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From: fish@ihu1g.UUCP (Bob Fishell)
Newsgroups: net.audio
Subject: Re: Consumer Reports and dbx
Message-ID: <418@ihu1g.UUCP>
Date: Mon, 11-Jun-84 14:16:02 EDT
Article-I.D.: ihu1g.418
Posted: Mon Jun 11 14:16:02 1984
Date-Received: Tue, 12-Jun-84 00:51:21 EDT
References: <268@whuxj.UUCP> <246@ihu1h.UUCP> <1350@vice.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
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(oo)

>What?  I think I'll pick a few nits on this reply since I'm feeling irritable.
>dbx does NOT work by preemphasizing the High frequencies of the compressed
>signal, to my recollection,  but does play tricks with the signal presented
>to the RMS detector.  High frequency response of the tape deck shouldn't have
>much to do with the reconstruction quality, since the RMS detector only looks
>at signals below 10kHz.
>(...,)
>the wandering squash,
>
>-- 
>				Shaun Simpkins

The following is a quote from the instruction manual issued with the dbx
Model 1BX dynamic range expander (page 14):

	"[dbx] noise reduction is accomplished by a 'compander,'
	a circuit which compresses the program before recording,
	and expands the program during playback.  In addition,
	dbx tape noise reduction systems apply pre-emphasis of
	high frequencies before recording, and de-emphasis upon
	playback to further reduce high frequency noise (hiss) 
	and tape modulation noise"

Now, my sources are pretty succinct.  Where did you get your information?
-- 

                               Bob Fishell
                               ihnp4!ihu1g!fish