> I'm trying to understand this problem. Are you saying that the microphon=
e is drawing power from the phantom supply in an unbalanced way, and possib=
ly causing different amounts of noise from the phantom supply to show up on=
the two legs of the (supposedly) balanced circuit? Or is it that the outp=
ut impedance of the microphone is unbalanced in the two legs and thus cause=
s the amount of noise in the two circuits to be unequal at the two inputs t=
o the microphone preamp?
Raimund,
Yes. The principle with phantom power is that any residual noise on the
phantom supply must finish up exactly balanced on both legs of the mic
input. Therefore the AC impedance, frequency response and gain on each mic=
leg must match to a close tolerance to get cancellation down to mic noise
levels.
Using a resistor to "balance" a one-legged mic input therefore is not
guaranteed to work. I don't know the recommended mod to the recorder input,=
but I guess it is a fat smoothing capacitor to quieten the phantom power
supply.
David Brinicombe
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