august 1974 volume 5 number 4
AUGUST 1974
VOLUME 5 NUMBER 4
RELATING RECORDING SCIENCE
TO RECORDING ART
www.americanradiohistory.com
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Re/p 5
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Since its birth almost two years ago, we've
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RECORDING
engineer/ producer
the magazine to exclusively serve the
all those
recording studio market
whose work involves the recording
of commercially marketable sound.
...
-
..
the magazine produced to relate
RECORDING ART to RECORDING
to RECORDING EQUIPSCIENCE
MENT.
.
AUGUST 1974
VOLUME 5 NUMBER 4
...
Editor /Publisher
....
-
MARTIN GALLAY
Associate Editor
TV uses recording studio and
concert sound techniques to produce:
THE MIDNIGHT SPECIAL
17
Gary Davis
EQUALIZER PERFORMANCE
REVISITED
33
Bob Easton
Bob Orban
MUNDANE APPLICATIONS
OF THE
FLUX LOOP
41
Peter Butt
49
Dave Harrison
WAYNE YENTIS
RON MALO
Engineering Editors
Acoustic Design:
THE MYTH OF THE
WILLIAM ROBINSON
GARY DAVIS
MAGICAL STUDIO
V.L. GAFFNEY
Business Manager
Letters and Late News
AES Program
New Products
Classified
9
56
59
66
!
RECORDING engineer /producer
is
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Subscriptions for other than qualified
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THE COVER: Roy Orbison's U.S. RECORDING
STUDIO (Nashville)
a view looking across
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floor below.
Acoustical design and construction: STUDIO
SUPPLY COMPANY. Photo: Dave Harrison
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THIS ISSUE SPONSORED BY THE FOLLOWING ADVERTISERS
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ALLISON
AMBER
AUDIO INDUSTRIES
AUDITRONICS
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MODULAR DEVICES
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Re/p 7
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Last year, we offered you
Studer tape recorders.
This year, Telefunkens.
What
-
happened?
The answer is on page 3 of our catalogue.
In the "Statement of Principles" bi- annually
published there exactly as we wrote it seventeen
years ago.
Since then, we've always vowed that, before
we changed a word of that credo, we'd rather
see the list of our companies change.
And this has now happened.
As our credo makes clear, Gotham prefers to
represent "equipment made in limited quantity
-
discriminating worldwide clientele."
This was Studer's orientation when we joined
forces with them many years ago. A tiny company
for
a
-
handful of people
dedicated to serving a
limited professional market.
But no more. Over the years they have
expanded enormously. Requiring mass marketing
only
a
-
goals.
It is a perfectly legitimate development we
can respect. But.
The credo, remember.
Ah, you say. But the credo also stresses
.
These people have a high and unique
responsibility
because it was Telefunken, after
all, who invented the tape recorder in 1942.
And how they do their job conforms
precisely with our credo. Because, to them as to
Gotham: "Not price but excellence, craftsmanship
and serviceability are the criteria" that count.
Some reasons why the M12 "Magnetophon"
is in a class by itself:
1. A 19" rack mountable 101/2" reel 1/4" tape
recorder incorporating an optional 4 -input
mike/ line slide fader mixer. Mike inputs are
Phantom® powered, of course, ready for
Neumann fet 80 microphones.
2. Heads made of ferrite and sintered ruby tape
guides; materials so smooth and hard we guarantee them both for the life of the machine
(15 years).
3. Ingenious tape tension control on both sides of
the capstan; no reel size switching.
4. Weighted Peak Flutter typically ± 0.02% at
15 ips; 33/4 ips speed available.
5. Price range: $3500 to $4500.
And after the technicalities, there is also
the matter of experience:
For over five years now, our experience
with the "Magnetophon" in Neumann's tape -to -disk
transfer systems has been eminently satisfying.
Satisfying? Superb!
And we look forward to the
same kind of results with Telefunken's
M12 and M15 "Magnetophon."
FUN
KEN
For ourselves and for you.
Write today for more
information:
.
Gotham's interest in representing companies that
are personally -run by men who "devote their lives
to the fulfillment of their dreams." Surely, you
say, the gigantic Telefunken operation can hardly
be described as personally-run.
No, it can't.
But the tiny enclave that we represent can.
For, within Telefunken there is a separate
department of about 45 people. Autonomous,
because they are completely apart
independently handling all the development, manufacturing,
and marketing of the M12 and M15 "Magneto phon" professional recorders.
-
!,
GOTHA
AUDIO CORPORATION
Headquarters:
741 Washington St., New York, NY 10014
(212) 741 -7411
West Coast Sales Office:
1710 N. LaBrea Ave., Hollywood, CA 90046
(213) 874 -4444
Re/p 8
www.americanradiohistory.com
Letters &
Late News
From:
MICHAEL RASFELD
CHIEF ENGINEER
ACME RECORDING STUDIOS
CHICAGO, IL.
I felt your article on "Visual Mixing"
was superb.
Far from being in left field, the author
described a way of talking about an
aesthetic that is very difficult to put
words on. His way of describing a mix is
very much how I think of it and I'd be
curious to hear some of his work.
From:
ED GIESE
SOUND CONSULTANT TO
MILWAUKEE WORLD
FESTIVAL INC.
MILWAUKEE, WISCONSIN
Perhaps the following feedback may
be of interest to your readers.
My father used to tell me that it
doesn't pay to be a sensitive soul and
that I'd have fewer ulcers if I let some
things go over my head. But there are two
details in
"The California Jam" article
that prompted me to ignore dad's good
advice.
Examination of excess attenuation at
differing frequencies and distances tells
us that the maximum distance that can be
reached with a flat acoustic response, in
an outdoor environment, and with' a 12dB
boost at 10,000Hz, is approximately 125
feet. It will also be seen that 10,000Hz
has an excess attenuation of 45dB at 500
feet. The nominal distance for flat acoustic response at 3,000Hz is 500 feet, and
this also has to include a 12dB boost
through the hardware. What this boils
down to is that it's a waste of money to
include 075's or similar tweeters in high level systems. Try taking a house curve
somewhere beyond 500 feet at your next
outdoor concert. Boost your high end to
its maximum. Then take another response
curve at something closer to the source,
say 250 feet. Compare the two curves and
you'll see the kind of monster you've
created. I've taken well over a 1000
sound surveys of outdoor sound systems
and I'd appreciate hearing from anyone
who knows of a way to overcome this
...
problem without resorting to a distributed
system.
Then there's one other small detail that
disturbs me, and I've heard the same
thing too many times from other sound
contractors to let it go over my head
again. And that's Mr. Gamble's statement,
"the prevailing Westerly winds would
carry the sound ... "
Common sense should tell us that
something speeding along at 770mph
could hardly be carried or blown by
...
something going along at say 25 to
40mph. The fact is that surface winds
cause temperature gradients which create
slight changes in sound velocity. The resulting effect causes sound waves to be
focused downward when wind and sound
are moving in the same direction and
focused upward when sound and wind
meet head on. So, let's end the misconception and start talking about how the
wind focuses the sound.
My apology to Mr. Gamble for picking
on a few bones in an article filled with all
that meat to chew on.
From:
HUGH S. ALLEN, JR.
EXEC. VICE PRESIDENT
GOTHAM AUDIO CORP.
HOLLYWOOD, CA
On behalf of the NEUMANN Company
HOWARD S. HOLZER
1928 -1974
The professional audio world has
been greatly saddened by the news
that Howard Holzer had failed to
survive the injuries he suffered in an
airplane accident which occurred
during take -off from Cuernavaca,
Mexico on July 28, 1974.
Holzer, a fellow of the AES;
awarded for "outstanding contributions to the industry," in 1966, was
the principal of Holzer Audio Engineering Co. (HAECO) the firm he
founded in 1961. Among the many
innovative products he provided to
the audio world were the early SC -1
stereo disc recording head followed
by the SC -2, a moving coil, dynamic
feed-back cutter; the CSG-2 compatible stereo generator; the CSG-4
quad generator; the SD -240 stereo driver Amp. Additionally Holzer
designed, constructed and installed
complete recording and mastering
systems throughout the world.
HAECO will continue in business,
headed by MARCUS HOLZER who
had been working with his father
for the past 3 years.
and the many users of NEUMANN lathes
and cutting systems who may read your
June issue, I object most strenously to
statements made by Kent Duncan as
interviewed by Gary Davis.
There are numerous mis-statements of
fact concerning the NEUMANN VMS -66
and VMS -70 computer controlled lathes
and VG -66S cutting electronics owned by
Kendun and many others in the Los
Angeles area as well as elsewhere in the
world.
The sum total of these mis-statements
gives rise to two erroneous impressions.
Firstly, the NEUMANN disk cutting
equipment, as delivered, requires extensive
modification
for optimum results.
Secondly, that all other users of NEUMANN equipment can't achieve such
optimum results.
Being completely familiar with the
Kendun NEUMANN systems, the truth is
that "Redesigning and modifying of the
lathe computer section" is a gross exaggeration of a minor modification made to
two input amplifier boards in an older
NEUMANN VMS -66 lathe. In total there
are 22 plug -in boards involved in the sys- resents about 35 watts more, not 100
tem. No modifications whatsoever have watts which would be double power.
The block diagram pictured, although
been made to the newer VMS -70 lathe.
Such modifications are neither approved not labeled as such, is essentially the
or reparable by Gotham Audio or NEUMANN SP 272 tape to disk transfer
console
NEUMANN.
with
additional
outboard
The completely erroneous statement is equalizers.
Other errors regarding the RIAA curve
made that "The output stage of the
NEUMANN cutter amplifier was modi- and the problem of tracing distortion
fied to develop a little more than twice would take too long to refute and explain.
Further these subjects are well covered in
the power of the stock amp."
the technical literature.
This erroneous statement resulted from
It is a well known fact throughout the
an attempt to explain the effective increased amplifier power reserve when the world, that the NEUMANN Company
NEUMANN VG -66S cutter driving elec- thoroughly understands disk recording
tronics are used with the new SX-74 requirements and technology. For over
cutterhead instead of the SX-68, with 40 years it has built equipment eminently
which most of these systems were suited to this purpose, without the need
for clients to make further modifications.
delivered.
The NEUMANN SX -74 cutterhead is
During the 46 year dedication of the
1.4dB more sensitive than the SC -68. This NEUMANN Company to the recording
could be interpreted as equivalent to 1.4dB and broadcast industries, it has innovated
more power reserve. However 1.4dB rep- new designs and has steadily injected new
Re/p 9
www.americanradiohistory.com
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Exclusive export agent: Gotham Export Corporation, New York
Re/p 10
Circle No. 105
www.americanradiohistory.com
improvements within the life of each
product. It should not be surprising that
a VMS -70 lathe would perform better
than a VMS -66 lathe, as a VMS -66 outperforms an AM 32B.
NEUMANN's latest innovation, the
SAL -74 disk cutting logic with six times
the power of the VG -66S system, includes
the TS -66 tracing simulator and many
other system innovations. Two of the
independent mastering systems mentioned
in the interview, Sterling Sound in New
York and Artisan Sound Recorders in
Hollywood already use this equipment, as
does United Sound Recorders in Burbank.
It is indeed unfortunate in our industry, that such erroneous information
is disseminated by your publication. I can
only suggest that, to avoid criticism and
the natural association of such misinformation with your publication, you take
one simple step. In the future preface
each of such recorded interviews with
words to the effect that "this is a verbatim
transcript of a recording of the following
interview." Further the transcript should
be submitted and approved by those interviewed prior to publication.
KENT DUNCAN'S REPLY
TO MR. ALLEN:
I am delighted at the interest sparked
by my interview. To me, the most interesting part of this industry is the learning
made possible by exchanges between
those of us who make records daily.
Mr. Allen has written an expected
letter disagreeing with two points I made:
modification of the computerized lathe
to produce better groove geometry, and
cutting power of the Neumann cutter
amplifier.
Mr. Allen suggests he is "completely
familiar with the Kendun system." I can
attest to that fact because about a week
after writing his letter to the editor he
dropped by to see just what we had done.
Before that, his familiarity with our operation included helping install our initial
system (leaving installed a factory shorting plug which resulted in less than
optimum performance of our system for
some time) and a telephone conversation
with one person, not a Kendun employee,
who participated in some of the evenings
spent re- thinking our equipment.
Basically, we are delighted with our
Neumann equipment. As a matter of fact,
in my interview I lauded Neumann for
the continual updating of equipment that
is so necessary in our profession. However, anyone can purchase this equipment
and essentially cut the same thing. This
leaves only engineering expertise as the
difference between studios. We have
simply gone one step further and extended
our engineering to include modification
of existing equipment to make it better.
It is absolutely true that we attribute
part of our success to the fact that better
results can be obtained with lathe modifications. We did not say that no one else
can achieve these results, however, to our
knowledge, no one has successfully accurately cut identical pairs with two different model Neumann systems.
We do believe that best results can
only be obtained by modifications of
both the VMS -66 and VMS -70 lathes. It
is hard for me to fathom why it is so holy
for Neumann in Germany to update and
improve the equipment and a sin for
Kendun in Burbank to attempt the same
thing.
An open door policy has always existed
at our studio resulting in a virtual parade
of competitors (Sterling, Artisan, Mastering Lab, USR, LRS), label engineers and
executives (RCA, CBS, Capitol, Motown)
and interested parties (JVC, JME, Westlake, CF) all to investigate what we do
and how we do it. Certainly this policy
extends to people who are interested in
determining what actually we have done
as outlined in my interview audibly,
electrically, or mechanically.
Let me explain our changes in a little
more detail. One of Kendun's lathes is a
VMS -66. When we attempted to cut identical pairs, we found that the VMS -70
outperformed the older model. After
many trying nights we came up with
modifications to the two boards Mr. Allen
mentions. Basically what was involved is
the alteration of the existing time constant
,
circuits resulting in improved groove geometry. Our only trouble then was that it
outperformed the stock VMS -70. Mr.
Allen states that nothing was done to this
system, which is not true. We applied the
same idea to the VMS -70 to achieve results matching our modified VMS -66. As
of this writing, we are still experimenting
with different value components to find a
combination that best performs for all
types of music.
After achieving such dramatic improvements, we offered to Gotham this information at our cost so it could be distributed to all owners of the VMS -66.
Gotham's response was negative.
Then comes the subject of power.
Kendun Recorders was the first or second
studio in the country with an SX-74
cutterhead. As a matter of fact, when it
was delivered we were surprised, as we
had ordered an SX -68. Because we had no
information on the new head, we contacted Gotham in New York and were
told that using the stock VG -66 cutting
system with the new SX -74 cutterhead,
we would develop 180 watts instead of
the 100 watts developed into the SX-68.
We are now finalizing a modification (including additional power supply capability) with some 22dB more power. Thus,
our claim of slightly more than twice the
power (22dB added to stock power of
180 watts). Mr. Allen now states that
only 135 watts is available stock. There-
fore, we must apologize to the reader for
passing on information supplied by
Gotham without checking it out.
Upon reflection, it seems that the 180
watt figure is excessive.
Mr. Allen states that the block diagram
pictured in the article "is essentially the
Neumann SP 272 tape to disk transfer
console with additional outboard equalizers." The following items shown on our
block were not included in the Neumann
SP 272 console:
1.
Studer A -80 preview machine
DBX noise reduction
2.
Dolby noise reduction
3.
4.
Burwen noise filter
5.
Haeco CSG
6.
2nd set of equalizers for A/B
switching
7.
A/B switching module
8.
Crossfade control
EMT Limiter /Compressor /Expander
9.
10. Studer copy /machine
11. Disc cutting lathes
12. Quad /Stereo speaker selection/
switching
13. Quad decoders
14. Monitor rack and filters
The block diagram graphically demonstrates the options available to clients in
our cutting chain for instance, switching
seven knobs of EQ in and dropping seven
others out instantaneously.
Additional equalizers and switching between pairs with a cross -fade control to
ll
K'
That's how more and more users are describing the
Orban/Parasound Dynamic Sibilance Controller. For the first
time, the conflicts between the vocal EQ you really want and
the sibilance problems that arise are eliminated. EQ for
optimal vocal timbre and let the Orban/Parasound DSC hold
sibilants to levels that sound natural and right.
Forget everything you know about de- essers- how they
pump; how they're fooled by certain low- frequency information; their relatively high noise and distortion.The Orban/
Parasound DSC is a new breed. Its dynamic response has
been optimized for inaudible action. Control filter selectivity
exceeds 18 dB/oct. Overload /noise ratio is an amazing 107
dB, and worst case harmonic distortion is under 1/4 %. And
it's amazingly easy to use. Just set one control for the sibilance
balance desired, and that relative balance uilï-be
maintained even tlt pi tj lWes a.c much as ¿Cl dB,
-
It's ideal for recording studios, cinema,T and radio
anywhere that excessive sibilance is a problem. Price is
another piece of good news -the 0/P DSC comes with three
independent channels on a 1 -3/4" rack panel and costs
less than $200 /channel.
Find out for yourself what many major recording and film
studios have already discovered: that today the Orban/
Parasound Dynamic Sibilance Controller is the de-esser.
For further information, contact
,,
own/peroround
680 Beach Street, San Francisco, CA 94109
(415) 776 -2808. or your local Orban /Parasound distributor.
-
ORBAN /PARASOUND
AMIC SIBILANCE CONTROLLER. THE DE -ESS SPECIALIST.
Circle No. 106
www.americanradiohistory.com
Re/p
11
smoothly change to a new equalization
are a requirement in a modern disc cutting
operation. Mr. Allen has told us Neumann
is studying these suggestions for inclusion
in future disc consoles.
I must say, however, that the most
dramatic improvements in cutting technology recently have been made by
Howard Holzer at Haeco Audio. He
recently developed a cutting system and
head capable of cutting far greater power
resulting in usable records with tremendous clarity and excellent geometry that
are most impressive. It is a loss to us all
that Mr. Holzer's tragic and untimely
death may slow the acceptance of his
system in the industry.
From:
STEVEN A.GUY
LOCATION RECORDING
SERVICE
BURBANK, CALIFORNIA
The June, 1974 edition of Recording
Engineer-Producer contains an interview
with mastering engineer Kent Duncan, in
which Mr. Duncan discourses, in a rather
self-serving manner, about several aspects
of disk recording with which he seems
unfamiliar, in view of the quantity of
erroneous information he presents.
We already have enough confusion
about disk recording among many in the
industry, with no need for Mr. Duncan to
add to it.
Some comments and corrections may
be in order:
1. In this interview, we are given a
general impression that Messrs. Cecil and
Margouleff visited several cutting rooms
in the Los Angeles area, all of whom were
unable to properly cut the "Innervisions"
material.
Casual conversation among several
of us who operate well-known independent cutting rooms has disclosed that
none of us ever had this album in for
cutting. We are not saying that other
cuttings were not made in the Los Angeles
area, but we would certainly like to dispel
the prevailing tone in Duncan's remarks,
that no company but his could properly
cut this album.
2. Mr. Duncan states that the output
stages of his Neumann cutting system
have been modified to produce, "A little
more than twice the normal power. " This
would be an impossible modification, because the standard output stages of his
Neumann cutting system can already
make full use of the supply capability.
We will state flatly that Mr. Duncan
is cutting with a standard Neumann
VG -66S amplifier system, having no significant increased power capability, and
will challenge him to produce measurements taken by an impartial, competent
engineer, to prove his claims.
3. Mr. Duncan's opinion of the storage
Listen to
the Sound
of Accuracy
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Circle No. 107
Re/p 12
www.americanradiohistory.com
duration of the Neumann lathe `computer'
is in error. He says he thinks that control
information is stored for six -quarters of
turntable revolution.
Stated as briefly as possible: Information requiring a change in depth -of-cut,
or information dictating a change in
cutting pitch (lines -per-inch) as a result of
flank modulation, is stored for more than
two- quarters, but not more than three quarters of turntable revolution. Information dictating a change in cutting pitch
only in order to accommodate an increased depth -of-cut, is stored for more
than four-quarters, but not more than
six quarters of turntable revolution.
4. Mr. Duncan tells us that, "Cutting a
10kHz tone will use something like ten
times the power of a 1kHz tone." We
only wish it were true! The absolute figure
would depend on the specific cutterhead
involved, but, to cut those two tones at
identical levels will entail a power difference of several hundred times.
5. The statement that, due to the
Vinyl shortage, "Some (pressing) plants
have gone to Styrene," is a little bit naive.
You don't simply `change to Styrene.'
The use of Styrene entails a completely
different process, with completely different (and very, very expensive) equipment. It would take months for a record
manufacturing plant to set up for, and
change over to Styrene, even if they
could eschew the great cost involved.
6. We are advised in the interview that
reference tones on a Dolbyed master tape
should be "Regular N.A.B. and stretched
Dolby." This advice appears to be selfcontradicting.
As a matter of convention, ref tones
on Dolby tapes are usually recorded with
the Dolby N/R switched `out,' and there
is a good reason for it: At normal tone
levels, the A -type Dolby displays, in the
record mode, a slight rise in response at
either end of the audio spectrum. This is
cancelled by a reciprocal droop when in
play mode. If the Dolby N/R is not
switched `out' when laying down ref tones,
these boosts and dips will be observed on
the meters of the tape machine, thus
giving inaccurate indication of tape recorder performance.
The statement that Kendun's Dolbys
vary in frequency response by ± 2dB
indicates an immediate need for maintenance. Hopefully, Kendun will receive
an offer of help from the Dolby organization.
Mr. Duncan also comments that
Dolby is, "A 2 to 1 situation. " That
statement is incorrect. DBX is a 2 to 1
situation. Dolby is not.
7. Mr. Duncan makes a statement
which connects centrifugal force with
inner-groove distortions.
Centrifugal force has nothing to do
with the matter, and even centripetal
force has, in most cases, relatively little to
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do with this problem.
The physics of inner-groove distortions are quite complex, and have been
treated in various technical papers. Putting
the matter as simply as possible, the
prime causes of it are:
A. The playback stylus radius being
larger than the modulation radius.
B. Plastic deformation of the mod-
ulation.
C. Correct lateral axis of playback
stylus motion not being tangent to groove.
D. Improper vertical modulation
slant in cutting, or improper vertical
tracking angle of pickup cartridge.
E. Contact area of playback stylus
changing with modulation.
As a point of interest, item `E' is
the distortion component which is corrected by the use of tracing simulation in
a cutting channel.
Finally, we must say that spending
two or three days presetting a computerized lathe to cut flat from a tape is a bit
far- fetched.
When set up precisely to factory
standards, (and these procedures do include a simple change for `pop' music)
the unusual and costly procedure described in the interview will not be needed.
As proof, consider this:
At least two independent cutting
studios, Artisan and LRS, obtained copies
of the `Innervisions "album, dubbed them
flat to tape, then dubbed the tape back
HOLLYWOOD, CALIF. 90028
flat to disk, and with no changes in our
standard Neumann systems, obtained, on
the first cutting, a ref disk that was
essentially identical to the pressings with
respect to level, sound, groove geometry
and ending diameter.
The "Innervisions" album is indeed
superb in its music, recording, production
and mastering. It is unfortunate that the
mastering engineer lucky enough to cut
it, could not accept his honors with the
same aplomb as did Cecil and Margouleff.
KENT DUNCAN'S REPLY
TO MR. GUY:
Mr. Guy suggests that it is a bit farfetched to spend 2 or 3 days to cut an
album flat with a computerized lathe. I
agree. However, to explain the confusion
in his mind I should note that the first
day was used in studio playback and
doing test cuts with various EQ settings
before deciding to cut it flat. The second
day was spent cutting some 8 or 10 ref
dubs (16 to 20 sides) for the producers
and the label. After ref approval, we then
began to cut lacquers, some 28 sides. It
should not be hard to understand that it
takes more than one day to cut some 50
LP sides. It was during the cutting of
these refs that experimentation with the
lathe took place. In addition, it is Bob and
Malcolm's policy to inspect the groove
from start to finish on each ref and
TELEX 67 -7363
lacquer, resulting in a wait between sides
of up to one hour while their inspection
took place. While I make no comment on
that procedure, with that kind of time
available, what engineer wouldn't take the
opportunity to futz with the material?
Incidentally, kudos should go to Guy
Costa and Motown Records for their efforts in the area of quality control. Before
lacquers are cut, their QC Department
carefully inspects the master ref and very
specific requirements must be maintained
by the cutting channel. Level, EQ, and
groove geometry of test pressings are
checked back against the master ref before pressing. Notations of instantaneous
peaks together with a test pressing accompany EQ tape copies that go to foreign
countries for mastering. Checks are then
made to assure the cutting matches U.S.
parts. Continuous checking such as this is
the only way to assure uniformity of
quality worldwide.
Mr. Guy goes on to intimate that he is
not sure that there were other cutting
rooms who failed to cut the album. In
fact, we were the fourth cutting room to
attempt the album. I will not list the other
three as it would serve no purpose, except
to point out that all four rooms were
delivered essentially identical Neumann
equipment, and we attribute our success
to the way in which we utilized our
system.
.
Continued on page 30
Re/p 13
www.americanradiohistory.com
SOMETHING REVOLUTIONARY,
SOMETHING A LITTLE REVOLUTIONARY
...AND SOMETHING YOU CAN BETTER
PUT YOUR FINGER ON.
ALL FROM
\\u\
REVOLUTIONARY: That's the word for the
JH -110 TRANSPORT AND ELECTRONICS
SPECIFICATIONS
REEL SIZE: 3" to 11 %"
TAPE TENSION: 4 oz., Supply and Take up Servo Controlled- Constant All Speeds and Reel Sizes
CAPSTAN DRIVE: Phase Locked D.C. Speed Variable 5 to
45 I.P.S. or 2.5 to 22 I.P.S. Dependent on Capstan
Diameter
FIXED TAPE SPEEDS: 3 %, 71/2, 15, or 71/2, 15, 30 (dependent on capstan diameter)
FLUTTER AND WOW: .05% DIN at 15 I.P.S.
START TIME: .2 Seconds at 15 I.P.S. on 71/2, 15, 30 I.P.S.
JH -110 series quarter- and half -inch recorder,
which we believe is the most sophisticated recorder of its type (available in mono, two- and
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Capstan
REWIND TIME: 85 Seconds for 2,400 Feet
FREQUENCY RESPONSE AT 15 I.P.S.: Reproduce:30 Hz16KHz ±2 db; Cue: 30 Hz -16KHz ±3db; Record:30 Hz16K Hz
-'3 db
SIGNAL TO NOISE (30 to 18 KHz): 2 Track Reproduce:
62 db Below +4 dbm; Cue: 60 db Below +4 dbm; Record
and Erase Less Than 4 db Noise Added to Bulk Erased
Tape
DEPTH OF ERASE: Greater Than 75 db Below 0 VU
ELECTRONICS DISTORTION: Less Than .1% THD at
KHz, Less Than .2% IM 60 and 6000-4:1
INPUT: Level -15 to +24 dbm for 0 VU Impedance 10,000
Ohms Balanced
OUTPUT: Level +4 dbm for 0 VU, Source Impedance 50
Ohm Balanced Maximum Output at Clipping, +24 dbm
EQUALIZATION: 3 Speed NAB Internally Switchable to
CCIR
BIAS AND ERASE FREQUENCIES: 120 KHz
BIAS ADJUSTMENT: Separate Bias Adjustment for Each
of Three Speeds
KHz at
RECORD HEAD -ROOM: Greater Than 20 db at
1
1
15 I.P.S.
CUE: Switches Automatically to Input When Entering Record
POWER REQUIREMENTS: 100V -220V Selectable 50 -60
Hz. Current Requirements for 120V Operation, 4 Amps.
HEIGHT: 35"
WIDTH: 25%"
DEPTH: 26"
SYSTEM WEIGHT: 190 Pounds
www.americanradiohistory.com
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A LITTLE REVOLUTIONARY:
Why "little "? Because we slimmed down the
width of our JH -24 cabinet from 47" to
311/2 " -making it MCI's first 24 -track recorder
in a 16- track -size cabinet (and if you don't
need the full 24 -track capability now, you can
buy an 8- or 16 -track configuration and add
the rest later, using the same cabinet). The
J H-24 accommodates 14 -inch reels, and, with
newly added handles and oversize casters,
boasts greater portability.
SOMETHING YOU CAN BETTER PUT
YOUR FINGER ON:
After exhaustive field surveys, MCI learned
that most fingertips are rounded, not square
so we responded to this anatomical revelation by replacing the square master status,
record ready and cue buttons with round
buttons, and adding a record LED on our
remote package. So much for that pressing
problem.
-
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4007 NE 6th AVENUE / FORT LAUDERDALE, FLA. 33308 / PHONE (305) 566 -2853 / TELEX 51 -4362
Circle No. 109
www.americanradiohistory.com
Re/p 15
If you want to lay down
an SPL of 113 dB*
with 28 to 18,000 Hz bandwidth
and dispersion of 120°
the Sentry III is it.
*4' on axis with
On the other hand,
if you need 4 dB more level
on axis, and are willing to
give up 22 Hz of bass, consider
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50 watts, with
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Both monitor systems share the same mid -range
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Sentry Ill. Sentry IVA. High- accuracy, high -efficiency loudspeaker systems. The two best ways
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ELECTRO- VOICE, INC., Dept. 846RP, 674 Cecil Street, Buchanan, Michigan 49107
www.americanradiohistory.com
Circle No
110
TV uses recording studio and concert sound techniques to produce:
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BY GARY DAVIS
The first broadcast of The Midnight
Special marked the beginning of a strong
new direction for the music business.
Prior to that show in January, 1973, there
had been no regularly scheduled rock and
roll television show with top quality
audio. In successfully merging a variety of
elements from record recording, live stage
performance and television production,
Burt Sugarman Productions broke new
ground. Joe Ralston, NBC's audio engineer who works on the show, told us
that The Midnight Special was the network's first real "series" rock show. The
NBC staff, in cooperation with the staff of
Midnight Special, learned a lot of new
techniques. They rented and eventually
built or purchased new equipment, and
they developed an approach that has
pleased not only the viewing audience,
but the performers and the studio audience, too. We wanted to learn all we
could about how the show is put together,
what makes it work, and how it compares
with record recording. Stan Harris, the
show's producer and director, very cordially explained his job and told us about
the many facets of this television
production.
The producer /director is the man who
has the last word in matters of talent
booking, script content, set design, light -
-
ing,video composition, and audio quality
in other words, everything that comprises
the show. Stan has a competent staff to
assist him with the substantial task of
planning, taping and assembling the weekly
shows. As we sat in his tastefully decor-
ated office, high above Sunset Boulevard
in West Hollywood, Stan discussed the
concept behind the show. Originally, the
show was to be television's answer to AM
radio's top forty format. To keep the
music current, there could be no reruns or
summer replacements. Although the scope
of the show has widened to embrace
blues, folk, country and even comedy,
the main fare is still predominantly rock.
AN OVERVIEW OF THE PRODUCTION
Unlike some music programs which do
little more than photograph and record a
concert, The Midnight Special is deliberately created to be a television program.
That means that the video, as well as the
audio, is given full consideration in the
planning and execution of the show. While
Stan told us that sound is probably the
more important element, he demonstrated
his concern that the video be clean, interesting, and appropriate to the performance.
The taping is done with a large studio
audience, so the show has a genuinely live
feel. Full sound reinforcement facilities
were established to provide separate stage
monitor and audience mixes, and to
deliver clean sound with precise coverage.
The stages are similar to concert stages,
yet there are obvious differences between
the taping we attended and a true concert
or club performance.
Often the tunes are taped out-ofsequence. Occasionally the performance
is interrupted so a technical adjustment
can be made, or simply because the artist
wants to take it from the top. Unlike
record recording, however, very little
overdubbing is done. In fact we learned
that only twice in the show's history has
a vocal overdub been added, and then
only to lay down a harmony part for a
female vocalist who had used a similar
effect on her album. Overdubbing not
only multiplies the production costs, it
detracts from the live and authentic
quality of the show. Stan feels so strongly
that the television audience should be
treated honestly that he has ruled out lip
sync audio. As a result, the show is taped
with surprising smoothness and continuity.
Smoothness and continuity
a good
phrase to describe the entire process of
-
making The Midnight Special. We observed
the taping of a show hosted by Randy
Newman, with Ry Cooder, Dr. John and
Maria Muldaur. The Turtles were to be
taped the following week and added to
the program. We saw numerous reminders
that everyone does his homework, and
the taping was painless, if not enjoyable,
for the performers, staff, and even the
studio audience. A detailed script is prepared in advance. It includes all lyrics,
the approximate length of each tune, the
stage arrangement schematics for each
act, notes on camera placement, mike
placement, video switching, and more. In
order to make the performers as comfortable as possible, they are asked about
preferences for stage arrangement and
miking before the final diagrams are prepared. Actual arrangements are developed
by the show's staff to provide adequate
audio separation, pleasing visual composition, good camera access, and to meet the
need for one performer to see and hear
another. This planning is all part of the
process called pre -production.
Re/p 17
www.americanradiohistory.com
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Re/p 18
Circle No. 111
www.americanradiohistory.com
duction assistant Ellen Brown makes that
job considerably easier. It is also no accident that there is a close working relationship between Stan and Joe Ralston, so the
audio tends to sound the way it should
with a minimum of direction. During the
actual taping, when things are most hectic,
associate producer Jacques Andres closely
video control booth (foreground)
separated by sliding glass door
the audio control booth .. .
THE PRODUCTION SCHEDULE
The actual production begins the day
prior to taping. This is the setup day, when
all instruments and amplifiers are brought
into the studio. Lighting and sets are
arranged on four stages which surround a
central floor space (the audience will sit
here). At this point, roadies may be helping with the setup, although NBC people
will complete the job. Union conflicts
apparently pose no real problem. The
average setup day runs between 12 and
14 hours.
The day of the taping, rehearsals begin
just after noon. Only one act at a time
will rehearse, so people don't have to sit
around waiting. The first part of a rehearsal is the audio runthrough. This gives
the performers an opportunity to loosen
up while the audio engineers and technicians get their levels, balances, equalization, and so on. Stan will use this time to
walk around the stage floor, get a feel for
the sound, and suggest any last- minute
changes he may want. Often a representative of the act, the manager, producer
or record company engineer, will go upstairs to the audio control booth; while
union regulations prevent him from touching the console, he can suggest ways to get
the sound that the act would want. Joe
Ralston, who has been the show's chief
audio engineer almost since its inception,
seems to fully enjoy the music. He will
listen to the records of any act he doesn't
know so that he can get a feel for the
right sound.
After the audio runthrough, which may
take 1/2 to 3/4 hour, there is a video run through. At this point, Stan is in the
video control booth; he is busy telling the
cameramen what he wants and advising
Jerry Weiss, the technical director, what
video switching and effects to use. There
are several intercom systems for communication with stagehands, camermen, the
lighting booth, and the remotely located
video tape recorders (VTR's). In addition,
a studio .talkback system feeds monitor
speakers, and a 2 -way radio is used for
exclusive communication with the stage
manager. A lot is going on, and Stan's
assistant director, Ron Cates, helps in
several ways. He is most helpful in keeping Stan's place in the script, timing the
musical passages, and anticipating video or
audio transitions. It is really an important
job because Stan's attention is riveted to
the five B &W camera monitors and the
three color program monitors in the video
control booth. Stan is also responsible for
dealing with the performers, and pro-
supervises the audio.
During the video runthrough, Joe has
another chance to polish up the audio,
note some level and equalization settings,
and help the engineer in charge of sound
reinforcement (which they call PA). The
reinforcement is done with a separate
console on the studio floor, but the feeds
to that console must be patched from the
audio control booth. We'll describe this
system elsewhere in the story.*
When the first group has completed the
audio and video runthroughs, the next
group immediately begins. There is a
lunch break around 4:00 pm, for an hour,
and then additional rehearsal until the
taping at 7:00.
WHAT IS THE TELEVISION SOUND
AND WHERE IS IT?
The Midnight Special is broadcast with
a monaural soundtrack. The producers
would like to use stereo sound, but NBC
does not have an affiliated FM radio network, so stereo is impractical. Besides,
Stan points out that the show's simulcast
competition charges around $18,000 per
minute of commercial time to cover about
*We would also like to describe the video
effects, switching, and recording in considerably more detail, but it would take a
hundred pages. Suffice it to say that the
video booth is where what you see on the
screen is basically determined, and this is
done in real time while the show is taped.
CELLOS
RISER
STRING MIKES ARE RE -20'S:
VIOLINS AND VIOLAS OVERHEAD,
CELLOS FROM REAR (ON FLOOR).
X
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X
VIOLINS
CELLO
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STAGE
MONITOR
STAGE
IS
APPROX.
2i' ABOVE
FLOOR
STAGE
MONITOR
set up for the Randy Newman segment
.
Re/p 19
www.americanradiohistory.com
MODEL 210
SIXTEEN INPUTS / EIGHT UTPUTS
EXCLUSIVELY AT
ANC KU_ CY
6912 MELROSE AVENUE
oun
HOLLYWOOD, CALIFORNIA 90038
(213) 937-1335
pretty well equipped. Joe says
that the SM -57 is the basic all- purpose
mike. SM -58's are commonly used for
vocals, MD -211's are piano favorites (stuck
in the sound holes), and ECM-22P's for
so they are
Dr. John set up
ECM -22P
GUITAR AMP
OVERHEAD
ECM -22P
OVERHEAD
PIANO
AMP
BASS AMP
DIRECT
SM -57
5M -57
I
RE -10
ECM -22P
BOTTOM
BASS
5M -57
X
GUITAR
X
5M -58
VOCAL
VOCAL
X
X
5M-58
STAGE IS APPROX.
2_' ABOVE FLOOR
SM -58
MONITOR
MONITOR
the same audience that The Midnight
Special reaches for some $9,000 per
minute. Stan wishes that television itself
were stereo, like his Sony videocassette
machine, and he philosophically conjectures that if the people who invented
video tape machines had provided two
audio channels, we would have stereo
television today.
The monaural soundtrack is stored on
a small portion at the edge of the 2"
videotape. The tape runs at 15ips past
several head stacks. The first head is the
master erase head. Then the vacuum assisted video head scans the tape at some
1500ips (actually 4 heads evenly spaced
on a rotating drum diagonally sweep the
tape). Past the video head is a pair of
audio heads with three channels. But
only one channel is for the actual soundtrack; the others are for an EECO time
code and for cues. Recording electronics
are adjusted so the audio input peaks at
OVU ( +4dBm). The frequency response
and noise level are comparable to standard
professional tape machines. One further
note about the video tape machine is that
the line frequency is 59.9 +Hz instead of
60Hz, so any auxiliary recorders must be
equipped with resolvers to run at the
correct speed.
During the taping, the audio engineer,
Joe, will send a mono program feed down
to the VTR room where it is recorded
with the video program. Prior to the
recording, a test tone is used to calibrate
and align all tape machines, and is placed
at the head of each tape. Known as
multi -tone, this complex signal is piped
throughout the NBC facility. The video
tape engineer, not the audio engineer, is
responsible for the alignment of the heads
on the video tape recorder.
MIKING
The miking is done with great care,
using a wide variety of condenser and
dynamic mikes. Placement is governed by
video and audio needs. For example,
Randy Newman was accompanied by 18
strings. If each had a mike on a floor
stand, a music stand, and an instrument,
there would have been a terribly cluttered
stage. So the decision was made to try
hanging the mikes by their cables from
the 42' high grid. It worked well. If possible, a mike is placed so that at least two
cameras can get a clear shot of the
vocalist's face. Yet mikes can't be located
very far away.
Tight miking must be used to avoid
feedback from stage and audience monitors. Studio techniques, such as baffles or
physical distance, are unsuitable when TV
cameras are there, Tight miking also reduces any leakage, leakage which could
degrade the mono mix. Stan and Joe like
the close -mike sound, and there are a few
EMT's available to put back the lost
ambience.
Mikes are chosen for their sound. Performers are given their preference if they
voice a strong opinion, and mikes will
be rented if necessary. But NBC has purchased many mikes since the show began,
the drums. The ECM -22P gives a crisp
drum sound, an important consideration
for the small television set speaker. RE -10,
RE -20's, MD -421's and other mikes have
been used often. Direct boxes are fitted
to some electric instruments, and mikes
are used for others. Barcus -Berry, Countryman and Helpinstill piano pick -ups are
used occasionally: usually at the request
of the performer, and usually to reduce
monitor feedback but not to feed the
program mix.
When we looked at the stages, the
miking could have been for a typical
multi -track recording session. While the
show is broadcast in mono, parts are well
separated and fully miked. Besides the
leakage and feedback factors we cited,
there is the advantage of precise balance
and equalization control, and the acts can
have exactly the stage monitor feeds they
need.
THE AUDIO SYSTEM USED FOR THE
PRODUCTION
The accompanying flow diagram illustrates the complex audio paths involved
in the production of The Midnight Special.
All mikes are brought through low impedance lines directly to a 980 -point
patch bay adjacent to the console. These
are patched into preamplifiers in the
console, and are multed to the input
channels. The mult outputs can be patched
through unused mike lines down to the
.
NBC CONSOLE
INCLUDES
74
IN
(60
2
I
2
IN
INCL SUBMIX)
MONO FROG
SUBMASTER
10 SUBMIX
FOLOSACK
MONITOR
4
Continued on page 24
OUT
OUT
RVB SND OUT
AUDIO BOOTH
NBC-BUILT CONSOLE
w/ LANGEVIN E0. F
PREAMPS, LA -2A
LIMITING AMPS
OUT
OUT
OUT
PWR
AMP
A
URMIXER OUTPUTS
Used
RVB
5N0
F-
JBL 4320
MONITOR
IN /10
(40
For Foldback
6
URMASTER OUTPUTS (24
(Used For Foidback G
ONO BOARD OUTPUT
8
OUT)
-Trk)
IN /4 OUT)
8
-Trk)
INPII
MAGNA -TECH
92C RESOLVER
X60
AUX PATCH FOR
AG -440 IN /OUT
AMPEX 300
PATCH BAY
MONO
48
;
X
_
xL
20
A
4
dB, PGM
FEED
AMPEX
>
AG -440
8
(TD VTR
t
VIDEO CONTROL BOOTH)
FROM STUDIO
\
59.9 Hz CAPSTAN SYNC
SECO/SMPTE TIME CODE
VTR CONTROL AREA
SIGNAL AND
FROM CENTRAL
SHURE SR -105
POWER AMPS
FOR FOLDRACK
IN -LINE PADDING USED AT
MICROPHONE CONNEC -ORS
TO A -7 SPEAKERS
30. OVERHEAD FOR
AUDIENCE REINF.
FPC -50
FAIRCHILD
16
STUDIO
TRACK
x8
EMT-
MICROPHONES AND
LINES
GUA,
x0
IN
/
CONSOLE
8
OUT
4
1
"=frit_I--
/3-OCTAVE EQ AVAILABLE HERE
Signal paths between control room and studio
PATCH.
BAB
TO STAGE MONITORS
(JBL COMPONENTS,
HOLLYWOOD SOUND
ENCLOSURES)
SHURE SR -105
POWER AMPS
Re/p 21
www.americanradiohistory.com
Nobody ever made a
monitor that could match
this sound.
Type of System
4 -way
Components
(2) 15" low
(1)
(1)
(1)
frequency
loudspeakers
12" midrange
loudspeaker
High frequency compression
driver with horn lens
Ultra high frequency
compression driver
30 to 20,000
Sensitivity (SPL at 30'
46.5 dB
ImW)
Power Output (SPL at 10 110dB
ff. in a room volume
of 2000 cu. ft. with
1/2 rated power input
-150 watts)
Crossover Frequency
250,1100 and
Frequency Response
Size
Net Weight
The 4350. Three years
Hz It
3dB
9000 Hz
35 "x48 "x20"
243 lbs (110 kg)
Configuration
Bi- amplification
Price
Utility finish shown $1314
Walnut finish
$1464
James
B.
only
Lansing Sound
ago
JBL's
technical staff
was asked to produce the best studio monitor
that technology and artistry could create. That
was their total assignment. Considerations of cost
and monitor size and studio application were
secondary. The search was for a sound. The name
was 4350. Its birthday was April 13, 1973. And,
from the day it was born, it was the best sounding
studio monitor money could buy:
A virtually flat frequency response from 30 to
20,000 Hz. Minimum phase shift throughout the
entire band pass. Extraordinary response to onset
and transient signals. Carefully controlled, semi diffuse dispersion pattern throughout the
frequency range. Uniform sound characteristics
from ppp to fff dynamic markings. Extremely low
transducer distortion within the recommended
dynamic range values of more than 90dB. High
sensitivity for maximum conversion efficiency.
But, wait. A spec is not a sound. Come hear the
4350 and see how far sound can go.
/ Professional Division / 3249 Casitas Avenue,
www.americanradiohistory.com
Los
Angeles 90039
Until now.
The 4340/41
Type of System
The 4330/31
The 4332/33
4 -way
3 -way
2 -way
(1)15" low frequency loudspeaker (1) 15" low frequency loudspeaker (1)15" low frequency loudspeaker
(1)10" midrange
(1) High frequency compression
(1) High frequency compression
loudspeaker
driver with horn lens
driver with horn lens
(1) High frequency compression
(1) Ultra high frequency
driver with horn lens
compression driver
Components
ultra high frequency
compression driver
35 to 20,000 Hz ± 3dB
44dB
(1)
Frequency Response
Sensitivity (SPL at
ImW)
30'
Power Output (SPL at 10 101dB
ft in a room volume of
2000 cu ft with 1/2
rated power input
37.5 watts)
Crossover Frequency
250, 1250 &
20,000 Hz
± 3dB
15,000
44dB
35 to
44dB
101dB
100.5dB
35 to
Hz ± 3dB
-
800 and 8500
9500 Hz
Hz
800
Hz
Size
38 "x 24"x20"
30 "x 24 "x 20"
30 "x 24 "x 20"
Net Weight
Configuration
179 lbs (81 kg)
121
lbs (55 kg)
for bi-amplification or with high
level network
to be announced
June 1974
96 lbs (44 kg)
for bi- amplification or with high
level network
to be announced
June 1974
Price
Availability
Circle No. 113
for bi- amplification or with high
level network
to be announced
June 1974
Four monitors. Virtually one sound. A matched set:
you could record on one, play back on another,
mix on a third and master on a fourth.
Four monitors. Their only differences are acoustic
output, cost and size.
Hearing is believing. Come hear what you can do,
www.americanradiohistory.com
;16L
Re/p 23
...
..
reinforcement console on the studio floor.
In addition to these microphone feeds,
submixer and submaster outputs are sent
to the reinforcement console. This arrangement is used because the booth can
accommodate all the mikes from all four
stages, but the reinforcement board has
only 16 inputs.
There are two tape machines. An
Ampex 300 is loaded with a mono tape
of Johnny Rivers' Midnight Special
Theme, with and without vocal. This
machine is used according to cues in the
script. Adjacent to the 300, an AG-440
8-track is loaded with Scotch 206 tape for
a continuous multi-track recording during
the taping; some five full reels were used
for the show we attended. One track of
Continued from page 21
.
the AG -440 is reserved for the EECO
time code, the same code required for
the VTR, and another track is for the
59.9Hz sync signal. A Magna -Tech Model
92C playback synchronizer is used to
resolve the sync tone and drive the
capstan motor. Both the time code and
the sync tone are generated in the VTR
room and fed to the audio booth.*
The console, like all consoles at NBC,
is custom built in house. It is ruggedly
designed, with heavy aluminum panels and
color-coded anodized aluminum knobs
machined at NBC. While the board is
similar in some respects to recording
consoles, it has many more levels of subassignment. The 24 11/2" wide modular
input channels have linear faders, Langevin
EQ-51B equalizers, and an unusual bus
assignment system. The channel can be
assigned to any of four submaster channels, two foldback chanels, or two reverb
send channels.
Each submaster and reverb channel is
equipped with an LA-2A limiting amplifier with front -panel controls mounted in
the module and the balance of the electronics mounted in the back of the console. Following the limiter, a large rotary
level control and an additional equalizer
are part of the submaster channel. The
submasters can be used as board outputs,
and some are. But assignment switches
allow them to be routed through either
or both of two rotary level controls;
designated Music Master and Cast Master,
they provide a single -handed way to
balance vocals and instruments. The Music
Master and Cast Master are routed to a
board master, which then provides the
mono program feed. But there is an
additional type of sub -group.
10 of the 24 input channels are pro*The EECO code is essentially the SMPTE
time code, a digitalized method to tab the
exact elapsed time of any point on the
tape. Special decoders can provide digital
readouts, and these can be displayed in a
The
box on the television monitor.
divisions are hours : minutes : seconds:
frames (30 frames /sec.).
N IS
]+N7j
7aE
a'
vided with submixers. The submixer is a
set of four individual rotary level controls,
followed by a group level control. These
are used to mix four inputs into one input
channel. So the ten submixers actually
add 40 inputs to the board. Since four
stages are used, the submix groups can be
used to feed the same instrument on the
various stages to the same channel of the
console. This avoids confusion in mixing.
Also, the inputs of one submixer may be
the mikes from one drum set, so that
input channel simply becomes the drum
channel. The submixer output is normalled
to the input fader of that channel, but it
can be patched to any point, including
the 8 -track recorder and the reinforcement
console.
Four VU meters are calibrated with
0 VU = +4dBm levels, and three of these
have rotary selector switches to provide
VU metering for additional board outputs.
Adjacent to the meters are a pair of small
B &W video monitors. One is the program
feed (the show being taped) and the other
is the preset bus (the camera or effect
about to be selected for program). These
B &W monitors are duplicated with larger,
wall- mounted monitors. And, as a result
of Midnight Special requests, a color
monitor sits atop the console. Sound is
monitored with a JBL 4320 hung on the
wall about 5' in front of the mixer's chair,
and a 5" speaker is mounted in the console for reference to the average TV set
speaker.
DETAILS OF THE AUDIO MIX
Relatively little equalization is used:
about 6dB of boost or cut was the most
we observed, and many channels used
none. There is some additional low end
to cut through the small speaker. And
because most small speakers have a peak
near 5kHz, the vocals must be held down
somewhat with respect to a good balance
1
lb N
7d
r
8j
11
j+
i
.
audio control booth consol
on the 4320. Because the mono, once
mixed, is difficult to equalize, nearly all
equalization is done during the taping.
Compression is held down to only 3 or
4dB, and mike levels are padded to prevent clipping distortion. Later, when the
show is broadcast, we asked whether
additional compression would be used.
Apparently it is held to a minimum, at
least among the NBC owned and operated
stations. However, quality control of the
broadcast audio is difficult. Phone lines
are commonly used to transmit the audio,
and one midwest market receives the
broadcast audio via lines from Chicago,
tapes the video and audio, and then rebroadcasts it later. So the only thing Joe
can do is to provide the best possible
audio and hope that it will get to people's
living rooms without losing too much
quality.
While the mono mix is being recorded
on the VTR, the AG-440 is recording a
multi -track mix on six tracks. This tape is
usually not mixed down. However, if
something is drastically wrong with the
mono mix, or if an album is to be made,
the 8 -track can be used.
POST PRODUCTION MEASURES
The first thing that is done after the
show has been taped is the video editing.
To completely arrange and assemble the
90- minute program, only about 4-8 hours
are required. Electronic editing is used,
rather than splicing, due to the nature of
the video recording. But a nice feature of
the electronic editing is that the edit
point can be precisely adjusted, frame by
frame, until it is just right (1/30 second
increments). And the time code gives an
editor the exact point for logging the edit.
.
Continued on page 29
Circle No. 114
Re/p 24
4
Guaranteed
Acoustical Performance
Specifications
.from Westlake Audio
"The Gold Record People:'
Westlake Audio is the only studio designer -builder
offering detailed, written guarantees of acoustical
performance to clients who entrust Westlake with
full responsibility for their projects from acoustic
design to downbeat. This guaranteed performance
is one major reason why so many hundreds of Gold
Records have been recorded in Westlake installations.
-
Westlake provides a complete "package" including
unequalled skills and experience for turn -key "gold
record" installations: pre -planning, site evaluation,
acoustic design, construction, equipment selection
and supply, financing, technical electronic interface,
training of personnel and studio management consultation. From 2 to 24 track, for live recording, mix
down, remote or mastering.
On the next two pages you will find the performance
specifications which are guaranteed when Westlake
assumes complete responsibility.
from acoustic design
to down beat...
Westlake
Audio
www.americanradiohistory.com
Guarantee of Acoustical
by West
I.
Control Room
Acoustical and Geometric Design by Westlake Audio
A. Frequency Response
s
1/3
Frequency
Dispersion
B. High
upon installation, 31Hz-16KHz measured with
octave, pink noise source.
3 dB
B & K,
±
2 dB maximum @ 10KHz across a minimum 10 foot
horizontal plane at the console (from left of the mixer to
the right of the producer or vice versa) from any one of the
four monitors, measured with pink noise source.
2 dB maximum @ 10KHz across a minmum 5 foot horizontal plane front to back of the mixer or producer from
any one of the four monitors, measured with pink noise
source.
C. Power
116 dB SPL minimum, linear scale, with broadband pink
noise source from one monitor measured at the mixer's ear.
The control room potential with four monitors is a minimum
of 128 dB SPL.
What the above really means is that as the mix is being created, the mixer and producer
will accurately hear the same music timbre balance.
Il. Studio
Acoustical and Geometric Design by Westlake Audio
A. Room Character
The characteristic "room sound" which results from recording in a three dimensional area is eliminated by the utilizatic
of an active ceiling providing a minimum of 50 dB attenuatic
@ 40Hz. This, in effect, produces an infinite third dimension
such as would be present in an amphitheater.
B. Decay Time
Multiple decay times of various frequencies may be incorporated into the studio design. Thus a tight rhythm sound
may be achieved in one area while a bright string sound is
obtained in another.
www.americanradiohistory.com
erformance Specifications
ke Audio*
C. Multi -track
Separation
D. Drum
Isolation
Active traps are built into the studio walls which allow
"in- studio" vocals, eliminating the usual need for vocal
booths. 40 dB of isolation can be provided between the band
and a vocalist only 10 feet away resulting in 40 dB of isolation @ 40Hz or tuned to selected frequencies.
A drum cage is provided, either built into the structure or
on a movable platform. Again an infinite third dimension is
achieved through an active ceiling design. The highest
sound pressure level (SPL) are generated by the bass drum
at 90Hz and the stick on the cymbal at 8KHz. These are
attenuated a minimum of 24 dB measured one foot outside
the drum cage. If desired, the cage may be built to project
mid frequencies into the studio to give the musicians a
better "feel." The "character" of the drum cage may also
be designed for bright, dim or variable results.
E.
Bass Traps
Bass guitar traps are incorporated into the design to provide 24 dB of attenuation at 40Hz with an SPL of 116 dB
exciting the trap.
F.
Piano Trap
A piano trap is also included for the purpose of
rejecting
unwanted sound from the studio to the piano microphones.
The broadband rejection to the piano trap will be in excess
of 20 dB.
Ill. Live Quad
Echo Chamber
Acoustical and Geometric Design and Active Components
by Westlake Audio
A. Timbre
Variable control of low frequencies from section to section
of the chamber.
B. Decay
Individual variable control of decays from all four chamber
areas.
C. Echo Mix
Variable mix of echo content, parent to decay.
D. Depth
A three dimensional effect in echo
content thru the use of
two MS stereo return (4 channel).
E.
Stereo
stated prior to construction, the quad chamber may be
used as two independent stereo echo chambers.
If
Which other professional studio design company will guarantee in writing
these features and specifications, prior to construction?
`On all jobs commencing March 1974 or later.
www.americanradiohistory.com
N
4iì
Kent R. Duncan, President, Kendun Recorders, Burbank,
California: "The new room has been in operation for six
months now and our success is as much a tribute to
Westlake Audio and Tom Hidley as it is to our long hours
and attention to detail (and possibly some good engineering). Our Westlake room made us a 2 studio operation but
instead of just doubling our gross, we went from $12,000 a
month to $60,000 a month. The incredibly accurate planning of our Westlake turnkey installation resulted in corn pletion exactly on time, response precisely as promised,
all equipment functioning within one day of installation,
and all within budget! In the past six months we have
mastered such acts as Stevie Wonder, Bob Dylan, America,
Buddy Miles, Fleetwood Mac, Rick Nelson, Tower of
Power, Livingston Taylor, Isley Bros., Rod McKuen, Nitty
Grity Dirt Band, Emitt Rhodes, Richard Greene, El Chicano,
Nana Mouskouri, Cleo Laine, Bola Sete, San Sebastian
Strings, Jo Stafford, Maxayn, Pharoah Sanders, Archie
Shepp, Ballin' Jack, Vickie Lawrence, Maureen McCormick
& Chris Knight, Don McLean, Vikki Carr, Bill Medley and
even Rodney Allen Rippy. Over half these acts were
recorded on Westlake monitors in various studios around
the country, attesting to the fact that truly, you are the
professional."
Christopher Stone, President, Record Plant Recording
Studios, Los Angeles: "As you know, we have used
Westlake Audio and yourself since the inception of the
company for all of our studio design, construction, electrical interface and implementation. During the past four
years you have designed and implemented eight studios
for us in New York City, Los Angeles and Sausalito.
Obviously we are known as a Westlake- designed operation. We have built our total reputation around your studio
design and have always been happy with our decision to
utilize you on an exclusive basis for all our acoustical
requirements and equipment consultation. The success of
your design speaks for itself in the form of our success as
an independent studio operation."
John Sandlin, Vice President A & R, Capricorn Records,
Macon, Georgia: "All of the work done was of a quality that
is almost non -existent today. The people from Westlake
cared, and saw to it that their work was of the highest
standards. The carpentry work is incredible. The complete construction and equipment interfacing went more
smoothly than can be expected in such a major undertaking. Westlake's delivery dates were either on time or
before the time they were promised. The real test, however,
is in the performance of the control room. Our room
sounds great and objectively measures great. Also, the
room is comfortable and easy to work in. It is really a
pleasure to work with people of the integrity and abilities
of Tom Hidley and Paul Ford and the rest of the Westlake
personnel."
Michael Nemo, Independent Recording Engineer: "My
clients and have found that the closest approach yet to a
true standard is the integrated concept of speaker and
room acoustic control found in studios built by Westlake
Audio. What a pleasure to go from one Westlake installation to another and not have to be concerned about compensating for too much or too little bass, or high frequency
response.
I
John Boylan, John Boylan, Inc., Hollywood, California:
"First of all, this is my third project in a row to be mixed on
your monitors and once again it looks like we have a
winner
record that sounds as good at home as it did
in the control room. From a producer's nontechnical viewpoint, this ability to trust a studio monitor and come out
with even results is extremely satisfying. Secondly, the
Westlake Monitor never seems to vary in any substantial
way from studio to studio, in the control rooms that you've
designed. So have no worries about consistency in
today's widely dispersed recording scene."
-a
I
Edward J. Green, Director of Engineering /General
Manager, MGM Recording Studios, Los Angeles, California:
"The studios and the control rooms have been completely
successful for MGM Records from the time they were
finished. Our mixers have, for the first time, the kinds of
`acoustical tools' that are needed for contemporary recording. That is, multitrack recording with all but complete
isolation of elements whose parts can be later mixed or
deleted and replaced. In the control room, the mixer and
producer must be able to accurately monitor the recording
so as to make technical and artistic judgements. Your
booth design and particularly the Westlake monitors have
proven themselves thoroughly workable and accurate. It is
to your credit that these recording systems have withstood
this test of time, particularly during'the last three years,
and that we wish to make no changes in studio or control
room design in the immediate future."
Robert M. MacLeod, Jr., Artisan Sound Recorders,
Hollywood, California: "Now that we have been in our new
building for a couple of months, thought you might like to
know how it is working out. About all can say is fantastic!
We have had nothing but good reactions to the monitoring
systems, and the acoustics of the mastering rooms are
superb. Almost everyone who comes in comments on the
quality of the workmanship. We have encountered no
problems at all, and we find it a joy to cut records without
the constant noise of the vacuum system in our ears.
Producers seem to agree, and am sure these beautiful
new facilities will put us in a far stronger competitive position in the industry. In today's world of shoddy workmanship, it is really a delight to see the results of such
painstaking care."
I
I
I
Complete, unedited photocopies of these and
many other testimonial letters are available on
request from Westlake Audio.
Phone or write direct to Tom Hidley, President.
to down beat...
Westlake
Audio
www.americanradiohistory.com
6311
Wilshire Boulevard
Los Angeles, California 90048
1213) 655 -0303
can take a lot of time. To hold it to a
minimum, four stages are arranged around
a central floor area and are set up in
... Continued from page 25
advance. The studio audience arrives just
prior to the taping, grabs padded floor
After the video tape is edited down to mats, and sits right in the middle of the
a 90 minute program, the audio has
studio area. In this way, the groups have
abrupt transitions. Since the order of only to wait for a few patches to be made
tunes may be changed, commercial breaks and the cameras to roll into position, and
and station breaks are inserted, and noises they can proceed one after the other. The
may be present, a process of sweetening audience will be given the opportunity to
the audio is required.* Sweetening is the stand up, stretch, and then sit down facing
term that television originally used to the next stage. It works surprisingly well.
describe the insertion of laughs or apA common problem arises with groups
plause to a comedy show. It now refers to who are used to big concerts. They crank
the broader range of cleanup and smooth- up their amplifiers so far that the sound
ing of the audio track.
has leaked through the studio wall, a row
The console in the post production of dressing rooms, across a hallway,
audio room is similar to the production through another row of dressing rooms
console, but with additional submaster and a wall, and into the next studio. In
channels and with monitor solo for all extremely loud cases, the video can be
faders. A MacKenzie cartridge machine is modulated by the audio due to micro loaded with up to 10 cartridges of audi- phonics in the camera tube. To get around
ence reaction that have been derived from the problem, a good stage monitor system
Midnight Special performances. These may was installed, one which beams the sound
be clapping, applause trailing off, ap- directly to the performer who wants to
plause building, laughter, and so forth. hear it. And the acts are asked to keep
The mono VTR track is transferred to 4 the levels down as much as possible withtracks of an AG-440 as follows: track A out being uncomfortable for them.
has the 59.9Hz sync tone at -10 VU, track
Sometimes the amplifiers brought in
D has the EECO time code at -7 VU, and by an act will be in need of maintenance.
tracks B and C have redundant mono dubs Hums, buzzes and crackles won't be
from the edited VTR (peaking at 0 VU).
tolerated, so the show has back -up equipThe sweetening process begins when ment on hand. There are even a couple of
the VTR rolls and the picture is viewed on Leslies, drum sets, and a Steinway piano.
one of two color monitors in front of the
Stan tells us that in the early days of
console. The 4 -track is run in sync with rock and roll television, many groups were
the VTR, and the music is re- recorded on- visually dull. Many special effects, gimto the videotape. Joe simultaneously mixes micks, light shows, and so forth were used
the audience effects onto the videotape. to enhance the video and keep the show
A cough may be used to cover a noise, interesting. But this problem has taken
and the output of the 4 -track can be care of itself in recent years. Exemplified
switched off momentarily while the Mac- by people like David Bowie, Alice Cooper
Kenzie cartridge is running. Assistant and Leo Sayre, a number of groups have
operators man the MacKenzie machine become 100% entertainment oriented.
and the 4- track, while the director or Generally the musical scene is more
associate producer work with Joe on the polished, so fewer visual gimmicks are
mix. Essentially, the whole sweetening now needed.
process is done in real time, laying the
sound back onto the same edited reel of WHAT AN ACT GETS OUT OF DOING
videotape that was used to make the 4- THE SHOW
track dub. So the finished videotape has
You won't make a pile of money from
second generation video and third genera- an appearance on The Midnight Special.
tion audio. Still, the audio sounds excellent. Just like The Tonight Show and other
What amazed us is that the whole shows, the pay is scale. But the exposure
sweetening process (exclusive of the 4- is something else. The sets are usually
track transfer time) is usually completed stark, with black backgrounds and the
in between 2 and 4 hours! It is this type performer's name in 5' -high illuminated
of efficiency that make it possible for the letters. Neilson ratings indicate there are
90-minute color program to be produced a lot of people watching, and the many
for a budget well below the average 12" gold records on Stan's wall support the
value of an appearance on the show. When
LP album.
a very successful group feels the exposure
PROBLEMS AND SOLUTIONS
is superfluous, Stan persuasively argues
The process of taping four or five acts that they owe it to the people who made
them famous to appear. Yet there is no
arrogance around The Midnight Special
*Actually, the breaks are simply blank office. They bend over backwards to
audio and black video on the master tape. satisfy the performer, and a friendly
The advertising and station identification atmosphere surrounds the whole producare inserted at air time.
tion. This is reflected by the hosting
MIDNIGHT SPECIAL
format of the show, which helps bring out
the personalities of the people in front
of the cameras.
THE MAN BEHIND THE SHOW
As a child in his native Canada, Stan
Harris was fascinated by a relatively new
medium
television. Stan played several
musical instruments, and enjoyed all of
them. But as he matured, he realized that
it would be difficult to attain excellence
as a performer because his interests were
so diverse. So he resolved to become a
director, and when he got out of school,
he went right into Canadian television. He
was producer and director of The Cross
Canada Hit Parade. When rock and roll
caught on, in the mid- 1950's, his show
successfully bridged the transition. Apparently there was a certain open- mindedness and flexibility that the show's U.S.
counterpart, The Lucky Strike Hit Parade,
just didn't have.
-
producer /director
STAN HARRIS
Stan has since been involved in man,
areas of television production. He worked
for a while in England, doing heavy drama.
He also lived in New York prior to
settling in Los Angeles. He has been associated with The Bob Hope Show and
The Jack Benny Show, and more recently,
with The Smothers Brothers Show. The
Smothers Brothers had a musical act,
usually rock, once a week.
Now, with the success of The Midnight
Special, Stan has been characterized as a
musical show director /producer. He halfheartedly objects, but he admits that with
The Midnight Special, he is really more in
the music business than in television.
Music trades, not TV trades, are sent to
his office, and Stan likes to listen to
music. He was with his stage manager one
day when Stan remarked, "Isn't this
great. Here we are getting paid to sit and
listen to music we love." Stan added, "It's
very nice to be in that situation."
Re/p 29
www.americanradiohistory.com
LETTERS
...
&
LATE NEWS
Continued from page 13
am not surprised that LRS was able
to test cut Innervisions acceptably. Inner visions was the first album ever cut at
Kendun Recorders and as stated in our
article we have since cut it in the same
fashion with more level and better
I
geometry.
Steve (Guy) has taken a number of
points out of context to deal with, so let
me address them in order. In regard to
cutting power, he states that no more
power is attainable. I can only refer him
to Mr. Allen above who tells us at least
35 more watts can be achieved if LRS
would care to update their SX -68 cutter head to the state of the art SX -74.
Steve more fully explains my statement
concerning six quarters storage duration
in the computer, however it appears he
agrees with me and contradicts himself.
Regarding Steve's sentence on power
requirements to cut various tones, he
echos all our sentiments "If only it were
true," and his explanation is correct.
The quality advantage of using virgin
vinyl over Styrene has been lessened
somewhat by today's use of extenders.
How Steve translated that to mean plants
were changing to Styrene escapes me. The
plants that use Styrene have been doing
so for some time. The producer should
also be aware of the shortcomings in
quality due to injection molding done at
some plants as opposed to compression
molding.
Steve then states that "centrifugal
force has nothing to do with the matter"
as I speak about playback tracking error.
It is a shame so many turntable manufacturers have wasted all their time coming
up with systems to eliminate tracking
error unnecessarily (according to Mr. Guy).
The point I was making however, is that
it is more desirable to cut records to end
at a larger diameter so that you avoid distortion which is caused by these various
problems. The point is not to get in there
at all.
We are then supplied with a brief discussion of the reasons why inner groove
distortion occurs. All of these are valid
and the reader can find more detailed
die
ELECTRONICS
THE CONSOLE COMPANY
Los Angeles (213) 349 -4747
(213) 845 -9661
Nashville (615) 794 -0155
information in several of the issues of the
Journal of The Audio Engineering Society.
It is interesting to note that virtually
each person who wrote taking issue with
my opinions said they felt education in
the disc mastering field was long overdue.
I get just a little tired of these Monday
morning quarterbacks sitting back and
firing off their petty little rhubarbs at
someone trying to initiate just what they
complain is missing.
As regards Dolby, Steve is lost. He tells
us that A -type Dolby displays in record a
slight rise at the ends of the audio
spectrum, and this is cancelled by a
reciprocal droop in playback. This is
absolutely false. In fact, after properly
doing a set of tones which should be done
with the Dolby in function but NR Out
(never in check tape) when the NR is put
in level will actually drop aboutV2dB (not
rise) and a reciprocal rise in playback will
exhibit itself.
Additionally, this level change is broadband and not at the ends of the spectrum.
The largest error generally encountered in
the mastering studio is when a studio will
record at elevated level, say +3, and you
will find the Dolby tone and the 0 level
tone at the same level. This shows that
the Dolby and machine were not properly
interfaced. If it had been done correctly,
the Dolby tone would be at 185
nanowebers and the frequency run would
be 3dB above that.
Steve's description of droop in playback at the ends of the spectrum suggest
errors in termination in his chain and he
should investigate and correct this problem
as it is the most common error by
Dolby users.
Steve then brings up the ratio of noise
reduction. The Burwen system is a 3 to 1
system and the DBX is a 2 to 1 system.
The Dolby is a 1 to 1 system from levels
-20 to 0 but a 2 to 1 system below -30,
acting essentially as a DBX below that
level. Also, frequency response errors
show up most at these levels due to the
2 to 1 situation.
ED:
Additional letters supporting the substantive points Mr. Guy projects (and which
Mr. Duncan answers) were also received from
other members of the Los Angeles disc
cutting community; namely Glen Glancy and
Bruce Leek of UNITED SOUND, Bob Mac
Leod of ARTISAN SOUND RECORDERS
and Douglas Sax of THE MASTERING LAB.
From:
BOB BERKOVITZ
HEAD OF ADVERTISING
AND INFORMATION
DOLBY LABORATORIES INC.
NEW YORK, NEW YORK
We found Kent Duncan's discussion of
Dolby unit alignment obviously wellintended, but we were unable to understand most of it. What came through
clearly, however, was the incorrect statement that Dolby noise reduction units
Circle No. 115
www.americanradiohistory.com
typically have significant frequency response errors. By allowing this mistaken
idea to go into print, RE /P has done a
grave disservice to its readers and to our
company.
Our overall
that is, the full encode/
decode process factory specification for
all units is ± 1dB, and it is comfortably
met by all of our equipment. I have just
looked at the records of a number of
units, taken at random from our files,
and all fall within +0.15, -0.45dB. As Mr.
Duncan correctly points out, there are no
adjustments which could affect response.
Every check we have made of field
stability indicates that our equipment is
at least as reliable as anything else in the
recordlreplay electronics chain of a studio.
We must therefore view the simultaneous
response errors ofall eight of Mr. Duncan's
units as a surprising and unique coincidence
or an error in his technique or
understanding.
As to the "suspicions" and "theories"
which Mr. Duncan claims to have confirmed in communication with our corn pany, they cannot possibly be correct if
they have led to the misunderstandings
expressed in his interview. There is no
Dolby system action at or near NAB
level, so that the circuit, even in the case
of a single unit (say) in the record mode,
is essentially bypassed at NAB level, and
is therefore extremely unlikely to introduce a response error. Any slight variation
which might occur, which would in any
case be less than 0.5dB, would be cancelled
in normal usage by the complementary
action of the unit in the play mode
following.
We have, at times, explained to engineers that an error of as much as 2dB in
alignment is unlikely to produce noticeable changes on most program material,
and it is possible that Mr. Duncan has
misunderstood this statement in some
way, and expanded upon his misunderstanding. Users of Dolby equipment will
know, of course, that the most important
statement in Mr. Duncan's interview is
that "there really is no substitute for a
flat machine and a flat tape." The best
way to use Dolby equipment is to align it
according to the instructions supplied
with it, switch it on, and forget about it.
-
-
KENT DUNCAN'S REPLY
TO MR. BERKOVITZ:
The purpose of contributing to periodicals such as REP is to further the education of the people involved. Of the people
who did not agree with our points of
view, only Dolby came to us directly and
said let's find out what is what and get it
right. I was extremely impressed by the
fact that Mr. Steve Katz of Dolby Labs
visited our studio to follow up on our
interview.
It is true however that Dolby has
allowed, by poor directions, the misuse of
their product. The "silence" card of
alignment instructions is complicated and
hard to understand. Indeed, it is a rare
engineer who professes understanding of
it. None of their literature has ever mentioned the droop in record level when NR
is put in and the compensating boost in
playback although this is uniform in all
units. This has complicated the comprehension of the operation of the unit.
Additionally, although elevated level recording has been with us for at least two
years, I dare say few studios properly align
for elevated level with Dolby.
In all of this, Dolby has remained aloof
personified by Mr. Berkovitz's statement
of "switch it on and forget it."
What Dolby needs is a clear, concise
printed procedure of alignment for all
studio personnel such as accompanies their
test unit for CAT 22 cards, taking into
account all the varieties of tapes and
level in today's recording (and possibly
some more level marks on the Dolby
meter).
Basically, Dolby relies on the fact that
cancellation of most error occurs when
replaying the stretched material through
the channel used in recording. This ignores
all situations where a different Dolby is
used for decoding such as where a tape is
mixed at a different studio, tapes used
for disc cutting, copies sent to other
countries, or those sent to cassette and
cartridge manufacturers for production. I
would venture to say that it is more often
than not that a Dolby signal is decoded
through a channel other than the one used
to encode that signal and this is when
error in frequency response (or alignment)
can be additive.
It is interesting to note that this
"technical" response is written by the
Head of Advertising for Dolby (ED: Mr.
Berkovitz is Head of Advertising and
Information.) and not the engineering
department. That fact and the outrageous
suggestion that an error of 2dB in alignment is not noticeable is indicative of the
aloofness of Dolby Labs. Such a suggestion
to a professional engineer is so appalling I
will simply not grace it with a comment.
It is such a pleasant change to be confronted with a Dolby representative who
THE.
MÓT-ACCURATE
PROFESSIONAL
ÌN°TÑE>WORLD!
FRAP
,,., 1410004( aB710..
R
GUITAR, PIANO
ANY ACOUSTIC
"
BASS
.
.
RUMENT.
FORMATION WRITE OR CALL:
FRA
FLAT RESPONSE AUDIO PICKUP
Box 40097. San Francisco 94140
interested and in touch (Mr. Katz), that
can only say to Dolby a logical move
would be to open an L.A. office to be
more accessible.
A truly brilliant discussion of noise reduction systems (Dolby, DBX, Burwen)
appears in the Feb /Mar '74 issue of
Studio Sound Magazine where not only
bench tests, but field tests of the units
were made by Aengus McKenzie and I
WESTLAKE BOWS NAS
Due to increased dem.
sultation and design service.
ville area, Westlake Audio aro
opening of a Nashville offic,
15, 1974.
The office will be headed by )
recommend that
on the subject.
headquarters.
Construction of the new permanent
quarters is now underway. Offices will be
temporarily located at 3250 Dickerson
Rd.,Suite 206, telephone (615)228 -1353.
is
I
From:
as
further information
MICHAEL EDSON
RECORDING DEPT.
SUPERVISOR
CAPITOL RECORDS, INC.
HOLLYWOOD, CA
. . . Due to the thorough manner in
which Mr. Guy and Mr. Allan have corrected the technical mis-statements propounded in the interview, we will add
little more to the technical aspects of
reply other than to correct the illconcealed inference that the majors adhere
to out-dated cutting parameters and employ engineers who "when they get a tape
that's hard to cut, they'll make it easy to
cut, either by taking the level down or
making it mono, etc., etc. " In answer to
the above, we must comment that our
studios also employ the Neumann VG66S cutting system, the TS66 tracing
simulator and the VMS -66 Lathe, and we
were among the first group of studios on
the West Coast to convert to the SX -74
head. Twice each day, we make sweep frequency measurements, (recorded on a
GR graph- recorder) of the entire cutting
channel and check the condition of the
cutting stylus by means of a high -power
shadowgraph examination of a wax impression of the groove cut on a lacquer.
Needless to say we hold to very tight
tolerances.
On behalf of our engineers we must
comment that the derogatory remarks
made are completely unfounded and in
bad taste. Our policy is always to use
whatever equipment and techniques are
necessary to make the best record possible, and to transfer to disc the artistic
result that the artists and producers have
worked so hard to create. We are sure that
this expresses the feelings of the other
major labels and the many fine disc cutting studios throughout the country.
We master our fair share of certified
gold records at Capitol. These are not all
Capitol records and many are mastered
here because of producer preference. We
do an excellent job on many more that
don't gain fame for other reasons. Our
engineers take pride in the quality of the
work they perform and for someone to
say that belonging to a union prevents
excellence in cutting is the height of
absurdity.
(415) 124.2223
Gardner, formerly chief engineer of L .sville Sound Studios in New York and
currently with Westlake's Los Angeles
ELECTRONIC MUSIC WORKSHOP SET
FOR NOVEMBER 11 -22, 1974.
As announced by BEEP (Boston Experimental Electromusic Project) this non mathematical, non -academic approach to
Electronic Music is designed to give producers, performers, composers and technicians the opportunity to learn about
and gain practical experience with electronic music.
Fee for the workshop is $75.00.
Complete information may be obtained
from: Mr. Robert Creely, BEEP, 33 Elm
Street, Brookline, MA 02146.
IRBY JOINS STUDIO SUPPLY
Tom Irby has joined the "professionals"
at Studio Supply Company, Nashville,
Tennessee. The announcement was made
by Dave Harrison, Studio Supplys' President, and Claude Hill, Vice President,
Sales.
Tom, a native of Paris, Tennessee,
brings to Studio Supply additional experience in the field of magnetic recording gained at 3 -M Company's Mincom
Division and Pertec, a prime digital recorder firm in Chatsworth, California.
Tom has a B.S.E.E. degree from the
University of California at Santa Barbara.
Tom's responsibilities at Studio Supply
include systems design, acoustical consultation, and sales.
ALTEC LOUDSPEAKER ENCLOSURE
DESIGN MANUAL NOW AVAILABLE
Altec Corp., Sound Products Division,
has produced a fully illustrated 32 -page
publication entitled "Loudspeaker Enclosures Their Design and Use."
Priced at $2.00, the publication was
created to provide an easy to digest source
of data for use in designing and constructing enclosures of predictable and
-
satisfactory performance when used with
Altec's quality loudspeakers.
The publication covers the entire gamut
of building enclosures, with topics including the function of the enclosure,
loudspeaker design theory, the various
types of enclosures from infinite baffle
and bass reflex enclosures
to tuning
the bass reflex port.
-
-
... Continued on page 68
Circle No. 116
Re/p 31
www.americanradiohistory.com
PROFESSIONAL
AUDIO
EQUIPMENT
STUDER, a standard of excellence.
From initial design to final checkout Studer
Audio equipment
is
subjected to rigorous
quality demands that insure continuing "Swiss"
performance.
For information on our tape mastering
equipment (from one to twenty -four track),
condenser microphones and quadraphonic
consoles, contact WILLI STUDER AMERICA
INC., 3916 Broadway, Buffalo, N.Y. 14227
phone 716 681 -5450. (In Canada: WILLI
STUDER CANADA LTD. 416 423 -2831)
-
AMERICA
Circle No.
117
Re/a 32
www.americanradiohistory.com
EQUALIZER PERFORMANCE
REVISITED
BY
BOB EASTON
360 SYSTEMS
There is a great deal of mysticism in many peoples' minds
regarding "phase shift" and "ringing" in equalizers and filters.
Mysterious differences in sound quality are blamed on these
phenomena. Mixers are understandably sensitive to variations
in the performance of these devices, and with good reason;
most tracks will be digested within their circuits at least once
during the production of a tune. A brief what's -what of filter/
equalizer theory follows, as food for thought during discussion
of several different design approaches for these devices. Consideration of these more theoretical elements produces some
interesting conclusions about why certain designs have become
favorites, while others hide on the back shelf and gather
expletives . . .
Provided that an equalizer is operated below its clipping
point, its performance can be described very well by linear
system theory. Two results of this theory are of particular
interest to the inquisitive individual:
1. Given the response of an equalizer to a step input, (a
very low frequency square wave will do) it is possible to find
the amplitude and phase response with great accuracy. Conversely, knowledge of amplitude and phase responses describes
behavior to step inputs. And the amount of ringing caused by
an equalizer is directly implied by its frequency response and
phase shift.
2. Practically every filter or equalizer encountered in
studio situations belongs to a broad class called minimum
phase networks. Conveniently, the frequency response of these
devices uniquely specifies the phase shift present, and vice- versa.
From principles (1) and (2) we can conclude that for
1.
Part
I
appeared in Vol.
2. On Aural Phase
5
I
I
BOB ORBAN
ORBAN /PARASOUND
practical filters and equalizers used in studio sound, both the
phase shift and ringing (transient response) can be deduced
entirely from the frequency response of the device. We find
that equalizers using inductors are more likely to ring due to
stray capacitance within the windings, than is the case with
those constructed entirely of resistors, capacitors, and opamps.
Stray inductances in the latter tend to be inconsequential. "So
what ?" we may say
well (1) and (2) above indicate that
ringing will also manifest itself as glitches in the frequency
response of the device. Differences in sound quality are far
more likely to be caused by irregularities in frequency response
(to which the ear is extremely sensitive) than to small differences in phase or transient response.
Then what effect does phase shift have on program material?
Much fear and trepidation may be relieved by listening through
a phase shifter that has been carefully verified to have flat
frequency response throughout the audible spectrum. (Not a
phase -cancellation device as used for special effects). For most
material it is impossible to tell whether the phase shifter is in
or out. The findings of footnote (2) may assuage the fears of
readers interested in the minutae of subjective phase shift
experimentation. Very large amounts of phase shift resulting
in time delays (greater than 2 milliseconds has been suggested)
produces distinctly audible timbral changes, as will phase shift
so rapid that appreciable shifts occur within a single 1/3
octave "critical band." It seems that very rapid phase changes
are associated with ringing once again, and are visible as sharp
peaks and dips in the frequency response of any equalizer
exhibiting such behavior. Since such resonances are very
...
No. 2 of R-e /p: The Equalizer, Audio Superstar by Jerry Milam of Milam Audio, Inc.
Detection, by Villy Hansen and Erik Rorbaek Madsen, J.A.E.S. vol. 22 p. 10.
Re/p 33
www.americanradiohistory.com
noticeable in their own right, once again the case for placing
blame purely on phase shift disappears.
FILTERS & EQUALIZERS
One of the primary differences between filters and equalizers in the practical sense is the complexity of the networks
involved. Filters are often called on to pass one portion of the
audio spectrum, while sharply rejecting another band. This requires a network of a fairly high order. For practical purposes,
the order of a network is equal to the number of inductors and
capacitors in use at one time, excluding coupling capacitors
and the like. As the order of a network increases, it becomes
more touchy to design. It can ring at many different frequencies simultaneously
. which most sharp cutoff filters do.
Figure 1 illustrates two filters having the same cutoff frequency.
.
.
O,Lwf504ar
voi"Fityre lA
Elliptic Function
1
Ktf'
Low ?ass Finer
Response curve made with five random -selected MD 421 microphones.
ALL
5 OF THEM!
UNUSUAL? Not for Sennheiser.
The fact that the response curves of the five microphones
are almost identical is commonplace for our engineers. And
the individually- plotted curve we provide with each unit will
confirm the fact. For besides the rigorous check of a response
curve, each and every Sennheiser professional microphone
undergoes numerous other inspections, to insure its absolute
acoustical, electrical and mechanical integrity.
Perhaps this uniformity and unusual performance influenced
the major recording companies in choosing Sennheiser microphones for both field and studio use (and made ours the
'standard' microphones of the continent).
You may think this kind of quality control is unusual for a
production instrument. However, we are very particular about
the kind of equipment bearing our name. Shouldn't this kind
of 'insured performance' be built into your audio facilities,
or those you install?
For further details, including full technical
specifications, and a list of microphone accessories available for the MD 421, please
v
FiuY 1rj
,utterworih function 110,
Low Pass Fitter
Filter A is very effective in supressing outband signals, and
rings like crazy. It is often relegated to use in digital audio
delay systems and similar chores where steep slopes are
essential. Filter B doesn't ring excessively, but doesn't cut off
as sharply either. It has been accepted as the lesser of evils for
oscillator
AC
vrvK
write or call.
evice
SENKHEISER
ELECTRONIC CORPORATION
o
o
0
10 West 37th Street, New York, N.Y. 10018 (212) 239 -0190
Manufacturing Plant: Bissendorf, Hannover, West Germany
Re/p 34
under test
Circle No. 118
www.americanradiohistory.com
0
fire
0
Z
The usual -frequency response Teal Set
majority of audio filtering chores, because it has little coloration effect on sound and modest stopband rejection.
Practically all equalizer designs are based on second order
networks, which are the simplest networks that can provide
peaking and dipping functions. ( "Tone" controls are essentially
first order, with shelving characteristics and a slope not exceeding 6dB /octave.) Figure 2 shows the standard technique for
a
measuring the frequency response of anything. Tests performed
by either this method or that outlined in paragraph 1 should
show no added dips in a peaking type equalizer, and no
added peaks in a dipping equalizer. If these problems show up
when only one band is used, it often implies that it has been
sloppily designed or manufactured; stray capacitances are
getting into the act and the order of the network has been
unintentionally raised.
Modular
Audio Products
VARIABLE
PARAMETER
GRAPHIC EQUALIZERS
A graphic equalizer is designed to provide peaking and
dipping equalization at roughly equal increments of bandwidth throughout the frequency spectrum. In contrast to conventional equalizers, all of the frequencies are available simultaneously. Each frequency is generally assigned its own slider
control; the sliders are placed side -by -side, going from low to
high. Thus the mechanical position of the sliders provides a
graphic approximation of the frequency response of the
equalizer. Commercially available graphics range from two octave wide controls (like the BSR Metrotech) to 1/3 octave
wide controls (UREI, Altec, DuKane, Dolby, etc.). The 1/3octave graphics vary widely in design (some can dip only) and
are designed principally for "tuning" sound reinforcement and
monitor installations for ideal response.
The frequencies offered in graphics for studio work are
generally spaced at octave intervals, which is a manageable
design if equalization is to be done by ear rather than with
instruments. The fact that the center frequencies are spaced at
octave intervals does ndt necessarily mean that the filter
characteristics maintain octave bandwidths as the amount of
peak or dip is varied. Bandwidth versus peak /dip characteristics are responsible for the variation in subjective qualities of
different graphics. (Figure 3)
EQUALIZER
Continuously variable center frequency-three indepen-
dent, overlapping ranges;
50Hz to 500Hz, 300Hz to
3KHz and 1.5KHz to 15KHz.
Continuously variable
bandwidth
-
5il{Q 5{I
High output capability
--
-
up to +27 dBm into 600!2,
TYP THD .05 %.
-
Low noise
- 85dBm unweighted 20Hz to 20KHz.
IN
-7db
mutuai a ice
Bandwidth
f
-
Equalization in -out switch
with remote D.C. control and
LED indicator
standard 5
volt logic levels.
EQ
Tjandwidfh Vs.
variable from
Discretely variable boost
twelve steps from
-12dB to +15dB.
and cut
1.11.0
Fore 5
-
6dB /octave to 15dB /octave.
/
Frequency
/
Level
zf
ißñ#tyip Yleponse
In addition, one band can interact with its adjacent neighbor
in unpleasant ways, perhaps causing unexpected dips in the
response. Graphics that are constructed along the lines of
Figure 4 are particularly prone to this problem; in fact, it is an
unavoidable weakness of this sort of design. In addition, it is
difficult to adjust this sort of design for truly flat response,
unless the bandpass filters are designed in an unusual way.
There have been several construction projects for this type of
graphic; their subjective performance has left us somewhat
underwhelmed. This type of construction does have one virtue
that we can think of: as the amount of EQ is increased, the
"Q" (sharpness of the peak) does not increase, so one can use
large amounts of equalization freely without increasing ringing.
The circuit in Figure 5 is a considerable improvement over
Figure 4, and is the basis of a number of commercial graphics.
Modular Audio Products is an engineering
oriented company providing a complete line
of console and studio components. In addition to supplying the finest quality products,
we also provide the technical and application
backup to go with them.
Call or write us today for
information on this and other
state -of- the -art units.
raw MOCILJLAR
AUOIO PROOUCTEi, Inc.
A UNIT OF
MODULAR DEVICES, INC.
1385 Lakeland Ave. Airport International Plaza
Bohemia, New York 11716 516 -567 -9620
Circle No. 119
www.americanradiohistory.com
Re/p 35
It uses both inductance and capacitance as well as an opamp.
Unlike Figure 4, the equalization curves are reciprocal: the
boost curve for any frequency will be a mirror image of the
dip curve. This allows one to precisely "undo" any equalization
that might have been performed earlier with the same equal-
We
'KC
are
proud to
present
Foire4
17,Ç
Tuned Graphic
oPAmç
Td
une
randya55
Filters
_
o
_ _ _
EQ
controls
Equalijers
%lire 5
Lc Tweed
izer. For example, at mixdown the producer might have
second thoughts about EQ built into the original multitrack
tape during the session. An important feature of the design of
Figure 5 is that when all EQ controls are centered, the response
is perfectly flat, with no phase shift, since the circuit is
minimum -phase. This type of graphic is highly useful in
practice, permitting the mixer to approximate a large variety
of equalization curves in a very straightforward manner. This
circuit does have several pitfalls however. The "Q" varies
greatly as the amount of equalization is changed; large amounts
of boost will produce a very colored ringy sound that may be
highly objectionable with many kinds of musical material.
Also, the various bands will interact, and this may result in
phase cancellation problems between adjacent bands . . .
particularly when the amount of equalization is increased.
PROKIT II
FEATURING
SLIDE FADERS
PAN POTS ON ALL SIX INPUTS
LED OVERLOAD INDICATORS
SIX INPUTS (LINE OR MIKE)
STEREO OUTPUT
PROFESSIONAL
Graphic Equali cr
2Y " VU METERS
20 DB MIKE INPUT PAD
STATE OF ART IC CIRCUITRY
OPTIONAL 48V MIKE POWERING
OPTIONAL TRANSFORMER OUTPUTS
HIGHEST QUALITY COMPONENTS
AVAILABLE KIT OR FACTORY WIRED
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ELECTRONICS, Inc.
57 West Hillcrest Ave.
Havertown, Penna. 19083
215- 449 -6400
1907 Division St.
Nashville, Tenn. 37203
615- 327 -1746
AND NOW, THE PARAMETRIC
Unlike the graphic, which has a long history in the movie
industry, the parametric equalizer is a development of the
past few years. (The impetus for its design as a studio product
may well stem from the Moog No. 904 and the ARP No. 1047,
long used in synthesizers.) As used in the professional audio
industry, the term parametric has come to mean an equalizer
whose three basic parameters, frequency, bandwidth, and
amount of boost or dip, are independently adjustable by
means of three non -interacting controls. In most designs these
controls are continuously adjustable; however, units for
mastering facilities have been provided with step switches for
repeatability and unit -to -unit tracking.
Figure 6 illustrates the action of the controls:
Circle No. 120
Re/p 36
www.americanradiohistory.com
In Figure 6a the frequency control is adjusted. The shape
of the curve remains the same, and is moved along the
frequency scale. Figure 6b shows the effect of the bandwidth
control. Note that this is not the same as a "Q" control. If the
"Q" were adjusted, the gain at the response peak would
change. The bandwidth control leaves the gain at the response
peak the same, regardless of its setting. Gain at the response
peak is adjusted by an equalization control, as in a conventional equalizer. Figure 6c illustrates this parameter. The
equalization control does not necessarily produce reciprocal
peak and dip curves, but reciprocal curves can be generated by
readjustment of the bandwidth control as necessary.
Frequency
A. Frequency Control
3
F6trt 6
ÿardwidth Control
C, -
9tpip
Control
Pdrnmeiric Ecjualí3er Turk-tons
Parametrics often provide many advantages over other
forms of equalizers. Very broad bandwidths results in equalization totally without ringing useful for making broadband
response corrections, such as an overall boost of the high end
of a track. In contrast, a graphic requires the use of several
high frequency controls to perform the same task. And, since
the bandwidth of a graphic's controls are narrower, there is a
strong tendancy for ringing to be produced. Control interaction
of the graphic may result in frequency response irregularities,
which the wideband- adjusted parametric does not exhibit.
-
Because there is no standard terminology in the field, a
parametric equalizer may take a wide variety of forms. Some
units are manually operated, while others may permit voltage
control of one or more parameters. And sometimes the variable
bandwidth provision is eliminated, or a choice of two bandwidths only is provided. Continuous tuning of the center
frequency may be the only "parametric" feature offered.
Some equalizers offer both peak /dip and shelving, while
others may be limited to 12 dB or so.
Typical parametrics offer three or four frequency bands,
each with continuously adjustable parameters. Because the
number of bands is small compared with a graphic, it is possible
to wire the bands in series
eliminating the possibility of
interaction. Parametrics also open some new doors: Narrow band equalization can give "effects" EQ, such as telephone
simulations, "old time" recordings, etc. Sweeping the center
frequency of a narrowband peak produces useful phasing-like
effects. And narrowband dip can remove hum or fixedfrequency interference with almost no audible effect on the
program material. Some parametrics even provide "infinite depth" dips for this purpose, while others may be limited to
-
12dB or so.
The only potential problem with parametrics is the requirement for familiarization caused by an "embarassment of
riches" in the control department. Experience has shown that
familiarization is quite painless, and that experienced parametric users are completely flummoxed when forced to go
back to less versatile equalizers.
It's often said that the quality of a sound is the measure of
a technical products' worth. Well, equalizers can't be bought
on that basis from data sheets; but clearly, some have musical
abilities that others don't possess. Evaluation of the versatility
and truthfulness of claimed specifications, together with some
study of a device's abnormalities, can reveal a lot about the
musical worth of an equalizer's design.
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Re/p 37
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Re/p 40
www.americanradiohistory.com
MUNDANE APPLICATIONS OF THE FLUX LOOP
BY PETER BUTT
SUPERSCOPE TAPE DUPLICATING
The flux loop is a much ignored piece
of inexpensive hardware that can shed
considerable light on the behaviour of a
magnetic reproduction system. I'll have
to admit that I've been one of those ignoring it until recently. Although aware of
the applications of the device in connection with analog and digital data recorders
and reproducers for some time, I just
never felt the need to actually go through
the process of constructing one and calibrating it for use. Since that need has
finally captured me, I thought some of
my fellows might be interested in its possibilities as well as some of the limitations.
A flux loop is, most simply, a coil of
wire through which an alternating current
is passed for the purpose of inducing the
resulting magnetic field into a magnetic
reproducing head and its succeeding amplification system. The general idea behind
doing this is to gain some sort of insight
into the behavior of the reproducing
system exclusive of the mechanical factors
of tape -to -head contact, tracking, wow
and flutter, azimuth, or fringing.' The
elimination of these influences permits a
more accurate appraisal of the purely
electrical behavior of the play -back system.
By inducing a test signal directly into
the reproducing head, the entire recording
mechanism is eliminated as a source of
uncertainty obscuring the precise behavior
of the reproduction system. Distortion,
transient response, output polarity, phase
shift and dynamic range are all factors
that can be evaluated with precision
unrealizable if the record process is relied
upon as the mechanism of excitation. It
is granted that many of these applications
are of greater interest to the research and
development oriented. The power of the
technique, relative ease and low cost of
the device make it attractive for routine
use in multi -track reproduce systems alignment and analysis, even if the more esoteric users are of no immediate interest.
My recollections of using the device
were awakened while listening to a paper
on the subject presented by Alistair M.
Hazelitt at the 45th Audio Engineering
Society Convention in Los Angeles.2 More
recently, the problem of verifying playback system response in cassette and 8track cartridge players caused me to reinvestigate the merits of the flux loop
response evaluation technique because of
the uncertainty of alignments performed
using standard tapes loaded into cartridges
and cassettes. Experience with use of the
device in these areas caused me to investigate the applications it might have at the
higher speeds more typical of the industry.
La
The results of experimentation with
the flux loop with multi -track reproduction systems proved to be rather gratifying. For example, given a loop with a
sufficiently large coil, not only are the
frequency response characteristics of all
of the tracks covered by the field easily
checked against each other simultaneously
but phase shifts from track to track may
be compared using either a phase meter
or an oscilloscope Lissajous display. The
phase relationships of multi-track reproducer outputs is not only a factor in
simple stereo -mono compatibility, but
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Re/p 41
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Re/p 42
you to operate. Our new
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also can have serious effects on material
destined to be processed as a quadraphonic matrix.
Driving the flux loop with a pulse and
observing the play back circuit response
with an oscilloscope will give some indication of the transient response of the
system. Consider also the convenience of
being able to check response flatness by
merely sweeping an oscillator rather than
rewinding an alignment tape and patiently
waiting for it to play through again.
Consideration of the interactive nature
of reproducer equalization adjustment
controls will reveal the time advantage
gained when successive checks are necessary to optimal alignment. Further, a
given signal can be fed to the systems for
as long as desired without running out of
tone or tape.
Figure 1 shows an elementary schematic of a flux loop system. The series
resistors serve to act as current limiting
resistors so that the current through the
windings of the loop is directly proportional to generator output voltage. The
playback head is sensitive to magnetic
flux intercepting its gap which is, in turn,
proportional to the number of Ampere turns of the flux loop coil.
In the case of flux loops I have recently
built, the value of the resistors involved
has been invariably 604 Ohms, L1%. The
reason for choosing precision resistors is
CelibrEitinS
VofTmeier
Af Genertilor
--J
Huy loop
F6re
1
The flu,x lcop
in CeIibrofiíon
purely one of electrical stability. Precision
resistors are generally available at moderate cost and their non -inductive properties
tend to minimize unexpected frequencydependant behavior that could inject
unnecessary uncertainty into the circuit
performance. It is also felt that stability
over a long period of time is desirable
as well.
Test points are provided across R2 for
the purpose of measuring the voltage drop
across that resistor and thereby determining the current through that resistor and
through the flux coil itself. The reason for
this facility will become apparent later.
The capacitor, C, is not mandatory but
it makes routine application of the loop a
good deal easier than without. If the
capacitor is used, it will shunt a portion
and ApplícAtion
of the generator current output away
from the field coil itself, resulting in a
reduction in flux seen by the head as
frequency increases. If the value of C is
carefully chosen, the rate of field reduction with frequency can be made to
closely approximate the inverse of one of
the playback system response curves in
wide use.3
That takes care of the high- frequency
portion of the reproduce response curve.
The low- frequency boost necessary to
generate the inverse of the low -end boost
incorporated in the N.A.B. characteristics
used throughout the United States, is a
problem sufficiently awkward to solve in
practice, for the case of a physically compact, passive, low impedance network,
for me to have abandoned. The proper
TABLE 1
REPRODUCING AMPLIFIER RELATIVE OUTPUT FOR CONSTANT FLUX IN THE
CORE OF AN IDEAL REPRODUCING HEAD
FREQUENCY
Hz
32
40
50
63
100
125
250
400
500
1000
1500
2000
4000
5000
6000
8000
10000
15000
PHILLIPS SPEC.*
1 7/8 in /s
(4.76 cm /s)
OUTPUT dB
10.4
8.7
N.A.B.*
3% in /s
(9.53 cm /s)
OUTPUT dB
5.5
4.2
3.2
2.3
N.A.B.*
(15 in/s) (38.1 cm/s)
71/2 in/s
(19.05 cm/s)
OUTPUT dB
CCIR **
DIN STUDIO
7/ in /s
(19.05 cm /s)
OUTPUT dB
5.4
4.1
0
o
3.0
0
2.1
1.0
0
0
0.8
0.2
0.6
0
0.1
0
0
o
o
0
0.3
3.4
5.0
9.9
0.1
1.1
2.2
3.4
7.7
0.1
0.4
0.9
1.4
4.1
0.1
1.0
1.7
11.7
13.2
15.6
17.5
21.0
9.4
5.4
10.6
13.2
15.0
18.5
5.9
8.6
10.4
13.7
6.9
8.7
10.6
12.7
16.1
7.1
5.6
3.1
2.2
0.6
1.8
1.1
2.6
5.4
CCIR**
IEC
DIN
15 in /s
(38 cm /s)
OUTPUT dB
CCIR **
IEC
DIN
30 in /s
( 76cm /s)
OUTPUT dB
0
0
0
0
0
0
0
0
0
0
0
0.3
0.9
2.4
3.3
4.0
5.0
6.7
0.3
0.9
2.4
3.3
4.0
5.0
9.8
AMPEX**
30 in /s
(76 cm /s)
OUTPUT dB
0
0
0
0
0
0
0
0
0.1
6.7
9.8
0
0
0
0
0
0
0
0
0
0
0
0.2
1.0
1.4
1.8
2.6
3.2
4.9
*Data adapted from "Standards for Magnetic Tape Records" RIAA Bulletin E5, July 15, 1965, Rev. Feb. 7, 1969.
* *Data interpolated from "Absolute Flux and Frequency Response Characteristics in Magnetic Recording: Measurements,
Definitions, and Standardization" J.G.McKnight,J'our.of A.E.S. July 1967, Vol. 15, No. 3 pp 264, 265, 267.
Re/p 43
www.americanradiohistory.com
for each of the reproducer characteristics
widely used. Also given are the ideal
values of capacitor C that should yield
proper high- frequency characteristics for
each curve. The formula used to compute
response of a reproduce circuit excited by
a properly calibrated loop is very flat
above a 400Hz reference frequency. Keeping this in mind, it's not too hard to
remember that the output should drop
3dB at 50Hz for the N.A.B. 33%, 71/2, and
15 ips reproducer characteristics. The response should drop 7dB in the case of a
Philips Standard cassette characteristic.
Table 1 gives the relative reproducer
output in decibels for each of the curves
mentioned above.4 EIA and CCIR characteristics as well as the 30 ips Ampex
mastering curve have no roll-off in their
low frequency regions and are therefore
flat, ideally, to 0Hz.
Construction of a flux loop should
take a fairly short length of time for those
interested. The values of Figure 1 resistors
Rl and R2 were chosen as 604 Ohms
because the output impedance of the
signal source to be used to drive the loop
happened to be about 600 Ohms. The
extra 604 Ohm resistor, R1, was provided
as an after thought in the event the loop
was to be driven from a 50 Ohm source.
In the case of lower source impedances,
the effective value of the capacitor needs
to be somewhat higher than for the 600
Ohm generator case, causing some uncertainty in its deviation from the ideal
characteristic.
The flux coil itself is wound on a coil
form made from a piece of perf board
with two small notches filed into it. The
coil wire, number 36 enameled wire, is
wound in an oval path for about 30 or 40
turns. For the case of a loop wound large
enough to cover a two -inch head, this
represents a length of about 160 inches.
This worst -case situation adds about 34
Ohms5 to the value of R2. For smaller
coils, the contribution is less.
Table 2 shows standard values for the
time- constants and transition frequencies
C is
C =
where:
structor should plan the initial layout of
the circuit with the expectation that some
trimming of the value of the capacitor
will likely be necessary. He should also
provide a means of strain relief for the
connecting cable for the external signal
source. A five -to -ten foot length of a
R
C is in microFarads
t is the time -constant in
microseconds
R is taken as 600 Ohms
in this case.
Precise values of C will depend on the accuracy with which the resistances are
known and the resistance contribution of
the individual loop windings involved.
Empiricism is encouraged in this respect.
For best performance, the flux loop
coil should be wound on the perf board in
such a manner so as to be capable of being
placed in very close proximity to all
reproduce head gaps to be excited simultaneously. The coil should also be sufficiently wide and straight to ensure that
all of the tracks on the head of interest
will be included within the windings.
Potting the coil will enhance mechanical
stability.
The currents passing through the loop
will not be of enormous magnitude in
general application. The magnetic flux
field produced will necessarily be rather
weak and it will be advantageous to
obtain the closest coupling possible to the
prospective reproduce head to maximize
system output. The coil, then, should be
wound as close to the edge of the perf
board edge as practical without unduly
compromising mechanical stability or risking possible damage to the fragile windings
in routine use.
The remainder of the perf board will
serve as a foundation for the mounting of
the resistors and the capacitors. The con-
light, flexible co-axial cable such as RG174 will suffice in most cases. This completes most of the construction operations.
It may be attractive to the builder to
consider the inclusion of a switch for
selecting more than one capacitance value.
This will permit wider application of a
given assembly than if only one time constant were available.
The calibration process for a flux loop
is fairly straight foreward. The loop is
driven in the manner shown in Figure 1
with an AC voltmeter connected across
R2. A reference reading on the voltmeter
is taken at a frequency of 400Hz and
then the generator is set to the turnover
frequency, fh, from Table 2 for the
characteristic desired. The value of capacitor C is then trimmed to yield a voltmeter
reading 3dB below the 400Hz reference
reading.
For a frequency twice the transition
frequency, the voltmeter reading should
drop 6dB below the reference reading
and for four times that frequency, 12dB.
The response characteristic should be
checked at several points along the high
frequency end of the characteristic so that
its response will be determined to be
uniform and in sufficiently close agreement with the ideal to satisfy the needs
of the user. Agreement to within 1dB of
specification has proved to be adequate
for requirements that I have had.
Circuit constants having tolerances of
-I5% or worse are fairly common in reproducer equalization circuits generally
in use. I find that my confidence in the
TABLE 2
SPEED
TRANSITION
EQUIVALENT
FREQUENCIES (Hz)
TIME CONSTANTS (µ sec)
TI
Th
CO
18
(AMPEX)
CO
35
(CCI R)
3,150
4,500
3,180
50
(NAB)
CO
35
(CCI R)
3,150
3,150
2,240
3,180
50
50
70
(NAB)
(EIA)
(CCI R)
0.0833
0.0833
0.166
3,180
50
1,250
1,600
1,800
3,180
120
100
90
(EIA)
(EIA)
(NAB)
0.200
0.166
0.150
50
100
800
1,250
3,180
1,590
200
120
(AMPEX)
(DIN)
0.333
0.200
cm /s
in /s
F1
Fh
76
30
0
9,000
4,500
0
38
50
15
0
19
7.5
50
0
0
9.5
3.75
50
0
4.76
1.87
Data derived from
"Flux
J. G.
VALUE OF "C"
= 6002)
(For R2
m
(11F)
0.0300
0.0583
0.0833
0.0583
and Frequency Measurements and Standardization in Magnetic Recording"
McKnight, Journal of the SMPTE, Vol. 78, p. 464
Re/p 44
www.americanradiohistory.com
end results of work performed varies
directly with the stability and accuracy
to the measurement tools used. This is the
reason for taking some care in establishing the accuracy of the flux loop inverse
characteristic to a precision limited by
voltmeter accuracy and generator output
frequency.
Comparison of measured response of
the loop as indicated by the voltage drop
across R2 with the appropriate data given
in Table 1 should yield adequate confidence in the conformance of the loop
network response against the standard.
In application, the flux loop assembly
is positioned in such a manner that the
field coil rests against the reproduce head,
the axis of the track gaps being wholly
within the coil winding to maximize the
field intercepted by the reproduce gaps.
The positioning is most easily accomplished while the loop is being driven with
a 1 to 10 volt rms input at about a 1kHz
frequency. The best position is that which
corresponds to maximum output from all
tracks of interest. The entire assembly
may be held in a stable geometry through
use of a rubber band or two.
The performance of this arrangement
is not terribly sensitive to separation but
a quick sweep to 15kHz will serve to confirm that the magnetic coupling is adequate over the band of interest. Generally,
a level indication of -5 to -15dB will be
observed at the reproducer outputs. Individual channel gains may now be adjusted
to a convenient reference indication and
readings noted with respect to frequency.
Playback response may now be adjusted
for optimal flatness over the frequency
range above 400Hz.
The low end roll-off incorporated in
N.A.B. standard reproducers will, as mentioned earlier, not respond in a flat manner due to the lack of provision for low end boost in the flux loop network. The
observed response at the reproducer outputs should ideally follow the characteristics shown in Table 1. The flux through
the head will be uniform with frequency
below 400Hz, and therefore the roll-off
will be directly observable. If the reproducers were excited by a flux loop not
compensated by inclusion of capacitor C,
the output observed, for a correctly
aligned reproducer would agree closely
with the positive and negative decibel
values given. This is because the tabulations are based on a constant short -circuit
flux induced in an ideal reproducing head.
This description fairly well covers the
routine playback response adjustment using the flux loop. J.G. McKnight reports
that frequency response measurements
performed using a flux loop agree closely
with measurements obtained using variable
speed techniques.7 He reports agreement
between constant flux injection, constant
flux plus inverse network, and the variable
speed method, to be within '/adB, his limit
of experimental error. He concludes that
the over -all response of an Ampex 351
reproducer using a commercial head is
flat to within '/ dB to 15kHz, dropping to
11/2dB at 20kHz. That, as the saying goes,
ought to be good enough for government
work.
All of the foregoing neglects the variations in reproducer output response when
magnetic tape is used as the source of
excitation flux. McKnight, in the same
publication, concludes that significant
losses in the magnetic tape case were
almost entirely due to wavelength effects.8
Since it is my expectation and hope that
reproduce heads "have improved somewhat
since circa 1960, I feel reasonably secure
in reliance upon the flux loop technique
for calibration of reproducer response
characteristics.
Empirical verification of the response
of a given reproducer using a 71/2 ips
N.A.B. alignment tape and a flux loop
shows agreement between methods within
2dB, above 250Hz. Fringing effects distort
the data below that frequency. This correlation is shown in Figure 2. I think it is
fair to mention that the alignment tape
in question had seen several weeks of daily
use at the time of the comparison and
could conceivably have lost some of its
accuracy at the shorter wavelengths. Even
a carefully handled alignment tape will
have a loss of from 0.5 to 2dB at 0.5 mil
wavelength after 50 playings and about
3.5dB loss after about 100 playings.9
("Test Tope 1Zèsxonse
Riferente
5d
Fllyc
20
30
toopxaPonx
500
100
Fi6ure z Compnrzsiive
lsponse of
11(
3lnrdmd jki
SK
IP5
?est
?t+pe.
6nd
ioK
qv Loop
The flux loop is not a replacement for
standard alignment tapes, however. It is a
tool that, when used within its limitations,
can provide useful information regarding
the dynamic responses of a tape reproduction system. It cannot, however, reveal
defects in the system due to factors such
as head grooving, tape path instability,
azimuth error, poor tape-to -head contact,
or excessive gap length. Clearly, it cannot
serve as a flux level standard, being as
geometry sensitive as it is.
Its value is greatest in the case of the
lower tape speeds where fragility of alignment tapes and variations in cartridge and
cassette plastics introduce considerable
uncertainty regarding the true nature of
the 8 -track cartridge and cassette reproducer. The major benefits realized from
use of the method have been accrued in
the areas of these consumer format products, as far as my experience is concerned.
A DIN cassette alignment tape is such a
fragile entity that I am led to distrust it
after only 3 or 4 uses. This includes the
slewing back and forth to re -verify previously observed points on the reproduce
characteristic. At a cost of about $50 per
cassette tape, it's not hard to see how
fiscal expediency can severely restrict
scientific objectivity.
As an illustration of this, I had been
experimenting with application of the
"B" Dolby c and DBX noise reduction
processes to high -speed duplication of
music program material earlier this year. I
was continually frustrated by the inability
of the decoded cassette to compare favorably with the quarter -inch source copy.
Notably, the high- frequency portion of
the duplicated spectrum seemed to suffer
from the encoding /decoding process after
duplication. This was true without regard
to the noise reduction system used. From
the best data obtainable, there was cause
for belief that the mastering and duplicating system were flat from 50 to 15,000Hz,
t2dB. A flux loop determination of the
evaluation cassette player response showed
that what had been presumed to be a flat
reproduce characteristic, referred to a
DIN alignment tape, was in fact a 3 to
5dB boost at 10kHz and a similar drop
at 5 to 8kHz. Re- adjustment of the
cassette player response and re- evaluation
of the experimental music samples verified
the validity of data determined independently.
Both noise reduction systems performed creditably through the rigors of
the high -speed (32:1) duplication process.
The cassettes using either noise reduction
system were very difficult to distinguish
from their 71/2 ips, quarter -inch sources
when sychronously A -B compared.
This experience brings to mind the
widely held and perverse contention
among audio professionals that noise reduction systems, the Dolby processes,
are most frequently mentioned, somehow
color, or unacceptably compromise the
Re/p 45
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Re/p 46
www.americanradiohistory.com
quality of the recordings processed. I will
admit to holding reservations regarding
this aparent problem, (falling a good deal
short of outright hostility, however). I
think that if maximum benefit is to be
derived from use of any noise reduction
process whatever, greater care in establishing truly flat recording system response
over the bandwidth of interest is necessary. After many years, I have begun to
observe that realization of this has been
expressed more frequently.
Variations in play -back equalization of
the 2 to 4dB magnitude are audible to a
critical listener, whether noise reduction
is used or not. Under close scrutny, the
effective change in Dolby decoder drive
level over the range of equalization disparity is indeed audible when compared
against results obtained for flat reproduction. How significant such differences
are to a consumer who has no access to
the master tape must remain an open
question for the present.
It is my suspicion that the complaints
regarding alteration of noise-reduction
processed program quality may be attributable, in large measure, to cumulative
variations in recording and reproduction
system frequency response, probably resulting from over-reliance upon alignment
tapes as absolute flux and frequency
standards beyond their truly useful life. I
can recall observing master tapes, Dolby ized, DBX'd, and flat N.A.B., that showed
considerable variance with standards to
which machines under my control are
customarily maintained. Most notable
among the variations, other than simple
azimuthal and level mis- matches, for which
I make corrections without comment, is a
2 to 4dB rise in response in the 5kHz to
8kHz region which is not easily correctable on playback equipment with which I
normally deal.
I feel fairly confident of the accuracy
of the response of equipment under my
control for two reasons. The first is that
the real-time record /reproduce characteristics of any given quarter-inch machine
repeatably fall within a ± ldB tolerance,
typically less, and that different machines
will respond within this tolerance to a
tape prepared on another. Second, comparison of flux loop response against
standard alignment tape response reveals
an error of less than ± 1.5dB as shown by
the curve of Figure 2. I further believe
that closer investigation of the relative
condition of alignment tapes versus flux
loop response versus record /reproduce
response may yield some beneficial information to the industry at large. It may be
that alignment tapes are being used without due regard to their fragility, potential
for aging degradation, and/or the condition of the tape -to -head contact mechanism upon which the entire magnetic
recording process depends. The obscure,
flux loop is offered as a means for verifi-
cation of reproduction system response
that is repeatably verifiable with regard to
calibration accuracy.
I think that flux loop techniques used
to establish system reproduce response, to
tighter limits than are generally considered
necessary, to be instrumental in preserving
spectral quality of processed program
material. I believe that experience has
provided sufficient evidence as to the
utility and benefit of both the Dolby and
DBX processes as applied to the magnetic
medium in both professional and consumer applications. The dependance of
any noise reduction system, with which I
am familiar, on a very flat frequency
response characteristic throughout the
program channel should not be minimized
as much as it apparently has been in the
past.
enthusiasm for the flux loop
method also stems from my inability to
establish slow speed reproduce system
performance with more widely relied
upon techniques. This enthusiasm is supported when more difficult reproduce
measurements such as total harmonic distortion and intermodulation distortion
are attempted. The uncertainties due to
contributions of the non-linearities of the
recording process involving tape saturation,
residual noise, and modulation noise make
true reproducer contributions to the measurement difficult to assess. Add to this
wow and flutter effects and the situation
is further complicated.
As far as dealing with the many reproducer response characteristics considered standard throughout the world,
there should be no serious need to maintain either a complete inventory of flux
loops or alignment tapes for each one.
J.G. McKnight has published a set of correction curves showing proper response
differences between IEC /CCIR machines
responding to an N.A.B. alignment tape
and a N.A.B. machine responding to an
IEC /CCIR alignment tape.l0
For those interested in more detailed
descriptions regarding the history and application of the flux loop, this information
may be found among the following publications, although I do not represent my
research as exhaustive. The earliest mention of the flux loop technique is given by
J.D. Bick in 1953.11 Daniel and Axon
rely on the method prominently in determination of core losses in a ring -type
reproducing head.12 R.L. Wallace used a
field coil, apparently wound completely
around the test head, for the determination of core losses in 1951.13
The flux loop is also briefly treated in
several published volumes. H.G.M. Spratt
describes the eddy current loss measure ment14 while W.E. Stewartl5 goes over
the same ground. Later date publications
cited above should be consulted for more
rigorous exposition of the applications
described in this article.
My
A final caveat in use of either the flux
loop or the standard alignment tape in
routine practice may be in order. I have
noted on several tape machines, of reputable and respectable manufacture, that
the V -U meter indication may not be as
flat with respect to frequency response
as we might ideally suppose it to be. In
many cases, direct observation of reproduce output level with a high accuracy,
wide -band indicator such as the HewlettPackard 3400A AC voltmeter will show
that the panel V-U meter response drops
noticeably in the range above 10kHz. I
have noted as much as 2dB difference at
15kHz on certain individual machines.
This observation considers any absolute
calibration deviation from the +4dBm:
0 V -U relationship.
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"Tape Reproducer Response Measurements With a Reproducer Test Tape" J.
G. McKnight, Journal of the A.E.S.,
April, 1967, Vol. 15 No. 2, p. 152
2 "The Use of Flux Loops for Calibration
of Magnetic Reproducers" Alistair M.
Hazelitt. Presented May 16, 1973 at the
45th A.E.S. Convention, Los Angeles. No
pre -print available.
3Hazelitt, Ibid.
4 "Standards for Magnetic Tape Records"
RIAA Bulletin E5 July 15, 1965, Rev.
Feb. 7, 1969
5 "Reference Data for Radio Engineers"
Howard Sams & Co. 5th Ed. P. 4 -50
6 "Flux and Flux- Frequency Measurements and Standardization in Magnetic
Recording" J. G. McKnight, Jour. of the
SMPTE June, 1969 Vol. 78 P. 464
7 "Frequency Response of Magnetic Recorders for Audio" J. G. McKnight, Jour.
of the A.E.S., July 1960, Vol. 8 No. 6,
1
rhr.i.nl..
Avalah
"Instrumental
in
Audio
11922 Valerio Street, No. Hollywood, California 91605
(213) 764 -1500
Exclusive export agent: Gotham Export Corporation, New York
p. 148
8lbid. p. 153
9 "Reproducer
Test Tapes: Evolution and
Manufacture" R. K. Morrison Jour. of
the A.E.S. Vol. 15, No. 2, p. 161
10"Measuring a Tape Reproducer with
IEC- Response, Using an NAB -Response
Tape" J. G. McKnight, Jour. A.E.S. 1969,
Vol. 17, No. 5, p. 572
11"Methods for Measuring Surface Induction of Magnetic Tape" J. D. Bick,
Jour. of the A.E.S. Jan. 1953, Vol. 1
No. 1, p. 4
12 «The Reproduction of Signals Recorded
on Magnetic Tape" E. D. Daniel and F. E.
Avon,Jour. of The Institution of Electrical
Engineers, 1953, Pt. III, p. 157
13 "Reproduction of Magnetically Recorded Signals" R. L. Wallace, Jr., Bell
System Tech. Jour., Oct. 1951, Vol. 30,
p. 1145
14"Magnetic Recording" H. G. M. Spratt,
MacMillan, 1958, p. 95
15 «Magnetic Recording Techniques" W.
Earl Stewart, McGraw -Hill, 1958, p. 78
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Re/p 47
www.americanradiohistory.com
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Re/p 48
Circle No. 130
"Visit the Otari booth at AES, September 9 -12"
www.americanradiohistory.com
THE MYTH OF THE
MAGICAL
STUDIO
BY
Surely each and every one of us in our
career has heard about, or worked in
some recording studio that was well
known to produce superb product acoustically, even under the most adverse
conditions. Quite frequently these studios
are reputed to have some magical quality
about them that for one reason or another can't be explained.
This generally occurs after somebody,
somewhere, without extensive studio design experience tries to duplicate the
performance of the room with careful
measurement of dimensions, attention to
detail, and lots of back breaking work.
The results of these efforts to "duplicate"
the excellent acoustics usually end up as a
dismal failure, and it's at that point that
the original studio begins to develop its
reputation as "The Magical Studio."
It just isn't so! That studio is magical
only to the person who does not understand totally the physical and acoustical
mechanisms at work in that particular
room.
That studio is no more magical than
television or air travel, both of which
would be attributed to some mystical
power by an Aboriginal Indian as yet
unexposed to the tools and toys of
contemporary society.
A recording studio fundamentally is a
physical plant, the purpose of which is to
convert some form of original performance into final recorded product.
A studio which carries with it a reputation for excellence generally has that
reputation because of the final product it
produces. Good product is the result of
the people, the room, and the gear.
Of these, the most important is the
people factor. Without good mixers, producers, artists, players and writers, the
best studio in the world can't produce
good product. There is, however, compensation in the fact that good people tend
to gravitate to good facilities to do their
work. That being the case, it is critical to
the commercial studio that they offer the
best possible acoustics and the most
complete complement of equipment consistent with the fiscal limitations.
Profitable operation is the goal of
almost every studio venture. Profit in any
business is the difference in what you
take in and what you payout.
DAVE HARRISON
STUDIO SUPPLY CO.
It is here that the services of a competent studio design engineer are critical.
This is critical to insure that the studio
will become an accurate extension of the
His skill and experience in the design and
construction phases of a project can
philosophy and personality of the people
who will own and operate it and not just
of myself. This does not mean to say that
we must have this input from the client,
or on the other hand that we will let him
get into trouble in any way. It's just that
we would like the finished studio to
reflect something of him and of us.
As we are determining the likes and
dislikes of a client, we are simultaneously
gathering financial data from him so that
we can understand the total budgetary
requirements of the project and quite
frequently assist him in obtaining the
necessary long term financing. In today's
climate of high interest rates and tight
money -lending policies, we can frequently
guide a client to a financial institution
that has extensive experience with recording studios and the music industry in
general. Often we find that local financial
institutions are hesitant to get involved in
loans or leases to an industry such as ours
where their historical experience is limited
or non- existant. Fortunately, there are
organizations that do have extensive experience in the music industry and are
aware of the extremely low failure rate
and good payment record of most recording studios.
Frequently the site of a studio is a
predetermined quantity if a client already
owns a building or piece of property.
Designing and building a recording studio
into an existing building that was not
constructed originally to house such a
facility presents special problems to the
designer, but they are almost never insurmountable. The increased construction
cost of working with an existing structure
that is not ideal may well be offset by the
fact that the building or space is already
bought and paid for.
Almost any building site available is
suitable for a recording studio. Extremely
noisy locations, both electrically and
acoustically, simply require a more corn plex design and attendant higher construction cost. These are facts that must
be openly and without bias presented to
the client because in the end the choice
must be his.
minimize the building cost and maximize
the acoustical performance of the finished
studio. And he can accomplish all this
with the secure knowledge that the performance of the studio will be as anticipated in advance; eliminating the costly
and time consuming process of working
with and changing the room until the
desired results are obtained.
A thorough integration of equipment
recommendation, systems design, and
acoustical design consistent with the
budget and performance requirements of
the client is critical to insure the financial
success of the studio. It is here, as well,
that the experienced studio designer performs a most valuable function.
A recording studio with lavish acoustics
and accommodations but inadequate or
incomplete systems design is just as bad
as a complete selection of the best gear
available installed in some warehouse,
basement, or ballroom where there has
been little or no thought given to proper
acoustics.
Studio operating personnel, no matter
how skillful they may be at mixing,
maintenance, mastering, etc., as a general
rule do not necessarily make good studio
designers. This is not because they are
not as smart as the studio design engineer,
but it is a simple matter of fact, that the
person who is engaged in an activity day
in and day out, year after year, can more
skillfully and expediently complete the
work at hand, usually at a lower overall
cost.
The recording studio design engineer is
primarily guided in his work by three.
constraints; budget, site, and client requirements.
As a first step, I almost always enter
into a series of discussions with a potential
client to determine what type of product
will be recorded in the completed facility,
what his personal likes and dislikes are in
the studios we have built, what the
budgetary requirements are, and perhaps
most importantly draw out from him any
prejudices he may have as to decor,
acoustical characteristics, or equipment
selection.
Continued
.. .
Re/p 49
www.americanradiohistory.com
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Using proprietary digital techniques the Delta -T 102 Series
provides, along with other advances, a 90 dB dynamic range and
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The 102 Series has been carefully engineered to meet a wide
range of requirements:
For example, the system may contain 1 to 50 outputs, 2 ms to
3.2 seconds of delay, and remote console mounted controls and
headroom indicator. Fully modular construction permits simple field
expansion and maintenance by module plug -in. Three basic
models in the 102 Series allow economic selection of frequency
response and delay interval for sound reinforcement, studio and
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And the cost of the 102 Series is revolutionary. Although providing
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Dealer inquiries invited.
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Re/p 50
Circle No.. 131
www.americanradiohistory.com
Visit us at Booth 105
at the AES Show.
MAGIC STUDIO
CONTROL ROOM:
The greatest sin we have seen any
studio owner commit, and it's happened
to us more than once, is to call in the
studio design engineer after construction
of the building has begun. It's one thing
to work in a building that has existed for
some time and was built and used for
something different than a recording
studio, you can't help that. But if you
are building a structure specifically for a
recording studio it doesn't seem to make
any sense to begin before complete plans
are laid out. You just lock the acoustical
designer into things that severely limit his
effectiveness, in addition to the probability that you'll have to spend more on
construction.
It's virtually impossible to give a
prospective studio owner a complete
course in studio design, just as it's impossible here in one article to present in
depth all factors that go into a contemporary acoustical and systems design for a
recording studio. However, I for One find
it very beneficial if the client is programmed with as many facts as possible, and
has as complete an understanding as possible of all the acoustical mechanisms at
work in the design.
Armed with this information, the
studio owner can take a real and active
part in the design of the studio that he
will live with for a long time. He should
never feel that anything is being forced
upon him. But rather, he should be free
to accept or reject any design feature or
detail after he has been given a total and
impartial briefing on its importance in
the final acoustical performance of the
facility.
As it is in most complex tasks, the
design of a recording studio must be
broken down into many little subsections
which when combined yield a completed
project.
The control room and the studio
proper must be considered totally independantly as to the desired acoustical
performance. A room whose characteristics are ideal for recording would in
almost all cases be a catastrophic failure
as a monitoring room. The reverse is also
true.
The first real part of the studio design
engineer's job, once he has his input from
the client, is to determine exactly what
the final acoustical characteristics of the
control room and studio will be when
they are completed.
General design goals for a control
room and studio that would apply in
almost all cases have been developed after
years of work and the experience gained
from building many studios. These goals
are not arbitrary but each has a real place
in the scheme of things, and is important
to the final acoustical performance of the
facility.
Dimensioning of the control room is
critical and each of the dimensions plays
an important but independant role in the
final acoustic performance. The length
(front to back) is critical to the warmth
of the room and should be between 20
feet and 24 feet. This warmth comes
from the ability of the room to support
a full wave in the 50Hz range. While it is
possible to "tune" an improperly dimensioned room with monitor equalization to
obtain the measured response in this
register, such response feels shallow and
to the human ear lacks the reality and
warmth of normal room modes. I should
quickly explain that this mode is not
allowed to become predominant in the
sound of the room as, it is heavily
trapped. It is however, not trapped so
heavily as to completely remove its warming effect; but only to the extent needed
to insure even monitor characteristics
in the room.
The side to side dimensions of the
control room should be between 12 feet
and 16 feet with 14 feet to 15 feet being
ideal. A room that is too narrow hinders
placement of equipment and movement
of people in the room. Additionally a
room that's too narrow makes it more
difficult to generate even monitor characteristics for all operating positions.
If the control room is made too wide a
great deal of monitor efficiency is lost,
particularly in the low mid range and
bottom regions. Also there is a lack of the
intimacy that is beneficial in mixing product that will relate well in its final use.
The beginning height of the control
room before treatment should be at least
10 feet, with the ideal being about 11
feet. This will allow an 8 inch to 12 inch
raised area in the middle and rear portions
of the room, giving the mixer and producer better visibility into the studio, and
lowering the vertical angle from the
--
-
5
5
-10
desirable to keep the window area as small
as possible consistent with good visual
communications. The lower boundary of
the window is set so that observers on the
couch can see on at least a horizontal
Lii
+i0
-
monitor positions to the center of the
monitors.
A trapped false ceiling is installed approximately 8 feet above this platform to
totally attenuate the vertical mode of the
room. A 16 to 18 inch depth in this trap
is generally sufficient to satisfy the requirements of this vertical mode trap.
Sidewall construction is such that
there is a high order of lateral dispersion
that is accurately calculated to generate
even monitor characteristics in the critical
areas of the room. These even monitor
characteristics are a result not only of
evenly dispersing the different frequency
ranges, but also must take into account
the fact that there must be a random
phase occurrence to prevent phasing and
notching effects in the middle ranges
which can occur on coherent center
channel information.
Front wall construction is generally
desigend with downward deflection to
prevent slap from the rear monitors back
to the prime monitoring positions. This
downward deflection is also useful in quad
monitoring, in getting the rear channels
into the observer's area in front of the
console. An upholstered couch and carpeted floors in this area help trap this information and keep it from coming back
into the room.
The control room rear wall is trapped
to the extent necessary to properly control
the front back mode of the room. As
previously stated, it has been found undesirable to completely trap this mode,
and the trapping here is in the nature of
accurate control and not elimination.
Windows in any acoustical environment are always a problem as they present
large flat surfaces to bounce sound without benefit of useful dispersion. It is
- --
--
Hill
If
Mixers Position
4
Ft. Behind Mixers Position
4
Ft. To Left Of Mixers Position
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Center Frequency In H.
LEFT FRONT SPEAKER
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Response curves at mixers position and extremes of a 4'x 8' area indicate the excel lent dispersion
and consistency of monitoring within this area. Top end roll off conforms to the Studio Supply
house curve which relates accurately to final product.
Re/p 51
www.americanradiohistory.com
plane out into the studio. This is usually
3 feet from the floor. The upper limit of
the window is set so that a person of
normal height, standing at the mixer's
position can see eye to eye with another
person of normal height, standing at the
far end of the studio. This dimension
varies slightly with the elevation of the
mixer's position, but is generally 6 feet.
Width of the windows is set by the necessity to see into as much of the usable
studio as practical.
It is highly desirable that space be
available on both sides of the control
room. On one side this will be used as a
sound lock and musician's lobby. On the
other, it will be used as an equipment
room allowing the racks to be built into
the side wall and sometimes allowing
machines to be recessed into niches. This
helps keep gear out of traffic patterns
and helps attenuate fan and motor noises
from the machines.
An absorbant carpet on the floor is
beneficial to the warmth of the room, and
the back of the console should not be
high enough to disturb the acoustical field
from the monitors and upper side walls.
Front control room wall slants to
deflect rear monitor information into
couch and carpet where it is absorbed.
At Music Mill in Muscle Shoals, Alabama machines
and rack are recessed into side wall of control
room within easy reach of mixer.
STUDIO:
The studio proper in today's contemporary facility is far different than the
historical studio you will find in the
reference books. The laws of physics
haven't changed, but the required performance of the room has.
With the advent a few years ago of
stereo product and multi-channel recording, there was a trend, fortunately now
reversed, to extremely dead rooms with
little or no beneficial reflection. These
rooms, known in some circles as sound
suckers, were built by people with little
or no knowledge of the necessity that
there be a number of early reflections in
the acoustic field. These early reflections
(within 25 -30ms of the original sound)
do not add a noticable ambience or room
sound to the recorded material. Reflections which have the general character of
and follow the original sound within this
time frame are perceived as a part of the
original sound. They are necessary for
good apparent loudness, good apparent
transient response, and a natural realism,
particularly in unamplified acoustical
instruments.
Acoustical instruments generate a
sound field with components going out
more or less in a spherical pattern. The
acoustical energy radiated on an individual
axis of this sphere very seldom contain
all the components necessary to represent
the true accurate sound of the instrument.
Our preconceived notion of how an individual instrument sounds is based upon
our listening experiences. Most of these
listening experiences have not been under
extremely dead or almost anechoic conditions, but rather under circumstances of
livelier acoustics where we had an opportunity to hear a more representative composite of the total acoustical energy. This
is why these early reflections from various
directions in the recording studio are so
critical to accurate recorded instrument
sound.
The mixer burdened with the job of
trying to get good sound on instruments
under extremely dead circumstances has
historically had a few corrective tools to
work with (equalization, reverb, double
track, etc.), but even after extensive processing such material lacks those qualities
that we have come to expect from a proper
recording environment.
Good apparent loudness and transient
response when recording in an acoustic
field rich in early reflections, is the result
of the increased total energy content of
the transients caused by random transient
repetition within a 25ms -30ms period.
Transients repeated very far outside this
time frame are heard as distinct and
separate sounds and unless they are part
of some sought after room sound or
ambience, are generally considered to be
undesirable.
It is readily apparent to the most casual
observer that most sound sources in the
recording studio occur in an area from
the floor to four feet above the floor, and
microphones in contemporary recording
practice are generally placed no higher
than 5 or 6 feet above the floor. More
likely than not, they are placed in the
general horizonal plane of the sound
source. With this in mind, it then becomes
obvious that the most beneficial reflections that would occur would be those
that had good horizontal dispersion with
limited vertical dispersion. Such is the case
in actual practice.
Another design goal of the contemporary recording studio is that of separation; that is, minimum leakage of one
instrument's sound into another instrument's microphone. All the reasons for
good separation such as improved control,
minimized undesirable room ambience,
and having the opportunity to replace
tracks without ghosting from other tracks
recorded at the same time, are well known,
so we won't go into that here.
In the normal studio, there are a great
many things filling in this space from four
feet down. Chairs, people, music stands,
pianos, organs, amps. etc.
With vertical dispersion limited, we
have to a certain extent contained a great
deal of the acoustic energy generated
within this bottom slice of the room
where it can be disipated and absorbed by
the usual clutter of things occupying
the studio.
In order for a room of this design to
work properly, however, it is absolutely
essential to completely trap the ceiling to
eliminate the possibility of bounce back,
which would totally destroy the beneficial
effect of the horizontal dispersed sound
field we have generated. Ceiling bouce is
detrimental primarily in two ways. The
first is that ceiling bounce is about the
only mechanism remaining to spoil separation other than direct sound from
closely spaced instruments that don't have
intervening dispersing or absorbant items.
The second relates to the first in that
these reflections will in almost all cases be
separated from the original sound in time
by more than the specified 25 -30ms.
Therefore, they will be heard as a separate
sound and as such are undesirable in
contemporary recording.
Many people believe that the degree of
separation you can get in a room is a
function of how dead it is. While this can
be a general truth in rooms without carefully planned and executed acoustics, I
think I have made it clear that intelligent
thought and proper design based on a
great deal of experience can generate a
room that has all the advantages of a
relatively dead room, without the detrimental effects.
.
(--
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Railroad Square, Box S, San Luis Obispo, California 93405
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WAREHOUSE SOUND CO.
Professional Products Group
Railroad Square, Box S, San Luis Obispo, California 93405
Phone: 805/544-9020
Continued
Circle No. 132
Re/p 53
www.americanradiohistory.com
MAGIC STUDIO
continued ..
..
.
.
In the studio, it is very desirable to
have some areas more live than others so
that the mixer may vary the density and
strength of the early reflections by proper
placement of personnel.
In my designs the livest area is generally
at one end and the deadest area at the
other with a fairly smooth transition. The
end of the studio with the control room
is generally designed to be the live end as
the undispersed reflections from the glass
are less detrimental there.
Dimensioning of the studio is less
critical than the control room. That's not
to say there are no restrictions, but the
restrictions are not as critical acoustically.
It is important that there be a minimum
of coincidence in room modes. These are
well trapped laterally as well as vertically,
but if the modes are coincident they must
be trapped more.
Drum booth is placed at dead end
of room as shown. Laterally dispersing
sections can be seen on wall.
The dependance upon bass traps without proper control of the room as a total
system can create many problems for the
mixer. Versatility of the room is severely
restricted if players can only be placed in
one position. Bass energy from specific
instruments may be attenuated in a local
area of the room, but if the room as a
total entity is not properly controlled, the
small amount of energy that does escape
can, through undamped resonances, cause
severe problems in other areas. The general
effect of these faults is an occasional lack
of sparkle and definition in the mix and a
general low frequency cloud under the
whole thing. It can sometimes be very
difficult to diagnose this problem as other
problems often accompany it.
Parqued wood floor in live area gives
warmth to the sound of instruments.
Bass trapping is done on an overall
room basis rather than at specific instrument locations. Low frequency energy in
a room is a function of the dimensional
modes of the room. It is very critical that
the room be considered a resonant system
at these frequencies and that the design
include measures to properly dampen
these resonances. With the room resonances properly damped, the free lowfrequency energy in the room is limited
to such an extent that individual bass
traps are not necessary.
Re/p 54
ISOLATION:
Acoustic isolation of rooms in a recording studio is important to satisfactory
performance and versatility. Isolation
(absence of harmful sound transmission),
between the control room and studio is in
my opinion the most critical; although
isolation between production and office
areas, and isolation from the outside
world, follow closely.
Sound traveling from one room to another is either airborne or structureborne.
Airborne transmission is the easiest to
control, but in improperly designed and
constructed facilities, is the most frequent
offender. Careful attention to design and
construction details can virtually eliminate airborne transmission without excesISOLATION BOOTHS:
Most experienced mixers and players sive building cost. Structureborne sounds
will agree that isolation booths are to be are more difficult to control, especially in
used only when absolutely necessary. It's pre -existing buildings. They too can be
true they help separation under marginal dealt with but it sometimes involves comconditions of acoustics and player balance, plex expensive construction.
In the design of recording studios, we
but they are detrimental in many ways.
Players or vocalists working in a booth at Studio Supply Company attempt to
tend to lose the intimate contact with stay with standard construction practices
their fellow performers that is critical to and materials as much as possible. There is
a spontaneous and "free" feeling per- a very good reason for this. If a set of
formance. Most isolation booths also have construction plans calls for exotic matermany of the undesirable acoustical char- ials and construction techniques, then it
acteristics of a very small room. Lack of can only cost the client more money to
density in the dimensional modes fre- build, particularly if identical results can
quently make a booth sound "boxy," be obtained with standard materials and
making instruments recorded in those practices. When contractors are asked to
booths sound radically different from in- deal with materials they are unaccustomed
to, and methods of construction their
struments recorded in the open room.
Gwnerally a drum booth is the only people are not familiar with, they tend to
booth necessary in a recording studio of inflate bids to give themselves a margin
good contemporary design. The same care for error. Additionally, some designs are
should go into its design as goes into the so complex that the use of an on -site
design of the studio and the considerations construction foreman, supplied by the
designer, is necessary to insure faithful
are almost identical.
execution. While in some cases it may be
necessary, and we do have people available, I don't hink it's fair to lock a
customer into this when the studio can,
with no compromise, be designed in such
a way that almost any competent professional contractor can handle the job.
I think a word about monitors is
called for. Monitor speaker systems cannot be taken and evaluated meaningfully
by themselves. They are a component in
a monitoring system that also includes
the monitoring room, the power amps,
the tuning, and the ears of the operating
personnel. The prime purpose of a monitor system is to accurately tell us what is
on a tape or is coming through the console and how it will sound when the final
product is later played and hopefully enjoyed by the consumer. The total monitor
chain should be highly linear, exhibit no
colorations, generate sufficient sound pressure levels, and have proper dispersion to
insure the accuracy of the sound field at
any critical listening position.
There is no one monitor system that
performs best in all applications and all
rooms. When we have the opportunity to
build a control room the way that we
prefer to, we have our favorite monitor
system. As the purpose of this article is a
discussion of acoustics in recording studios
and not an ad for speakers, I prefer only
to say that the system we use performs to
our total satisfaction only when used in a
room properly designed for it. This is the
case with any speaker system.
It is just as proper to design a monitor
system for an existing room as it is a room
for an existing monitor system. This is
often the case where total control of the
room is not possible.
We at Studio Supply Company are
proud of the studios and control rooms
we have designed and the complete facilities we have built. We work just as hard
to bring an older existing studio up to
contemporary standards as we work in
designing a brand new turn-key installation. We have the same pride in the work
we do for the client with a small budget
as the client with unlimited funding. Most
importantly, we have never had to make
apologies for any job we've been involved
in, even those with very limited funds. If
a client has only a limited construction
budget, we know that we're going to help
him get the best studio possible within
the confines of that budget.
The proof is in the pudding, and I
guess the bottom line is being able to sit
down and listen to the product produced
in the studios we've built; and to know
that we have had a real part in making
that product good and competitive by
sharing the knowledge gained through
many years of hard work and experience.
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Re/p 55
www.americanradiohistory.com
SESSION A
AUDIO IN BROADCASTING
MONDAY, SEPT. 9, 9:30 AM
JADE ROOM
Chairman:
Orville J. Sather,
A
-1
A -2
A -3
SEMINAR SERIES
Registration: A $5.00 registration fee includes
four Seminars. Only those who register for
Convention Technical Sessions or Exhibits may
attend.
all
The purpose of these four initial seminars, conducted by the Audio Engineering Society, is to
introduce interested members in the practical
methods and techniques employed in audio
engineering. The Society is trying in this way to
better serve the whole membership by offering
an educational service that may aid in improving
the understanding of current -day audio technology and its application.
Monday
- Sept. 9 - Astor Gallery
THE DESK TOP COMPUTER IN COMPUTATION & DESIGN
-
-
2:00 5:00 pm
SEMINAR
INTRODUCTION TO PROGRAMMING (D)
A primer of programming with application to
the desk top computer. This seminar will introduce the rudiments of machine language programming step -by -step, so that the attendees
will be capable of using a simplified machine
language OP CODE to program a problem. This
first session will aid participants in the evening
I
seminar in practical applications.
-
7:30 pm
SEMINAR II
APPLICATION OF THE DESK TOP COMPUTER TO AUDIO ENGINEERING (F)
A discussion and demonstration of current day
hardware and software. Particular emphasis will
be given to unique applications in audio engineering. This seminar will be divided into three
general areas: (1) Demonstration and application
of the latest equipment manufactured by Hewlett Packard Co. (2) Discussion of available
stock software as well as specialized programs.
(3) Discussion of application of the hardware
and software to specific design problems.
-
-
-
10:oo am Noon
SEMINAR III
WHY,
TAPE RECORDER ALIGNMENT
WHAT AND WHERE (H)
Although the studio technician may satisfactorily
perform routine tape recorder alignment procedures, his understanding of the various adjustments is often based largely on rote training.
-
The complete record playback system includes a
series of compensations; some fixed and others
adjustable. A better understanding of the tape
recorder as a system will enable the user to
better realize its full potential. In this session,
Mr. McKnight will discuss, and demonstrate, the
significance of each step in the alignment
procedure.
-
EXHIBITION OF
more harm than good. Mr. Hansen will
briefly cover the basic principles of sound
transmission, and discuss the practical application of acoustic materials in the studio.
do
a
F
SCH
OF DISC RECORDINGS
A -5
A-6
TRANSMITTER LIMITATIONS IN
ACHIEVING HIGH AMPLITUDE
MODULATION PERCENTAGES
STATUS REPORT OF THE JCIC AD
HOC COMMITTEE FOR THE STUDY
OF TELEVISION SOUND
Sunday
Monday
Tuesday
Wednesday
Thursday
SESSION B
Septemk
Septemk
Septemk
Septemk
Septemk
AUDIO IN MEDICINE
MONDAY, SEPT. 9, 9:30 AM
ASTOR GALLERY
Philip Kantrowitz,
Chairman:
New York, N.Y.
B -1
LANDMARK TECHNIQUE FOR
IDENTIFYING ULTRASONIC CARDIAC ECHOES
B -2
LONG -TERM MONITORING OF IMPLANTED CARDIAC PACEMAKERS
B -3
BIPHASIC HEARING INSTRUMENT
B -4
B -5
B -6
B -7
SYSTEM
A MINI CARDIAC DYSRHYTHMIA
DETECTOR
MEASUREMENTS OF PHYSIOLOGICAL
SIGNALS IN THE AUDIO SPECTRUM
ACOUSTIC ENERGY TRANSFORMATION IN THE HUMAN AUDITORY
SYSTEM
A WEARABLE MASTER HEARING
AID
SESSION
E
Monday and Tuesday
Wednesday and Thursd
E
PHILOSOPHIES EMPLOYED IN THE
DESIGN OF BROADCASTING
CENTRE, JOHANNESBURG
NEW RTE RADIO CENTRE IN
-3
E -4
DUBLIN
E -5
JADE ROOM
David L. Klepper
Chairman:
KM K Associates, White Plains,N.Y.
C -1
A STAGE MONITOR FOR ROCK PA
C -2
AN AUDITORIUM WITH NATURAL
C -3
C-4
C -5
C-6
C -7
VARIABLE REVERBERATION
EQUALIZATION SIMPLIFIED
AUTOMATIC MICROPHONE MIXING
LOUDSPEAKER DRAWING BY
COMPUTER GRAPHICS PROGRAMS
HIGH FIDELITY SOUND SYSTEM
EQUALIZATION BY ANALYSIS OF
STANDING WAVES
SOUND FACILITIES AT THE
EDYTH BUSH THEATRE
SESSION
SESSION G
(Part One)
TUESDAY, SEPT. 10, 9:30 AM
JADE ROOM
John R. Gillion
Chairman:
G -1
Buchanan Spider Works
Buchanan, Mich.
APPLICATIONS AND DESIGN CONSIDERATIONS FOR A HIGH -QUALITY
UNIDIRECTIONAL LINE LEVEL
G -2
G -3
G -4
G -5
G -6
MICROPHONE
ULTRASONIC CAPSULE FOR
REMOTE CONTROL PURPOSES
DEVELOPMENTS IN BINAURAL
RE-CREATION: CONCEPTS,
SYSTEM REQUIREMENTS,
APPLICATIONS
ELECTRO-ACOUSTIC TRANSDUCERS
WITH PIEZOELECTRIC POLYMER
FILMS
VIBRATION SENSITIVITY MEASUREMENTS ON SUBMINIATURE
CONDENSER MICROPHONES
HORN THEORY AND THE
PHONOGRAPH
E
SESSION
BROADCASTING AND MUSIC
RECORDING ABROAD
JADE ROOM
Derek Tilsley
Chairman:
Rupert Neve & Company Ltd.
Melbourn, Royston, England
MULTITRACK RECORDING OF LIVE
E -1
PERFORMANCES WITH SIMULTANEOUS FILMING
TELEVISION AUDIO IN GREAT
BRITAIN
Re/p 56
www.americanradiohistory.com
I
TRANSDUCERS, LOUDSPEAKERS
AND MICROPHONES
(Part Two)
MONDAY, SEPT. 9, 7:30 PM
E -2
SOUND IN BROADCASTING AND
MUSIC RECORDING IN FRANCE
TRANSDUCERS, LOUDSPEAKERS
AND MICROPHONES
C
ARCHITECTURAL ACOUSTICS
AND SOUND REINFORCEMENT
-
SEMINAR IV 2:00 3:45 pm
PRACTICAL STUDIO ACOUSTICS (J)
The working recording engineer will seldom be
called upon to specify the acoustic treatment
of the studio in which he works. However, some
acquaintance with elementary acoustic principles
will help him in using his studio to better
advantage. Especially in the case of separation,
acoustic materials are often badly misapplied,
and an improperly designed baffle may actually
Directly following this seminar, Session K,
Panel Discussion on Studio Design
will be held.
FORTY -N
WOR- Radio, New York, N.Y.
INTERMODULATION DISTORTION,
BROADCASTING AND THE FCC
AUTOMATIC NOISE FILTER FOR
TELEPHONE LINES
A BROADCAST MONITOR LOUDSPEAKER OF SMALL DIMENSIONS
RESTORATION AND PRESERVATION
MONDAY, SEPT. 9, 2:00 PM
Jade Room
Tuesday Sept. 10
RECORDING STUDIO TECHNOLOGY
-
A -4
AUDIO ENGIN
TUESDAY, SEPT. 10, 2:00 PM
JADE ROOM
John R. Gillion
Chairman:
-1
A NEW TYPE OF TWEETER HORN
EMPLOYS A PIEZO- ELECTRIC
I
DRIVER
1
-2
A VARIABLE DIRECTIONAL AXIS
DIPOLE LOUDSPEAKER
LING SOCIETY
M -3
M -4
M -5
INVENTION
;IONAL PRODUCTS
M-6
M -7
)F EVENTS
Astoria
M-8
k City
ATION
4:00 pm to 8:00 pm
8:00 amto9:00pm
8:30 am to 9:00 pm
9:00 am to 5:00 pm
9:00 amto8:00pm
HOURS
1:00 pm to 9:00 pm
11:00 am to 5:00 pm
I
SMALL VENTED ENCLOSURE
LOUDSPEAKER SYSTEMS FOR
SPEECH REINFORCEMENT
A NEW SET OF SIXTH -ORDER
VENTED -BOX LOUDSPEAKER
SYSTEM ALIGNMENTS
LOUDSPEAKERS AND ACOUSTIC
DAMPING
-3
I-4
I
-5
SYSTEMS
SESSION N
MAGNETIC RECORDING
WEDNESDAY, SEPT. 11, 2:00 PM
JADE ROOM
Arthur E. Gruber
Chairman:
AEG Associates,
East Rockaway, N.Y.
N -1
SPEED, PITCH AND TENSION
REVISITED
PROFESSIONAL 1/4" CASSETTE
N -2
AND ITS RANGE OF APPLICATION
N -3
OPEN -CIRCUIT VERSUS SHORT CIRCUIT TAPE FLUX
MEASUREMENT
NOISE MEASUREMENTS IN AUDIO
N -4
SESSION O
FORENSIC AUDIO ENGINEERING
(The application of audio engineering
knowledge to questions of civil and
criminal law.)
SESSION K
STUDIO DESIGN, SYSTEMS
AND STRUCTURE
(A Panel Discussion)
TUESDAY, SEPT. 10, 4:00 PM
ASTOR GALLERY
Chairman:
Erik Porterfield
CBS, New York, N.Y.
A question and answer discussion of the design
of modern pop recording studio installation.
SESSION L
The New York Section Presents
SYNCHRONOUS SOUND SYSTEMS
FOR DISNEYLAND PARADES
(No registration fee for this Session)
TUESDAY, SEPT. 10, 7:30 PM
JADE ROOM
Albert B. Grundy
Chairman:
Institute of Audio Research
New York, N.Y.
This system, and the parade, will be described
with slides and an audio demonstration by Mr.
Shawn E. Murphy of Disneyland.
WEDNESDAY, SEPT. 11, 4:00 PM
JADE ROOM
Chairman:
Stephen F. Temmer
Gotham Audio Corp.
New York, N.Y.
Papers presented by both lawyers and engineers
will be followed by a panel discussion and
questions from the audience.
SESSION P
DISC RECORDING
THURSDAY, SEPT. 12, 9:30 AM
ASTOR GALLERY
Chairman:
P -1
P -2
P -3
SESSION M
SIGNAL PROCESSING
WEDNESDAY, SEPT. 11, 9:30 AM
JADE ROOM
Chairman: Irving L. Joel
Joel Associates, Teaneck, N.J.
M -1
M -2
APPLICATIONS OF THE TWO QUADRANT TRANSCONDUCTANCE
AMPLIFIER /MULTIPLIER IN AUDIO
SIGNAL PROCESSING
A VOLTAGE PROGRAMMABLE
PARAMETRIC EQUALIZER FOR
AUTOMATION AND REMOTE
CONTROL
PRACTICAL CONSIDERATIONS IN
ACTIVE FILTER DESIGN
EFFICIENT DIGITAL CONVERSION
OF AUDIO SIGNALS
MINIMIZING MEMORY REQUIREMENTS FOR MEMORY MIXING
CONSOLES AND SYNTHESIZERS
IMPEDANCE TAILORING VIA
FEEDBACK
THE EFFECTS OF SHUNT OR SERIES
MIXED FEEDBACK ON STATIC AND
DYNAMIC DISTORTION IN
DIFFERENTIAL AMPLIFIERS
DESIGN CRITERIA OF A UNIVERSAL
COMPANDOR FOR THE ELIMINATION OF AUDIBLE NOISE IN TAPE,
DISC, AND BROADCAST
P-4
P -5
P-6
Daniel Gravereaux
CBS Laboratories
Stamford, Conn.
PERFORMANCE TRADEOFFS IN
DISC RECORDING
A NEW ELECTROSTATIC
PHONOGRAPH CARTRIDGE
MEASUREMENT OF RECORDED
LEVEL AND CHANNEL SEPARATION ON PHONOGRAPH DISCS
USING OPTICAL INTERFEROMETRY
TECHNIQUES
100dB DYNAMIC RANGE DISC
RECORDING
DEVELOPMENT OF COMPOUND FOR
QUADRA DISC
ADVANCE HEAD -LESS VARIABLE
PITCH /VARIABLE DEPTH LATHE
CONTROL SYSTEM
SESSION Q
AUDIO INSTRUMENTATION
THURSDAY, SEPT. 12, 2:00 PM
ASTOR GALLERY
Chairman:
Edward J. Foster
By -Word Corporation,
Armonk, N.Y.
Q -1
Q -2
Q -3
Q-4
DESIGN OF A DIGITAL CONTROLLED
AUDIO LEVEL INDICATOR
FREQUENCY -SWEEP TEST TAPES:
DESIGN AND USE
A HIGH SPEED AUDIO TAPE
DROPOUT COUNTER
STEADY STATE AND TRANSIENT
RESPONSE OF LOUDSPEAKER
SYSTEMS
Q -5
MEASUREMENT OF SOUND POWER
AND ENERGY DENSITIES
SESSION
R
QUADRAPHONICS
THURSDAY, SEPT. 12, 4:30 PM
ASTOR GALLERY
Leonard Feldman
Audio Consultant
Great Neck, N.Y.
A METHOD OF ANALYZING THE
QUADRAPHONIC SOUND FIELD
DEVELOPMENT OF THREE IC CHIPS
FOR MATRIX DECODING AND
Chairman:
R -1
R -2
R -3
R-4
R -5
SYNTHESIZING
FOUR-CHANNEL SOUND IN
HISTORICAL PERSPECTIVE
SOUND IMAGE LOCALIZATION OF
THE SQ SYSTEM
THE DEVELOPMENT OF A NEW QS
QUADRAPHONIC SYNTHESIZER
THURSDAY, SEPT. 12, 12:00 NOON
JADE ROOM
ELECTRONIC MUSIC CONCERT
performed by
The Electronic Music Ensemble of the
University of Colorado at Denver
conducted by Roy Pritts
SESSION
S
ELECTRONIC MUSIC
THURSDAY, SEPT. 12, 2:00 PM
JADE ROOM
David Friend
Chairman:
ARP Instruments
S -1
LIVE ELECTRONIC MUSIC PERFORMANCE IN QUAD
S -2
SOUND ANIMATION BY DYNAMIC
FILTERING
3 -3
A PROGRAMMABLE CONTROL
DEVICE FOR ANALOG
SYNTHESIZERS
S-4
RECORDING SYNTHESIZED
INSTRUMENTAL MUSIC
ELECTRONIC RHYTHM UNITS
S -5
HUMANIZED
MAN /MACHINE COMMUNICATIONS
S-6
AND COMPUTER MUSIC
SYNTHESIS
SESSION T
HOW
VALID ARE HI -FI
EQUIPMENT TESTS?
(A Panel Discussion)
THURSDAY, SEPT. 12, 7:30 PM
JADE ROOM
Moderator: Larry Klein
Technical Editor Stereo Review
Re/p 57
www.americanradiohistory.com
11149)iAabiB
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tape recorder /reproducers. Our superbly
designed and engineered machines are available in a variety
of standard formats, from 4 to 24 tracks, or you can
keep on trackin with Stephens' unique 32 track
and 40 track 2-inch machines.
Pictured (front -to -rear) are the 4- track,
40-track and 24 -track machines.
professional
STEPH
ELECTRONICS, INC
3513 Pacific Ave., Burbank, Calif. 91505 Phone (213) 842 -5116
Re/p58-.°
4
No. 135
www.americanradiohistory.com
Battery powered portable units are
also available.
NEW PRODUCTS
NEW AKG PROFESSIONAL ELECTRET
CONDENSER MICROPHONE SYSTEM
IN MODULAR FORMAT
Mr. Andrew A. Brakhan,Manager AKG
Products, North American Philips Corporation,recently announced the introduction
of a new Modular Professional Electret
Condenser Microphone System.
The units use a gold -vapored Teflon
diaphragm, that makes the unit impervious
to humidity and insures against deterioration due to climatic conditions and ageing.
The electret element carries a regular full
year warranty.
Said to be extremely stable under unfavorable climatic conditions, the AKG
Professional Electret Condenser Microphone Modular System consists of: one
basic powering module, 4 interchangeable
capsules, and accessories.
POWERING MODULE SE -5E incorporates: Battery compartment for 5.6
volt (Mallory PX -23) battery; unique onoff switch function moves battery within
compartment, thereby continuously cleaning contact points; 550 hours of continuous operation can be expected from one
battery; suitable for phantom powering
off DC supply, available in mixer or tape
recorder.
module and SA-11 /1 stand adapter, in case.
CE -510 for Lavalier Operation
consists of CE -10 lavalier element and SE -5E
powering module, in case.
The Electret Condenser Microphone
System will be available for shipment
August 1974.
AKG, 100 EAST 42 STREET, N.Y.,
N.Y. 10017.
-
Circle No. 136
ORBAN /PARASOUND STEREO
SYNTHESIZER
ORBAN /PARASOUND announces the
availability of a new model Stereo Synthesizer. The STEREO SYNTHESIZER,
Model 245E has been designed to take any
mono signal and create lifelike pseudo-
stereo. Unlike many other techniques, the
patented ORBAN /PARASOUND stereo
synthesis technique, according to the company, causes no change in spectral balance,
does not blur the transient definition, and
adds not the slightest audible noise or
distortion to the mono original. The stereo
output sums back to the original mono
for total mono /stereo compatibility.
The STEREO SYNTHESIZER creates
a stereo effect by dividing the mono
source signal into five frequency bands.
Three of these bands are placed in one
stereo output channel; the remaining two
are placed in the other channel. The
filters are synthesized so that the sum of
the two output channels is identical to
the mono input. In addition, the sum of
LOOKING FOR
A BETTER INTERCOM
F
SYSTEM ?
tar'
INTERCHANGEABLE CAPSULES:
CE -1 Cardioid capsule, includes condenser
microphone preamplifier. CE -2 Omnidirectional capsule, includes condenser
microphone preamplifier. CE -5/1 Cardioid
capsule with integral suspension and wire
mesh windscreen. Includes condenser microphone preamplifier. CE-10 Miniature
lavalier condenser microphone attachment
with integrated FET preamplifier.
Each component, plus accessories, may
be obtained individually immediately, or
added to the system later.
Three combination systems are available: CE -501 for Cardioid Operation
consisting of CE -1 cardioid car'ile, SE -5E
powering module, SA -11 /1 stand adapter
and W -3 windscreen, in attractive case.
CE -505 for Cardioid Operation
with
integral suspension and windscreen consists of CE-5/1 capsule, SE -5E powering
-
-
ULTRACDMM
*Double Insulated
Remote Sta-
tions end sparks and zapped
operators.
*Requires only two conductor
unshielded cable - zip cord,
Telco lines, speaker cable.
*Balanced
lines eliminate
crosstalk in snakes.
*Available as modules for custom installation.
*Operates with your existing
headsets - dynamic or carbon.
*Rugged and roadworthy - 5
year guarantee.
*Super bright automatic cue
lights.
*ALC
on each microphone
compensates for shouting
caused by high levels.
*Rack mounted power supply.
ULTRACOM
TM
A PRODUCT OF
COUNTRYMAN ASSOCIATES
424
UNIVERSITY AVE. -PALO ALTO , CA.
Circle No. 137
www.americanradiohistory.com
94301 -PHONE 415- 326 -6960
Re/p 59
r_421-
,.,
i a, i
s
.
R
.,
.
,
-
The Model 10 Mixing Console
When you've got more talent than money
Any mixing console is simply a creative tool.
Getting the most out of it calls for
imaginative insight into music and
skill in the practical application
of sound.
If you've got the talent but
you don't have the money,
you're exactly who we built this board for.
The basic 8 -in, 4 -out board starts
at just $1890. From there you can
go to 24 -in, with options and accessories enough to fill a studio.
The TASCAM Model 10.
It gets your inside outside.
TIISCAM CORPORATION
5440 McConnell Avenue
Los Angeles, Calif. 90066
Re/p 60
Circle No. 138
www.americanradiohistory.com
the powers in the left and right output
channels is equal to the power in the
mono input signal, guaranteeing that the
stereo will have the same perceived frequency balance as the mono source.
The STEREO SYNTHESIZER is now
available in standard 19" rack mount and
requires 1 3/4" rack space. Price of the
unit
is
$299.00.
PARASOUND, INC., 680 BEACH ST.,
SAN FRANCISCO, CA. 94109
Circle No. 139
GATELY PROKIT II MIXING SYSTEM
Gately Electronics announces introduction of its new Prokit II mixing system.
This mixer, available in kit or factory
wired, features slide attenuators and pan
pots on all six inputs. Each input is
switchable from mike to line input. The
mike preamp gain is switch selectable and
each mike input has a switchable 20dB
pad. The professional VU meters are
backed up by LED overload indicators.
Components used in the Prokit II are
from the most prestigious manufacturers
including slide pots by Duncan, rotary
pots by Allen Bradley, indicator type push
button switches by Schadow and input
transformers by Jorgen Schou of Denmark.
Other features include optional transformer output and optional +48 volt
microphone powering.
GATELY ELECTRONICS, 57 W. HILL CREST RD., HAVERTOWN, PA 19083.
Circle No. 140
AMBER
MODEL
4550
compact instrument for applications
where the conventional VU meter provides insufficient information.
The device incorporates a solid state
High speed cassette duplicators and
disc mastering facilities will find the in-
signal.
decay time and sensitivity are available on
special order.
AMBER ELECTRO DESIGN LTD. 613100 FRANCOIS, MONTREAL QUEBEC,
CANADA H3E 1G2
formation the display gives about master
tapes useful in spotting potential problem
display and uses a digital time -sharing areas caused by excessive energy in a
technique to achieve an inexpensive and particular portion of the spectrum. FM
light weight instrument. The display di- and Television broadcasters will find a
vides the audio spectrum into 10 octave - similar application in identifying the
width segments, giving a total coverage of source of high end distortion.
10 octaves (20Hz to 20kHz). Each octave
The instrument is supplied in a portable
is displayed on a vertical column of 10 enclosure and accessory hardware is availlight emitting diodes. The total 10 x 10 able to permit rack mounting where
matrix thus gives a real time display of desired. Variations in certain parameters
spectral energy content of the audio such as filter frequencies, response and
Included in the device are two accumulative memories, useful when it is desired
to retain frequency distribution for later
evaluation or comparison. Each memory
has a MEMORY ENTER switch and an
ERASE button. In addition, a SAMPLE
button allows short duration (effectively
instantaneous) samples to be memorized.
Four audio inputs can be accommodated
and selected in any combination by front
panel push buttons. A step type attenuator varies the input sensitivity in 2dB
increments to accommodate a wide range
of audio levels.
Applications for the device include
analysis of program information prior to
media processing, evaluations of room
acoustics, comparisons of audio programs,
frequency response testing and noise and
signal study.
Circle No. 141
LEXICON ANNOUNCES NEW 90dB
DIGITAL DELAY SYSTEM
Lexicon, Inc., Waltham, Massachusetts,
has announced a new family of digital
delay systems featuring a 90dB dynamic
range for recording studio, sound reinforcement and laboratory applications.
A second generation system, the new
Delta T Model 102 Series has up to five
delay outputs, each independently adjustable on the front panel. Additional slave
units (up to 50 outputs) may be cascaded
for long delay requirements with no
degradation of audio output. The new
Sescoms
quality is showing!
quality at the AES Fall Convention on September 9
in Booth 78 at New York's Waldorf- Astoria.
You'll be impressed by our products. So don't miss the show
and don't miss Sescom.
See Sescom's
- 12
AUDIO
SPECTRUM DISPLAY
The Amber Audio Spectrum Display
provides a real time presentation of the
spectral energy content of an audio signal.
SESCOM MANUFACTURES
QUALITY ENGINEERED SOUND PRODUCTS:
MICROPHONES MIC ACCESSORIES MIC SPLITTER
CABLES CABLE TESTER SPLIT MATCHER
AUDIO TRANSFORMERS
This information, previously available
only by using expensive lab quality analysers, is now available in a low cost,
Qujlity Engineered Sound Products
P. 0. Box 590, Gardena, CA 90247 U.S.A.
(213) 770 -3510 TWX- 910- 3286189
Sescom, Inc.
Circle No. 142
www.americanradiohistory.com
Re/p 61
Swiss Performance
We Repeat
Electro Sound's new ES -505
series recorder /reproducers
have a heritage of classic
design and precision
performance. They've been
engineered specifically for
broadcasters, recording
studios, and other
professional users.
Electro Sound builds
professional, high speed audio
tape duplicating systems.
The ES -6000 is our 240 ips
version. Long lasting,
versatile hardware.
-
European or American
no other machine has more
significant "Operator
Engineered" features.
The ES -505
Disappearing headgate, built in audio oscillator, optical
motion sensing, continuous
bias monitor, differential disc
brakes, optional edit third
reel, fully lighted controls
and much more
We're noted for sophisticated
state -of- the -art designs that
produce a finished tape of
unquestioned high quality.
That's what pays off in
operating profits for our
customers.
And Electro Sound is the
only single source for
duplicators, loading racks, QC
reproducers, mastering
devices, cartridge and
cassette winders and splicers.
.
The ES -505 is available in
1/4" or 1/2" versions, with one,
two or four channels of
electronics in console,
portable or unmounted
configurations.
Performance specs -we
match or beat the best!
And at American prices.
The ES -6000
ELECTRO SOUND
725 KIFER ROAD,
(408) 245 -6600
Re/p 62
SUNNYVALE, CA 94086
TELEX: 346324 LECTROSND SUVL
Circle No.
143
www.americanradiohistory.com
Whether you duplicate
retail music, broadcast
syndications, or "spoken
word" cassettes, we have a
system for you. After all, the
giants who pioneered the
pre- recorded tape industry,
as well as those just joining it,
are using Electro Sound
systems in 30 countries.
system offers up to 320 ms of total delay
per main frame in 5 ms increments in
economical 40 ms modules (or up to
128 ms delay per main frame in 2 ms
increments in 16 mm modules). The Delta
T offers extensive options for both studio
and sound reinforcement applications. Its
fully modular cons :ruction permits convenient field expansion and maintenance.
signal output from -74dBM to +4dBM.
The signal generator is designed so that it
may be turned on or off without intro-
ducing transients into the circuitry.
The Model 800 is solid state and its
compact size (3'/2" x 11/2" x 2 -7/8 ") makes
for easy installation. All controls are
located on the front panel. Some operating specifications are: frequency tolerance
± 10% of selection; THD less than .05 %,
100Hz to 15kHz, .1% at 50Hz.
The SPECTRA SONICS Model 800 is
available for immediate shipment, reasonably priced at $84.00.
SPECTRA SONICS, 770 WALL AVE.
OGDEN, UTAH 84404.
quency contours; it can duplicate the
curves of standard peaking-type equalizers
as well as produce a variety of curves
beyond their means. The device permits
highly selective control of the different
elements of timbre; interaction between
bands is minimal. The contour created by
the switch levers during operation serves
as a visual indication of the frequency
contour created.
Circle No. 145
WEIGHTING NETWORK FOR NOISE
MEASUREMENTS
Features include a five- position LED
headroom indicator to verify correct operating settings. Transformer coupled inputs
and outputs are standard and all units are
manufactured with computer quality components and construction for high
reliability.
Complete specifications covering all
within the Model 102 series are available
from: LEXICON, INC., 60 TURNER ST.,
WALTHAM, MA 02_54.
FROM JOEL
ASSOCIATES
This unit is designed to be placed between the device whose noise is to be
measured and a high impedance audio volt
meter. The curve obtained is based on the
"A" curve, ASA standard S1.4-1961, and
adopted by the NAB in 1965. It is also
the curve recommended by Ampex and
other tape recorder manufacturers in
making weighted noise measurements.
Circle Alo. 144
SPECTRA SONICS
SIGNAL GENERATOR
The SPECTRA SONICS Model 800
Signal Generator has five selectable frequencies (50Hz, 1 OUHz, 1 kHz, 10kHz,
and 15kHz) and a controllable level of
IN
OUT
o
100
50
/
¡10K
1.K
!\ 15K
A weighted noise measurement is designed to give a response curve similar to
the ear at low volume levels and is
intended to give a more useful indication
of the subjective signal to noise ratio
then unweighted measurements.
The unit measures 1 1/8 x 3 1/4 x
2 1/8 with banana type plugs and 5 way
binding posts on standard 3/4 inch centers.
Available from stock $34.50.
JOEL ASSOCIATES, 528 RIVER ROAD,
TEANECK, N.J. 07666.
Circle No. 146
FREQUENCY
E
FYI= -700-1
\ /
-5
-2
'
.
- +2
-10
oo--/
0
GAAN
\-+4
NINE -BAND GRAPHIC EQUALIZER
MODEL 559
The Audio Processing Systems Model
559 Equalizer provides nine -band graphic
equalization in a compact console- or
rack -mountable module. Using leverwheel
switches to provide 12dB of cut to 15dB
of boost in bands centered at 35Hz, 75Hz,
160Hz, 350Hz, 750Hz, 1600Hz, 3500Hz,
7500Hz, and 16kHz, the Model 559
allows the user control over virtually all
portions of the audio spectrum simultaneously.
The Model 559 is capable of generating
an almost inexhaustible number of fre-
A pushbutton switch, LED -illuminated,
activates the equalization circuits. Size is
11/2" wide by 51/4" high by 6" deep; noise
is -90dBm and distortion at full output
( +24dBm) is less than 0.25% THD. The
Model 559 is available direct from AUDIO
PROCESSING SYSTEMS, INC.,
and
through AUTOMATED PROCESSES,INC.
MELVILLE, NEW YORK, and is fully
compatible with Automated's Model 550A
Equalizer.
AUDIO PROCESSING SYSTEMS, INC.
98 WOODLAND RD., SOUTHBOROUGH,
MA. 01772
Circle No. 147
J. SCULLY INTRODUCES THE
"PREVIEW MASTER"
L.J. Scully Manufacturing Company of
Bridgeport, Connecticut has announced
that the Preview Master is now available
at a cost of $4525 f.o.b. Bridgeport.
Utilizing solid state, logic control circuitry, the Preview Master is a versatile
L.
Re/p 63
www.americanradiohistory.com
machine for disc cutting companies interested in updating old systems or adding
new equipment.
The Preview Master operates with the
L.J. Scully closed loop drive which substantially improves wow and flutter. Other
L.J. Scully features incorporated into the
Preview Master are NAB /CCIR equalization, ability to accommodate most preview
times, and cue modes for easy loading.
The Preview Master can be ordered for
use on a standard rack or to be mounted
on their specially fitted, hinged -top formica console. The additional cost of the
waist level console is $503.
L. J. SCULLY, 138 HURD AVENUE,
BRIDGEPORT, CT 06604.
Circle No. 148
HAECO `VP -1000' COMPUTERIZED
FOR DISC RECORDING
SYSTEM
LATHES
HAECO introduces its VP -1000, the
first completely digitally computerized
'98
WNW
000óia®0000°?.
t8
S800®
00
Variable Pitch /Depth System for disc
recording lathes. A major breakthrough in
Mastering technology, this unique control
system employs a specially designed wide-
range, low noise, high output, dual 300
millisecond Audio Delay Line, thereby
eliminating the need for any preview
channels. The new unit, according to the
manufacturer, was developed to significantly improve the performance of all
lathe systems, regardless of vintage. Aside
from permitting more time, with better
geometry, the VP -1000 provides total
automation of all lathe functions.
HAECO, 14110 AETNA STREET, VAN
NUYS, CA 91401.
Circle No. 149
MODULAR PLUG-IN DESIGN, MANY
OPTIONS ADD FLEXIBILITY TO NEW
API AUDIO CONSOLE
A new audio control console, Model
1604, from Automated Processes, Inc.,
80 Marcus Drive, Melville, N.Y. 11746,
offers great flexibility to the audio professional. Performance options can be
selected from among plug -in modules,
and a variety of interchangeable equalizers
is also available.
The relatively low cost of this console
makes it suitable for use for either fixed
or remote recording, and by broadcasters
as a production or on- the -air console. It
will accommodate 16 inputs, 4 echo
channels, 2 foldback circuits, 4 output
channels, 4 submasters, 4 speaker monitoring, slate, tone and intercom circuits,
and audition and cue facilities. For broadcast applications, the 1604 console has
the necessary foldback, audition, intercom
and program interlock features, and may
be equipped with optional modules offering remote control of tape machines and
turntables, or remote input pre -selection.
All external connections are plug -in to
allow rapid installation.
The Model 1604 may be tabletop
mounted or free standing, and optional
features may be added at any time, since
all are factory pre- wired, permitting easy
field installation.
For additional information and catalog,
contact AUTOMATED PROCESSES,INC.
80 MARCUS DRIVE, MELVILLE, N.Y.
11746.
Circle No. 150
DUAL EQUALIZED REVERB UNIT
FROM MULTI -TRACK
Multi -Track of Hollywood, California
has announced the introduction of the
new Dual Spring Reverb Unit. Each of its
channels has input-delay time control,
L.E.D. overload indicator, low and high
frequency shelving equalization, and output drive level control. The electronics
Reverb breaklhrough!
2channels:$500°°
The Clover R -500
professional quality
reverb suitable for recording,
broadcast, and P. A. applications.
Hi & low Z inputs and outputs
Four transmission lines per channel
Decay time: 1.8 secs Signal to noise: 75dB
is a
Dealer Inquiries Invited
CLOVER SYSTEMS
Re/p 64
6232 SANTA MONICA BLVD., HOLLYWOOD, CA 90038
Circle No. 151
www.americanradiohistory.com
(213) 463 -2371
fiers, a compact 7 1 /2 -15ips transport,
and an eight- track, two channel shifting
head assembly.
The shifting head assembly on the
Model 511 eliminates the need to use a
conventional eight-track studio recorder
for duplicator work master production.
The two channel operation of the
and the springs are complete in one rack
mount package. The front panne' is black
annodized with silver dial markings for
long life and the knobs are aluminum
with EZ grip knurling and indicator line.
A special input gain stage lias been
added to the unit so it is compatible with
the Tascam Series Mixers.
The dual unit will sell for $550.00.
MULTI -TRACK, P.O. BOX 3187, HOLLYWOOD, CA 90028.
Model 511 minimizes service and production cost. The Model 511 is also more
compact than most conventional eighttrack recorders. The solid state circuitry
and tape transport are housed in a durable
attractive case. For user convenience the
Model 511 is available in a table top
cabinet or a floor console unit.
The Audio /Tek Model 511 is the first
in a series of professional studio recorders.
Circle No. 152
NEW LOWER COST MAGNETIC TAPE
TENSION GAGE OFFERED BY TENTEL
TENTEL of Campbell, California, has
introduced a new tape tension gage for
audio, video, and computer tape trans-
ports. TENTEL offers hand -held instruments that quickly and accurately measúre
dynamic or static tension on magnetic
recording tape of all widths.
Tape tension on video machines can be
accurately set while the machine is operating; thus eliminating time base errors
due to tape stretch. Head wear is optimized
and transient problems can be detected.
The unit is self contained, requires no
external power, operates irk any orientation and reads both in ounces and grams
of tension. Models are available in 5, 12,
or 20 ounce full scale ranges.
Prices start at $179 complete with
fitted carrying case.
TENTEL,
1210 CAMDEN AVENUE,
CAMPBELL, CA 95008.
After you use the 1056,
we'll know one thing
about your dub quality:
it just got better.
Professional studios that make lots of dubs for radio, welcome the
speed and quality they get using the Gamer 1056. It offers a whole
new set of advantages for producers of reel -to -reel duplicates for
radio, AV, or educational needs. Some of those are: Single capstan drives the master and all five copies. Solid -state electronics
and special heads provide outstanding frequency response.
Two speed drive allows either 30 or 60 i.p.s. duplicating.
Extra -fast
rewind of master tape speeds production.
Unique forward tilt of
transport mechanism aids threading.
Conveniently located controls feature push button operation.
Circle No. 153
CHANNEL RECORDER FOR
EIGHT -TRACK MASTERS
The Audio /Tek Model 511 eight- track,
one inch recorder is specifically designed
to prepare duplicator work masters.
The Model 511 is comprised of two
single channel reproduce /record ampliTWO
GARNER ELECTRONICS
4200 NORTH 48TH STREET
LINCOLN.
NEBRASKA 68504
Circle No. 154
www.americanradiohistory.com
Re/p 65
Price: floor console unit $4,950, table
top unit $4,850.
AUDIO /TEK INC., P.O. BOX 5012, SAN
JOSE, CALIFORNIA 95150
Circle No. 155
SPECTRA SONICS IMPROVED AUDIO
AMPLIFIER
MODEL 110
SPECTRA SONICS has developed an
improved version of the time proven
Model 101 Audio Amplifier. This new
audio amplifier is designated the Model
110 and like the Model 101 is unconditionally guaranteed for two years. The
Model 110 fills the need for an audio
amplifier of professional calibre with increased output ( +24dBm) for use with
bi -polar (t24 VDC) power.
-
SERVICES
LOCATION RECORDING: up to
16 tr. 300' mike lines; Video /talkback
& Stereo playback systems. Separate
Quad wet monitoring w/4310 JBL's.
MCI 16 tr or 8 tr; Tascam boards.
CALL: LEE HAZEN, (615) 824-2311,
OR WRITE TO RT 2, HENDERSONVILLE, TN. 37075.
Recording and duplicating services for
radio commercials, live recording, on
location recording, studio and equipment rentals and demos. WESTFIELD
STUDIOS, 780 WESTFIELD AVE.,
BRIDGEPORT, CT. 06606, (203)
371 -0151.
EQUIPMENT
-
Circle No. 156
Classified
CLASSIFIED ADVERTISING
RATES
Prepaid with submitted copy:
$20.00
One column inch (1" x 21/4 ")
14.00
1/2 column inch (1/2" x 23/4")
`(If billing is required add 20 %.)
components, $250 per system; Ampex
440, full -track, $1050; Scully 280,
full- track, $1125; 3 DBX 157, $375
each; DBX 187. $1450. SOUND 80,
MINNEAPOLIS, MN. (612) 721 -6341.
1
Reel Specialists: Boxed 101/2"
reels $3.00@ flanges $1.25@.
101/2" Precision reels $6.50 @, flanges
$2.25@ Heavy duty or Tapered.
Wanted: used 1/4" NAB & Precision
hubs. SOUNDD INVESTMENT CO.,
POB 88338, ATLANTA, GA. 30338.
101/2"
NAB
COLLEGE FOR RECORDING ARTS,
665 Harrison,SF,94107. ENROLL NOW
for October 21st Semester on RECORDING TECHNIQUE, MUSIC, LAW, BUSINESS. Prof. 16 -trk studio.
(415) 781 -6306
Typical of SPECTRA SONICS quality,
the Model 110 is guaranteed to be superior to any other audio amplifier in
such critical functions as noise, distortion,
frequency response and peak -overload.
Some of the specifications are: Output
noise, not over an input equivalent of
-127dBm, unweighted 20Hz to 20kHz,
input terminated 600 ohms; total har( +21dBm,
monic distortion
20Hz to
20kHz) unmeasureable, less than 1 /100th
of 1% (measurement residual); frequency
response ( +21dBm) within .1dB from
10Hz to 200kHz; peak -overload, 1000 %,
recovery time, 1 microsecond.
Some applications are: microphone
pre -amplifier, booster amplifier, mixing
amplifier and etc.
Solid state, contained on a printed
circuit card (21/4" x 5" x 1/2 "), the Model
110 is available from stock.
Price $72.00.
SPECTRA SONICS, 770 WALL AVE.,
OGDEN, UTAH 84404.
SPECTRA SONICS CUSTOM 22 -in/
8 -out remix console, $3,950. 8 Altec
9846 -8A, $350 each; 8 JBL 4320
ONE STOP FOR ALL YOUR PROFESSIONAL
AUDIO REQUIREMENTS.
BOTTOM LINE ORIENTED.
F. T. C. BREWER COMPANY
P.O. Box 8057, Pensacola, Florida. 32505
SPLICE FASTER, BETTER BY SHEARING REPLACES RAZOR. Has attached
splicing tape dispenser. Professional quality.
Specify 1/4 inch or cassette groove. Price:
$24.95 plus $1.00 for handling. Distributors wanted. Details: NRPR, BOX 289,
MCLEAN, VA. 22101
Send for FREE Catalog
and Audio Applications
MARK -A -TRACK WRITE -ON STRIPS
are now available! End the guesswork
during basics or remix with custom made
write -on panels that fit right above the
faders. Specify color desired, number of
faders, and width of individual fader.
$15.00 prepaid
MARK -A -TRACK PRODUCTS
3557 Dickerson Road
Nashville, Tenn.
37207
FOR SALE: New 14" NAB Ampex
aluminum flanges have never been
removed from original box. Package
of 10
$8.00 prepaid. SOUNDD
INVESTMENT CO., POB 338, DUN WOODY, GA. 30338.
-
One Way Noise Reduction (10 -14dB) for
cutting rooms /tape copies; + monitor
equalizers at $75 /channel; + free room
equalization with purchase of 1/3 octave
filters; + 1000's of state of the art studio products, customized
aligned
calibrated
biased, etc. Music & Sound
Ltd.,
11'/2 Old
-
York Rd., Willow Grove,
PA 19090. (215) 659 -9251.
All Shipped Prepaid/Insured
$1.00
SOME INFORMATION ON THE MUSIC
INDUSTRY AND HOW IT WORKS
Seven Arts Press, Inc. Dept. REP
6605 Hollywood Blvd.
Hollywood, CA 90028
Circle No. 157
We're scrapping a Custom Console:
Fairchild
Gotham Attenuators $25
661TL Autotens $15 ; Large VU Meters
$15.; Hi -Lo Equalizers $10.; Jack Panels
$8.; (16 of everything) Plus Table Racks,
Power Supplies, Amplifiers, Relays and
Transformers. One Grand takes all.
(212 / 581 -0123)
-
-
OPAMP LABS
1033 No. Sycamore Ave.
Los Angeles, CA 90038
(213) 934 -3566
1/4"
:
WANTED: Tele 251 mike with power
supply and cable. Peppenhorst Productions, P.O. Box 11211, Memphis, Tenn.
38111.
UNITED AUDIO RECORDING, the audio
marketplace. Sales and Service for Scully/
Metrotech, and Neuman, EMT, ElectroVoice, Shure, Quad Eight, Spectra Sonics,
DBX, Interface Electronics, MicMix Master room Chambers and others. (512)684-4000,
5310 JACKWOOD, SAN ANTONIO, TX.
78238.
Re/p 66
www.americanradiohistory.com
* SERIES "B" MIXING CONSOLE
* VARI -BAND 5 SECTION
*
*
*
PARAMETERIC EQUALIZER
DUAL EQUALIZED REVERB
LONG & SHORT THROW SLIDE
FADERS
HIGH BALLISTIC VU METER
P.O. BOX 3187
HOLLYWOOD, CA 90028
(213) 467 -7890
Circle No. 158
High Intensity tuned sound reinforcement systems including narrow band
(5Hz) feedback suppression, detailed regenerative response room equalization
± 1dB, 15% articulation loss of consonants. 1000's of customized professional
products, all shipped prepaid /insured.
Music & Sound Ltd., 111/2 Old York Rd.,
Willow Grove, PA 19090
(215) 659 -9251
Inventors / Engineers
FOR SALE: AKGC -24 Condenser Stereo
Twin Mike with M -S Control Box. $1050.
Four AKG C451 Mikes with C5 Capsules,
$150.00 ea. Excellent condition. Scotch
176 tape on 7" reels, 4 passes maximum,
$1.25 per reel, quantities of 100. NPR
ENGINEERING, 2025 M Street, N.W.
WASHINGTON, D.C. 20036
NEW YORK'S LEADING PRO
AUDIO /VIDEO DISTRIBUTOR
GO 24 TRACK!
24 -16-8 track machine and
don't spend the big bucks. With one
machine you can offer all 3 configurations for what you'd expect to pay for a
16 track alone. This is the original MCI
with individual meter modules. Corn plete with autolocator, digital timer &
FOR
AUDIO, VIDEO, BROADCAST,
PUBLIC ADDRESS & HI -FI STEREO
SYSTEMS.
Representing over 130 audio/video
manufacturers, featuring such names
as:
AMPEX SCULLY, TASCAM, SONY,
J.B. LANSING, NEUMANN, ALTEC,
factory authorized
SALES SERVICE PARTS
SYSTEMS DESIGN - INSTALLATION
-
320 WEST 46 STREET
NEW YORK, N.Y. 10036
(2121 541 -5900
FOR SALE:
PHONE: (312) 529 -1001.
&
BILL.
BEST SSS SAVINGS
Hound Dog
Recording Studio
,'58 E Coiorago Bivg
Pasaopna Cahf 91101
WESTFIELD AVE., BRIDGEPORT,
CT.
06606, (203) 371 -0152. AN
ALTEC LANSING ACOUSTA -VOICE
SOUND CONTRACTOR.
16 like new I'I'I Para-
metric Equalizers, free power supplies
& custom formica equipment cabinet
with purchase of all sixteen. Also
available, one MCI j11 -16 16 -track
recorder with auto- locator, mint condition. Contact: ALAN KUBICKA,
P.O. BOX 556, MEDINAH, IL. 60157,
BEST IN ENGINEERING
YOUR PALS DOUG. RUSS
All major lines of Pro, Music and PA
audio equipment, equipment rentals
and professional audio services.
ALTEL SOUND SYSTEMS, 780
MARTIN AUDIO /VIDEO CORP.
.
BEST IN EQUIPMENT
AMPEX. ALTEC. JBL NEUMAN
-
Write for FREE CATALOG!
..
WHO GIVES YOU
Kendun
modifications to eliminate
punch -in /out clicks and reduce hum.
Reason for sale
going to a machine
with film -lock. Price $22,000. Many
extra cards, motors, other spares available. A real bargain for a one machine
studio. Maintained in A -One condition
by
Kendun Recorders /Kent Duncan
(213) 843 -8096.
McINTOSH, AKG, DYNAIR, T.V.
MICROTIME, UREI, 3M and other
major brands.
The largest "in stock" inventory
of equipment, accessories and parts.
Competitive discount prices.
-
WOOf!
Buy this
(213) 449-8027
STOP KIDDING YOURSELF
.
.
.
ABOUT HEAD DEGAUSSING!
Use a full power degausser and
then measure the results with a
magnetometer.
The Annis Han -D -Mag measures
over 400 Oerstads .
. more
than
5 -1/2 times as powerful as the head
degausser you're probably using now.
Then check the results with the Annis
Magnetometer, included in the Han -DMag kit for S29.75. Prepaid anyplace
in the U.S. from Audiotechniques,
Inc. Send your check or money
order to:
AUDIOTECHNIQUES,
INC.,
142
HAMILTON AVENUE, STANFORD,
CT. 06902, (203) 359 -2312.
.
SALE:
AMPEX 16 track MM 1000
Excellent
condition non -servo, 15 -30, 21/2 yrs. old.
$ 13,000.00
STUDIO WEST (7141 277 -4714
FOR
1
1
1
1
1
-
FOR SALE
Ampex 440-4 includes two track stereo
head block IN CONSOLE 71/2-15 ips
$2950.00
Ampex 300 top plate MCI electronics two track IN CONSOLE
71/2-15 ips
$1950.00
Ampex 351
top plate MCI electronics
two track IN CONSOLE
71/2-15 ips
$1850.00
Ampex 351
top plate MCI electronics in Scully portable cases
two track stereo 71/2.15 ips
$1750.00
MCI 16 track tape machine with
matching 8 track heads and guides
autolocator IN CONSOLE
-
-
-
EMPLOYMENT
-
-
-
15 -30 ips
$12,500.00
CRITERIA RECORDING STUDIOS
1755 NE 149 St.
Miami, Florida 33161
(3051 947-5611
Major audio -visual recording studio Production House needs maintenance
engineer-mixer. Experience necessary in
maintaining Ampex, Scully & Fairchild.
Will train, if necessary, in dramatic
mixing. NO MUSIC. Age, sex, color,
nationality no object prefer left- handed.
Experience with theatre lighting equipment handy. Salary open.
Call 515 -282 -8306 NOW.
Gait
in hal
.
Half the cost, time,
and worry, at
fDick McGrew
Recording Service in Dallas.
Dick beats the
with
record
competition
master costs like $30
per side for stereo 12 inch 331/3 rpm, and
$10 per side for 45's. The day he receives
your tape, he'll groove your master with the
Neumann SX 68 cutter, the ultimate in cutting
machines. Dick'll give it the individual and
expert attention of a man who does a lot of
producing himself.
For no extra charge, Dick will provide equalization, reverberation, or other special services
at your request. And he's used to giving attention to problem tapes.
Interested in album pressing or singles?
Dick's got a competitive price list for these
services, too. Let us hear you!
-
continued ...
7027
TWIN
HILLS AVE
DALLAS 75231
214 691.5107
.
Re/p 67
www.americanradiohistory.com
ò
LETTERS and LATE NEWS... .
continued from page 31 ... .
EMPLOYMENT
continued
Chicago recording studio in need of
department head for its technical staff.
Should be capable of engineering design.
Studio facilities consist of 6 recording
studios, with film mixing. Please call or
write to: D/B Studios, Inc., 676 North
LaSalle Street, Chicago, Illinois 60610.
312/944-3600
Attention: ROGER C.
PETERSEN
-
Maintenance
Engineer
RCA Records has an immediate
opening for an experienced Maintenance Engineer. Knowledge of
Neumann Disk Mastering equipment
and transistor technology required.
Excellent starting salary and
company-paid benefits.
Please forward a resume, including
salary history to:
S. J. Ness
RCA Records
1133 Avenue of the Americas
New York, N.Y. 10036
are an equal
employer M/F.
We
opportunity
ncn
Since Altec is a major producer of raw
frame loudspeakers, several suggestions
are made for incorporating one or more
Altec speakers into a new enclosure. For
example, Altec provides enclooure construction dimensional drawings for using
the famed 604, 15 -inch duplex speaker,
"Voice of the Theatre," systems, and
other speaker system combinations for
smaller enclosures.
Much detail is given to selection of
materials for the enclosure, including the
type of board, acoustic damping material,
stiffeners, and the grille.
Other useful material found in the
publication includes a chart of common
sound pressure levels, frequency ranges of
musical instruments, and a glossary of
audio terms.
The publication can be ordered by
sending $2.00 to Altec Corp., 1515 S.
Manchester, Anaheim, CA 92803. Page
size is 81/2 x 11 ".
LA SALLE AUDIO EXPANDS
Cindy Guzzo, General Manager of La
Salle Audio announces the addition of
Jon Hanson as Sales Engineer. Mr. Hanson
was formerly Chief Technical Engineer at
db Studios in Chicago and, prior to that,
a Systems Engineer for Dukane Corporation in St. Charles, Illinois. La Salle Audio
is moving to a larger facility, 740 N. Rush
Street, Chicago, Illinois 60611 as of September 1. The new office will afford
complete demonstration capabilities for
the convenience of their customers.
`LOGICAL LOOK AT LEASING' DISCUSSES ITS ADVANTAGES
"A Logical Look at Leasing," a new
C.I.T. Leasing Corporation booklet, des-
cribes the advantages, alternatives and
"how's and why's" of one of the most
widely used forms of acquiring equipment
and machinery leasing.
Although leasing is not new, its growth
as a source of capital has been especially
rapid over the past ten years. Essentially,
leasing is a way of obtaining the use of
equipment without the need to buy it,
and differs from other forms of financing
in that it is designed for those who realize
it is not the ownership of equipment that
contributes to profits.
The new booklet describes the two
basic types of leases available, and discusses a true lease and the IRS, end -oflease alternatives, and balance sheet and
cash flow effects.
"Probably the most important single
reason for leasing is to conserve working
capital," the booklet states, but it points
out and discusses many other advantages.
Copies of "A Logical Look a4 Leasing"
may be obtained by writing to Harold A.
Post, assistant vice president, C.I.T. Leasing Corporation, 650 Madison Avenue,
New York, N.Y. 10022.
-
MARSHANK PRO -AUDIO DIVISION TO
BE HEADED BY HEADRICK
Marshank Sales Co., 10455 W. Jefferson
Blvd., Culver City, CA 90230 is pleased
to announce the establishment of a Professional Audio Division to be headed up
by Marvin Headrick.
Headrick, for the past two years, has
been Western Regional Sales Manager for
McMartin Industries covering Broadcast,
BGM, and Sound Contractor Markets.
Prior to this time, he was Marketing
Manager for Quad-Eight and Sales Manager
for Longevin Co.
Marshank Sales Co. is celebrating its
54th year in business.
Magnetic Reference Laboratory
Whether you're using low noise or high output tape,
with or without Dolby, from 1/4" to 2 ", 33/4 to 30 ips,
you'll choose MRL ... because only MRL guarantees
every test tape they manufacture.
Their dependability and accuracy have made MRL the
world wide choice of most major recorder manufacturers
.. and, after all, they would know what test tape is
best for their recorders, they're the people
who design and build them.
Distributed exclusively through
Fullerton Pkwy.
Chicago, Illinois 60614 (312) 935 -4900
B. W. Associates, 415 W.
Exclusive Export Agent: Gotham Export Corp., New York, N.Y.
Re/p 68
Circle No. 161
www.americanradiohistory.com
Studio Supply Company's enviable reputation as turn -key recording
studio builders and designers is well -known and respected, so we won't
tell you about something you know about.
Let's talk about something that most studio builders make you ask
about -what happens after you've got your studio and we've got your
móney. SERVICE!
-Studio Supply Company unconditionally warrants any turn -key studio
installed by us
-total
system and
individual
pieces
-parts, labor and travel expenses for
STUDIO SUPPLY HAS ACCESdfO MANY LEASING
PLANS AND OTHER SOURCES. .
.
WHY NOT CALL US TODAY.
(615) 327 -3075
SUPPLY XOMPANY
.
.
of equipment
a
period of
90 days from completion, over and above any manufacturers warranty
This isn't new -it's been that way since Day One. When manufacturers
parts and labor warranties exceed this, we back them to the hilt.
Of the two major turn -key studio builders in the United States, only
Studio Supply Company has complete service staff, spares, and full inhouse bench and field support for every item we sell. We have even been
asked to (and are glad to) fix gear the other guys have sold.
From the day we take our first look at a new product, to determine its
performance, suitability and reliability, our service guys are reading the
manuals, talking with the designers, and intimately learning all circuits and
systems to insure that from the first piece installed, service is timely and
competent.
Our people have more experience, knowledge, and expertise in the service
of our systems and the gear we sell than any similar organization. Each
prime field service man has over 150 hours of intensive classroom training
and our guys collectively have wéll-river 100 years of professional service
experience.
The reason we accept long term service respon3ibïty for the studios we
P.O. BOX
280
build
is....
NASHVILLE, TENN. 37202
WE DO IT RIGHT THE FIRST TIME
Circle No. 162
www.americanradiohistory.com
Studio equipment homy /hopping guide
In the world of the professional sound engineer, advance follows advance,
and new product follows new product. Bring yourself up -to-date with the
Shure Professional Products Catalog, 24 pages of Shure products to make
your job easier: the SM61 Microphone, beautiful to look at and virtually
immune to noise in hand -held applications
the SM7 Microphone, with
built -in, visually monitored, response tailoring
the ultra -versatile SM53
Microphone, with its own sy:tetn of accessories
the SE30 Gated Compressor /Mixer, for "hands- free" gain riding ... the SC35C Phono Cartridge,
the first cartridge optimized in design especially for on- the -air playback ..
and the incomparable V -15 Type Ill Phono Cartridge! For your own copy of
the catalog No. AL 312, write:
Shure Brothers Inc.
222 Hartrey Ave., Evanston, III. 60204
...
...
...
.
In Canada: A. C. Simmonds & Sons, Limited
Circle No. 163
www.americanradiohistory.com
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