AM1032 Mixer / Distributor

Overview The ARP 1032 module was announced in  the Tonus August 1970 catalog as “COMING SOON……” but the module never made it to a prototype or production stage. No images of the module are available and the brief feature set is described as:

Eight voltage controlled amplifiers in a voltage controlled mixer / distributor; 1 in 8 out — 8 in 1 out

There are no ARP schematics for the 1032 but I have taken inspiration from the 1050 module. It has 8 inputs with push button mute using XOR logic (where only one channel can be active at a time). What if Tonus were planning to put this logic around 8 VCA’s and a mixer? Maybe they were planning to use the new CA3080 OTA chip for the VCA’s?

AM1032 Module Eight linear VCA’s are at the core of the module and use LM13700 chips (Dual OTA’s). The level of each channel can be controlled by the GAIN rotary pot, or by patching in a CV signal where the depth is adjusted by the GAIN pot. The GAIN pot is normalised to +10V at the CV jack socket. All the VCA outputs are mixed via a high quality Op Amp.

Each channel input goes via an analog switch which is switched ON/OFF by a momentary push button, which illuminates an internal LED when ON. Similarly each channel output goes via an analog switch with a momentary button (with LED) switching the channel output ON/OFF.

The neat bit of design is that the momentary switches can be set to function in XOR mode, whereby only one can be active at a time. A slide switch sets whether the module is in MIX or DIS (= Distribution) mode. In MIX mode the output switches are in XOR mode, so that only one channel out can be active. All the channel inputs can be active and are mixed together. (8:1 mode)

In DIS mode the input switches are set to XOR, whereby only one input channel can be active. The selected channel goes via its respective VCA , the mix Op Amp and to all the outputs that are switched ON. The active input channel signal is thereby “distributed” to  the active outputs (1:8 mode).

The module has the following front panel controls:

  • 8x GAIN rotary pots with ARP 2500 knobs
  • 2x position MODE slide switch (MIX,DIS)
  • 8x Momentary Switches (Input ON/OFF)
  • 8x Momentary Switches (Output ON/OFF)

There are 24x 3.5mm jack sockets on the front panel:

  • 8x Signal Inputs
  • 8x Signal Outputs
  • 8x Control Voltage Inputs

Build Outcomes The idea of using XOR logic came about in Spring 2024 and a prototype module was created soon after for the XOR logic control (which is shared with the AM1026 module).

2024 Update AMSynths developed a range of Eurorack 2500 modules in 2024 using SMD components and remanufactured ARP 2500 control knobs. The AM1032 module has  been included and is available in our webstore here.


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