Boxoffice-April.07.1958

difficulties in the full-wave tubes. Heavy
duty full- wave rectifier tubes, namely, 5Z3,
5R4GY and 5U4G are some of the most
FKjpular rectifier tubes used in theatre
sound systems.
HEAVY DUTY CONDENSERS
The major filter condensers in modern
theatre amplifiers are heavy duty, some
amplifiers using double 8-microfarad units
of not less than 450-475-600 volt capacity.
These capacities give a very liberal margin
of safety and excellent filtering. Some
power supplies also use heavy duty chokes
for better filtering in connection with the
filter condensers. Of course, some makes
of amplifiers use special types of filter
condensers, such as 4 microfarads and 600-
volt capacity; others use 1,000 microfarads,
25 volt, and filter condensers 40x40 microfarads,
500 volts, etc., in power supplies.
We are pointing out some of the values of
condensers in various makes of amplifier
power supplies to give you some idea of the
importance of filter condensers and using
correct values in replacement. Good filtering
is absolutely necessary in order to secuie
good operation and hum-free performance.
Most manufacturers use a single condenser
type for all circuits which greatly
simplifies maintenance problems, even in
the event one condenser may fail in one
or more individual condenser sections. More
than one condenser, of course, is used in
the filtering assembly.
If your sound reproduction is not up to
par, and the equipment is several years old,
it is possible to "modernize" the sound system
and obtain very satisfactoi-y sound
reproduction. A major job of doing a modernizing
job on the amplifier or pre-amplifier,
or both, requires knowledge of electronics
and high-quality test equipment
and test films.
CAN MODERNIZE SYSTEM
Sometimes one can make some circuit
changes in order to secure good overall response
from the amplifier, and then the
addition of a late-type, two-way loudspeaker
system will materially improve the
sound quality. In some situations, it may
be necessary to change the sound heads
in order to improve quality and eliminate
distortion and flutter originating in the
sound heads. On the other hand, a modern
pre-amplifier and power amplifier may
do the job, plus overhauling and adjusting
the sound heads for better operation.
We do want to emphasize the importance
of matching all the components in quality,
or your modernizing job will fall flat on
its face; because one inferior component
can ruin the modification of other units.
All cormponents must work as
a "team" in
order to secure perfect results. F^-ankly, in
many cases, it is easier to rebuild an amplifier,
if it does not have too much age,
and make it reproduce satisfactory sound
output than to rebuild some types of
sound heads that are ten or 15 years old.
And the addition of a modern, two-way
loudspeaker will greatly improve sound
reproduction, if you have ased single speakers
or the loudspeakers are a very old type.
The two-way loud.speaker system gives
vastly superior sound p)erformance over the
single-type installations. Excellent overall
frequency response, from 40 to 15,000 cycles
can be reproduced. The crossover, or socalled
dividing network, either at the loudspeaker
assembly or in the power amplifier,
produces .sound that is natural and life-like
in reproduction, if properly installed and
the amplifier is adjusted to fit local auditorium
conditions. While not a cure-all
for all sound defects, such as poor
acoustics, poor quality output from amplifier
or reproducer, a good loudspeaker system
will "help" to improve many conditions
if some adjustments are made in the
Brjlliance-
Definition-
Contrast/i
sunin
I
N.I
balance of the sound system. We have
vastly Improved .sound by installation of
either RCA or Altec-Lansing Coi-p. speakers,
for any of the leading sound systems.
The Altec-Lansing loudspeakers are used
with Simplex, Century and Motiograph,
but can be used with other systems.
While RCA's fine line of speakers is u.sed
with RCA equipment, it can be u.sed with
other makes of sound systems, with proper
imjjedance matching and networks.
In conclusion, one .should set up a daily
routine of cleaning the .sound head, .sound
lens, sprockets, guide rollers, rotary .stabilizer
and exciter lamp for correct adjustment.
Dirt or dust on the sound lens will
cause a loss of volume; poorly focused and
For sparkling screen play
that leaves your patrons
ready for more, use only
SUPER SNAPLITE Projection Lenses.
Belter equipment is the surest way to Better
Boxoffice . . . and your lenses are the most vital
element in equipment set-up. Ask your equipment
dealer for a copy of Bulletin 222.
/injlOl..liA%Olt4;KW
\sj_--^
Northampton, Mossachusetts
Continued on following page
BOXOFFICE AprU 7, 1958 49