Boxoffice-May.03.1952

does not move on shaft, use small taper
reamer and ream holes out slightly
(ream out the big end of hole, of course)
Reamers may be purchased from factory
or supply dealers.
Never force a sprocket on a shaft as
you may spring the shaft and then you
will really have trouble. Re.iect any
sprocket that you cannot carefully push
on shaft. You want a good tight fit but
should not have to force a part on and
spring & shaft.
What arc the frequejicies the human cardrum
luill respond to?
Due to the elasticity of the eardrum
it will respond to frequencies from 16
to around 15.000 c.p.s. One must have
very good hearing if he can hear as
low a frequency as 16 and as high as
15,000—hearing decreases with age in
most individuals. The human ear is
most sensitive, according to authentic
data, to 1,000 c.p.s. Modern amplifiers
and sound heads will reproduce all the
frequencies faithfully if kept properly
adjusted and checked regularly. For
brilliant, clear sound reproduction equipment
should be checked with test equipment
regularly every 60 days.
/ have used your books on sound systems
with good results. Noiu I need some
information on servicing BB intermittent
movements— how to repair, rebuild and adjust
correctly. Appreciate your help in securing
this service data or if you publish
a book on repairing intermittent movements.—
Gotfred Olson, Fessenden Theatre,
Fessenden, N. D.
I am very happy that my booklets
have been of help to you in general
maintenance of sound equipment. I do
not publish a book on repairing and rebuilding
intermittents at this time but
I am compiling an article now which
will be published in Modern Theatre
soon. In the meantime, I am sending
you some tips on repairing and suggest
that you read my article in Boxoffice
Modern Theatre Buyers' Directory and
Reference Section, Page 71, issue Nov. 24,
1951, which should prove helpful in repairing
BB intermittents.
I do appreciate the many nice letters
about articles in the Modern Theatre
Section each month, and many kind
words regarding the service booklets.
/ have followed your articles on sound
and projection in Modern Theatre a long
time and find them of great interest and
help. I need some advice on building a
small pre-amplifier and rvill appreciate
your help in the matter. My soundheads
use Cetron CE-2 P.E. cell which operates at
90 volts: will use DC current for exciter
supply. This setup will be used in a small
parish hall and we will appreciate if you
would send this data via air mail as we
are in a hurry. Thank you.— Carl P. Anderka,
135 Fern St., San Antonio, Tex.
I
a
immediately sent the required schematics
and data on building
pre-ampUfier,
P.E. cell circuits and other data.
The reason I am not using the .schematics
in this department is because this
was a special setup to be u.scd with a
Grunow radio and fed through the
phonograph jack and would not be of
help to our readers using theatre audio
amplifiers. I am always ready to help
our readers in any problem, but please
am
allow sufficient time for a reply as I
"snowed under" with correspondence
most of the time.
HOW MANY OF THESE CAN YOU CORRECTLY
ANSWER?
What is a rotary converter ivhcn used in
projection room?
Wfiat causes condensers to leak wax?
Become defective?
What arc sojne of the causes of resistors
becoming too hot or emitting smoke?
What should be the length of the arc gap
of a reflector-type, direct current, highintensity
projection lamp? What sizes of
carbons arc used for 40 to 43 amperes?
(Answers next month)
New Magnetic Sound System
Is
Announced by DeVry
A new, profesisonal-quality, magnetic
sound system for recording and reproducing
magnetic sound on 16mm motion picture
film has been developed by engineers of the
DeVry Corp.
According to W. C. DeVry, president, this
magnetic sound system has been adapted
to the standardized U.S. armed forces
16mm sound motion picture equipment, as
developed and manufactured by DeVry.
In the premiere demonstration of the new
equipment, held in Washington, D. C, before
military officials and dignitaries of
foreign governments, 16mm motion picture
film with magnetic sound was reproduced
in many languages, including Fi'ench, German,
Chinese and Spanish, with perfect
synchronization between the picture and
sound.
This recorder-projector records and
plays back sound by means of a narrowstripe
of magnetic iron oxide bonded on the
edge of either 16mm sound or 16mm silent
motion picture film.
DeVry, in announcing the new equipment,
said: "Magnetic sound-on-film is
unquestionably a major development. It
has a definite and fruitful use in education,
religion, industry, business and for the
home movie-maker. However, it is the consensus
of opinion among film producers and
equipment manufacturers that the high
quality optical .sound as now recorded on
16mm or 35mm motion picture film will
continue to be the universally accepted
sound-on-film medium."
YOUR CAR
using
DROLL PROCESSED
DOLLARS
CARBONS
A continuous trim that burns the
entire carbon and cuts your carbon
costs 10% to 25%.
AVAILABLE FOR THESE HI TRIMS;
NEGATIVES
POSITIVES
6 mm. X 9" 7 mm. x 12" and 14"
7 mm. X 9" 8 mm. x 12" and 14"
ond 136 mm. x 22" (machined for odaptcrs)
to provide twenty minutes more burning
time.
Shipped prepaid at regular carbon list prices,
plus $1.15 per hundred for milling, drilling
and clips (on 13.6 mm. x 22", $1.50 per
hundred), less 5' on carbons, 10 days.
Liter.ilure on request.
G. C. ANDERS COMPANY
(Formerly Droll Theatre Supply Company)
317 S. SANGAMON STREET
CHICAGO 7, ILLINOIS
Improvement
" PAYS...
Do It
NOW!
TO increase and hold
patronage for your theatre
TO strengthen moviegoing habits
. . . make
your theatre more
attractive and comfortoble
in every way possible.
MOVIES ARE BETTER THAN EVER
. . . How
About Your Theatre?
EVERYTHING FOR THE CONCESSIONAIRE
Popcorn Equipment
Candy Floss Equipment
Popcorn, Oils, Boxes and Supplies
Kiddie Rides
Write for cotolog . . .
3918 Sccor Rd
Toledo 13, Ohio
CONCESSION SUPPLY CO.
BOXOFFICE May 3, 1952 45