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Path: utzoo!linus!philabs!cmcl2!lanl!unm-la!unmvax!nmtvax!c20
From: c20@nmtvax.UUCP
Newsgroups: net.audio
Subject: Re: Tuner Leakage Problem...
Message-ID: <853@nmtvax.UUCP>
Date: Tue, 5-Nov-85 15:54:44 EST
Article-I.D.: nmtvax.853
Posted: Tue Nov  5 15:54:44 1985
Date-Received: Fri, 8-Nov-85 06:15:00 EST
References: <4960004@acf4.UUCP> <276@mit-eddie.UUCP>
Organization: New Mexico Tech, Socorro
Lines: 49

>
> things about tuner leakage here ... 
> 
> I've been wondering about something related to playing records that bugs
> the hell outta me - on some records there is a very faint "ghost" of sorts
> that comes about a second or so before the real signal (eg. when listening
> during the space between songs, the beginning of the ensuing song can be
> heard faintly to precede the actual music by about a second).  Some of the
> records I have (like OMR's and other half-speed masters) are pleasingly
> free of this disturbance.
> 
> The question in my mind is this:  are there any turntables around that
> can handle this sort of quirk?  Also, how on earth do the recording
> companies get away with this sort of bad-quality production?  Ack.
> -- 
> 
> 				-Mike
> 
> genrad!mit-eddie!zzz  (UUCP)    ZZZ%MIT-OZ@MIT-MC  (ARPA)

This "ghosting" effect is caused by making a record with the grooves too
close together for the recording level.  When the record is pressed, the
vinyl between the grooves is stressed slightly (note:  the vinyl is slightly
warm at this point).  After the die is removed from the record, the record
begins cooling.  However, before it cools enough, the stressed plastic
*between* the grooves begins relaxing, and each groove takes on a little
of the waveform of the NEXT groove.  If you check, you should find that
the ghost sound starts exactly one revolution (slightly less than two
seconds at 33.333 rpm) before the equivalent real sound begins.

It's bad enough to hear the ghosting effect before the song starts, but
it's worse when you realize that if this happens on the first groove, it's
probably happening on all the other grooves too.  So every part of the
music you hear has this not-quite-hearable "fuzz" on top of it, which is
the very-quietly-played sound of both of the adjacent grooves.

A record company can prevent this either by increasing the inter-groove
spacing, or by making quieter records (i.e., records with smaller wiggles
in the grooves)

greg
-- 

Greg Titus                  ..!ucbvax!unmvax!nmtvax!c20     (uucp)
NM Tech Computer Center     ..!cmcl2!lanl!nmtvax!c20        (uucp)
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Socorro, NM 87801           c20.nmt@csnet-relay             (arpa)
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