Low-cost standalone reverb

[Mick Bailey]

I posted this over on MEF a while back but thought it may create more interest here;

A couple of years ago I had an idea to build a tube reverb without the expense of special transformers. Here in England, tube (more correctly 'valve') transformers are pretty expensive and I wanted to see if something useful could be had from easily-available parts. Here's the schematic exactly as-built. It works very well, though I've yet to sort out switching the reverb on/off. I tried the usual method of grounding the input to the recovery tube, but this introduces too much noise.

The transformer is a low-cost toroidal - just because that's what I had to hand.

The TIP35C was used because it just happened to fit the spacing of my tagboard. Only the MOSFET needs heatsinking. The tray I used is from a mid-90's Marshall and I've tried a half dozen different other types and they all worked well. I'm not sure if the circuit will drive a Fender-type low-impedance tray, but the drive from the MOSFET is very strong.

I know there are lots of design flaws, and room for improvement, but it works much better than you'd expect. With the level turned up it acts as a nice overdrive, too.



Here's the (almost) finished unit - still needs the case finishing off...



Note; Since the original posting I've added a simplle FET switch to kill the reverb, wired right onto the grid of the recovery tube and this works really well.