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Subject: Re: Acoustic Feedback reduction
Organization: Nobody nowhere
X-Newsreader: Microsoft Outlook Express 6.00.2720.3000
Date: Fri, 10 Jan 2003 19:55:21 -0000
NNTP-Posting-Date: Fri, 10 Jan 2003 19:55:26 GMT
"Nico Coesel" wrote in message
> "g0mem" wrote:
> >"Spehro Pefhany" wrote in message
> >> Many years ago in good old _Wireless World_ (long before "wireless"
> >> acquired its present meaning(s)) there was a design published for a
> >> device used to allow higher volume levels in PA systems before
> >> feedback occurred (with a given microphone). IIRC, they used
> >> one or two multipliers in a circuit that shifted the audio pitch by
> >> around 10Hz.
> >> Has this sort of thing been integrated into a single chip?
> >I never come accross that method before but there is no reason why it
> >shouln't work. Another technique to cure feedback on a PA system is to
> >graphic equalizer. The method is to turn the volume up until the feedback
> >occurs, and turn down the appropriate frequency slider on the graphic
> >the feedback disappears. And repeat until the desired volume level is
> This is really not the way to do it. You'll only make it worse because
> it will get more difficult to hear what is said through the PA.
> There is another way though developed by someone named Larssen. He
> came up with a system that shifts all frequencies by a few Hertz.
They use graphic equalizers for curing feedback in concerts see:-
All the above are based on equalization and not frequency shifting.
Frequency shifting would be OK for speech but not for music and singing. As
soon as you shift the frequency of music even slightly, it goes either Sharp
or Flat depending on which way you shifted the frequency.
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