.... wow .... this thread has knocked some cobwebs off the memory banks .... spring reverbs!!! ..... I started out playing acordion (the popular portable keyboard of it's day) .... the accordion and amp (tube, of course) were made by SANO, in NJ, USA ...great sounding box.... the amp had a spring reverb, and you are all correct ... accidently bump it and it sounded like 'thunder' .... I've still got the amp and accordion, but the amp has not been plugged in in quite some time ... I also have an "echo-rec" machine... it was an echo effects machine that used a tape to record and playback instantly giving the 'echo' effect ..... while in high school I worked in a music studio that sold the Epiphone line ... went from accordion to codovox (which had some pretty neat sounds for the time) and then in the 70's I used a fender rhodes, which I 'enhanced' with a phase shifter ... for a while I also had the 'vox lying on top of the rhodes for organ and other sounds...
t.