Boxoffice-January.08.1955
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SERVICING<br />
SOUND SYSTEMS<br />
Continued from preceding page<br />
that is not in good condition. You will<br />
seciire better sound reproduction, avoid<br />
"flutter" and other troubles.<br />
Motiogi-aph manufactures equipment for<br />
the reproduction of single optical, single<br />
and four-channel magnetic and Perspecta<br />
sound recording. Models range from 20, 40,<br />
75 and 150 watts of power output. The<br />
writer has serviced and inspected all the<br />
various models of sound and projection<br />
equipment and found it very rugged in<br />
construction, delivering excellent sound reproduction,<br />
both optical and magnetic: the<br />
projectors and arc lamps giving long service<br />
and fine projection in every respect.<br />
Sound equipment is also manufactured<br />
for drive-in theatres for the reproduction<br />
of optical sound prints. By the addition<br />
of penthouse reproducers, and additional<br />
preamplifier and switching apparatus, all<br />
systems can also be modified to reproduce<br />
single and foiu--track magnetic sound at<br />
a very reasonable outlay of money. The<br />
multiple amplifier systems are best suited<br />
for drive-in theatres of from 250 to 850<br />
cars, as the exhibitor can obtain emergency<br />
faculties at a lower cost in this type<br />
of system.<br />
Data on the S3 and S4 Systems—The S3<br />
system is provided with three amplifier<br />
channels and the S4 system has an additional<br />
fourth channel for amplification of<br />
the auxiliary or effects track. Each channel<br />
contains the preamplifier and equali-<br />
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Plant: 347 King Street<br />
Northampton, Massachusetts<br />
NEW YORK OFFICE:<br />
YOU can BUY<br />
coitroirATioK<br />
30 CHURCH STREET, NEW YORK 7, N. Y.<br />
zation necessary for magnetic repro'<br />
and the power amplifier stages nee<br />
to drive theatre speakers. The am<br />
channels, a single power supply, all o<br />
ing controls, and relays for changeov<br />
tween two magnetic reproducers ar<br />
tween magnetic and optical sound 1<br />
are all contained in a single cabinet<br />
cabinet may be floor or wall mountt<br />
cording to space available in pro;<br />
room. AU controls and indicator ligl<br />
contained on a sloping top panel, the<br />
layout making it very handy to opera<br />
see for the projectionist. Tubes, coi<br />
ers, resistors, transformers and othei<br />
ponents are very easy to get at and s<br />
ONLY TWO TUBE TYPES<br />
Features which promote ease and<br />
><br />
omy of maintenance are the use c<br />
two tube types in the amplifiers (<br />
for the fourth channel which uses ar<br />
tional 12AT7 typei, and the emplc<br />
of plug-in construction so that each<br />
fier channel may be quickly remo<br />
replaced as a single independent u<br />
spare amplifier should be kept on h<br />
case of trouble in any one of the arr<br />
units. The amplifiers are mounte(<br />
aU wiring, components and controls<br />
the front of the cabinet. Tubes n<br />
serviced by loosening a thumb-sere<br />
connecting the input and gain<br />
plugs, and swinging the amplifier fc<br />
When the single bracket that clam<br />
amplifier to its mounting-rod is rt<br />
and the power and output wiring c<br />
tors are loosened, the amplifier n<br />
lifted out of cabinet. All amplifie<br />
power supply may be removed easily<br />
projectionist for servicing or a good<br />
ing of all the components.<br />
In this<br />
CAN OBSERVE TUBE OPERATION<br />
model the power rectifier<br />
three rectifier tubes, 5U4G, are pic<br />
the bottom, of the cabinet behind a<br />
on the front panel. The operation<br />
tubes may be easily obseiwed withoul<br />
ing the cabinet. In order to keep th<br />
'<br />
ages at recommended value at the<br />
tube elements and points in the cir<br />
the power and preamplifier, it is ve<br />
portant that you check, in a goo<br />
checker or by your local radio servi<br />
all rectifier tubes at least every<br />
three months. It is also importar<br />
filter condensers, etc., in power sui<br />
kept in good condition and replace<<br />
they become defective or have been i<br />
ice a long time.<br />
Another very nice feature of th;<br />
ticular model: it has been designed t<br />
addition of the fourth channel at ai<br />
after original installation. It can b(<br />
installed and electrical connectio<br />
simple to make. It contains, in add<br />
switching circuit to control speaker<br />
tlon from a 12KC signal on the<br />
sound track and filters to remc<br />
12KC signal from the audio outpu<br />
fourth channel amplifier is ident<br />
size, mounting arrangement, and eli<br />
connections with the other three.<br />
The use of low-noise tube types<br />
42 The MODERN THEATRE S:
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