DOEPFER / A-135-3 VC Stereo Mixer

Variations

The A-135-3 is a 4-input voltage-controlled stereo mixer with 8 linear VCAs (voltage controlled amplifiers) behind an 8HP front panel and only a mixer based on it.

Controls, inputs, and functions for each input:
level (manual control of VCA amplification), small rubber knob (L1-L4)
CV input has an attenuator (CV1-4), but the full range of VCA control requires a CV voltage of approximately 0 to +5V (the attenuator is clockwise (increases with rotation).
Signal Input Left/Right (InL 1?4 / InR 1?4)
The signal inputs do not have attenuators, but the VCA can handle all signals up to 15Vpp / -7.5?+7.5V without clipping. For higher levels, an external attenuator is required (e.g., A-183-1), which can handle all signals up to 15Vpp / -7.5...+7.5V without clipping. For higher levels, an external attenuator is required (e.g., A-183-1).
The sum of the left and right signals is shown on sockets OutL and OutR. The maximum amplification should be about 0.5 to avoid clipping at the mixer output (otherwise a 15 Vpp signal at each signal input may distort the output with full amplification). If another maximum amplification (e.g., 1) is required, the two resistors should be replaced. All inputs and outputs are DC coupled. As a result, the module can be used to process both audio and control voltages.

Additional technical specifications for each VCA (based on the specifications of the VCA circuit CEM3360/AS3360 used in the module):
Crosstalk between two channels: -80dB
Signal attenuation at 0V CV: -80dB
Total harmonic distortion: typ. 1%
Control voltage feed-through: max. 15mV

Width 8HP
Depth 45mm
Current consumption
+12V : 40mA
-12V : 40mA