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From: ejp@bohra.cpg.oz (Esmond Pitt)
Newsgroups: sci.electronics
Subject: Re: CD Subcodes
Keywords: CD
Message-ID: <241@bohra.cpg.oz>
Date: 15 Dec 89 00:15:20 GMT
References: <2688@radio.oakhill.UUCP> <3449@vine.vine.COM> <6546@pbhyf.PacBell.COM>
Reply-To: ejp@bohra.UUCP (Esmond Pitt)
Organization: Computer Power Group, Melb, Australia
Lines: 27

In article <6546@pbhyf.PacBell.COM> rob@PacBell.COM (Rob Bernardo) writes:
>In article <3449@vine.vine.COM> ksh@vine.UUCP (Kent S. Harris) writes:
>+  The control information
>+consists of such things as number of audio channels, whether pre-emphasis
>+should be engaged,
>
>Aha! My new cd changer has an "emphasis" light, which comes on during
>play of certain cd's. The manual, written in the most gawdawful "Japanglish",
>mentions the light but never says what "emphasis" is. So what *is*
>preemphasis?? Inquiry minds want to know.

Pre-emphasis is treble pre-emphasis, as seen in FM transmission,
usually according to a time constant of 25us or 50us, and in cassettes;
i.e. the treble is boosted during manufacture of the CD master, and
correspondingly reduced by the player on playback. The CD standard
allows for pre-emphasis to be either present or absent, with an
indicator in the CD header; players are supposed to play disks of
either kind correctly.  I don't know that the pre-emphasis actually
adds much fidelity to the CD process, and I have the impression that
it's not widely used in CD's.

-- 
Esmond Pitt, Computer Power Group
ejp@bohra.cpg.oz
-- 
Esmond Pitt, Computer Power Group
ejp@bohra.cpg.oz