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(possible sticky?) DIY pedal modifications

Discussion in 'Effects [BG]' started by nil, Feb 6, 2005.

  1. We all know there are often good mods to pedals that can be done without necessarily a Doctorate in Solderology. Y'know, things like changing input and output filter caps to increase low-end response, additional clipping stages in Distortion pedals, additional tone and blend controls, etc, etc.

    How about those of us who have made successful (and not-so-successful!) mods to their pedals post them up for others to enjoy?
  2. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    I finally got my DOD 250 today. I plan on making a couple of mods to it. I want to try a bigger input cap and replacing the diodes with FETs.

    Check out the simple mods/tips page here: http://www.diystompboxes.com/pedals/index2.html
  3. let me know what you come up with seanm!
  4. Brad Barker

    Brad Barker

    Apr 13, 2001
    berkeley, ca
    it would be quite awesome if you could record "before" and "after" samples of the pedal.


    getting a 250 is something i want to do, and i'd like to know if doing some mods would be worth me getting my soldering skills up to par.

    (my prior experience with soldering involved a "blinky board"...that didn't work. :eek: )
  5. I modded a Big Muff pi (russian). I bought one and when i got home I really wasn't impressed with the sound (i did try it at the store but i sounded different). I changed the input and output caps from .1 to 1.0. I then decided to put a wet/dry blend knob in. I attached one end of the 100k pot to the clean input end of the muff, and the other to the effected signal end. I then severed the connection between the effected signal and the output plug itself, and connected the remaining wire from the pot to the output plug. I used some resistors as well (100k maybe?) one on each of the in lines to the pot.

    The result? It sounded considerably better. It retained a lot of the clean signal and allowed me to dial in as much or as little distortion as I wanted. I found I was able to get the sort of heavy overdiven sound that I was looking for, rather than a total fuzz sound. I had one problem though. Once I turned the knob to the point where I dialed in about 80% effected signal I began to get feedback - a very unpleasant squeeling noise. I think the problem was that I was using the wrong pot. I believe I should have used a 250k pot, but I didn't have one on me. I think the effected sound was escaping through the pot (which wasn't offering enough resistance) and going through the clean signal and getting distorted over and over again. I don't know much about electronics so I could be wrong.

    Anyway, it sounded heaps better. I undid the mod though because i didn't want to drill into the Big Muff casing to mount the blend knob. I decided to just make an effect mixing pedal that will allow me to run an effects chain with 2 knobs. One for clean/effected blend and the other for level.
  6. I've done a similar thing to my Voodoo Lab Superfuzz.

    Connected a lead from the right lug of the volume pot, thru a SPDT switch to the output socket. With the switch on, the fuzz is quite subdued, you have to crank the volume to maximum to get it good (unity is around the 3o'clock mark), but it also changes the sound to a darker buzzy tone. Useful tonal addition IMO. The switch was mounted in the hole for the status LED, that LED just tucked inside the case out of harms way (still connected though).

    Then I did pretty much what you have, but made an FX loop pedal so I had more flexibility. I too, on some settings get a nasty feedback drone tone, but it's not too bad.


    Input is routed to the Send, and via a 100K Linear pot to the Output (and yeah, maybe a 250K pot would work better, i'm no expert either!). Not so much a blend but more a dry level control...I kinda prefer separate levels for dry and effected to dial in the perfect sound.

    Return is routed via a .0015uf capacitor (kills 95% of the feedback, different value caps gave a different feedback point and tone...possibly this value may not give the best results with pedals other than the Superfuzz), with another .022uf cap wired in parallel (with a SPDT switch) as a "fat" boost.

    DPDT footswitch has been wired with a status LED (meaning I have to run a 9v battery, but it's a purdy blue light! :D ). With the switch off it simply routes the Input to the Output, bypassing the Send/Return.

    This is where is got weird, as even with the switch off there was bleed through the FX loop. But as a result i've got so many fuzz tones it's not funny. Soft fuzz with the Superfuzz on and the FX Loop off, and boosted fuzz with the FX Loop on.

    Switching the "fat" boost on with the FX Loop blend favoring the effected signal gives a healthy low-end boost, but has the unfortunate effect of causing feedback with the Loop off but Superfuzz on.

    Best fuzz/distortion i've heard on bass so far with this setup. I've now gotta try the FX Loop with other pedals and see how they respond (initial tinkering with a Rat2 in the loop wasn't as good).

    I can send the schematic for anyone interested in dissecting some REAL bad electronics! :D
  7. If you want to make an effects loop that is apparently really good (so I've heard) and proven to work well, visit www.moosapotamus.com. I think thats how it's spelled. The FX loop is called the paralooper. There are some sound samples on there too. I'm going to put one together soon. Good work on making your own FX loop though. I don't think I know enough about electronics yet to make my own one!
  8. Been there, done that, all links on that site are dead! Do you have the schematic or build instructions for that Paralooper?

    I've got schematics for simple mixer and loop circuits, I (probably like you) figured I could get away with a simple non-powered circuit and not have to build some complex mofo.

    Works well enough for the low $$ injection!
  9. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    I did some sample recordings and after going through my cheap mixer and really cheap audio chip in the computer, you lose some of the bass :(

    It was recommended that rather than change the input and output caps, I would get more bass from changing the feedback cap. This is the .05 uf cap off pin 2. It is marked C1 in the reissued 250.
  10. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Ok, here are my first samples. They sound much better through the amp, but you can detect the added bass. Still not completely happy, but it is better.

    Here are the changes:

    Input cap .01 to .1
    Output cap 4.7 to 10
    Feedback cap .056 to .1
    Diodes replaced with 3 1N4148

    I ment to get Ge diodes, not Si.

    Stock, gain at full
    Mods, gain at full
  11. Definitely sounds a lot better in my opinion.
  12. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Just finished modding a Boss Super Overdrive SD-1 to make it sound like a Fulltone bassdrive. I have not been able to do an A/B test, but it does sound good. It is not true bypass. Simplest mod in the world: short out one cap.

    It turns out the Fulltone bassdrive is basically just a tube screamer with mods for bass.
  13. Apparently a lot of Fulltone products are just existing products with slight changes. I'd rather make my own version for a fraction of the price of a fulltone.

    If you do a search for 'fulltone' at the www.diystompboxes.com forum, you'll see what I mean. Also search for 'fooltone' :D.
  14. Does anyone have a schematic for the Fulltone Bass-Drive?

    I built a version myself using a modified version of the "Screamer+" (found here):


    If I recall correctly, the Bass-Drive is a Full-Drive modified for bass.

    Thoughts appreciated!
  15. Petary791


    Feb 20, 2005
    Michigan, USA
    Did that moosapotamus guy make his own pedals?
  16. Yeah, from existing designs and schematics on the web (he links them), but with his ideas and modifications. They look pretty cool, esp. that looper...and anything that self-oscillates! :D
  17. Yep, and and I believe the Full-Drive a slightly modded Tube Screamer.