AM1045 Synthesizer Voice

ARP 1045 VC Voice

Overview This is a replica of the ARP 1045 Voltage Controlled Voice from the ARP 2500 Analog Modular Synthesizer. The module consists of three circuits in one module; 1004 VCO, 1006 Filter Amplifier and two ADSR’s. This is a very high density design which delivers a complete syntheszier voice.

AM1045 Module My design uses the same schematics laid out on three large 150 x 150 mm PCB’s, metal film resistors are used with no attempt to use legacy carbon composition. 1/8″ shaft potentiometers are used through out along with a multi-way rotary switch for waveform selection and a LED indicator. The module has the following front panel controls:

  • Fine and Coarse Frequency
  • Rotary waveform switch
  • Toggle switch for VCO on/off
  • Pulse Width, FM1 and FM2
  • Env Amp, Delay, Attack, Sustain, Release for VCA
  • Env Amp, Delay, Attack, Sustain, Release for VCF
  • Filter Cutoff and Resonance
  • VCA Gain and Mode switch
  • Ext CV amount to VCF
  • Ext CV amount to VCA

There 12x 3.5mm jack sockets mounted on the panel:

  • FM1 and FM2 inputs
  • OSC output
  • Gate and Trigger inputs
  • Ext VCF and VCA inputs
  • Env1 and Env 2 outputs
  • VCA Output

Module Build The five circuits were laid out on three 150 x 150 mm PCB’s in Spring 2017, along with smaller sub module PCB’s so that I could encapsulate the VCO exp converters at a later stage. I originally designed the circuits with THAT transistor arrays, but these did not work well and were swapped out for Linear dual transistors to give the correct gain structure.

The VCA, VCF and ADSR’s went into build and tested out OK. The 1004 VCO is a new design to AMSynths and requires 100R Tempco resistors, which we use Panasonic SMD components for. As at February 2018 I was still waiting to test the 1004 and order a panel.

Copyright AMSynths 2017