[Scott Dorsey]

Ty Ford wrote:
I'm with John on this one. 3 million years ago when I got my first DAW (AKG DSE7000) I set it up only to find that the CRT was blowing a ring of noise right at my 421. I moved on to a Gefell M71.

This also is direct magnetic interference. CRTs are awful for this... big
coils operating at 30 Hz and 17 KHz, spewing magnetic fields all over the
place. They couple into microphones.

And, as noted, the 421 is specifically designed to deal with magnetic fields
using a bucking coil, so if the 421 is picking it up, you've got a big one!

The good thing about direct magnetic interference is that, as Mike noticed,
it's directional. Turn the microphone until it's parallel to the field and
the noise goes away. Secondly, as you should notice if you have ever played
with permanent magnets on the fridge, the field drops off very quickly with
distance.

I am thinking the cell tower is a red herring and that what you've got here
is a magnetic field.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."