Hahhaha! Nice one. I've just seen the post on Facebook.
When I first got interested in a DIY reverb unit, I thought that the spring was part of the circuit, i.e had a current running through it. But no!!! It is all about miking up the springs vibrations, or 'reverberations', and then mixing the wet and dry signals together to create the effect.
I hoped this video would clarify that aspect of reverb and inspire more people to attempt their own version.
I've just remade it with PVA glue instead of wax and it doesn't sound as good. I think the PVA has muffled the speaker cones vibrations.
I've made a wooden box to house it in but I'm having problems with the wiring. I can't figure out how to control the reverb mix with the dry signal. Any sugestions?
By the way Matt, I was very inspired by your reverb unit.