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Kevin McMurtrie
 
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In article , Eiron
wrote:

John Schutkeker wrote:

I'm designing a system for shattering wine glasses with high intensity
sound, but my design doesn't "feel" right to me, and I need somebody to
tell me if I've forgotten something important. I need an oscilloscope to
measure the resonant frequency of the glass and a frequency generator to
produce it. I need stereo speakers and a stereo amplifier powerful enough
to generate the sound to break the glass.

But how do I correctly get the signal from the frequency generator into the
stereo amplifier. Do I need a pre-amp, or do I just wire it straight in?
If I need a pre-amp, how do I spec it, on the outputs of the freq generator
and the input of the amplifier? What if I'm using a receiver with the pre-
amplifier and the amplifier built-in? Can I just use the pre-amp that was
intended for the turntable?


You don't need a 'scope or a signal generator.
Stick a contact microphone on the glass base, plug it into a low-level
input on a guitar amp, turn it up to 11 and let feedback do its work.


I've tried that and it didn't work. The feedback loop finds many odd
local resonances based on them having much better phase alignment than
the primary resonance frequency. It would take a lot of fussing with
the microphone and speaker positions to make it work.

You could rent a soprano for a couple of hours from your local
choral society.

http://www.worldofglass.com/exhibiti....asp?NewsID=12