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.

Friday, December 12, 2014

Earthquaker Devices Crimson Drive (2-knob version)

Here's a good sounding overdrive from Earthquaker Devices. This is for the first incarnation of the Crimson Drive with just level and gain controls. Uses a J201 in a buffer stage and a PNP AC128 in the gain stage.

Dirk_Hendrik from FSB traced one and drew this schematic.

The power filter section makes me scratch my head a bit, as it uses 2, 100µ caps. To keep things a little simpler on the board I just put one 220µ cap, since the equivalent capacitance of two parallel capacitors is the sum of the individual capacitances.

Also note that the schematic calls for a low current LED, hence the 10k resistor from the power supply. Change that resistor to around 2.2k if you're using a more common LED.


  1. Verified.I built it with ac117 transistor. But there is a little bit hissing and noise, when i turn it on with my usual 9v power supply, anyway, pedal working well with battery. Thanks.


  3. I'll try with 2SB54 and add Rat's filter.
    Where do you suggest to add it? right after the diodes clipping? or after C6?

  4. Finished!
    Used one 2SB54, very confusing about the 1N4148 and 1N4007 :-D
    Sounds AWESOME

  5. Hi, adding a 100 ohm resistor in series with the 9v reduce a lot of hiss and noise. It's simple to add if you get rid of the 10k for the led. And in my experience much transistor leakage makes some problems. Thank you for the layout! Very nice pedal!

  6. Instead of the 15K resistor put a 50K trimpot between the collector of Q2 and the ground; this way you can adjust the bias of the transistor. Before biasing I had a gated sound,after bias it was nice and smooth