Feedback problems, generally (audio feedback)

Subject: RE: Feedback problems, generally (audio feedback)
From: GUEST,JohnB
Date: 16 Jul 01 - 12:48 PM

Some systems have a "Ground" switch on them, with two possible directions to place it On. You can sometimes eliminate a Hum by switching this switch to the other On. There is more technical background to this but it is Monday. JohnB

Subject: RE: Feedback problems, generally (audio feedback)
From: GUEST,JohnB
Date: 16 Jul 01 - 12:48 PM

Some systems have a "Ground" swith on them, with two possible directions to place it. You can sometimes eliminate a Hum by switching this switch to the other On. There is more technical background to this but it is Monday. JohnB

Subject: RE: Feedback problems, generally (audio feedback)
From: Whistle Stop
Date: 16 Jul 01 - 08:16 AM

One of the first things I often do at a gig is to turn off any fluorescent "beer lights" near the stage. Wait until the bar owner is looking the other way (some of them are quite partial to these things). I have often found that this quiets things down significantly.

Having extra shielding on all the wires would be nice, but we use an amazing amount of cable, and I can't guarantee there aren't breaks in the shielding somewhere in the system. I also keep a supply of ground-lift adapters close at hand, but one has to be careful with these -- you can get shocked if you're not cautious.

Subject: RE: BS: Feedback problems, generally
From: Amos
Date: 14 Jul 01 - 10:37 PM

This sounds like an inductance problem, paddymac. Try wrapping cables in tinfoil or using grounded-shielding cables? Just speculatin' here. The EMF flux on flourescents and large monitors is significant.

Mebby little circular magnets around the cables?

A

Subject: Feedback problems, generally
From: paddymac
Date: 14 Jul 01 - 09:52 PM

There's another thread called "Upright Bass Feedback Solutions?" It got me to thinking about feedbak and related kinds of problems in a more general sense. Our group uses a variety of mics and pickups to a second-hand non-powered mixing board, run thru an amp and then out to thirty-year-old speakers. Most times is perfectly fine, but we have come to recognize that some flourescent lighting fixtures cause an obnoxious buzz that seems almost immpossible for us to get rid of, and that the huge tv screens (6-8 ft diagonals) are especially problematic. I guess these kinds of problems might be more properly referred to as "bleedthru" rather than "feedback", but the effect is the same.

What kinds od similar problems have other 'Catters experienced, and , more importantly, were you able to resolve them, and how?