contact mics and springs

[Curtin, Steven D (Steven)]

Matt,

> This has all led up to my next project, which I'll need a little help
> with. I've got a huge pile of metal pipe, about an inch in diameter. I
> need a formula to figure out the length that i'll need to cut these
> pipes to. Does anyone have a formula for this?
> 
This sounds like a cool project. Unfortunately due to variations in the
density of the pipe, a formula can give you a ballpark, but you will then
have to file the metal to get exact frequencies.  This formula would have to
take into account the density of the pipe.  I remember seeing a documentary
on PBS about how the company that makes the Woodstock just intonation chimes
has a computer-controlled system that hits the metal, then grinds a little
until the pipe is the right frequency.  When they lined up a bunch of pipes
that all had the same pitch, they were all slightly different in terms of
length.  An old Gamelan trick is that if you've ground out too much, add a
little wax to one and of the pipe or bar to make the pitch a little flatter.
Good luck.

Steve C

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Steven Curtin  
Lucent Technologies Microelectronics
ph: (732)949-4404   fax: (732)949-6711
http://www.emf.org/subscribers/curtin/
sdcurtin at lucent.com
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