Doepfer A-135-2

Quad VCA / Voltage Controlled Mixer

 122,00 ( 100,00 + VAT)

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  • One of the most compact voltage-controlled four-channel audio mixers on the market
  • Separate All and Selected outputs
  • Each channel has an attenuator and a gain control on both the audio and CV inputs
  • Can be used as a mixer, as a dual stereo VCA, as a quadruple VCA or as a quadrophonic distributor
SKU: 50166 Categories: , , ,
SKU: 50166
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SKU: 50166 Categories: , , ,
SKU: 50166

Doepfer A-135-2

Quad VCA / Voltage Controlled Mixer

The popular Doepfer A-135 has been reduced to 8HP, making it one of the most compact voltage-controlled four-channel audio mixers on the market. The new version now offers separate All and Selected outputs for even more flexibility! The volume of each channel can be modulated via control voltage. In addition, each channel has an attenuator and a gain control on both the audio and CV inputs. The module can be used as a mixer, as a dual stereo VCA, as a quadruple VCA or as a quadrophonic distributor. Thanks to DC coupling, it can also be used for processing control voltages.

Module A-135-2 consists of four linear VCAs with mixing function.

The input level is adjusted with the attenuator. The volume control of each input signal can be controlled manually with the gain potentiometer and via a control voltage at the CV input, and can be tapped at the individual output, just like with a normal VCA.

In addition, the A-135-2 mixes the four signals at one of the sum outputs with a maximum gain of 0.6 to avoid clipping.

At the Selected output the sum signal of all VCAs appears, if no patch cable is plugged into the Out jack of the respective VCA. VCAs with a patch cable plugged into the Out jack are removed from the sum.

The All output always mixes all four channels.

Thanks to internal jumpers, the four signal inputs can be normalized with each other. Thus a signal can be distributed to 4 different channels by voltage control (e.g. for quadrophonic distribution of audio signals).


Specifications

Controls, In/Outputs and Functions of each VCA:

  • Level (manual control of the VCA amplification), small rubberized knob (L1…L4)
  • Control voltage input with associated attenuator (CV1…CV4), for the full VCA control range about 0…+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker
  • Signal Input
  • Signal Output
  • All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. to control the level of LFOs or envelopes)
  • The signal input is not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5…+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).
  • The available amplification range is  0…1, the maximal amplification is 1 (i.e. it “clips” and remains at 1 even if the control voltage goes beyond the value that corresponds to amplification 1)

Functions of the voltage controlled mixers:

  • two outputs (“Selected” and “All”)
  • Selected output: the ouput if a VCA is removed from this sum signal when a plug is inserted into the corresponding VCA output.
  • All output: sum of all VCA outputs, regardless of inserted plugs into the VCA outputs
  • The maximal amplification is  about 0.6 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications)

Special functions of the voltage controlled mixer (selectable by internal jumpers)

  • Dual Stereo VCA: In this case the control unit of VCA1 (L1 + CV1) affects also VCA3 and the control unit of VCA2 (L2 + CV2) affects also VCA4. The control units of VCA3 (L3 + CV3) and VCA4 (L4 +CV4) are out of operation.
  • Quad VCA: In this case the control unit of VCA1 (L1 + CV1) affects all four VCAs. The control units of VCA2, VCA3 and VCA4 are out of operation. In this mode the module has the same function as module A-132-2. That’s why module A-132-2 will be discontinued.
  • Normalling of the signal inputs: by means of internal jumpers signal input 1 can be normalled to signal input 2, signal input 2 to signal input 3 and signal input 3 to signal input In 4. That way the same input signal can be distributed to four different channels by means of control voltages (e.g. quadrophonic distribution of audio signals). Suitable control voltage sources are e.g. A-144 (Morphing Controller) or A-143-9 (Quadrature LFO).

Additional technical specification for each VCA (based on the specifications of the VCA circuits CEM3360/AS3360 used in the module):

  • Crosstalk between VCAs: typ. – 80dB
  • Signal attenuation at 0V CV: typ. -70dB
  • Total harmonic distortion: typ. 1%
  • Control voltage feedthrough: max. 15mV

Width: 8 HP
Depth: 45 mm (measured from the rear side of the front panel)
Current: +40mA (+12V) / -40mA (-12V)

Depth

45 mm

Width

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Return and restocking option is available for private customers only. We will issue a refund/credit if you are not satisfied with your purchase and notify us within 10 days of product receipt. It must be returned in the original packaging and in saleable condition and must be returned freight prepaid. Return and restocking rights are not applicable for Audio/Video and software products. Shipping and handling charges to and from are not refundable.

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