Re: arsclist Re: 45 rpm record groove depth

["George Brock-Nannestad" <pattac@xxxxxxxx>]

From:           	Chuck Howell <ch40@xxxxxxxxxxxxx>
Send reply to:  	ch40@xxxxxxxxxxxxx
To:             	arsclist@xxxxxxxxxxxxxxxxxxxxxxxx
Subject:        	arsclist Re: 45 rpm record groove depth
Date sent:      	Fri, 8 Sep 2000 16:05:12 -0400 (Eastern Daylight Time)

> Does anyone out there in listserve land happen to either 
> know the depth of a 45 rpm microgroove or know where I can 
> find this information?  This question was posed to us by a 
> researcher, and we haven't been able to track it down.  
> Width yes.  Depth no.
> 

Yes, I know: because the included angle in the groove is very close 
to 90 degrees, simple Pythagorean relations tell us that the depth 
is half the width. However, this only goes for mono grooves. If you 
have a stereo groove (45 rpm maxi or disco single or even a single 
or an EP), then it is a stereo signal, and here both width and depth 
vary differently and simultaneously around a mean. And in the case 
of the disco single the figures approach those of the 78 rpm record 
in places!

Best regards to all

George Brock-Nannestad
Preservation Tactics


> Thanks,
> 
> Chuck 
> 
> ----------------------
> Chuck Howell, CA
> Curator, Library of American Broadcasting
> Hornbake Library
> University of Maryland
> College Park, MD  20742
> (phone) 301-314-0401
> (fax) 301-314-2634
> ch40@xxxxxxxxxxxxx
> 
>