Tech 21 SansAmp Classic debugging/fix

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Tech 21 SansAmp Classic debugging/fix

aelling
This post was updated on .
When I first build this there was alot of layout errors and a wrong resistor value, here are my findings and how they make this layout like the original SansAmp.

EDIT: Added layout here for reference. http://4.bp.blogspot.com/-giA-7d3plvs/VknwbkJdygI/AAAAAAAAALs/nG6zm4IiMTo/s1600/SanClassic%2BCuts.png

First the 10K resistor (was 100K in the schematic) on pin 7 of IC2 is wrong, I found this out by the layout Alex made with the Kurt Cobain settings/no DIP switches. With those settings on an original where you have Amp Drive & Presence Drive all the way off it would be like a cleanish booster, but with the 10K in there on
the layout it would distort way too much. A 220K resistor should replace that 10K (100K) and it will sound like the original.

And the errors on the layout are Amp Drive & High pots are wired backwards which means when you have the DIP Sw 11 to Amp Drive lug 1 it won't sound like the original, DIP Sw 11 should be to Amp Drive lug 3. The High pots just worked backwards so High lug 1 should go to Output lug 3 and High lug 3 should go to the pin 13 junction of IC1.

Lastly, again when I made the Kurt Cobain settings layout that Alex made, I found that the layout didn't sound exactly like an original, there's alot of high end fizzle that can be tamed by adding a low pF capacitor between pin 13&14 of IC1, I mention here that I went up to 330pF and still sounding like an original. So, maybe a socketed one to test out what works here would be best.

With these findings you should get a clone of the SansAmp Classic.
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Re: Tech 21 SansAmp Classic debugging/fix

aelling
aelling wrote
First the 10K resistor (was 100K in the schematic) on pin 7 of IC2 is wrong, I found this out by the layout Alex made with the Kurt Cobain settings/no DIP switches. With those settings on an original where you have Amp Drive & Presence Drive all the way off it would be like a cleanish booster, but with the 10K in there on
the layout it would distort way too much. A 220K resistor should replace that 10K (100K) and it will sound like the original.
Okay, a little correction here, it was not the 10K resistor causing the distortion at this point, but the fact I had DIP sw11 to Amp Drive lug 1 instead of lug 3. Now that is fixed the 10K resistor on the layout is too small and will have way more volume than the original, same with the 100K that is on the schematic. The 220K I recommend is spot on same volume as the original.