Anyone knows tested mods for Boss ODB-3?

[gigimarga]

Hello,

I've just bought a Boss ODB-3 and I like it, except the shrilling highs from some settings.

The schematic can be found here (thanks to mrslunk!): http://www.diystompboxes.com/smfforum/index.php?topic=76569.0.

The only mods that I found are here: http://www.talkbass.com/forum/showthread.php?t=369882.

Indyguitarist seems to know some mods for it: http://www.indy-guitarist.com/inc/sdetail/102.

Excepting the well-known clipping section mods, anyone knows (or tried) other mods?

Thanks all!

[gigimarga]

 

[gigimarga]

Very strange tone controls for my knowledges...

[gigimarga]

 

[gigimarga]

Another try...seems to be like a Boss Blues Driver BD-2...but I have no ideea how to modify it

[mrslunk]

what do you want to get out of modifying it?

[wampcat1]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

[gigimarga]

what do you want to get out of modifying it?

Hello mrslunk,
I want to eliminate some shrilling highs and to try to get a fatter distorsion, too (like a Woolly Mammoth). I tried it on guitar, too, and it sounded not very good

Thx a lot!

[gigimarga]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

[gigimarga]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

Thx a lot Brian!
How it will sound with these mods?

[wampcat1]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

Thx a lot Brian!
How it will sound with these mods?

hmmm.... it's been about 4 years since I had the pedal... IIRC, it just sounded much smoother and fatter but less 'flabby' as well.
bw

[gigimarga]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

Thx a lot Brian!
How it will sound with these mods?

hmmm.... it's been about 4 years since I had the pedal... IIRC, it just sounded much smoother and fatter but less 'flabby' as well.
bw

OK...I will try as soon as possible

[mrslunk]

Here's what i'd suggest:
in the clipping path, there are 7 caps.
Try bypassing each cap with another cap of the same size. Remeber that capacitors in parallel add...
If this gets you further away from the sound you want, you probably want to decrease the size of the initial cap.

Fatter distortion means you prolbably wanna increase the pre-clipping treble roll off slightlly, and maybe increase the gain a little.
Taming the shrill high's will mean you probably want to increase the treble bleed off across the clippers.
You could also tweak the distortion texture by using different diodes, I'd suggest that if you do, use 2 in series on each, ie: 2x1n4148 || 2x1n4148.
All the usual diode tricks should apply.

I'd focus my attention on the 330pf caps, the 1.8k/10uf and the 1.8k/0.1uF parts, making thorough use of my audio probe to work out what the circuit was doing, since i can't visualise what was happening.

I'm guessing(can someone with a more electronic trainig confirm) that the 2 back to back fets form an inverter. If that is the case, the 330pf's across the inverted/noninverted signals would cancel some treble and the 1.8k/10uF would bleed some of the low frequency content of the inverted path to ground, when combined via gain pot, this would introduce a low frequecy boost...
Changing the caps will change the locations of the rolloff, chaning the 1.8k resistor will change how much of a low freq boost you get.

[gigimarga]

WOW....very nice advices...thx a lot mrslunk!

[gigimarga]

easy mod to make it much nicer:
c10: 1uf
r31: 1k
c8: .001uf
for more smoother compressed tone, change d2 and d3 to 1n4148's

I made these very simple mods and ODB-3 sounds much better: fatter, without the shrilling highs!
When I will have more time, I want to tweak around the clipping section

Thx a lot Brian!