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Does anyonr have a service manual for the Tech21 Sansamp bass driver di pedal?

never seen any service documentation from Tech 21
Behringer BDI21 is VERY similar circuit wise
bajaman

found this in my travels

yep - that's the Behringer - just replace IC2 with a TLC2264 and you are 99% there

Thanks alot gentlemen.

bajaman wrote:yep - that's the Behringer - just replace IC2 with a TLC2264 and you are 99% there

That's really helpfull...which one is "IC2", and where would I put clipping diodes, for mor distortion from the "drive" control? (sorry for the nOOb questions, I'm prety new to modding prdals )

IC2 is called U2 on the schematic.
You dont need clipping diodes, the sound of the TLC2264 is what you are after

First of all sorry about the necrothread... does anyone figured out how the Ground lift and line/inst switches work? I´ve built it and it works great, but i´ll like to have those 3 switches options. Had the chance to compare it to my bass player´s Original Tech 21 Bass Driver, going direct to a mixing console and using the XLR output (each pedal used a different desk channel, exact same settings, being switched with an A/B box to try to make the comparaison as neutral as possible), and with all pots at maximum, the original is way hissier/noisier than my build!!! I´ve used 1% MF resistors and Bipolar electrolytics for the 2.2uf coupling caps, maybe that´s the reason why is quieter. Also used plain vanilla TL072 & 74, they sound pretty close and with a less scooped feel, anyway I have sockets so I will try the TLCs. My build´s output level is definitely instrument level, compared to the original. I´ll like to add the switch to get LINE level, the volume difference is huge and very useful when going direct to a PA or mixing board, I believe the difference is 0dB vs -10dB, any thoughts on how to achieve this? Thanks!

Could the TLC2264 be replaced with any other dual opamp (another TL074 for instance), or does it have to be that particular chip for the drive sound?

The TLC2264 (and 2262, the dual version) is definitely key to the Tech21 sound. Nearly all of their designs rely on opamp clipping, which is pretty rare in effects in general because it usually sounds very bad - but they found an opamp that clips well the way they use it. It's pin-compatible with the normal stuff, but I expect anything else would sound very different.