Any cool mods you can do to the Boss SD1?

[Instant Dan]

Traded my 2005 MXR Phase 90 for a late 90's Boss SD1 tonight. It's cool in the sense that it's a more aggressive tube-screamer but otherwise it gets kind of dull and lacks bass. I was wondering what type of mods are out there for it? Keep in mind, I am not that saavy when it comes to soldering. I can get do the basic stuff like speakers but never done pedals before.

[The Riffer]

Lots of things to do with this one. For more bass,replace C2 and C6 with 1uf film caps. If that's too much bass, try a .47uf. Also look at experimenting with Diodes 4, 5 and 6. You'll find alot of variation with different clippers.

[showdown]

Replacing the ceramic/electrolytic caps with higher quality film caps will also "open up" the sound a bit.

[Hemisaurus]

Pulled from craigslist

Monte Allums SD-808 Modded Boss SD-1 Super Overdrive - $40 (Trivoli)

Date: 2011-05-14, 2:07AM CDT
Reply to: sale-xxjcq-2380219037@craigslist.org [Errors when replying to ads?]

Only a couple weeks old, comes with the box and all the included paperwork.
Here's some info on the mod that was installed.

With this mod I take the SD-1 and mod it to TS808 specs. The circuit of the SD-1 is very similar to the TS9. This mod includes all the mods in my regular SD-1 mod, plus you get three extra components that will take the SD-1 to TS808 specs. I have also included a JRC4558D chip. The stock SD-1 comes with the JRC4558DD op-amp chip. Some feel the JRC4558D is a better sounding chip than the JRC4558DD in the SD-1 circuit. I also include a 3mm Super Bright Blue LED and a resistor replacement that will increase the brightness of the LED. What's really amazing is how great this pedal sounds with this Mod.

I also include the symmetrical clipping mod for those that prefer Ibanez TS808 clipping over Boss asymmetrical clipping. This mod is absolutely the best SD-1 mod sold anywhere by anyone at any price! The complexity of the tone after the mod is startling. We also mod the clipping section to symmetrical clipping like Ibanez uses in the TS9. You can also change the character of the pedal buy swapping out different chips which I now sell above. Compared to my regular SD-1 mod this mod will take the SD-1 and add presence and much more complexity of tone. It's like taking a blanket off the speaker in your amp. The tone is very open, airy and transparent. Very smooth, yet biting gain. Controlled feedback and sustain is incredible with this mod. This is the ultimate SD-1 mod!

[inductorguitars]

For all your pedal needs: http://diystompboxes.com/pedals/schematics.html

[VOLVO)))]

I used this, it made it sound 100% better because it no longer made a sound.

Hopefully this helps.

[inductorguitars]

LOL

I was trying to be nice and show him there are other pedals out there...

[Hemisaurus]

If you can't solder pedals, there's not a lot of mod'ing you can do. They're like small and finicky, and easy to break, especially Boss who tend to cram a lot into one (other manufacturers do to, not just picking on Boss)

That above diagram is awkward for you, because it doesn't have any numbers on the components, so it'll be trickier for you to find them on the board. You kind of want two different things though, more bass, and a brighter (usually considered less bass-y tone), more bass you'd trace the main signal path and bump up any 'strangling' capacitors in this case the .047 on the input and the .018 to the op-amp, I'd try moving the .047 to the .018 spot and replace the .047 with a .1, or just replace 'em both with .1 if you like, or 1 if you are really wanting to shake it up.

For the brightness, not really so sure, I tend to be making things bassier. I'd try switching out the clipping diodes, try different things, LEDs, germanium, zener what have you, also tweak the tone control, maybe try a bigger cap on that to shift the tonal range down, maybe something in the .1 to .2 range.

So there you have it .1's all round  

NB, this is all speculative, I have never mod'd an SD-1, I'm just looking at the schematic.

Oops, I posted this before I read the other replies

[Fuhgawz]

Lots of things to do with this one. For more bass,replace C2 and C6 with 1uf film caps. If that's too much bass, try a .47uf. Also look at experimenting with Diodes 4, 5 and 6. You'll find alot of variation with different clippers.

The C2 increase is a good one! C6 may be better if it's removed entirely. Experimenting with the diode clippers is also a really good idea! I personally don't like LED clippers in overdrive pedals. I would prefer in this circuit to jumper D5 and change D6 to a 1N4001. Just changing D5 to a germanium 1N34a would probably also sound sweet. Perhaps the best way is to combine them with D4 is 1N4001 and D6 is 1N34a.

Another good one to increase is C3. That's the cap that gets changed in the Tube Screamer to give it more bass. Try 0,1uF. Note that this is more bass before the overdrive, so don't increase it too much or it will sound mushy. If you increase C3 to 0,22uF and combine it with decreasing R6 to 2,4k you get a similar bass increase as with 0,1uF, but with more gain. This mod if often coupled with decreasing R5 to 20k to give it less overdrive at the start of the pot. The combination of these three components (C3, R6, R5) is what Keeley calls his "less/more mod" that he uses on Tube Screamers to increase the range of the drive pot in both directions. If you still want more bass into the circuit after this mod just increase C3 and leave R5 and R6 as they are, or you could increase C1 to 0,1uF.

It might also be a good idea to change the tone stack to handle more bass. I would increase C4 to 0,022uF or maybe even 0,033uF and C5 to maybe 0,047uF. Finally, you could increase C7 to 2,2uF or more. This lets more (clean) bass out of the circuit, but it may not be necessary. Increasing the bass capacity on the outputbuffer does seem like a good idea too if your effect is more bass heavy, so make C8 0,1uF.

If you don't have lots of experience soldering it is advised to solder these mods in one by one and testing your pedal after each component change. That way you always know when a mistake is made. Another advantage is that you can hear the influence each component change has on your pedal.

EDIT: Here's the schematic:


EDIT 2: Here's a nice sheet with mods: http://www.indyguitarist.com/mods_new/sd1-mods-206.pdf

EDIT 3: This seems like it could be a good idea: http://www.indyguitarist.com/temp/sd1-bypass-fix-406.gif

EDIT 4 and FINAL edit: please don't go changing the opamp to bullshit 'mojo' 4558 or something. It only has a really REALLY subtle influence on the sound.

I lied, one more edit: This component layout could be useful:


In short, this is what I would do to SD-1 if I had one:
C1: 0,1uF (maybe)
C2: 0,1uF
C3: 0,22uF
C4: 0,022uF
C5: 0,047uF
C6: Remove
C7: 2,2uF (maybe)
C8: 0,1uF

R5: 20k
R6: 2,4k

D4: 1N4001
D6: 1N34a

The value changes with "(maybe)" behind them may not be necessary, so you could try the other mods first. The rest of the changes are solid and I'm 100% certain that they will improve your pedal. If you think it's not bass heavy enough after these mods, then you can do the maybe-mods and increase C4 to 0,033uF and you can even increase C3 to 0,33uF, but I personally think that one would be a little too much.

Good luck and let us know what you end up changing to your pedal!