This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Wednesday, February 25, 2015

AMZ Dr. Quack

The Dr. Quack is Jack Orman's improvement on the EHX Dr. Q envelope filter. Basically, there's an added input buffer to increase the input impedance (which is kinda low in the Dr. Q) and offers better range control. Check out Jack's blog post on the circuit for more information and a few mods.


  1. think there is a pad missing on the pcb for the 10k to pin 3 of the ic, it seems to go to pin 2 in the present pcb, so i went ahead and punched one more and i got sound coming thru but i only have some quack when my finger act as a resistor behind the pcb...
    scratched all tracks good, brushed it, reflowed it, changed ic, j201, and quack, but no voltages anywhere on the 3904...

  2. Hmmm... I added the missing pad and went over the layout and schematic again. The only problem I found was the output cap was wrong. I had it listed as 4.7n instead of the correct 47n. Try swapping that cap out, but it sounds like there may be a bigger issue than that...

  3. its working.. d2 blinks, d1 lights up,..
    great site..thanks..

  4. Hello, I'm looking for EHX Bass Micro Synth scheme.

    1. I found this, but with no values.

  5. Built a second one, this time the PCB variant. Had weird noise issues, like if there is sound like wind coming even if you don't strum. Found the problem in an old salvaged foil capacitor (the 1nF). Changed it, now it works like a charm.