# Zapper gain mod



## Nostradoomus (Oct 24, 2019)

Quick and dirty! Swap the 50K pot for 250K, strap a couple diodes across the gain pot. Done!









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					ibb.co


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## andare (May 5, 2022)

Zombie thread. Does this mod add gain?


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## Dan M (May 5, 2022)

I think yes.  If I’m doing this correctly, the gain across IC2 is (1+50k/1k) = 6.

If you increase the pot it would be (1+250k/1k) = 26.

But I think the diodes will lessen the impact.  Maybe someone else will chime in on that part.


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## Feral Feline (May 6, 2022)

The diodes will add op-amp clipping kind of like on a tube screamer, as opposed to straight to ground — It does go to ground, looking at the schematic, but the clipping hits R7 & C5 before ground... so, yeah.

Diodes'll lessen the impact but I think the gains made by the 250k pot will counter any loss. I'll let somebody else do the math and see if that's an accurate assessment.

What diodes were used?


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## Coda (May 6, 2022)

Nothing against the Zapper (I have one and it’s fabulous), but if you want a grainier version, the Systech Overdrive is pretty good…https://www.pedalpcb.com/product/systemoverdrive/


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## Nostradoomus (May 6, 2022)

Couldn’t tell you the math, this was awhile ago haha. I used 5817s. It just adds a bit of grit, nothing spectacular but I like it a lot.


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## andare (May 6, 2022)

Thanks everyone for chiming in!


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