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Re: Mic/Earphone Headsets

Bruce Chadwick <nospam.bpc1@columbia.edu> wrote:
: worked.  I got some low freequency feedthrough, but I suspect that
: shielded cables will take care of that.

Maybe. If it won't work, there could be a different problem/solution :
Is this low frequency the same frequency as your power supply ?
(We here in Germany have 230 Volts at 50 Hz, I don't know exactly, but
in the Us it is probably 60 Hz. Is that right ?)
If so, you maybe have a so called net-humm.
There are several solutions for this :
1) Don't use asymmetric wires longer than 50 centimeters.
2) Cut the Ground of your wire at one side of the cable from the plug
(but that would also spoil the phantom power for the mic)
3) Use a so called di-box to make the signal symmetric (prices for such
a box are about 50 DM, which is about $30 )
4) Try switching all "Ground Lift" switches in your equipment (Maybe
your preamp has one)
5) In _some_ cases a very simple and extremly cheap thing helped in
similar situations : If your power plugs have three pins, one is used
for ground, one for phase and one for neutral. Just make sure, that
at one of your power plugs ground is not longer connected (e.g. use
gaffa tape around the pin ..) Sometimes you get even more low
frequency, sometimes you'll get a really fine signal. It depends on the
specific problem.
One last thing with this : If you do this, you'll do it on YOUR OWN
RISK ! You'll loose the security of the fuses in your cicuitry ! So, if
one of the machines is malfunctioning, the fuse won't blow, and you
_could_ get hurt. (That once happened to Rock-Star on stage with his
*really* ELECTRIC-Guitar  :)) 
Here in Germany this method of suppresing low frequencies is strictly
forbidden .... But it works fine, if nothing else will help.

Grueslies,

Andi
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