I made an update to the RunOffGroove UBE Screamer from a suggestion in their notes. This version adds a mix control the blends some of the original signal with the distorted signal.
The original uses Rx to set a fixed mix amount. The notes suggest a value of 100K to 470K for this resistor with a 100K for lower output pickups like single coils and 220K to 470K for hotter pickups like humbuckers. There is a suggestion in the notes to make this a trimmer. With this board I made this an outboard control.
These boards were done through PCBWay.com. The quality is great. It was abut $25 for 11 boards so the price is pretty reasonable.
I built his up and after testing I realized I needed another resistor in the mixing section. I should have seen that earlier, oops. This wasn’t hard to fix by cutting the leg off the blend pot and inserting a 100k resistor in its place. This idea will take a another revision to get it working as it should.
I left R13 out. This is needed mixer is not working when the Blend pot is at a low resistance. I clipped a leg off the blend pot and replaced it with a 100k resistor as a patch. Then updated the schematic.