[NJARC] Record speeds

[Jim Whartenby]

Alex and Nick
It is my impression that Berliner and Johnson got around Edison's
patents by making some obvious changes in method.

Using a disk instead of a cylinder.

Encoding the sound in the record grove sides instead of the grove
bottom.

Changing the speed from 80RPM to 78RPM.

Most important from the consumer point of view, charging less then a
buck for a record!
Regards,
Jim

--- amagoun <amagoun at davidsarnoff.org> wrote:

> Visit our web site - See http://www.njarc.org
> _______________________________________________
> Nick,
> 
> 78.26... was the speed for records played on a worm-drive electric
> motor, standardized in the 1920s.  Until then, what we call 78s
> varied in correct speed from the 60s to the 80s in rpm.
> 
> 33 1/3 was the initial speed AT&T used for its talking picture
> records, based on record dimensions and groove pitch to match a
> 15-minute reel of 35mm film.
> 
> 45 was at the low end of about 9 rpm that RCA Victor engineers
> determined would fit both fast and practical record changing and
> the least noticeable forms of harmonic distortion to the record. 
> They were also aware of the convenient additive coincidence with
> 33 and 78.
> 
> 16 2/3 was apparently Peter Goldmark's choice for the 7-inch CBS
> longplaying record initially designed to double the playing time
> of an LP in a glove-compartment-sized turntable for automobiles. 
> Others later adopted the speed for spoken-word recordings that
> require less frequency range than much music.
> 
> Alex
> 
> njarc-request at mailman.qth.net wrote:
> 
> Message: 4
> 
> > Date: Sat, 3 Mar 2007 20:47:55 -0500 (GMT-05:00)
> > From: Nick Senker <ns539 at earthlink.net>
> > Subject: [NJARC] Record speeds
> > To: NJARC <njarc at mailman.qth.net>
> > Message-ID:
> >        
>
<11445780.1172972875999.JavaMail.root at elwamui-hybrid.atl.sa.earthlink.net>
> >
> > Content-Type: text/plain; charset=UTF-8
> >
> > Does anyone know where the standard recording speeds came from
> (16/33/45/78 rpm)?  They seem to be odd intervals.  Nick Senker
> 
> --
> Alexander B. Magoun, Ph.D.
> Executive Director
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