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Re: [Rollei] OT: Re: What did you do in the war? (long)



- ----- Original Message ----- 
From: "R. R. Creason" <rcreason  >
To: <rollei  
Sent: Monday, May 19, 2003 8:05 PM
Subject: Re: [Rollei] OT: Re: What did you do in the war?
(long)


>
> Very interesting Richard.  I had a lot of experience as a
movie
> projectionist in the mid to late '40s.  It was easy to
tell the WE sound
> track from the RCA.  Just from looking at the WE
soundtrack, I always
> thought it's frequency response would be better.  It
looked much like
> spectral lines while the RCA looked like a modulated
envelope.  The WE had
> fine spectral lines and looked like it had more HF
content.  Was this the
> reason for the better sound?
>
> Bob C.
>
  This is off topic but has some photographic content.
  Early on WE and RCA used two different formats of sound
track. The Western Electric method was called variable
density, RCA used a method called variable area although it
should properly be called variable width.
  The density tracks were made by varying the gap between
two ribbons. This slit was imaged on the film. The result
was a band of density which varied in accordance with the
sound. The RCA method was to use a mirror galvanometer which
swung the image of a slit across the film. Essentialy, it
was an osicilograph making a continuous picture of the
waveform. Many variations of area tracks were used in order
to avoid some of its problems.
  The area method is the one which finally won out mostly
because the tracks are less vulnerable to scratches and
dirt.
  Both methods are capable of equivalent performance but the
Western Electric recording devise, called a ribbon light
valve, had better fidelity than the RCA galvanometers. RCA
tracks were limited in recording to a frequency range of
about 80 to 6000 hz. The Western Electric system to about 50
to 8000.
  Both companies could make both kinds of tracks with
modifications of their recording devices.
  There is much more to this, both technical history and
business history, too much to go into here.
  When Warner Brothers released the first successful sound
movie "The Jazz Singer" , they used a system they worked out
in co-operation with Western Electric, called Vitaphone.
This was a rather simple system of mechanical
synchronization of large (16") phonograph records with the
film. Once it became successful W.E. decided to force
Warner's out by increasing the royalties on electronic
amplification and vacuum tubes enormously. Warner's shortly
after became a Western Electric licensee. The same thing
happened to Fox Film Company, who had become partners with
Theodore Case in the development of a photographic sound on
film system, which they called Fox Movietone. Case had
developed a variable intensity light source, called an
Aeolight, which was the basis of the system. As soon as
Warner's had their success both W.E. and RCA decided to
freeze them out by refusing to licence them for either the
amplification or tube patents. Fox also became a Wester
Electric licensee and dropped the Movietone system in favor
of Western Electric's system, although they continued to use
the Movietone trademark as Warner's continued to use
Vitaphone for a long time.
  At first there was no very good understanding of the
sensitometric requirements of either area of density
recording. It was thought that density recording would work
best with an exact reproducton gamma of 1. It turned out
there were other factors. At first, it was thought that the
area system was immune to sensitometric errors. In fact, it
turned out to be very sensitive. Both systems eventually
relyed on electronic distortion measurements to determine
the optimum recording and printing characteristics.
  We have now come full circle to sound-on-disc with the
latest digital disc systems. They do not rely on mechanical
synchronization but on electronic synchronization and have
the means to compensate for short sections of missing film,
as where a splice must be made.
  At its best photographic recording was capable of very
high quality but such tracks were not heard in theaters
because of cost of the equipment and the need of much more
intensive servicing. However, the systems used in the
studios for original recording were very good, especially
those used at M-G-M and Twentieth Century - Fox.
  Theater sound should not be judged from the restored
prints seen and heard on Turner Classic Movies or Fox Movie
Channel since they are often many generations removed from
the originals.
- ---
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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