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Old 14th October 2017
Lives for gear
David Rick's Avatar
Originally Posted by Bushman View Post
Anybody else? Is this snake oil or real science?
Ferrite cores are a useful tool when solving Radio Frequency Interference (RFI) problems. I keep a few in my gig box, and have built audio snakes with ferrites on the fan end. But before you rush out and order a box of them from eBay, there are a few things you should understand.
  • The "noise" problems they can help solve are those related to unwanted pickup of radio signals.
  • Ferrites won't help with thermal (Johnson) noise or with flicker (1/f) noise, which are the most important noise types when amplifying low-output ribbon mics.
  • Ferrites won't help with AC line noise.
  • Even at radio frequencies, ferrites are not a "one size fits all" solution. They need to be chosen to match the interference frequency and the input impedance of the device under challenge.

A very good reference on the use of ferrites in audio is this paper by Jim Brown

David L. Rick
Seventh String Recording