This amuses me -

http://www.asphaltandrubber.com/recall/harley-davidson-dyna-low-rider-ignition-switch-resonance/#more-67780

The following is perhaps one of the more interesting recalls to come across our desk, and it affects the 2014 Harley-Davidson Dyna Low Rider. It seems that if owners install “certain optional performance electronic control module calibrations” the bike’s ignition switch can go from “IGN” to “ACC”, thus causing the motorcycle to shutoff mid-operation.

The reason for this though is because the aftermarket ECU upgrade allows the 2014 Harley-Davidson Dyna Low Rider to rev its motor beyond the stock 5,600 rpm redline, where at 5,800 rpm a resonate frequency with the ignition switch occurs. Held at this frequency, the key can turn to the accessories position — a dangerous, if not fascinating, show of physics.

It makes one wonder if some reports of erratic on-stage behavior of synths and other gear might not be due to unstable AC power, but rather to high SPL at the “right” frequency.

I could just imagine a manufacturer’s warning…
Dear owner: It has come to our attention that exposing your keyboard to sufficient sound energy may result in erratic operation. SPL above 120 dB may prove detrimental not only to your hearing, but to your gig by causing panel controls to move without your physical intervention. We especially suggest limiting sustain pedal usage under these circumstances until such time as we determine which frequencies should be avoided.

;-)

I can see it. I periodically tighten screws in various gear that manage to loosen through time. At times with busy material I use a stool on stage, and had one collapse when the hardware checks came loose. Down in a flash with a loaded double tier coming at me. A swift Bruce Lee move secured the boards and the whole matter was quite dramatic. I am not eager to repeat it however.