UBZR1 contains two ADSRs to allow for two distinct contours with distinct timing and sustain levels.

One ADSR is fixed to feed the VCAs of the three VCOs and the Noise Generator.

The other ADSR can be used for various purposes, for example controlling the VCF cut-off frequency.

Functional Description

The ADSR is fully voltage controlled.

My design uses a 1/2 LM 13700 as a voltage controlled integrator.

Attack, sustain and release output voltage levels can be chosen freely between -5V and +5V.

Thus you can generate any contour shape with three different levels, e.g. also an inverse contour.

I am not aware of any similar ADSR designs. Originally I designed that feature to avoid analog multiplication and to move multiplication of ADSR control voltages out to the controlling digital part.

Another unique feature is the multi-output capability: The ADSR can be built having one or more outputs. Distinct ADSR outputs can have completely independent attack, sustain and release output voltage levels. They do however all share the same timing.

Performance Specs

Schematics as PDF or JPG



Last change: 2015-09-17
© 2002-2017 Dr. Thomas Redelberger