Question:
I have a spring reverb tank from a busted amp... any way to make this into a reverb unit of some sort?
Answer:
Here is one example schematic. I have no idea how good it is. I've never built a reverb because I never had a spare reverb tank laying around to do it with.
The basic idea's always the same. Buffer the signal. Split it into two paths. One path goes to the reverb unit, the other doesn't. Amplifiy the signal coming back out of the reverb, and mix the two signals together.
There are are all sorts of controls you can add, adjusting the signal strength going into the reverb tank, cutting various frequencies before and after. Three possibilities for mixing: 1)Reverb level, keep original level the same, 2)reverb level & dry level w/ 2 knobs, 3)wet/dry mix on a single knob. Add a switch or two and you might be able to change the number of reverb springs you're using.
A phase switch might be useful. First, for possibly cool cancelation effects, and 2nd because you might get unwanted cancelation.