[BC] ...Seriously pal?...

[jpotter at jpotter.com]

Yes, this will work -- I've done it -- it's just an application of the old 'noise cancelling mic' principle.  The trick is to get the 180 degree phase reversal at the center of the band of frequencies you want to attenuate.  Ya know, capacitors can do this, but their function is frequency sensitive (preaching to the choir).  Best done with an active circuit involving op-amps.

Regards/J

Jim Potter
 
The path of the righteous man is beset on all sides by the inequity of the selfish and the tyranny of evil men. Blessed is he who shepherds the weak through the valley of darkness for he is truly his brother's keeper and the finder of lost children

>-------- Original Message --------
>From: donroden at hiwaay.net

>Quoting Steve Schoon <steven.schoon at uni.edu>:

>>
>> Mix it into your recordings 180 degrees out of phase, and presto! Instant
>> noise cancellation!
>>
>> (yes, I'm kidding)

>I put an out-of-phase mike in the ceiling of a recording booth to cancel
>airconditioner rumble and it works great. no kidding,

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