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.

Tuesday, July 28, 2015

Bearhug FET Compressor

Here's a simple compressor design by Jon Patton (aka midwayfair) that's good for guitar and bass. In Jon's words:

The Bearhug is a tonally transparent, ultra-quiet, tiny, and easy-to-build compressor. It occupies some middle ground between the ultra-subtle compressors like the Flatline/Afterlife and Orange Squeezer and the super squishy compressors like the Ross.

For more info on the design, Jon goes into detail in this thread on DIYSB.

I built this one last night and it's everything Jon says it is. Very subtle, and a little bit of volume boost if you want it. Here's a few pics of my build.


  1. Hey!! Just letting you know that the topmost 1n4148 is around the wrong way. Was having eons of strife with this circuit, but now it works :)

  2. It's a little bit different in schematics that there are in jon's site, more like the update of the first version, not the second version. Position of 2n5457 seems different, and also position of electrolitic condenser near volume 3 is different from schematics(negative at pin 3 in jon's schematics

  3. In the original scheme there is a trimpot, for the adjustment of the bias; Is it that even without the trimpot it works?

    1. Pretty sure Jon revised the schematic and this follows the newest version.

  4. Just two questions:

    1) the diode marked with "9.1v" it's a zener?
    2) If I change the 2.2k* (2.2k-4.7k) resistor with a 2.2k resistor + ~2k pot the sound would be affected in any way?

    1. 1) yes
      2) It might, but probably very subtly. Probably best to just stick with a fixed value.

  5. Which tranny do you use for Q2 ?
    Would J201 make the job ?

  6. Ok, got this answer fom this document
    MPSA18 or 2N3904 or 2N5089 should work fine...

  7. finished to build, but has a low volume Will it be that the cover 1uf of volume 3 is negative on the back?
    bs170 2.5v drain is it ok? any ideas

  8. Congratulations on the portal, it is an inspiring source to build these equipments.
    But, gentlemen, I am a beginner in electronics, yet music lover and I would like to make this compressor myself.
    Please, where to find the list of components?
    Especially with the capacitor types and the voltage of the electrolytic capacitors?
    The list I got did not have this information.
    Advance grateful to all.

  9. Hi!!
    Iam new to circuits so i have (a probably stupid) question.
    When there is no OUT pad on the circuit, where is the OUT where the volume 2 goes?
    I found out that there are some circuits ( like the dead austronaut x fuzz) where there is no IN/OUT pad as well. Your help is vital!!!( as i said i'm new to all this ;) ) .
    I just love this site!!
    Thank you in advance!!

    1. The out in question is the circuit output. So it'd go to the footswitch. With the X Fuzz the input is lug 3 of the gain pot.

  10. Hi, thanks so much for all your hard work on these layouts, I’ve had great fun building many of them.

    I’m currently filling my etched board for the Bearhug and I think you have the polarity wrong on the top left most 4.7 uf electro and the bottom most 10uf (going to volume pot)