Spring reverb amplifier circuits

Man, I missed the boat when they had these as kits for sale. Now their prebuilt units are going for 300-400 bucks. Ugh!
The first kits were all through hole components and looked pretty straightforward to build, then they offered an assembled board of mostly SMD components. I like the one JM posted for the tank driver circuit, and it wouldn't be hard to put together a decent preamp and recovery stage using either op amps or jfets.