Re: unbalanced inputs to the 722

["stoatwizard" stoatwizard]

> Has anyone else experienced problems using unbalanced and/or
impedance
> mis-matched inputs to the SD 722? Using either my homemade
piezoelectric
> contact mics or my new Core Sound binaurals, I get noticeable
> electromagnetic interference from the hard drive writing when
recording.

Beats me on the binaurals, but for the piezo disc you NEED a FET
buffer - something like this http://www.scotthelmke.com/Mint-box-
buffer.html

You'll get a massive increase in output, and a far better LF response.
A piezo is a bit like an electret mic - a voltage source in series with
a capacitance and you attenuate the ouput and end up with a 6dB/octave
fall to low frequencies unless you drive it into a high impedance. If
you are DIYing the piezo there is much to be said for putting the FET
at the piezo disc end so cable capacitance doesn't also lose you signal
in the high impedance circuit.