Reverb tank driver and mixer
22 Dec 2019
I purchased an Accutronics/Belton reverb tank (BL2AB3C1B) a long while ago, and this project has been sitting on the bench for at least a year. Earlier on I thought I would try a JFET/MOSFET driver, but I could never get it to work quite right. In the end I switched to an op-amp driver, which I'm happy with. A lot of ideas came from the ESP website about reverb.
Earlier prototypes included things like trying to blend a reverb tank sound with a Belton brick reverb. This was... well... underwhelming. Apparently mixing a reverb with another reverb will just sound like reverb. Huh.
The final circuit has a clean volume/boost, separate reverb drive, volume and tone control, optical bypass for clean and reverb, with tails, and the option to use a remote foot switch for the clean and reverb switching.
The output section can be switched between a mixed output on one jack, or a split output (reverb + clean) on two jacks, if you want to send the reverb part of the signal to another amp.
The power supply for the op-amp reverb driver requires a dual rail power supply (+15 and -15v), so I made a small PCB that can take 9v and convert it to +/- 15v.
Prototyping, and the final PCB. The PCB got named 'Springus', after the ancient Roman god of reverberation.
The controls have been mounted on a 3mm thick strip of aluminium, and I'll be fitting the whole assembly into a wooden enclosure at some point in the new year. I'll be making a wooden box for the tank and PCB, and a matching foot pedal for remote control.