Nobels ODR-1 Mod Question

guiltless · May 12, 2013, 02:38:06 AM

So I have a Nobles ODR-1 and I like the sound. My only complaint is that it feels a tiny bit stuffed... If it were an amp I would think it had too much negative feedback.
Being proficient with working on and tweaking amps I figured I would have a look at the schematic... Yeah, pedals are a different ball game. The one thing I did notice was an area of negative feedback near the output. I have a schematic below and I highlighted the area that I am looking at. Would adding a trim pot in the looped area below be the same as reducing the negative feedback? My goal is to have a more open, less compressed ODR-1.

Thanks!

aron · May 12, 2013, 03:39:01 AM

Put 2 diodes instead of one for d1 and d2. Maybe even d3 and d4. Start with that.

alexradium · May 12, 2013, 06:23:18 AM

+1

guiltless · May 12, 2013, 09:51:17 AM

Thanks! I will absolutely give that a try this week. For the sake of my own education, what is the reason for adding those diodes?

aron · May 12, 2013, 02:12:33 PM

You are going to love this. This type of document starts a whole bunch of trouble:
Read the first mod:

http://www.diystompboxes.com/wiki/index.php?title=Simple_mods

guiltless · May 12, 2013, 11:10:54 PM

Quote from: aron on May 12, 2013, 02:12:33 PM
You are going to love this. This type of document starts a whole bunch of trouble:
Read the first mod:

http://www.diystompboxes.com/wiki/index.php?title=Simple_mods

Oh crap... You just opened up a can of worms!

MartyMart · May 13, 2013, 03:30:08 AM

The ODR-1 is a little "cracker" I like it as much as a good TS-9, tone control works better too IMO.

Doubling up the D1-4 with extra 1N4148's helps, IIRC I also reduced the cap to ground around D3/4, which brightens the
"crunch" a little ( to 1nf/1000pf ) and also reduced the small pf cap across D1/2 to 47pf.

There are also a couple of other caps that I changed as i found the pedal a little "dark" sounding, can't remember which and that
schem is a bugger to read !

Welcome to a VERY large can 'o worms :-)

Marty.

HOTTUBES · May 13, 2013, 04:17:53 AM

I have modded a few of these , they can sound very nice with a few mods !!

here's my suggestions ..

C1 - 1 uf ( less low end from the factory value of .22 uf )
C34 - .047 uf ( also cuts a touch of low end )
D2 - 1N4001 +1N34A germ in series ( far warmer clipping that stock )
D4 - 1N4001 + 1N34A germ in series

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Nobels ODR-1 Mod Question