Sparkle Drive "Clean" Option in a TS808 build

[joelap]

Hey, this is my last question about a tube screamer build, I promise.  This is gunna be my first build from scratch, I'll let you know how it goes.

I'd like to add an option to a Tube Screamer build for a "Clean" knob like found on the Voodoo labs Sparkle Drive.  How would I incorporate that?  I'm assuming I'd need another chip from looking at the Sparkledrive Schematic and then I wouldnt be able to use the www.buildyourownclone.com circuit board, but that's alright.  How hard would this be to implement?

Much thanks!  I promise this is my final question before I order the parts!

Joe

[David Barber]

The TS is in phase at the output, so it would make sense to run a clean boost/blend circuit in parallel that maintains phase and the final mixer stage could either be in phase or inverting depending on your preference or requirements of this project. An op-amp would be a likely choice to be able to maintain phase and also offer a virtual earth output mixer (although phase is inverted). You could use FET devices instead, if you do you could replace the standard emitter output of the TS with an inverting FET, run the boost/blend with a FET inverting circuit and then sum it all to an inverting FET mixer and keep the whole thing in phase at the output.