Ian Fritz 2 x AD/AR PCB/Panel

Timo Rozendal's 4 hp eurorack adaptation of the Ian Fritz AD/AR.

This is a PCB/Panel set in the Eurorack format.

Availability: In stock




This novel envelope generator (EG) provides a versatile, cost-effective alternative to other designs. It will take just about any signal you feed it and generate an envelope. For example, its main input can accept either a trigger or a gate signal. Driven by a trigger pulse, the unit's output is an attack-decay (AD) envelope; driven by a gate its output is an attack-release (AR) envelope. And you can even use a continuous signal like an LFO for the gate! An auxilliary circuit produces a delayed, fixed-width pulse (monostable, or "Mono") which also drives the EG circuitry. This pulse may be initiated by any signal with a positive-going 1.5 V crossing, for example, a trigger pulse or a waveform from an LFO, noise source or chaos generator. A dedicated output jack for the pulse generator allows other, independent, timing applications.

This version also has the following modifications: 

  • It has twice the ad/ar envelope circuit 
  • It is without the delayed pulser part 
  • There is a led indicator to show if an envelope is active 
  • Input of the first envelope is normalled to the second envelope 
  • There is an additional switch that converts a gate into a trigger, combined with the previous modification this can result an a simultaneous AR and AD envelope with one incoming gate signal 

Specs & Downloads

Specs & Downloads

Manufacturer Timo Rozendal
HP 4
Depth No
+12V No
-12V No
+5V No
Additional Resources Build Guide & BOM


Customer Reviews (1)

Great envelopes, small footprintReview by shayshez
This is nice to have A/D generator, if you have free 4hp in your rack, get this one.
very easy to build.

in the original design the output is to low (around 2v), I recommend to remove the voltage divider before the output if you want the output around 7.75v (remove r12 and short the holes of r11)
or leave r11 2.2k) and replace r12 to 4.7k if you want it around 5v.
(Posted on 11/5/2017)

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