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, September 11, 2018

Sunn 200S Preamp

Here's a simple bass preamp circuit derived from the Sunn 200S using JFETs. It's pretty similar to the Bassman Preamp, but with the EQ section at the end of the circuit instead of the middle. Original S200S amps didn't have the Mid control, but it's kind of necessary IMHO. Bias the JFETs to 4.5v and adjust to taste. Not sure if the BAT85 diodes are necessary as they're not in the Bassman Pre, but I left them in just in case. Also not 100% sure if the below demo follows this schematic exactly, but it should be in the ballpark. Should fit nicely in a 1590B.


  1. Hello!! good job!!! I will try to do it for a friend who plays bass. When will we see a sunn model t preamp? I do not have stripboards to do the tagboardeffects. regards!

  2. Does anyone know if this would work as an acoustic guitar preamp?

  3. I guess you can count this as verified, I did this today in the morning and it works. I skipped the BAT85 diodes though.

    1. Awesome. Thanks for verifying and commenting about the diodes. Didn't think they were necessary.

  4. May as well add the Sunn model T preamp:)))

  5. Bowie style. Verified. Excellent. bat85 onboard. Thanks!


  6. Hi, I'm looking for a cabinet simulator with an equalizer, a preamp ... is it good for me to use when playing without an amplifier on a mixer pad?