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From: fish@ihlpg.UUCP (Bob Fishell)
Newsgroups: net.audio
Subject: Re: Are DNR noise reducers sold commercially?
Message-ID: <236@ihlpg.UUCP>
Date: Thu, 7-Mar-85 13:30:56 EST
Article-I.D.: ihlpg.236
Posted: Thu Mar  7 13:30:56 1985
Date-Received: Fri, 8-Mar-85 05:12:11 EST
References: <494@hou2e.UUCP>
Organization: AT&T Bell Laboratories
Lines: 42


>    
>    has anyone one the net heard a DNR unit operate? i would be very 
> interested in opinions !
> 

***     AC  T              YOUR     AGE ***

Don't expect miracles from DNR.  The system will make a difference
when listening to inherently noisy sources like old 78's, AM radio,
or non-hi-fi video tapes played through a stereo system, but you
can't get something for nothing.

I have a DNR unit connected between my VCR and my stereo.  While
it does cut down on a good deal of hiss, it also cuts into the
already limited bandwidth of the VCR's audio playback capability.
The amount of noise reduction is pot-adjustable, but the more noise
you cut out, the more of your highs you lose.  However, the effect
is much better than what you get by using a simple lowpass filter
(like your tone controls or an equalizer), which takes out everything.
At least with DNR, high-frequency sound recorded at relatively high
levels still gets through.  Unfortunately, any treble information
recorded near or below the noise level is lost, although your ear
can normally distinguish it from the surrounding noise (the cocktail
party effect).  

Nonetheless, a DNR unit is worth having if you have cause to listen to
noisy sources.  If you really want to get exotic, though, you can get
a 3bx or 4bx audio expander from dbx.  Such a unit can really clean up
sound, doing a much better job than DNR.  Unfortunately, it will also
clean out your wallet.  I have a much simpler (and cheaper!) 1bx dbx
expander which, when used in conjunction with my DNR unit, provides
a fair amount of noise reduction without hurting the bandwidth any
more than what can be attributed to the DNR unit alone.  While it
makes watching TV and listening to some of my old, abused, and 
irreplacable records much more enjoyable, it's not the same as listening
to a high-quality recording.  You can't make a silk purse out of
a sow's ear.
/_\_

				Bob Fishell
				ihnp4!ihlpg!fish