Pedal Mods

Here are a few PDF files on some pedal mods I've done.  The infamous R28 Mod for the MXR Phase 90 has been around for quite a while and not something I came up with.  I just chose to share it here. The Boss SD-1 and DS-1 mods I did come up with on my own.

Boss Pedal Mods

MXR Phase 90 Mods

Disclaimer (please read):

Keep in mind, I am not responsible for busted, broken, burned up or fried effects pedals while performing any of the mods listed here. I was able to successfully perform them on mine without any serious problems and was able to troubleshoot when there were problems. That being said, if you don’t know what you’re doing, stop. Get someone who does to help or to do the mods for you.


  1. for al the phase 90 modders out there:
    very nice schematic, adds a depth/range, mix/blend and a feedback control
    feedback is very similar to R28 mod.
    but it replaces the resistor with a resistor and a pot.
    so you have to find the sweet spot but can make it self oscilate.
    i scratched a bit of the pot internals away to make it act as a switch at the end and got rid of the resistor for more noise and sounds that have nothing to do with music ;)
    installing this in a stock peddal is going to be a hard job.
    i build a clone and modded it...
    btw: srry 4 bad grammar :P

  2. Erik, Hello, Can you post your CE-2x bypass circuit? I am dropping a small stomp switch and LED indicator into my CE-2B to flip the box to Vibrato. I would like to have the bypass foot switch still work properly. I was thinking of buying the Allmuns bypass circuit but if I can do it for less than 30 bucks that would be ideal. Thank you

  3. Replies
    1. Hi. I meant to reply last night but was too busy. Glad you figured it out because I don't have a bypass circuit for that pedal. The Boss bypass circuitry is fine as it is.

  4. HI Erik, Yes the bypass circuits are great, I ended up introducing another switching FET into the dry bypass line. I am toggling it from the other side of the switching flip flop. So when the pedal is engaged, it becomes a vibrato. I then put manual mini toggle switch in parallel with the FET, so I can switch the pedal from chorus to vibrato. Its fabulous.

  5. oh yeah, I increased the gain of the vibrato circuit so when I top out the gain knob for teh chorus blend I get equal level between bypass and vibrato.

  6. Hi Erik, I find you posted a mod for Phase 90 so probably you can help me :). I have an EVH Phase 90, but it suddenly stopped phasing. it worked for a couple of minutes but then it just stopped phasing, the blue led works (but that's the only thing that works). Do you have any suggestion about what can be causing this issue?. Thanks!

    1. Are you getting any signal at all? If not, change out the cables with known good ones. If still nothing, it could be anything internal causing it from a bad switch to a bad component. If you are getting signal but no phase, it could be a bad switch or a bad component but tough to tell without using an audio problem and tracing the signal through it. These are surface mount component boards so working on them is trickier than conventional through hole components. If it is brand new, take it back and change it out. I hope this helps.