[78-L] Speaking About Really Early Film Sound Technology -- Read This. Whoa!

[Michael Shoshani]

On Mon, 2010-06-21 at 22:55 -0700, Michael Biel wrote:
> From: Michael Shoshani <mshoshani at sbcglobal.net>

> > And his talking about how the film needs to be flipped for alternate
> > tracks? ...No. Reversible mechanism. If a 16MM motion picture projector,
> > the kind that once graced every school classroom, can have a "reverse"
> > switch, so can this. 
> 
> There is a "capstan direction" switch in my still shots under the deck. 
> But that would be "pushing" the film thru the machine, just like that
> asinine Ampex 400 which had the capstan to the left of the head block.  
> 
> But also, don't you remember that the classroom projectors always lost a
> loop whenever you put it in reverse?!  Especially if you did it too
> fast!  

By the time I got to school, they had those Singer slot-load projectors.
It's only because I got a war-beaten Bell&Howell Filmosound 285 that I
even know about flywheels and stabilizing springs in the sound head.
However, I would think the loop loss is moot, since it didn't require
one. The loop is to take up slack for the intermittent movement through
the picture gate, and that would be completely unneccessary on the
Pallophotophone.

> 
> Most of the films had the tracks going in the same direction, and these
> guys didn't understand the concept of a continuous loop at first.  It
> turns out that the machine DID record and play with a continuous loop. 
> But they also had experimented with using reels and a reverse mechanism
> on the recorder.

Corbis has two images (with copyright shared with the Schenectady
Museum) of what I presume to be the 1922 incarnation, since it has a
horn. It also has a supply/takeup magazine, so it would seem that at
least for recording some versions used film on cores or reels or
whatever raw stock feeds from. 

http://www.corbisimages.com/images/67/771CCE8D-DC31-4D98-BCB5-70D64A936BE3/HQ001364.jpg (Dr. Hoxie with Jackie Coogan)

http://www.corbisimages.com/images/67/00C65E15-31C2-41E8-8D15-C542E1A1F762/HQ001369.jpg

These may even be two different machines. And they certainly appear to
have a very large flywheel near the bottom, presumably where the film
would be recorded. This is more visible in the first image where the
machine's cover is removed. Both pictures show a machine whose movement
is electrically driven, even if the actual recording mechanism is not.

> On a similar note, we had a presentation at ARSC warning us that you
> CANNOT record an analogue track in reverse onto a digital medium and
> expect to be able to digitally reverse it.  You wouldn't believe what
> the waveforms looked like when he shows them to us.  Reversed square
> waves had loop-de-loops!!!  Analog reversal is generally OK -- there
> were some occasional problems that tape duplicators had discussed in the
> 1960s-- but digital is absolutely OUT.

Interesting. Well, there's always 1/4" fulltrack mono tape, if they can
find a machine that's been properly maintained. Invert the tape and
there we are. 

MS