Dual Channel Boost and Clipping Unit
This project was inspired by the MOJO CLIPPER by Ethan Winer , who wrote an excellent article on passive analog saturation here : https://www.audioxpress.com/article/you-can-diy-build-the-mojo-maestro
The unit has two channels of even harmonic clipping, a switch for hard clipping (more odd harmonics), and a switch for a filtering capacitor to mellow things out.
I wanted the unit to work with a range of input impedance and volumes, and output a reasonable signal strength. This circuit uses TL072 opamps with single supply DC (6v-15v), biasing the signal to half of the DC voltage. This solution does not provide the same headroom as a bipolar unit, but for near line-level signals from an interface, the solution works fine. I intended to use a passive EQ/attenuator before the unit, as the op-amps configuration is designed for boost.