I've built a few of these now so I'm selling an extra one. I won't be making any more of them so this is the ONLY one available for sale. The originals run on AC and are in a somewhat funky enclosure so I mounted this one in a standard 1590BB and it runs on 9-12 volts to make it much more pedalboard friendly. This one is completely hand made on vero-board and it sounds great with a bass or guitar. I prefer it with an NOS USA 12AU7 (and that's what I'm shipping it with) but it can also run with any 9 pin dual triode like a 12AX7,12AT7, 12AY7, or 5751 etc.