All Goofyness Shall Be Revealed #2—the Luxo Lamp spring reverb
The above photo is snagged from the good folks at Luxo, but in lieu of an endorsement deal, this’ll have to do.
Often referred to here as the piezo driven Luxo Lamp spring reverb, it begins as any old Luxo lamp with spring loaded arm segments. A sound signal from a Monotron or whatnot is fed into a small amp of some kind. I generally use this Radio Shack mini amp that Nicolas Collins mentions in his Handmade Electronic Music book. (Something basic built around an LM386 chip will also likely do.) It has a speaker output and that signal can be run through an audio transformer to drive a piezo disc to vibrate. (Indeed, Collins describes this whole arrangement with the amp, the transformer and piezo disc driver in a tutorial video.)
Anyway, clamp one such vibrating piezo driver to one end of a spring loaded Luxo lamp. That makes the lamp—springs & all—vibrate. And clamp a piezo disc mic, say, on the far end of the lamp from the driver to pick up the vibrations. That mic signal is the output of said piezo driven Luxo Lamp spring reverb. Maybe feed it into another mini amp or amp or use it DI.
Now technically what most folks call a spring reverb is more sophisticated. Mine is a broad minded and somewhat ironical application of the term. Like a “real” spring reverb would have a direct uneffected signal with which the effected one could be blended as desired.
A mixer and such could wangle that. But Collins presents the piezo driver as a sort of sound alteration device and I take it as such with few amenities. If I say Luxo Lamp spring reverb, that’s probably exactly what’s transpired without a direct signal in parallel.
Even with the Crowbar mix matrix or whatnot to create some sort of blend, the whole value of the Luxo rig hereabouts is its funky Gilligan’s Island coconut radio pollywollycrappyness of tone, its spiky uneven response. This ain’t no Altiverb.
The fact that it sounds wonky or might feedback etc., such things are features not bugs, opportunities not problems.
Along similar lines, other objects like little paper Dixie Cups and plastic jugs etc. can become speakers with piezo drivers. Happens all the time. Again this is all from Collins, who is in turn shouting out to David Tudor.