Doepfer A-132-8 Octal Poly VCA

hese controls and in/outputs are available:

• Default Gain 1 (GL)
• Default Gain 2 (GX)
• CV Inputs for the four VCAs #1
• CV Inputs for the four VCAs #2
• four Audio Inputs
• four Audio Outputs
• Audio Sum Output

The module features two Default Gain controls (GL, GX), that enable the opening of the first four VCAs (L) and/or second four VCAs (X). For this the controls GL and GX generate two internal control voltages 0...+10V which are connected to the switching contacts of the sockets 1L...4L (control GL) and 1X...4X (control GX). As long as no patch cable is inserted into the socket in question the internal default control voltage (GL or GX) is used to control the corresponding VCA. This is necessary when the VCA in question is not in use (i.e. no external CV available). Otherwise the VCA would close and there would be no output signal even if the other VCA in the chain is open. The controls GL and GX are also useful for testing polyphonic patches (e.g. for tuning the VCOs).
As soon as a patch cable is inserted into a CV input socket the corresponding internal default control voltage (CL or CX knob) is no longer used to control the VCA in question. Rather the external CV patched to the CV input socket does now control the level of the VCA in question.
The sketch below shows the internal structure of the module.

Factory settings:
The trimming potentiometers of the CV inputs are adjusted for a CV range 0...+10V - matching to the polyphonic ADSR module A-141-4. But the sensitivity of each CV input can be adjusted by means of a trimming potentiometer to adapt the CVs even to other control voltage ranges.
The jumpers for the second VCAs are installed for linear control scale (i.e. also the VCAs labelled "X" are linear VCAs from the factory).

Application:
polyphonic patches with two VCAs per voice.

The following document shows the positions and functions of the jumpers and trimming potentiometers of the module: A132_8_trimming_potentiometers_and_jumpers.pdf