My favorite analog audio storage = B&W variable-density opti

[Green Xenon [Radium]]

John Larkin wrote:

"
glucegen1@excite.com> wrote:

Hi:

My favorite analog audio storage medium consist of the optical
equivalent of magnetic tape. It is similar to the optical tracks of old
analog B&W films -- except without the video or any images. My optical
tape records audio optically on a tape using variable-density encoding
[not variable-area] and is monaural.


Film is nonlinear as hell, which translates to distortion. That's one
reason that variable-area is better. They figured that out a long,
long time ago.

John

In variable-density, what determines the quality of the audio?

 

[Green Xenon [Radium]]

Arny Krueger wrote:

" <glucegen1@excite.com> wrote in
message news:47fd6ce6$0$6158$4c368faf@roadrunner.com
Hi:

My favorite analog audio storage medium consist of the
optical equivalent of magnetic tape. It is similar to the
optical tracks of old analog B&W films -- except without
the video or any images. My optical tape records audio
optically on a tape using variable-density encoding [not
variable-area] and is monaural. As with any photography,
the tape must not be exposed to light before recording or
development and must not be exposed to extraneous light
[light other than the optical audio signal] during or
before recording/development. Such exposure will corrupt
the film. After recording. The film is developed using
photographic chemicals. This tape is like a reel-to-reel
[i.e. not a cassette] film using optics and chemistry
instead of magnetism.

A close, long-time friend used to be one of the go-to guys in this city for
optical transfers. Detroit used to be a center for the production of
training films (now on video), so this was a very non-trivial business at
the time.

There is no doubt in his mind, or the minds of almost anybody who
understands electronic media, that optical sound is rife with daunting
technically challenges and unresolved issues. It was a major stumbling block
to sound quality in the theatre even in the late 1930s.

What characteristics in the film material itself [e.g. the chemicals
within the film, "grains", etc. etc.] determines the audio quality [e.g.
the bandwidth, dynamic range, SNR, clipping point, treble response, etc.
etc.] of a VD track?