contact mics and springs

[Paul Perry]

At 08:24 AM 9/09/99 -0700, Matthew Helt  wrote:

>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?
>I would like to have between six and ten pipes, each a half step higher
>then the previous.

The main practical problem is, how to suspend the pipes. You might get some
hints from looking a xylophones.
And, since the resonant frequency of a metal pipe depends on where it is struck,
what material is used, diameter, and of course length etc, there is no real 
formula, but I would cut a long and short piece, observe the frequencies,
and then you could make an approximation.
1/F = a + bL where F = frequency, L=length, and 'a' and 'b' are determined
from your observations. Analogous to organ pipes, with the end correction.

paul perry Melbourne Australia