[78-L] Lighten my darkness

[Michael Biel]

John G. wrote:
> Can any kind person tell me when Brunswick stopped using the "light ray"
> method of recording ?
>   

It was used only in 1925 and maybe a little into 1926.  The only place 
light was used was in the microphone.  It was a cone-shaped ddiaphragm 
with a tiny mirror at the back tip.  A light shined on the mirror and 
the vibrating reflection was read by a photo-electric cell. 


It was part of an entire system developed in 1922 by GE engineer Charles 
Hoxie, the Pallophotophone.  This was a system which recorded sound on 
film, and in 1922 he recorded VP Coolidge, Jackie Coogan, David Sarnoff, 
Marconi, and several other celebs for a Christmas program on WGY.   (A 
number of reels of WGY broadcast airchecks from 1928 and 29 were 
discovered a couple of years ago, and just last night I received a 
report on the successful  development of a machine to play the films.  I 
am panting in anticipation of hearing these -- I know basically what is 
on them and with one exception, they are totally unique.) 

> And can someone also explain to me how  it worked ?  I understand how
> light ray recording was done for film soundtracks; but how was it
> applied to produce a master disc ? And are the results really much
> better than the traditional needle-in-a-groove  method ?


In addition to the microphone, film recorder, and film playback unit, 
Hoxie also developed and patented amplifiers, and a phono record 
recording head.  Brunswick got left out of the Western Electric 
licensing, and since they had contacts with RCA -- they had started 
broadcasting on RCA's WJZ in December 1924 -- they went to RCA which 
gave them access to the microphone, amps, and cutter head for "Light Ray 
Recording", and the amps and playback head for their Panatrope 
electrical phonograph. 


> I have some early (British) Brunswick paper sleeves : the first  reads
> "Electrical light ray process records"  in bold type, and over on the right,
> under two small graphs,   "Electrical light ray recording"  and  "Electrical
> light ray reproduction."   However, instead of the last-named, another cover
> now reads  "Electrical Panatrope reproduction". 

Hoxie never used light and mirrors in disc playback so they probably 
were told to stop using the phrase.  I think the disc pick-up head they 
did use was based on a head Paul Fortin cobbled out of a modified Victor 
acoustical reproducer in 1916 by adding coils.  That same phono pick-up 
was also used as a contact microphone for pianos at WGY in 1922 by 
digging the needle into the piano soundboard.  In the early 70s I 
inspected the head and Fortin's papers at the Smithsonian a couple of 
weeks after he dropped them off, and  I briefly corresponded with him.

>  Finally,  another, more
> common,  cover simply refers to "electrical"  records with no mention of
> light rays at all.
> I am guessing therefore that it didn't last long.
> Regards  John  Goslin

They started using normal microphones, probably carbon and condenser, 
but probably continued using RCA Hoxie amps and cutter heads.  As the 
Western Electric Vitaphone sound-on-disc system started popularizing 
talkies, RCA utilized the film recording part of the system for their 
RCA Photophone system, using condenser microphones and then ribbon and 
dynamic mics instead of the light-ray mic. 

Eventually in the late 30s, Philco used light in a phono pick-up.  Again 
it had a tiny mirror connected to the needle, and a light shining on it 
with a photoelectric cell picking up the variation in light.  The head 
is triangular, but that same outer casing is used for standard 
pick-ups,  so not all Philcos with the triangular head on the tone arm 
are light ray pickups.  And lastly, at about the same time RCA 
advertised their Magic Brain changer using the word "light" to describe 
the pick-ups.  Light in this case referred to the tracking pressure.  
They are crystal pick-ups.

Mike Biel  mbiel at mbiel.com