Pedal Mods

Before continuing, please read the below disclaimer carefully.

***Disclaimer***

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.

I began doing pedal mods in 2004. It started with my Dunlop Crybaby and went from there. Many pedals that I have modded have been sold or traded off. I have a couple left but not many. I just don't use pedals in my setup very much. Most of the mods that I have been hosting can be found elsewhere so I am no longer including them here. In several cases, the circuit boards have changed from conventional through-hole components to SMT (surface mount) components making the mods irrelavent since the part numbers in many cases no longer apply. However, mods that I have done by looking at schematics, making the changes and noting them, I am including here. These only apply to through-hole component boards.

Below are mods for the Boss DS-1 Distortion and SD-1 Super Overdrive. MXR Phase 90 mods can be found on the MXR Phase 90 Mods page.

Boss DS-1 Distortion Mods

This is my minimal mod that really changes the sound of the pedal enough that it can be a standalone distortion through a clean channel with a good full sound.

Here is another low parts count mod that I call, Minimal Mod Part II. C5, C11 and C13 are back to their stock values, 0.47uf, 0.022uf and 0.047uf respectively. R14 was raised to increase the lows. R16 was lowered to increase the mids. These three changes make the DS-1 in to a great sounding distortion. It sounds excellent with both single-coils and humbuckers.

Boss SD-1 Super Overdrive to OD-1 Overdrive Conversion

There were two versions of the old yellow Boss OD-1 Overdrive; the early 14-pin quad opamp version and the later dual opamp version. The quad opamp versions go for pretty high dollar these days and are more sought after but the dual opamp versions are still good pedals.

A Boss SD-1 Super Overdrive can be changed to the later (dual opamp) OD-1 specs fairly easily. The tone control needs to be removed from the circuit and the input to the opamp after the clipping stage needs to be changed to go to the inverting input (pin 2) rather than the non-inverting input (pin 3). There are a couple of other part changes necessary as well.

First let’s look at the differences and then the conversion process.

Differences
SD-1 Part No. / Value
R1 – 10k
C2 – 0.018uf
C6 – 0.01uf
2nd 1/2 IC – Pin 3
R11 – 22k 		OD-1 Part No. / Value
R1 – 1k
C2 – 0.0047uf
C4 – 0.018uf
2nd 1/2 IC – Pin 2

Conversion

Ok, so what about the sound differences between the quad opamp OD-1 and the dual opamp OD-1? They do sound different, no doubt about it. The later dual opamp versions are a bit brighter sounding. Many prefer the sound of the quad opamp version. If you have the dual opamp version, you can get 90% of the tone of the quad version by making the following changes (thanks to Analogman for this). You can read up on this in the diystompboxes.com thread discussion.

*Please note, the 4 changes above pertain to the OD-1 part locations. For SD-1 part locations, read on.

Now that we know this, we can take our now converted SD-1 and make these same changes.

There are a few other part differences between the quad and dual versions. The SD-1 uses the same values as the dual. These changes are as follows (SD-1 part locations).

I noticed that these last three changes gave it too much of a tube screamer like quality so even though those are the quad version values, it sounds more like a quad with the stock values, to my ears anyway.

Once finished, tape down the disconnected wires that lead to the tone pot to the inside of the enclosure so they stay out of the way.

This is an excellent mod, in my opinion. It sounds very close to the old OD-1 after this, as well as it should considering how the two circuits are so similar.

Boss SD-1 Super Overdrive to Ibanez TS808 Tubescreamer Conversion

This was fairly easy to do though I must stress, this DOES NOT make this pedal a TS808 in any way. There are several more part differences than these between the two. The biggest difference between the TS variants and the SD-1 is the diode clipping. Ibanez uses symmetrical and Boss uses asymmetrical. Remove D6 and put a jumper in its place to make the SD-1 have symmetrical clipping. D4 and D5 are a pair of the stock silicon diodes.

Some capacitors need to be adjusted.

Next are a few resistor changes.

And lastly, if you wish, change the LED to green from the stock red. It’s easier than repainting the whole enclosure. It’s just my own little personal touch. Everybody else uses blue or purple or some other color. So, I picked green.

Again, these changes don’t make the SD-1 a TS-808, but they do get it in the ballpark and give it that flavor, which is what I was aiming for.