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System a - 100, A-149 /1, User examples – Doepfer A-149-1 Quantized/Stored Random Voltages User Manual

Page 5: Doepfer

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doepfer

System A - 100

RCV

A-149 /1

5

4.2 Stored Random Voltages

%

CV D In

This socket is the Control Voltage input for the
probability distribution "D".

&

Clk In

This socket is the Clock input for the Stored Random
Voltages section. Each rising edge of this signal cau-
ses the generation of a new random voltage at the
outputs / resp. (. Any clock or gate signal can be
used to control this input.

/

(

These sockets output the random voltages of the
Stored Random Voltages section. Socket / is the
output with equal probability distribution, socket (
outputs the voltage with adjustable distribution "D".
The voltage range for both outputs is 0 to about +5.3
V
, the voltage steps are about 1/48 V (i.e. 1/48 V
quantization). This corresponds to about 1/4 semitone
intervals when used to control the pitch of a VCO.

5. User examples

The Doepfer web site www.doepfer.com shows some
typical examples of the A-149-1, including sound
examples in the mp3 format. Even more details con-
cerning the technical realization of the module can be
found. An excellent description of several applications
of random voltages like those generated by the A-149-
1 can be found in the Allen Stranges "Electronic music
- systems, techniques and controls" from page 82. The
examples in this book are based on Don Buchla's
modules 265/266 but are valid for the A-149-1 too.

The following patch is taken from this book and shows
how to create very complex permanently changing
sound structures by means of the A-149-1 in combina-
tion with the voltage controlled LFO A-147 and some
additional standard modules (VCO, VCF, VCA,
ADSR):

A high magnitude voltage at the N+1 output of the
A-149-1 causes a high VCO pitch and simultaneously
sets the value of N higher so that the next pitch is
taken from a greater range of possibilities. If the N+1
output is low the VCO pitch will be low too and sets the
value of N so that the next pitch will have a more
restricted range of possibilities. Simultaneously the 2

n

output controls the frequency of the filter and the