Evening star. [volume] (Washington, D.C.) 1854-1972, 1929-02-17
RADIO FANS DIFFER
ON SPEAKER TYPES
Each of Three Kinds Widely
Used Has Its Ardent
Supporters.

NEW YORK (Pl.-As long as the pet
radio needs a loudspeaker there will be
differences of opinion as to what is a
real reproducer.
Any radio enthusiast will point with
pride to a certain piece of apparatus
end declare such and such speaker is
the best.
Three types of speakers have been
given wide use. Each has its ardent
supporters Some day there may be a
much wider range. including the re-
Gently announced condenser type repro
ducer, with a corresponding increase in
opinions.
Faced with a problem that almost
any one Is willing to solve to the salts
faction of the person giving the advice,
the listener has the choice of dy-
manic or moving coil speaker, mag
netic cone, or horn which has lost its
gooseneck shape to coil all around itself
as an exponential.
Many Factors in Question.
Many factors enter into the question.
Among them are the type Of audio am
differ in the receiver, the volume de-
sired, the tone range, whether pitched
high or low, and last but probably as
important, appearance.
The last year has seen much con-
ccntration on the dynamic, 1t has
been due partly to the demand for low
notes and more realistic reproduction.
This speaker has a coil fastened to a
bell-like diaphragm. The coil floats in
field created by an electromagnetic re-
quiring a separate power source. Prev
ious to the dynamic, which in sense is
power cone, the magnetic cone had
the field Roughly it Is an diversified
'phone" unit. Its paper or cloth dia-
phragm is fastened to a pin connected
to an armature that vibrates in step
with current flowing through a per-
manent magnet.
The exponential horn has long
throat proportioned fundamentally
from q small opening to haring bell
The throat generally is eight feet long
and is wound around the bell to save
space The air column in the horn Is
moved by speaker unit, either mag
netic or dynamic.
In q number of tests under average
operating conditions several interesting
conclusions were to be noted. The
dynamic, when operated as engineers
say 1t should be, had few If any rivals.
Effectiveness Obtained.
The full effectiveness Of the dynamic
was not obtained until it was placed in
a proper battle board and supplied by a
receiver output coming either from the
17la's or 210's in push-pull or from a
single $50 output stage. The greater
the output the better the reproduction,
provided there was no attempt to force
the speaker. Its lowest operating point
came with a single lila in the last
audio stage.
feet square, with q hole cut In the
center slightly smaller than the bell of
the dynamic. The bell was fastened
securely to the board. Increasing the
Rizs Of the baffie added to the efieiency.
A somewhat similar effect was OBJ
tained by placing the speaker in the
center Of the front of console In an
ordinary sized speaker cabinet, which
also acts as battle, the dynarnis re-
produced adequately, although there
seemed to be a tendency toward tones
That one listener described as 'barrel-
The cone did its best On 4 171a out
put tube, being close TO the dynamic
operated in similar manner. IN
creasing the set output brought drop
N the cones efficiency, as it overloaded
quickly.
The biggest drawback to the expo-
MENTAL horn came from its size and
cumbersomeness. 1t reproduced with ap-
proximately the same fidelity as the
cone when a proper speaker unit was
used. The larger the horn the better
was the music. although some Of the
sizes tried were out of the question for
the home. The larger horns also re-
CURED dynamic units and power am