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9.5 mm SOUND

Mike Trickett

In 1937, Pathe introduced a strange looking projector, which they called the Model “S” (“S” for
Silent?). This machine was basically the yet to be released, VOX sound projector without any of
the sound parts included. Within a year, Pathé was offering to upgrade the “S” to sound and was
offering the complete unit as a Pathé VOX 9.5 mm sound on film projector.
As with a lot of Pathé equipment,
the VOX was unconventional. The
machine had an off-set film path,
necessary to allow the gate and
lens assembly to lift up to thread or
clean the gate. The lighting source
was a 15 volt 200 watt lamp with a
strange off-set filament (see
illustration), which was mounted
base up. The reason for this
arrangement became evident when
the sound system was examined.
The projection lamp was also
utilised as an exciter lamp, the
exciter lens being mounted directly
under the lamp house, picking up
light from the projection lamp and
focusing it on the sound track.

The sound system was yet another
unusual setup. The light from the
projection lamp was focused by the exciter lens as a narrow slit onto the
sound track . Once the light passed through the sound track, the resultant Below: The VOX
lamp. Note the
varying light intensity was reflected by a small mirror up to the photocell off-set filament.
which protruded from the amplifier compartment.
There was no volume
Exciter lens control in the
conventional sense on
the machine, instead
there was a rotary
shutter covering the
photo cell which could
be rotated to allow
more or less of the
reflected sound track
light to get to the
photocell. (A system
that Pathé again used
on their 17.5 mm Home
Talkie).
Rotary shutter (volume control)
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