This article details how I modified my Paia 6710 Vocoder for much better noise and sound. Here's a picture of the finished product:

Front panel L-R: Instrument input, instrument level, hole for peak indicator LED, mic input, mic level, hole for peak indicator, HPF switch, Main output, mic threshold, bypass switch, output jack, power indicator.

Here is the original schematic, which is referenced below:

I thought I'd post some of the musical instruments i've built:

some cookie tin banjos.

Tweakable Dr-Rhythm Dr110. This isn't finished yet.