Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site nicmad.UUCP
Path: utzoo!decvax!linus!philabs!cmcl2!seismo!uwvax!astroatc!nicmad!brown
From: brown@nicmad.UUCP
Newsgroups: net.audio
Subject: Re: Print-thru: Magnetic or Mechanical
Message-ID: <428@nicmad.UUCP>
Date: Thu, 14-Nov-85 02:03:56 EST
Article-I.D.: nicmad.428
Posted: Thu Nov 14 02:03:56 1985
Date-Received: Tue, 19-Nov-85 00:04:54 EST
References: <937@cvl.UUCP> <2860@wateng.UUCP>
Reply-To: brown@nicmad.UUCP (Mr. Video)
Distribution: na
Organization: Nicolet Instrument Corp. Madison WI
Lines: 44

In article <2860@wateng.UUCP> gtward@wateng.UUCP (Greg Ward) writes:
>Your argument for why mechanical print through would be stronger on one
>channel then the other is incorrect. You seem to be suggesting that each
>channel is recorded on a different side of the groove. In fact, how the
>two channels are multiplexed in the groove is that one channel is
>recorded in the side to side variations of the groove, and the other is
>recorded in the up and down variations.

Sorry, but the gentleman you are referring to was correct.  On record,
each wall DOES pertain to a certain channel.

Remember, stereo and mono records are compatable.  Mono records have side-
to-side movement.  Stereo is just like that, except:

	1. When, say the left channel, is modulated and the right channel
	   isn't, the grove will not move horizontally left or right, but
	   at a 45 degree angle.  So the plain of movement is shifted at
	   a 45 degree angle.
	2. When both the left and right are modulated, in an in phase signal,
	   as the left wall is moving say, to the right and up, the left
	   channel will be moving right and down.  The net effect is that
	   the groove will move left and right on the horizontal plain,
	   making the stereo cut compatable with the mono cut.

The way you describe it, a stereo signal would have one channel not heard
on a mono turntable, because a mono cartridge only knows left and right
movement.  Yes, a single channel modulated grove moves left and right
and up and down.  The mono cartridge will pick up the signal at a lesser
volume because it will only get the left and right movement.  The up and
down energy will be lost.

What about out-of-phase signals.  Yes, they will not be heard on a mono
system, but will give the stereo listener a wierd sound effect.  The same
effect that can be heard if your mono tv signal is fed to one speaker
wired in phase and wired out-of-phase to the other stereo speaker.

To verify what I am saying, visit your local library and read about it.

Oh yes, groove modulation interference does exist.  You will get pre-echo.
I have some records that have it, and it matches the distance of one
rotation.
-- 

Mr. Video   {seismo!uwvax|decvax|ihnp4}!nicmad!brown