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Re: [ARSCLIST] Recording Innovations
From: Patent Tactics, George Brock-Nannestad
just a short remark, re Bob Hodge:
> Competent projectionists would splice in black film equal to the number of
> frames damaged. Just a normal part of projection.
> Ideally, the rotational pivot should be midway in its travel for maximum
> flexibility. It couldn't rotate 360 degrees due to the leads from the
> tonearm. But more than enough to compensate for subtle difficulties. And why
> a second set of discs were shipped with each film requiring them.
----- at first I thought that having the pivot midway would compensate for
having put too many black frames into the gap, but then I remembered: there
is no synchronization mark on the Vitaphone disc, so when it is first put on
the turntable you do not know where it is on the turntable. For this reason
you might have to go back or forth to find the sync.
----- by the way, the black film replacement would only work for silent
stock. When a frame was lost in a sound film, the best you could do as a
projectionist was to paint fade-in and fade-out on either side of the splice.
Re-sync would not happen after 20 frames anyway. I think that my worst
experience as a projectionist in our little cinema (35 mm Ernemann, though!)
was in manual rewind. If you got the reels up to speed and lost power in your
winding arm towards the end, the loop would rise above the reels, and if you
were not diligent, above 3 feet in height would threaten with havoc. What
could you do, except clamp your hand on the other reel, getting burn tracks
in your hand. I wore a left-hand leather glove after that. You did not want
to use the brake, because it would slow down the process to a safe speed.
Films had to take a lot of abuse (the reason why nitrate survived for so long-
-it was not only more transparent but also much tougher than acetate)
> From what I've seen in photographs and first hand WE had the best equipment
> in the U.S. But you paid for that privilege! And why there were other
> companies making sound on disc and sound on film apparatus. Most of them got
> a turntable drive from the intermittent flywheel on the projector head.
> WE used a double shafted motor- one shaft drove the projection apparatus
> gearboxes- the other the turntable via extendable shafts and gearboxes.
----- the patent situation was extremely complex, and there are people out
there specialising in this history.
> -----Original Message-----
> From: Association for Recorded Sound Discussion List
> [mailto:ARSCLIST@xxxxxxx] On Behalf Of George Brock-Nannestad
> Sent: Thursday, June 25, 2009 2:40 PM
> To: ARSCLIST@xxxxxxxxxxxxxxxx
> Subject: Re: [ARSCLIST] Recording Innovations
> From: Patent Tactics, George Brock-Nannestad
> Hello, Bob Hodge wrote re catching up with missing film frames in a
> disc projection system so that lip sync could be maintained:
> > The method of retard or advance was a special mount that allowed the
> > to be advanced or retarded while the record continued at a constant
> > The tonearm mount rotates on a portion of the support column below the
> > turntable gearbox.
> > Darned clever those WE engineers!
> ----- yup, you could say that. However, a bit of calculation demonstrates
> that there is a limit to the total number of frames for a whole reel that
> could be corrected.
> The records ran at 33 1/3 rpm, which calculates to 200 degrees per second.
> This corresponds to 24 frames. This means that you have to move the pivot of
> the tonearm 8.33 degrees for each frame lost, or a right angle (give or
> for 11 frames lost. If the WE equipment was good and the film reasonable I
> suppose this never happened. So, we may conclude that if the tonearm mount
> was swivelable over a right angle they would be home free. However, the
> differential that was used by other makers was continuously variable and did
> not have to be reset when a new reel (corresponding to a new disc) was
> Kind regards,