AM8007 SH05 Envelopes


Overview The AM8007 module is a replica of the ADSR and AR envelopes used in the Roland SH-5 analog mono synthesizer from 1976. It use transistors to switch between the various phases of the envelope generator and a JFET transistor to act as an output buffer. The ADSR has a uni-junction transistor as its core, there are no Op Amps in the original design.

Euro Rack Module:   14HP wide
User Manual:          Download PDF

Detailed Description The AM8007 is an exact replica of the original circuit but with the addition of output Op Amps to buffer the signals and provide both positive and negative going envelopes. The envelope section timing is all the same using 1MA slide potentiometers, instead of the Release being twice as large as Attack and Decay. This is simply due the difficulty of getting 2M log potentiometers. The original Attack and Decay times are stated in the user manual as 0 to 7 seconds, with the Release at a maximum of 14 seconds.

The gate signal of each envelope generator can be switched from the Doepfer Bus (Internal) to Panel Jack (External ), the push button is always active for initiating either generator. The presence of a gate signal is shown by the red panel LED. The sliders are Bourns PTL30 with red LED’s which are supplied by a separate +5V power supply and are always on.

Euro Rack Module:   14HP wide
User Manual:          Download PDF

There are five 3.5 mm jack sockets on the base of the front panel:

  • External GATE input
  • AR envelope output, normal and inverted (AR-, AR+)
  • ADSR envelope output, normal and inverted (ADSR-, ADSR+)

Module Outcome & Availability The PCB’s were laid out in late 2017 and ordered as prototypes in March 2018. This worked correctly and a LM393 comparator chip was added to convert the lower EuroRack +5V gate signals into the required +10V. The AM8007 will be available in 2018 as a completed module and PCB.

 

Copyright AMSynths 2017