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Electronic Instruments for the Musician

K-A-MOOG CO-

TRUMANSBURG, NEW YORK 14886 * AREA CODE 607 387-9200

November 25, 1964

Professor Otto W. Henry
Chairman, Dept. of Music
Washington and Jefferson College
Washington, Pennsylvania

Dear Professor Henry:

Thanks very much for your long letter in which you outline
your equipment needs. Let me comment upon your requirements in
the order in which you presented them.

(1) An oscillator bank: We do not have one to spare but
will probably have a laboratory model by the end of the year.
I'll be sure to send you one as soon as it is available.

(2) A bandpass filter: Same comments as above.

(3) A time compression machine: Such a machine presents very
difficult design problems, and we will probably not attempt to
build any of these in the foreseeable future. Some composers feel
it is a worthwhile addition, while others so not see only limited
application, As you say, you'll have to try one out for yourself
to see if it will be useful to you.

(4) A speed control device: This is a simple design prob-
lem, but I can't promise when we will design and build one. It
will definitely be before the summer, however,

(5) A frequency divider: A frequency divider can be built
to halve the frequency of any audio note. I hope you understand
the limitations of such a device. First, the input must be mono-
phonic, i.e., a frequency divider can only operate on one tone
rather than a chord. Second, the timbre of the output of the di-
vider will bear no relation to the timbre of the input. The out-
put of a frequency divider is a square wave which can be further
operated upon to make either sawtooth waves or triangular waves.
The frequency multiplier has similar restrictions. Even with
these restrictions, they are useful in electronic music compo-
sition. We have no plans to design such a divider or multiplier,
but I may get a chance to throw one together for evaluation next
year.

Moog to Henry
November 23, 1964
Page 2 -

(6) "Or" gates: In computer technology, an "or" gate is a
device which is on when any one of the inputs is on, and is off
when none of the inputs is on. It would have limited usefulness
in elctronics music composition, I believe, because there are
no intermediate states between "completely on" or "completely
off". Of more usefulness is an"amplitude follower" which controls
a variable gain amplifier so that its gain follows the ampli-
tude of the controlling signal. This is something we are work-
ing on right now for Professor Ussachevsky of Columbia University,
and I might be able to send you our prototype very shortly.

(7) A sound-into-light device: This is a straightforward
but large-scale design project. We have little interest in it at
the present time, because it is not directly related to the compo-
Sition of electronic music. In fact, we are working toward the
goal of producing equipment which can be played in real time, and
will thus allow live performance of electronic music. This alone
would give the audience "something to look at",

(8) A rythmic instrument: This is also on our design pro-
gram, but will probably not be worked on for another six months.

(9) A light-sensitive volume control: I was not impressed
with Dr. Schaeffer's ""Hamograph". I think the same thing could be
accomplished with a rythmic instrument in combination with an

envelope generator (bell gate) of sophisticated design. I hope
to develop this idea next year.

That's our situation now; lots of promises, but nothing inm-
mediate for you to try. I should have an oscillator bank for you
in a couple of months, however.

Thanks also for your suggestions regarding the proposed sem-
inar. I am delighted to know that you are interested in partici-
pating. Please tell me when you will be able to participate next
summer. I anticipate a total duration of about four weeks, during
which time I would conduct a session on basic musical electronics,
and one or two practicing electronic music composers will instruct
in the esthetics of electronic music composition, and in studio
technique, I anticipate further to have two or three studio setups
available by that time,

Thanks again for your interest. Please let me know at your
convenience, if you will be able to take four weeks during the
summer to participate ina seminar here. Also, I would appreciate
receiving tapes of some of your compositions.

Sincerely yours,

Robert A. Moog