boss sd-1 easy mod

[catalin gramada]

Salute You all guys !

It is my very first post on this forum and I looking for some help please.
Have  a sd-1 and I want to do some improvements: 1. need more bass . 2. need to smooth distorsion (it is little "raw" and "harsh" for me at any level), but I don't want to loose SD overdrive character.
PS: I did't found any schematic for SD1 with values and equivalent PCB component number, maybe can help me please.
Thanks
Catalin

[Derringer]

here's a good place to start
schematic and pcb layout

http://www.hobby-hour.com/electronics/s/sd1-super-overdrive.php

[catalin gramada]

Thank Derringer
That's I'm talking about.

[catalin gramada]

K
After a quick study of some materials at this forum I decided to do this modification :
C2, C3 - go to 0,1 uF
C6 - removed
0,47 pF over diodes
C7,C10 - 1uF elko replaced with 1uF  poly
Please if someone can give me a confirmation if these modifications are reliable according with my intention.
Thanks
Catalin

[BAARON]

Replacing C7 and C10 with film/poly caps probably won't make an audible difference.  Electrolytic caps might function poorly at high frequencies (100 kHz and up, according to here), but those frequencies are far beyond the range of what the human ear can hear (20-20kHz) and definitely beyond what the guitar can play (~82-1300 Hz playable range, plus a few octaves of harmonic partials).  The amount of THD they add is also below audible thresholds... especially considering that the signal is already distorted.

Experimenting with your clipping diodes is definitely worthwhile.  Try different types so you know what they sound like: silicon, germanium, LEDs, and combinations thereof.

[seanm]

I would try the "fat mod" first since it is very simple I have an image of it here: http://ftp.seanm.ca/stomp/sd1-guts.jpg

Just replace the cap with a wire, or for bonus points, add a switch to short the cap. You cannot just remove it.

Or you could try adding a pot for experimentation.

That should add more bass. If you want less distortion, then play with the clipping diodes.

[Derringer]

I'd imagine replacing C8 with something larger would add some more lows without making them too tubby

but I've never had an SD-1 or modded one either


glad you're getting some mileage out of the link!

[BAARON]

I'd imagine replacing C8 with something larger would add some more lows without making them too tubby

but I've never had an SD-1 or modded one either


glad you're getting some mileage out of the link!

C8 need not be changed.  The R-C cutoff frequency is already 3.4Hz, well below the range of human hearing.

[Derringer]

that's what I get for shooting from the hip