DOEPFER / A-135-5V POLY VC MIXER / SUB OCT GEN.

Variations

The A-135-5V is a module that combines the functions of a voltage-controlled polyphonic mixer and sub-octave generator.

Twelve voltage-controlled amplifiers (VCAs) are arranged in a 4x3 matrix. Up to three 4-voice polyphonic signals (e.g. the output of the 3 polyphonic VCO of the A-111-4) can be mixed here. The levels of the three polyphonic channels (A, B, C) of 4 voices each can be controlled manually or by an external CV with attenuator.

Furthermore, the module features 4 frequency dividers, allowing the sub-octave to be derived from the 4 input signals of channel A. The sub-octave signal is internally wired to the channel B input. As long as the channel B socket is not patched, the sub-octave signal of channel A is used as the input signal to channel B. The sub-octave signal is a symmetric square wave with half the frequency of signal A. For example, if the 2 polyphonic VCO of the A-111-4 is patched to channels A and C, channel B provides the sub-octave signal of channel A.

The 12 inputs and 4 outputs are internally wired to pin headers on the back of the board. This allows the module to be pre-patched internally with other polyphonic modules (e.g. 4 inputs A to A-111-4, 4 inputs C to another A-111-4, output to polyphonic filter A-105-4). This internal patching can be overridden by using the inputs on the front panel.

Controls
Lev.A, Lev.B, Lev.C control knobs: Adjusts the signal level of channels A, B, C
CV A, CV B, CV C control knobs: Attenuators for each CV input
Mute A, B, C toggle switch: When the toggle is in the lower position, the channel is muted
Inputs/Outputs
A1 ~ 4 input terminals: Channel A input
B1 ~ 4 input terminals: Channel B input
C1 ~ 4 input terminals: Channel C input
CV A, CV B, CV C input terminals: CV input terminals for channels A, B, C
Out 1 ~ 4 output terminals: Output terminals
Sum output terminal: Sum output terminal specialized for paraphonic use, such as sending all voices to one VCF/VCA
Features
If more than 3 polyphonic channels are required, the number of channels can be increased by connecting multiple additional modules.
To avoid clipping, keep the overall maximum gain below 1 (you can change the gain to 1 by replacing resistors, but clipping may occur in that case).

The maximum input level without distortion is approximately 16Vpp (-8V to +8V for control signal processing).

The voltage range of each CV input is 0 to +5V (CV attenuation knob fully clockwise). Higher CV signals (0 to +10V, etc.) can be adjusted with the attenuation knob.

The sub-octave signal level is approximately 5Vpp.

This module should only be used with DC-coupled VCO outputs (A-111-4, A-111-3, etc.). With AC-coupled VCO outputs (e.g. A-110-1, A-110-2), including the sub-octave in the output will introduce a DC offset into the output.

A135_5_INTERNAL explains the location and function of the pin headers on the board, as well as how to connect two A-135-5s.

Width 10HP
Depth 55mm
Current consumption +12V: 50mA
-12V: 40mA