Spring reverb doesn't really need to be hi-fi, as such...it just needs to be
low noise. It is possible to have a low-noise spring reverb that sounds
good. As has been mentioned on this list before, a couple of channels of the
Anderton/PAIA "Hot Springs" reverb makes for a pretty good sound at a decent
price. To make a decent MOTM-like module out of it, you just need to design
some kind of input/output amplifier/mixer.