Just got a brand new DOD Gonkulator and being a bass aficionado I did not like the over-the top distortion that you cannot turn off. Then I realised that distortion is paralel to ringmodulated signal. That got me thinking, how much work is it to have it converted into a clean channel.
There are schematics online for the old version and I think Digitech did not change it that much, at least for the distortion side.
Anyway, if you remove the pair of diodes placed after the distorsion op-amp, you can achieve the clean blend. When I opened it up, it took bit to realise that nowadays you can get diodes paired up in single SOT-23 IC.
To mod this, you just have to desolder and lift that side with a single leg. It's not simple as those are tiny a.f. Great thing is, if you ruin the component (but you still want the dirt to be switchable or you are not sure if you want it), they are easily replaceable with regular diodes. Heh, you might even put some asymmetric clipping or Si/Ge pair for prettier distortion grain and more headroom. Anyway, pics ahoy!
This is the general position of the distortion segment and the diode pair:
Closeup, marked up:
I used scalpel to apply lift tension to the component, while at the same time heating up the sole bottom leg. Now detached, it is hanging in the air, about 1mm from the solder point. This way, one could simply install a SPST switch and have the distortion at the ready if the situation calls for it.
QUESTIONS, a plea for help:
(#1) There is still quite a bit of gain on that op-amp. I am guessing someone using a bass guitar with hotter output could have the problem not completely avoid overdrive/distortion (not tested). What component would be the best to change, and to what value. I'm guessing either that 470R that goes from inverting input to ground or 10kR in series with the gain pot.
(#2) I think there is some bass cut in place, is 50pf installed between the output and the inverting input acting as a filter. What about that 10uF electrolytic that is going to ground?
TL;DR: Detach one leg of one component and you get a clean channel with drive and blend.
There are schematics online for the old version and I think Digitech did not change it that much, at least for the distortion side.
Anyway, if you remove the pair of diodes placed after the distorsion op-amp, you can achieve the clean blend. When I opened it up, it took bit to realise that nowadays you can get diodes paired up in single SOT-23 IC.
To mod this, you just have to desolder and lift that side with a single leg. It's not simple as those are tiny a.f. Great thing is, if you ruin the component (but you still want the dirt to be switchable or you are not sure if you want it), they are easily replaceable with regular diodes. Heh, you might even put some asymmetric clipping or Si/Ge pair for prettier distortion grain and more headroom. Anyway, pics ahoy!
This is the general position of the distortion segment and the diode pair:
Closeup, marked up:
I used scalpel to apply lift tension to the component, while at the same time heating up the sole bottom leg. Now detached, it is hanging in the air, about 1mm from the solder point. This way, one could simply install a SPST switch and have the distortion at the ready if the situation calls for it.
QUESTIONS, a plea for help:
(#1) There is still quite a bit of gain on that op-amp. I am guessing someone using a bass guitar with hotter output could have the problem not completely avoid overdrive/distortion (not tested). What component would be the best to change, and to what value. I'm guessing either that 470R that goes from inverting input to ground or 10kR in series with the gain pot.
(#2) I think there is some bass cut in place, is 50pf installed between the output and the inverting input acting as a filter. What about that 10uF electrolytic that is going to ground?
TL;DR: Detach one leg of one component and you get a clean channel with drive and blend.
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. From the schem, looks like at minimum gain (GUNK) the 10K is in series with 100K (pot). This should mean that increasing the 10K to ~200K (for starter) would bring down the gain.