A-135-1

Quad Linear VCA/Voltage Controlled Mixer.

Module A-135 is a quad voltage controlled mixer. It is made of 4 independent linear VCAs. The VCA outputs are mixed to a common output. For each VCA the following inputs and controls are available: audio input with attenuator, control voltage input with attenuator, gain (preamplification).

Applications: voltage controlled mixing of up to 4 signals with separate control voltages (e.g. delivered by LFO's, ADSR's, Random, Shepard generator, MIDI-to-CV interface or other control voltage sources). In connection with the Morphing-Controller A-144 the soft fade-over of 4 signals with only one control voltage is possible.
Inputs: 4 x Signal in, 4 x CV In
Output: Sum Out, 4 x Single Out
Controls: 4 x Signal In Attenuator, 4 x CV Attenuator, 4 x Initial Gain

The A-135-1 is able to process also slowly varying control voltages because the signal in/outputs are DC coupled. It has in addition four single outputs available and can be used as four independent linear VCAs. The new version is manufactured from May 2013 and can be identified by the additional four single outputs, the 18 HP front panel width and the VCA circuits (SSM2164 or V2164)
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From January 2014 a revised version 3 of the A-135-1 is shipped. Compared to the previous version 2 of the A-135-1 the inputs and outputs of the new version are normalled and for the sum output it can be chosen between all and selected VCAs:

• All signal inputs are normalled, i.e. signal input #1 is normalled to signal input #2 unless a plug is inserted into signal input socket #2, same is valid for the signal inputs 2 > 3 and 3 > 4, each normalling (1>2, 2>3, 3>4) can be interrupted by removing a jumper

• All CV inputs are normalled, i.e. CV input #1 is normalled to CV input #2 unless a plug is inserted into CVl input socket #2, same is valid for the CV inputs 2 > 3 and 3 > 4, each normalling (1>2, 2>3, 3>4) can be interrupted by removing a jumper

• the mode of the sum output can be chosen between "All" and "Selection" by means of a jumper. In "all" mode all four VCAs are mixed together. In "selection" mode a VCA is removed from the sum signal when a plug is inserted into the corresponding single output.

• It's not possible to add the All/Selection feature to the first version of the A-135-1 module. But it's possible to add the normalling of the signal and CV sockets.

• This pdf document shows the positions and explains the functions of the additional jumpers: http://www.doepfer.de/a100_man/A135_1_V3_jumper.pdf

• if your A-135-1 is version 3 can be identified by the additional jumpers shown in this document. The two versions can be distinguished also by the pcb printing on the smaller board (BOARD A): "V2 2013" for version 2 and "V3 2014" for version 3.

http://www.doepfer.de/a135.htm