On Tue, 6 Jul 2004 12:44:00 +1000, "Phil Allison"
wrote:

** Do the test I suggested with a length of insulated wire, XLR and
pre-amp. Then think how a voltage is created in the coil of a dynamic, mic
sent down the cable to the pre-amp and is amplified. Then realise that the
connecting cable is just an extension of that same coil.

Recall that a dynamic mic hums when placed near an AC power transformer (
except for those with effective, internal hum bucking coils).

Then recall how the hum bucking coil works. Perfect example.

(Hint: it's in the same field as the innocent but offending coil).

(What the heck, another hint: to be within the "same" field
means to be within a small-compared-to-wavelength average
distance)

(OK, one more final hint: average. How to be reliably average...)

Chris Hornbeck