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16 November 1964

Mr. Robert A. Moog
R. As Me Og Company
Trumansburg, New York 146866

Dear Mr. Moozs

Thank you for your interested reply. I have a bell gate and a
ring. modulator, but I would be very interested indeed in trying out a
bank. of oe as Bip d Rem ag Department has just @egked to have its
audio gene

in reply to your questions about my greatest needs at the moment,
I am supplying the following list (you asked for it!).

1. An oselliator bank. Selfeexplanatory.

A beand=pass filter. I heve examined various types of commercial
filters but cannot afford any of them. They seem to me to be
overpriced, especially since I"ve been told thet one can assemble
a reasonable facsimile for about $50. I have not been able to
Locate a schematic, however, and my math will not stand up to de-
signing my own. Perhaps you know where I could obtain such a
schomatic or else a reasonably priced kit.

>> A Springer Zeiltmasse machine. Dr. Schaeffer has seen one of these
in Europe, but says it has only limited application. Basically
it is similar to the Bell "Edispot". With it one can viiry the
pitch of a particular envelope without affecting its length or
duzvation, because of the rotating miltiple tape heads. I'd like
to "see for myself."

A speed control device. I've read that an A.C. tape transport
motor ean be controlled by hooking wp a@ sine generator, a 100 watt
basic amplifier and a variable transformer. The generator supplies
the 60 cycles and deviation from this will speed up or slow dow
the motor. I have a deck attached to a variable transformer. but

ae this only controls the voltage. I eam unable to do anything more
nen slow ea tape dow. The range is very small and varies according
had "7 syiction involved. Usually. the best I can do is about a

Otherwise I am limited to octave transposi-
-t40n. This te a very 'real handicap. Perhaps you can advise me
It seems to me that if this is a practical manner in which speed
control can be managed, someone ought to mut out e paeiiges wnt
imu which all these components are matched.

A Prequency divider. I*ve budlt one of these, but it has only a
limited use because it has to be reetuned for every other note.

Mr. Robert Ae Moog
Movesber 16, 1964

Pace Two

a frequency divider and/or miltiplier can be truly independent
of frequency, this would be ea useful instrument for thickening
a lines and building spectra from pre-existent sources.
I'd like to see a unit thet would contain both @ divider and a
ay which could be used interchangeably. Perhaps it could

mtein a control which would allow @ivision/mltiplication at
Gaareke other than the octeve,.

Gosincidence and "Or" gates. I've seen diagrams of these in Elec�
tronics texts, but have not experimented with item as yet. I bee

Eteverthese could be adapted for use by electronic music composers.

I'm only ettessing, but I suspect that some of these instruments are
already used in Music Synthesizer computors. These gates could be
useful. For instance, if one has a rhythmic figure and wishes to
e6d further sounds to it, the "and" gate wits simplify the process.
I don't know how you would do it otherwise. except by a long
splicing process. New rhythms could be snenbad trim vabetine mate
erial by mixing tape loops through the gate. Only when they all
strike @t once will a sound be passed.

A soundeinto�light device. Dr. Schaeffer has one of these but I
�id not have a chance to examine it. I heave been trying to set
wo my own to use at a projected concert here at the college. Pere
haps you can help me. It consists of a set of band pass filters
which trigger small relays. The relays control a bank of colored
i@hte which are focused on a mobile�like collection of hanging
mirrors, which in turn reflect the lights onto a screen. The screen
econeeals the whole device, which is hidden behind it. This has
nothing to do with the production of music, dbut it would give the
audience something to look at during a concert. I heave learned of
an instrument called the "Andio-Golor" made by CONAR (5939 Wisconsin
Avemme, Washington, D. C. ), but I assume it is om & smaller scale
than the one which I envision. I enclose a dlagrem of my idea.

A Roythmic Instrument. I have seen diagrams of the Wurlitzer "Side
Men" and the Baldwin "Tempo Mate" both of which ave electronic organ
sceessories designed to supply drum and trap accompaniments in a
variety of dance rhythms. I have also noticed a machine called the
"Belloti Trinome" (fang and Dinner Inc. abd N, Sacramento Avenue,
Chicago) which is capable of clitking out a v variety of rhythms ("a
rhy thad c metronome"). I hmve also heard of a device called a
'yhythmicon", an invention of the composer Henry Cowell on which any
Kiar deere of pulkites may be obtained. I would like to have en
inetrument combining all of these features which would supply a
variable series of rhythms or a combination of rhythms at once.
This instrument might consist of several electronic switches and
might also include noise generators and bell-drum gates. There
might also be imputs which would allow the mixing or substitution
of exterior sound sources as well.

Mr. Robert A. Moog
November 16. 1964
Page Three

A light-sensitive volume control. I have seen Dr. Scheeffer's
"Hamograph" which accomplishes this. 'This is a device to con-
ol sound rorya only, I believe that this instrument works
this manner: light-powered | '@ arranged im such a way
to eut off an interstage tube by the application of a negative
5

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sage

cr

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if =

jas to the grid. An insertion between the light source and the
wihinte cell reduces this bias (if that's the right term) allowing
sound source to pass. Dr. Schaeffer's auve i Doge vera: c@lluloiad
oy on which are pasted opaque pieces of cloth, shaped to form

is esired envelope. I believe there prion be meat tents applying
to this instrument that might cause difficulties.

fas

a = a 2 ot
u

*

eliy, I am very interested in your seminar. I would Like to
LLowiL ng manana ious � ased on my own experience.

Fit "y
o,4 j
S he oe

L. Unless you have a great deal of money for this project, it
might be wise to require the participants to supply their own
cottonepicking tape. Free tape is just too mich of a temptation.

8. Besinners in
cilities involved

I would consider operatine at least two studic
this idiom are often overthelned. by the possib
and consume great quantities of studio time.

I would encourage the participants to ine at much of their
own equipment as they can for the same reasor Much splicing
and editing can be done independently if one has his own ree
corder, thus saving studio time.

I would be very interested in participating in this workshop, should
you care to consider me. As you know, there are several approaches to electro�
nic music and you should include composers who represent the scientific com-
putericed approach as well as the less learned but perhaps more practical side.

I am preparing a detailed and annotated catalogue of my compositions
and the instruments I employ in my studio, which I will send to you in a few
weeks. If you know of any interested parties, I would be meh obliged for
their addresses. I feel this account may be of interest especially to be-
sinning composers as it traces my own development in this idion.

Again, many thanks.

Sincerely yours,

Qheirman, Dept. of Music