In Reply to: RE: " better EMI/RFI rejection " is it really an issue for speaker cables ? posted by Dave_K on February 12, 2015 at 12:18:54:
"the output stage should effectively become a sink for any induced noise currents at frequencies within the bandwidth of the output stage"
Yes, spot on!
The rub is that the interfering signals, at least for "RFI" by definition, are outside of it's bandwidth and therin lies the rub. The loop can't control it because it's GBW is too low at the interfering frequency but yet the final device junctions are plenty fast to rectify and thus "detect" it. Things go rather downhill from there as it's modulations get cought up in various feedback loops.
In general all systems must be protected so that none of their ports are exposed to signals that they can't handle. Lots of the time it's just common sense. If you are having an audiophile lawn party and a fast front comes through you probably will expect some problems with your preamp after a lightening bolt hits the tonearm.
Well, RFI is just a tamer version of the same thing. The general term for this sort of thing is EMI (Electromagnetic interference) and the tendency to be susceptable to this ilk of problem is called it's "Susceptibility".
The bottom line is it's common to virtually everything and the cure is to prevent ports from getting hit by energy that they can't handle. That usually involves passive filtering between them and the cold hard world.
Rick
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Follow Ups
- RE: " better EMI/RFI rejection " is it really an issue for speaker cables ? - rick_m 14:26:42 02/12/15 (0)