Beyer, Can- non, dbx,
JBL, Lexicon, MicMix,
Neotek, Neumann, Nortronics, Orban/
Parasound, Orange County, Otari, Pul- tec, Robins, Russco, Scully, Sennheiser,
Technics, more. For
UREI rurther information plus many on these and other specialty items from our fac- tory operations contact: Midwest
60629. (312) 767 -7272.
MODERN RECORDING TECHNIQUE. by
Runstein. The only book cov- ering all aspects of multi -track pop music recording from microphones through disc cutting.
For engineers, pro- ducers, and musicians.
2B, $525.00; all Haeco cutterheads new, other cutter
- heads reconditioned and in specs. Inter- national Cutterhead
N.J. 07666. (201) 837 -1289.
DISCOUNT PRICES on fresh name
- brand tape. Check our prices in bulk, reels, boxes, carts, and cassettes. P.B.P.,
4100 West Kennedy Blvd., Tampa,
33609. (813) 877 -7125.
REELS AND BOXES 5" and 7" large and small hubs; heavy duty white boxes.
-M Sales, 1118 Dula Circle, Duncan- ville, Texas 75116. (214)
RANSTEELE custom heavy duty wall/ ceiling speaker mounting brackets for
Big Reds, etc., $160 pair.
/ch stereo cutter drive amplifiers; used Westrex and Haeco cut
- terheads; complete line of custom disc mastering room audio equipment not available anywhere else! Reconditioned
Scully lathes; complete turnkey master- ing rooms. Ransteele Audio, Inc. 1697
Broadway, New York, N.Y. 10019. (212)
265 -5563. GOING OUT OF BUSINESS. Ampex
MM1100 16- track; Scully
- tronics501 console,
/16 -out, wired
/patch and producer's desk; dbx
-910; much more outboard equipment
-mics, amps, etc., all in perfect running order; most under one year old. (516)
Sound effects re- corded in STEREO using
Dolby through- out. Over 350
$100.00. effects on ten discs.
18145, Denver, Colo. 80218.
NAGY SHEAR -TYPE TAPE SPLICERS t
K IN. TAPES
Filter is required for optimum bass response in your system.
MODIFICATION, variable pitch for
A -77; in
A -77 or A -700; pro- grammer for
A -77; rack mounts, slow speed
17/s; full track; auto rewind; high speed
A -77. for
-77; Slidematic for
Machines available with or without mods at low cost
-77 from $695). All mods professionally performed by
Revox trained technicians. Entertainment
Sound Services, Inc., 78
Hempstead, N.Y. 11550. (516) 538 -2220.
ROADSHOW EQUIPMENT. Clearing wide range new
& used items including mix- ers (from $350 to $3,500), bass
& bins (w
& treble w/o speakers,
$125 up). lenses, horns, etc.: limited quantity: be first.
(516) 538 -2220.
Hempstead, N.Y. 11550.
FOR SALE: Ampex
-track heads, search to cue, VSO
Take over lease or best offer. Also, Ampex
440 mono, 440
2- track, two
3300's. Lar- rabee Sound,
Ca. 90069. (213) 657
Electro- Voice: mixers, equal- izers, amps, mics, and raw ers. Write or call loudspeak- for low mail order prices. Sonix
Head, Md. 20640. (301)
UPDATED OUR EQUIPMENT. Used mics by
Neumann; Sennheiser; Beyer; etc. for sale. (415) 232 -7818.
ONE -THIRD octave real time analyzer,
Hewlett- Packard Model
8050A with trav- elling case, cords, and
Altec pink noise generator. Perfect condition.
100 com- plete with
-track stack and guides, spare elect.
/remote sync master; both stacks like new; $10,500. 16x16 APSI console with patch bay plus spare
(4 para), bi- f.e.t. elect. Very flexible board
Whites Pressure sen- sitive;
12 upon an 111/4" x 71/4" sheet; packed
(1200 labels) per pkg; die cut and ready to print or type.
(312) 640 -1030 www.americanradiohistory.com
4400 retrofit and factory recai, perfect.
PM3232 dual beam scope, two probe sets, cables, Polaroid Scope Camera. All for
Copies of db
Copies of all issues of db
Sound Engineering Magazine start- ing with the November
1967 issue are now available on 35 mm. micro- film.
For further information or to place your order please write di- rectly to
North Zeeb Road
Arbor, Michigan 48106
WEST COAST engineers
Area sixteen -track; fully equipped with tube Neumanns, Schoeps, etc., EMT;
DDL's (2); acoustic chamber; Dolby A;
Spectrosonics; Scully; Ampex. Free flight for out
-of- towners. Tewksbury.
CHANNEL sound reinforcement mixer foot snake, balanced input,
3 band eq,
3 submixers, monitor, echo, solo
UREI model 527A graphic equalizer. Must sell! Asking price
B. C. & G.
751 -5991 or (303) 424 -6151.
WANTED: Karlson model
-U enclo- sures. State condition and price. B.
24 x 16 with patching),
24 x 4 monitor, e.q.,
4 echo sends,
2 cue sends, many other features. Available with
550 e.q.'s. (550 not
-5780. sold separately.)
FOR SALE: Mavis road cases
15/4 road boards in with snakes.
(616) 392 -2379.
RECORDERS at low, low price
Brand new batch just re- ceived in manufacturer's sealed car- tons, manufacturer's warranty. It's a steal.
Other models available including
-700's at $1,350. Write for full listing or make
$15 checks or money order
A -77. N.Y. residents add appropriate sales tax) payable to Entertainment Sound
Ser- vices, Inc.,
Ave., Hemp- stead,
N.Y. 11550. (516) 538 -2220.
WANTED: Recording equipment of all ages and variety: Neumann mics. EMT. etc. Dan
Bernhard, Rich- mond,
Ca. 94805. (415) 232 -7933.
Coast disc mas- tering facility seeks an experienced maintenance /chief engineer who is look- ing for a bright future and who is com- pletely familiar and is able to maintain
Neumann, Scully, Westrex, and Capps cutting room equipment. Other duties will include occasional cutting,
&D projects, and construction. Applicant must be able to work with little or no supervision and be of high calibre.
Ex- cellent company benefit programs.
Salary commensurate with qualifications.
Reply with resume to
81, db Maga- zine, 1120 Old Country
SCULLY recorders in and stock for immediate delivery; new rebuilt.
Silver Spring, Md. 20910. Write for product list.
1024 -24 recording console;
/out. Producer's desk.
18 months old, excellent condition, $25,000.
(805) 966 -6630, 966 -1271.
PROFESSIONAL AUDIO COMPONENTS:
AKG mics; Badap
Crown; dbx; Delta
Malatchi; MasterRoom; Nagra; Neu- mics; Orban; Otari; Pentagon;
RTR; Sennheiser mics; Switchcraft;
-Sync; and UREI. These products are on demo in our show- room and in stock for immediate de- livery. Our paid. shipping is insured and pre-
19096. (215) 667 -3048 or 649 -2965.
FOUR 3M -64
/reproduce tape machines; all machines in excel- lent condition.
O'Day Broad- casting, Don Winget,
Wa. 98101. (206)
CURRENT MCI console, JH528; stereo quad; 28 -in
/24 -out; operated only a few weeks; latest factory mods. Cherokee
(213) 653 -3412.
FREE PROFESSIONAL CASSETTE specs. w/
AUDIO DESIGNS 16x8 board, separate stereo
& mono mixdown. Now in ser- vice. Mint condition.
Arthur Productions. (303) 832 -2664.
A7 speakers, $300 ea;
700B power amps, $500 ea;
-FET power amps.
3DI1 cutter head with amps, $3,000;
Neumann com- plete disc cutting system with
SX -68 head and JG66 amps, console, tape deck, eq., etc., $20,000;
1 x 12
-track re- corder,
$6,000. All prices FOB
6000 Sun- set Blvd.,
Ca. 90028. (213)
AMPEX SERVICE COMPANY: Complete factory service for Ampex equipment; professional audio; one
-inch helical scan video; video closed circuit cam- eras; video systems; instrumentation; consumer audio; professional audio motor and head assembly rebuilding.
Service available at 2201
Lunt Ave., Elk
Hackensack, N.J. 07601.
IMPRESS your manager. Save money on:
Technics, Ampex, Scully, Nortronics.
Betar, Orban, etc. Val
Inc. Call collect,
MASTERING ENGINEERS. The
Coast's largest independent disc mastering house is in need of two ex- perienced cutters, preferably with a good technical background and cus- tomer following. Excellent salary and benefits. Apply with resume to: Dept.
82, db Magazine,
Old Country Rd.,
WANTED: Engineer (local) to design audio equipment. Partnership agreement possible. Ace Audio
Co., 532 5th St.,
WANTED: Apprentice engineering posi- tion. Experienced in sound and video studios; will relocate, self starter, hard worker, and dedicated. References.
Contact: Michael Ciesinski, 5611 South
-TRACK recording studio,
NYC seeking experienced maintenance engi- neer, preferably familiar w /Neve, Studer,
3M. Salary requirements, references.
101, db Magazine, 1120 Old Coun- try Rd., Plainview, N.Y. 11803. www.americanradiohistory.com
Festivities for a
Light, celebrating Thomas Edison's invention of the electric light, which culminated on October 21, 1879, are being planned by the
(P.O. Box 1310,
Greenwich. Conn. 06830.) Focus of activities will be at
Edison shrines. such as
Menlo Park, N.J. and Ft.
Myers, Fla. Because of the close con- nection between Henry Ford and
Edison. the Museums at
Mich. will also participate. Educa- tional materials for science fairs and exhibits will he provided by the
The post of semi
-professional prod- ucts sales manager at dbx, Inc. of
Newton. Mass. has been filled by
Emil Handke. Mr. Handke's appoint- ment is part of an executive expan- sion sive program. Mr. Handke's exten- experience in recording and sales was
Tenn. mainly acquired in
Lawrence G. Jaffe has assumed the position of vice -president in charge of marketing at
Uni -Sync Inc. of West- lake Village. Ca. Mr. Jaffe joined
Uni -Sync at the time of its purchase by
BSR last year, as marketing manager.
The newly- formed Creative Audio and Music Electronics Organization
CAMEO, is a combination of elec- tronic manufacturers and distributors who serve musicians and production people engaged in creative and origi- nal sound. Charter members include:
AKG, Alter. ARP,
BGW, dbx, Fen- der- Rogers- Rhodes of
Instruments, ITX- Aphex, JBL, KM
Records. MXR, Oberheim, Phase
Li- near, RolandCorp US, SAE, Sirius
Music, Soundcraftsman, Tangent, Tap
- co, and TEAC Tascam. Headquarters are
Suite 3501. LaSalle Plaza.
LaSalle St.. Chicago. Ill.. 60601 (312)
332 -7400. David
Schulman is the ex- ecutive director.
New manager for antenna engineer- ing at is
RCA's Gibbshoro. N.J. facility
Bruno F. Melchionni. Mr. Melchi- onni has been with RCA since
1941 except for a period of Air
Force ser- vice
RCA. during World War
II. Also at
Campbell has been appointed manager of industrial elec- tronic services marketing at the RCA
Service Company. concentrating on the company's vices operation. industrial electronic ser-
The Meadow Lands.
Pa. facility of
RCA has acquired the services of
L. Rocamora as manager of broadcast transmitter equipment engi- neering and product management. Mr.
Rocamora has been with RCA since
1952 as an electrical engineer.
Several managerial level appoint- ments have been made at Shure Bros.
Patrick J. Dalton has been sales named domestic distributor manager and Ken Reichel will head the technical markets and product management department. Working with
Mr. Reichel will he
John F. Phelan. professional sound products:
Groh. high fidelity products:
Quest. manager of communications and gov- ernment products. Lee Habich has been appointed as manager of adver- tising and sales promotion.
Mr. Habich are three section managers.
Ruth Delke, Jim Paton, and Shelly
Here's an opportunity to win some
"esoteric" audio equipment. Just think up a brand name for the
Carver audio line.
Further details may he obtained from Mr. Bob Carver, P.O. Box 604.
Woodinville. Wa. 98072. The contest. open to residents of the continnental
Howard Harman has been appoint- ed to the post of western regional sales manager of
Audio -Technica, of Fair- lawn, Ohio. Mr.
Harman had been previously covering the northern Cali- fornia district for Harman International. the
The promotion of Almon Clegg to position of assistant general man- ager. product engineering division at
Panasonic, of Secaucus.
N.J. has been announced.
Mr. Clegg, who has been with Panasonic since 1974, has also been associated with
General Electric and has been a professor at
Research and development pro- grams at
Kustom Electronics, Inc., of
City. Mo. are now in the hands of
William Goodson. Mr. Goodson has been with the firm since 1973. in the capacities of design engineer and pro- ject engineer.
The Society of Motion Picture and
Television Engineers has organized a committee. "Working Group for Inter- face of Television Broadcast Studio
Equipment." The intent is to create an optional control interface communications scheme
tape recorders, film chains.
digital for video character generators, still stores, audio tape decks. audio consoles, video switchers, frame synchronizers. etc. The committee is under the direction of
Vital Industries, Inc.,
Lane, Hicksville, N.Y. 11801.
The importance of telecommunica- tions has gotten the nod at Switch
- craft, of Chicago.
Ill. with the ap- pointment of their first telecommuni- cations marekting manager.
Fred Fitz- patrick. Mr. Fitzpatrick, who comes from Amphenol, will focus on new programs to market electromechani- cal components to telecommunications customers through authorized tele- phone distributors. Another personnel item at Switchcraft is the appoint- ment of Gerald F. Olsen as vice pres- ident in charge of finance. Mr.
Olsen had previously been with the Ray- theon Company.
Sales in Europe, Africa. and the
Middle East will be the special respon- sibility of Milo L. Cermak, recently appointed vice president. international marketing at
Corp., of Sunnyvale.
Cermak has served as an international advisor for a number of companies. including
Terminals. Paul Olmstead has assumed the job of corporate controller.
After a number of months of fa- miliarization with the executive work- ings of the company.
Shepherd has assumed the post of president of
Company, the television marketing or- ganization of
Electronics Corporation of Stamford,
Conn. Mr. Shepherd's activities. since
1956, vania have been mainly with the Syl- portion of the company.
Rodgers has been appointed president in charge of engineering at
Fisher -Burke Professional Audio, of
Phoenix. Arizona. Fisher -Burke spe- cializes in broadcast consulting. www.americanradiohistory.com
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you're an engineer, the
Select make to you.
One button operation simulta- neously switches three interrelated record, panel will a source, lot of functions: sense tape/ and
need for three arms.
you're playback/ decode /encode thus eliminating the this a musician, human ing factor you won't engineer- means have wait
the to engineer and lose the sponta- neity
your music in the process.
you tracks, means need you only
have one choice: the new
exclu- at these
(714) 645 -8501
San Francisco, Ca.
Nashville Studio Systems
Music Circle South
(303) 279 -2500
(405) 525 -3343
E AÇ new generation
A for a new generation
'Prices subject to dealer preparation charges where applicable.
:: st Hoed ly
White Electronic Deve.opment Corporation.
Your ears believe won't what they're not hearing!
Feedback has plagued sound systems since the day they were invented. It's something city councils, church choirs and boardrooms have had to cope
something most sound system manufacturers have learned to live with
Altec never gave up their search to find a better way of controlling nagging feedback.
It wasn't an easy task, but it was the kind of challenge that Altec has been meeting for over
... applying advanced research techniques to perfecting sound system technology. That's why they're the leader.
Altec, being a leader also means being an
Several microphones can be used simultaneously with this newly- patented device that automatically divides the system's volume among the in -use microphones, compensating for the number of persons speaking into them
affecting intelligibility or the overall volume of the system. Each person will still be heard loud and clear all the way to the back of the room.
If only one microphone is in use, it receives the maximum system attention while the others are automatically silenced.
1628A also automatically turns the various microphones up or down as persons speak or stop speaking into them. And, up to five
1628A's can be linked together to accommodate up to 40 microphones.
That's an innovation!
The difference with automatic microphone
In conventional systems, multiple microphones used simultaneously have had to rely on manual techniques, or, in some cases, a less- than -adequate "voice gating" system.
Neither has been successful.
The sophisticated 1628A operates on the principle of adaptive threshold audio gating (unique to Altec), which means that its activation point is automatically adjusted. allowing the system to discriminate between various noise levels and the voice signal that activates the microphone.
Let a professional Altec sound contractor demonstrate the
1628A to you.
Your ears won't believe what they're not hearing. Write today for further information.
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