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.

Monday, May 4, 2015

Crowther Audio '77 Hot Cake

A lot of awesome things came out in 1977: the op amp version of the Big Muff, the grey box DOD250, Fleetwood Mac's Rumours, the Sex Pistol's Never Mind the Bullocks, and STAR WARS (May the 4th be with you). The Crowther Audio Hot Cake also made it's debut in 1977, and you could say it was one of the first "boutique" stompboxes ever made. It featured an 741-type IC and a unique way of bypass switching. To quote Steve (bajaman) from FSB:

It used a 120k resistor and simple shorting switch from the bottom of the drive pot, 1k, 470p, 12n, 12n, and bottom of the level pot, to earth. When the switch is open all the foregoing components were lifted by the 120k resitor - hey presto bypass mode. When the switch is closed: bingo, tons of boost.

To add an LED on/off indicator, I would suggest using a DPDT switch. One side can be used to bypass the effect, and the other side for the LED. 

As many know, an updated version of the Hot Cake was released in 2003. This has a presences control instead of the mids lift/normal switch in the original, and has a more Fender-like sound compared to the Marshall-like sound of the original. Many say that as you turn the drive control up, the tone gets muddy, but with the volume cranked and lower drive settings, the Hot Cake really shines. I've added a polarity protection diode, a power filtering cap, and a resistor for the LED on the board. For more info, check out the FSB summary page.


  1. please do prunes and custard..

  2. hi , ive just started building this and ive noticed that an output filter cap is incorrectly placed . the 12n on the top right should be between the 2 10k res (from pin 6) and not at the level pot.

    ill reply after the build to verify if all else is proper.

    its a nice layout ,thanks

    1. pls correct me if im reading that 12n cap wrong

    2. You're correct. That 12n cap was way off and the value of the resistor on the far right was wrong as well. All fixed now. Thanks for pointing that out! Let me know how the build turns out

    3. All done . it works proper like it should . havnt had a lot of time with it yet to fine tune the caps n voltages , but you can mark this as verified . no oscillations no odd noise ...even without a box .
      thank you

    4. hi, i can confirm the above. it works perfectly, and has a nice smooth tone. thanks so much!