Another one of Tim Escobedo’s Circuit Snippets. The envelope control mod is way cool. Go listen to it at Tim’s web site. Mine came out sounding exactly the same as his, except for the ‘Freek mod’ that I did.
The Freek knob is a 50K pot wired between the input and output. The Freek switch is a SPST that switches the Freek pot in and out. Switching it in drops the volume a bit, but also gives a big low frequency (bass) boost.
BTW – this is an older version of the circuit (v.4) using 2n3904 transistors instead of the LM386 driver in the newer version. Here’s my layout.
This one started out on the breadboard.