This is basically a giant spring reverb made from 10 Slinkys. I have tried to make the best sounding spring reverb possible. I think I have achieved this but it is probably the most inconvenient effects unit ever made. The reverb time is so long that the springs need damping and I found that the best material for doing this is a slice of cucumber wedged under the end of each spring, other materials like foam or rubber tend to kill all the treble.
Each spring has its own input and output volume control. The springs are powered by 10 separate 10w amps. They are driven by moving magnets, the magnets are tiny 2mm neodymium types, stuck to the springs, the drive coils can be seen on the right of each spring. The pickups are a similar design but in reverse. The outputs of alternate springs are sent to left and right outputs, the stereo effect is quite amazing. The longer springs need to be suspended in the middle with threads, this actually improves the quality of the sound by blocking the low frequencies.
I originally made the pickups without a magnet stuck to the springs. This was so I could rotate the pickup around the springs to vary the tone, the same principle as on an electric guitar, the closer the pickup is to the anchor point (bridge) the brighter the tone. It made a really interesting phasing sound as the pickup was moved, but the output was very low so now I usually use a static pickup with a magnet stuck to the springs.
I used the golden ratio to work out the lengths of the springs, this was to prevent resonances occurring at the same frequencies and at harmonically related frequencies. The quality of the reverb is excellent, as good as a plate but with a different character
Although it is very inconvenient as a reverb, it is very good for making horror sound effects by playing it with a violin bow. This is the only type of sound recordings on this page, I don't have any examples of it being used as a proper reverb.