this was the final build before it shipped out. circuit is a simple MOSFET (BS170) driver stage followed by two JFET (J201) recovery stages. i’ve included a sound sample of a similar reverb i built later without the second recovery stage and clipping diodes. it makes for a much more subtle reverb, but also tames the noise floor from the Belton module.
[audio:http://abrammorphew.com/notes/wp-content/uploads/2013/02/sqrt_reverb_demo_02.mp3|titles=sqrt() reverb demo #01]this is the actual first build. the “dirty verb” comes in towards the end which just switching on a pair of germanium clipping diodes. you get more reverb for your buck with the second JFET stage, but i haven’t found a way to cool down the noise just yet. that’ll be revision 5… maybe 7. [audio:http://abrammorphew.com/notes/wp-content/uploads/2013/02/reverb-test02.mp3|titles=sqrt reverb demo #02]