After quite a bit of experimentation I built with this one to be a versatile bass overdrive that also gets into heavy distortion. It can be run as a nearly clean boost as well. It's based on the vintage TS808 Tube Screamer circuit, but with a lot of modifications so that there is zero low end loss and capable of more distortion. The center toggle switches between silicon diodes/none/and red LEDs for the clipping. It comes in a polished and etched 1590B, with all top jacks and a relayed true bypass. If you like the 'flavor' and smooth natural grit of a stock Tube Screamer, but find them to have a way too limited bandwidth (especially lacking low end) when using a bass, I think that you'll love this one. This is a completely hand made pedal.