Date:         Thu, 19 May 2005 19:50:33 -0400
Reply-To:     Association for Recorded Sound Discussion List
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From:         Dick Spottswood <[log in to unmask]>
Subject:      Re: Fw: [88sOn78s] Exit Grooves on Shellac and Early Vinyl
Comments: To: Association for Recorded Sound Discussion List <[log in to unmask]>
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I believe the first run-off grooves were designed to trip automatic stop
mechanisms on your old wind-ups.  Brunswick (1920) may have been first to
use them.  Victor's eccentric double circles came in 1923.  I don't know
when the first record changers were made, but run-off grooves activated
those devices, especially when agitated by the tone arm moving back and
forth.  They were essential for juke boxes, which couldn't use any discs
without them.  Juke boxes also liked lead-in grooves, introduced here by
Decca in 1935, and quickly adopted by the rest of the industry.  Vinyl lps
were rarely used on record changers or juke boxes, so run-off grooves went
back to the Brunswick style.  I guess (I can't resist this)  what goes
around comes around.

Dick





Steven Smolian <[log in to unmask]>
Sent by: Association for Recorded Sound Discussion List <[log in to unmask]>
05/19/2005 05:40 PM
Please respond to Association for Recorded Sound Discussion List

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        Subject:        [ARSCLIST] Fw: [88sOn78s] Exit Grooves on Shellac
and Early Vinyl


Sending this to the ARSC list.

Steve Smolian

----- Original Message -----
From: Jody
To: [log in to unmask]
Sent: Thursday, May 19, 2005 2:10 PM
Subject: [88sOn78s] Exit Grooves on Shellac and Early Vinyl


Hi Folks:

I've never been able to find a clear answer on this, though I suspect
it has something to with hardware co-operation on old record changers
(ie. velocity trip).

My question is: Why do electrically recorded shellac discs, and early
vinyl LPs have an exit groove that zig-zags back and forth, when it
spins? Why did they go to a stationery exit groove in the early 60s?
Can anyone accurately/technically answer this.

Much appreciated,

Jody Thornton
(Hamilton, Ontario)





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