AM1033 Dual DADSR


Overview This is a replica of the ARP 1033 Dual Envelope Generator module from the ARP 2500 Analog Modular Synthesizer. The module consists of two traditional ADSR envelope generators plus a Gate Delay. This envelope generator is known for its snappy 1ms fast attack and decays but the longest phase times are only 2 – 3 seconds. There are panel controls to select trigger options, an incandescent “gate on” lamp and a manual gate push button.

AM1033 Module My design uses the same schematic laid out on a large 150 x150mm PCB. 1M Log 1/8″ shaft potentiometers are nearly impossible to locate, but I eventually found some in Mousers catalogue and bought a set, enough for three modules. I was going to use 45mm sliders with ARP style coloured caps, with an Initial Delay control on a rotary pot, maybe later. The module has the following front panel controls for each Envelope Generator:

  • Delay
  • Attack
  • Initial Decay
  • Sustain Level
  • Final Decay
  • Toggle switch for Multiple or Single Trigger
  • Red Incandescent Indicator Lamp for Gate On
  • Manual Gate Push Button

There 10x 3.5mm jack sockets mounted on the rear the panel, for each Envelope Generator we have:

  • Gate
  • Trigger
  • Gate5V
  • Inverted Output
  • Normal Output

Module Build The PCB layout was laid out in September 2006 and then updated for a large 150 x 150 mm PCB in September 2015 (9 years ….). 4x PCB’s were ordered, with the first one as a trial using metal film resistors as I suspect this circuit is going to be tricky to get working. I left the build until February 2016 as I had a backlog of PCB’s to sort out and get working. The circuit works fine, except the JFET pin out was incorrect.

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