AM8142 Dual ADSR


Overview This module is a replica of the Roland 705 moule which appeared in 1976 as part of the System 700.  The AM8142 contains two identical traditional ADSR format envelope generators with variable Attack, Decay, Sustain and Release. The module uses 30 mm travel slide potentiometers and has toggle switches to switch between 2 different set of timings – slow or fast.

Description  The AM8142 follows the original circuit design with only a few upgrades: 2N6027 UJT, TL072 Op Amps and USA transistors (2N3904/6). The module contains two envelope generators each with three timed stages: Attack, Decay, Release. The Sustain control adjusts the level to which the Decay time reduces to. In the original the ADSR’s are triggered by an internal gate and trigger signal, or an external Gate signal.

The AM8142 is triggered by an external gate signal (GATE1, GATE2). The envelopes can be retriggered from the attack start whist a gate signal is present by connecting a trigger signal to the trigger jack socket. There is a red push button (MANUAL GATE) to gate both ADSR’s on together. The correct 2M log slide potentiometers were custom manufactured for this module.

AM8705 from 2011

The TIME toggle switch selects normal (x1) timing or a shorter timing (x0.1.) which enables very fast envelopes to be generated. Normal and inverted output control voltages are available for each ADSR, making it easy to patch an ADSR into both a VCF and VCA simultaneously. There are red gate led’s for each ADSR.

Module Availability  The AM8142 is based on the AM8705 module which was produced in small numbers in 2011. Production ceased in 2012, mainly because it was time consuming to build with the hard wiring of the LED’s and switches.

In 2023 the module was developed into the AM8142 to provide an accurate dual ADSR, with a 16HP panel compatible with our new range of 100M modules. The correct Attack time is retained by using custom manufactured 2M log slide pots (PTL30 with subtle red LED’s).

EuroRack Module: 16HP wide
User Manual:  AM8142 User Manual

AM8142 Mockup

  • Attack = 1.5 ms to 7.5 seconds
  • Deacy = 4ms to 15 seconds
  • Release = 4ms to 15 seconds

Front Panel The AM8142 has a grey powder coated front panel with white silk screen printing. The basic panel and holes was drawn with Front Panel Designer and exported as a DXF file. This was then imported into Illustrator and used as a background layer to position and draw the lettering. The finished drawing was exported as a 300 dpi PDF and sent for manufacturing along with the DXF file and the choice of panel colour (close to Pantone Mid Grey 5U).

Module Outcome & Availability  The AM8142 was developed in the spring of 2023.  Production modules with grey powder coated panels will be available in April 2023.

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