Here's a nice little boost from ROG that originated from trying to design a FET-based Rangemaster treble booster. I've laid it out for a 1590a with board mounted 9mm pots. More info, schematic and sound clips can be found here.
This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.