O'Cello Preamp and Pickup Enclosure and Knee Rest

thingiverse

I wanted to replicate the electronics used in Petercb's O'Cello build and my own Mina electric violin project, but I didn't want to use any glue, as it makes plastic harder to reclaim into filament. I also wanted to keep all the electronics hidden behind the O'Cello cover and out of the tuning pegs cavity. This knee brace base is designed to work with Petercb's knee rest pads. The holes in my design fit 3/8" aluminum rods, which should also fit the holes in Petercb's knee pad design. I've included an OpenSCAD file for my design, making it easy to enlarge or shrink rod holes as needed. I use Petercb's bridge, which has a cutout for the piezo pickup. This enclosure is designed for use with a CV-210E pickup and preamp. You'll need to remove the preamp faceplate and the battery cover. There's a cutout in the battery enclosure allowing recharging a 9v battery without removing it. The switch cutout is designed for a tension-held rocker switch like one on eBay. You'll need to splice the switch into one of the battery terminal wires. See photos for an example. The screw holes on the preamp have a slight offset. If they don't line up, try turning the preamp around. If they still don't line up, you might be able to get away without using them at all. The fit around the preamp is fairly snug and its edges should be pressed against the electronics cavity's edges, which may keep it from moving much even without screws.