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Re: Sound head of the 'Moviola'

Thanks for the links.

Do you have a reference (or a short explanation) for the variable area encoding? I looked for it on the web, but still some aspects are not clear: the "RCA-Photophone" entry in Wikipedia states:

"variable-area" film exposure system, in which the modulated area (width) corresponded to the amplitude of the audio signal"

But the amplitude does not carry all the information needed to recreate the sound. Similarly, the "Sound-on-Film" entry states:

stereo variable-area (SVA) recording, encoding a two-channel audio signal as a pair of lines running parallel with the film's direction of travel through the projector. The lines change area (grow broader or narrower) depending on the magnitude of the signal.

Again, what encodes the frequency/phase?

Thank you


On Wed, Dec 29, 2010 at 12:35 AM, Kevin Austin <kevin.austin@xxxxxxxxxxxx> wrote:

The McLaren DVD set (7 DVDs).
There is also information on the techniques used.

A particular example:
and more on YouTube

As I understand it, most [all?] of his work was done with variable area optical tracks (as distinct from variable density).


On 2010, Dec 28, at 2:02 PM, ita katz wrote:

Hi Sam and thanks for the details.

Generally I am interested in both, but particularly I am interested in the work of the Canadian animator Norman Mclaren, who used the Moviola to synthesize musical soundtrack to his animation. I plan to investigate the sound production mechanism of the optical pickup (since I find the sound very interesting), and I guess it is mainly influenced by the coupling to the electronic circuit and the electronic circuit itself, producing the unique 'analog' feel of the sound. So any further information (in addition to your suggestions) in that direction would be helpful.


On Tue, Dec 28, 2010 at 8:20 PM, Sam Jelfs <JelfsS1@xxxxxxxxxxxxx> wrote:


Are you interested in the Moviola particularly, or optical audio in general? If the latter, then  http://en.wikipedia.org/wiki/Movie_projector#Optical has a good basic intro to how traditional optical-encoded amplitude modulation works, as well as more modern Dolby Digital / SDDS / DTS digital-optical audio encoding. You may find more luck searching using terms such as "sound-on-film".

Sound Recording Practice (ed. John Borwick) (http://www.amazon.co.uk/Sound-Recording-Practice-John-Borwick/dp/0198166087/ref=sr_1_1?ie=UTF8&qid=1293560292&sr=8-1) has a section on the technology used in audio reproduction for film as well, might be worth looking in your library for.

Sam Jelfs

From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of ita katz
Sent: 28 December 2010 15:55
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: [AUDITORY] Sound head of the 'Moviola'


I am looking for information about the optical sound head of the movie-editing machine called 'Moviola'. http://www.alangordon.com/sales/used_equipment/editing_equipment/moviola_ud-20-cs.html

Specifically I would like to know about the working principle, how the visual marks are sonified using the optical head.

Thank you,