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Re: advice: electromagnetic induction and hum
You could just check that the lead actually is properly balanced - it's
not uncommon for them to have been altered. SM58s are normally quite
robust in terms of hum rejection - the mic's not damaged, is it?
Dr. Peter Lennox
Signal Processing Applications Research Group
University of Derby
Int. tel: 1775
>>> Eldad Tsabary <tazberry_docs@xxxxxxxx> 15/06/2006 14:59 >>>
I ran into a Hum problem in my home studio being picked up by my SM58
The mic is connected (balanced) to a USB M-Audio (Fast Track Pro) and a
audible hum is generated (and also transferred to the recording... not
on the monitoring part). I shut everything off including the monitors
used headphones to limit the possibilities.
Disconnecting the mic from the cable while keeping the input and output
max kills the hum, so it is not picked up by the cable it's definitely
I tried this mic and cable somewhere else and they work fine.
Moving the mic around the room the hum level changes and I finally
discovered that the strongest spot is a line running in the ceiling -
could imagine a cable's position just by following the hum line with
My conclusion at that is that there's some kind of strong
induction being generated by a single cable; however it is pretty
the hum is picked up by the mic in the entire studio room and outside
Any ideas of how to get rid of it? (short of moving my studio
Also, I tried my condenser mic with my minidisk and it has no problem
this induction; do condenser mics less prone to picking up
induction (since they work on the electrostatic principle?)
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