Vilas County news. [volume] (Eagle River, Vilas County, Wis.) 1896-1927, 1923-01-31
PRESERVING TONE
III LOUD SPEAKER
How This Can Be Done and the
Maximum Amount of AmpI-
fication Obtained.


OF every radio novice. as with one OF
these Instruments greater range OF the
received signals is obtained and the
necessity OF wearing the head phones
Is eliminated. The loud speaker also
permits greater number OF people To
hear the concert, as with head phones
tie number hearing the concert is
limited 10 the supply OF head phones,
while with the ampllfication the mum
Der OF people hearing the concert Is
limited 10 the range Of the device.
There are several problems involved
In obtaining the maximum amount OF
application, and yet az the same time
preserving the original tone so that il
VIII retain Its pleasing qualities.
Most Of these problems are involved
IN tile maintenance Of the quality OF
the received tone. as it is a compara-
lively simple matter to amplify the
received signal sufficiently.
Ia order to eliminate or minimize
loud speaker distortion, 1t is necessary
to know the causes involved. The
source Of the trouble may be in the
amplifer. In the loud speaker itself,
or In both.
Amplitier distortion may be caused
by unequal voltage transformations In
the coupling transformer at different
radio frequencies. by the operation Of
the amplitier tube at the wrong point
Of its characteristic and by overload
lng the tube to the point of saturation.
For good application OF telephone
signals, the inter-stage transformer
should be capable OF giving a uni
form transfer OF voltage from about
200 10 5000 cycles per second. A good
many transformers now IN use do not
DO this, and their operation is one Of
the principal causes for unsatisfactory
signals. For any particular plate vol
tage applied TO the amplifier tube there
Is a corresponding value Of negative
grid voltage which should he applied
In order to operate upon a straight por-
ton OF the characteristic curve and
thus secure uniform application.
For connecting 70 the loud speaker.
especially when using a power tube
for the last stage. 1t is preferable to
use an intermediate transformer with
the proper constants. instead Of plac-
ing the loud speaker directly In the
tube plate circuit. This keeps wind
ing and prevents the polorizing effect
that il would have upon the dia-
phragm.
A two-stage ampiilier viii general
" give enough intensity 20 operate n
loud speaker In an ordinary living
room. while the loud speaker mechan-
ism itself may he Of the head tele-
phone type with suitable horn. Some
receivers operate very well at moder-
ate lntensltles, but when very stron-
signals are applied TO them they vi
hrate SO violently that the diaphragms
hit the pole pieces and produce harsh
sounds instead of good reproduction
Of the original signals. To handle the
proper amount OF energy. therefore,
the construction must be such that rea-
sOnably strong vibrations viii not
force the diaphragm 20 its limit 81
travel. The material and shape Of the
diaphragm are also important In de-
ternlnlng the resultant tone qualities
since whatever natural periods Of VI
bratlon Il may have will bring cut Ger
tain tones in greater proportion than
they should be 20 the remaining tones
OF a musical selection.
The size. shape ond material Of the
horn are likewise important factors
IN the final result. The high natural
period of a small horn viii tend to ac-
eentuate the higher tones TO the ex-
clusion OF the lower ones. The ma
terlal from which the horn Is made
should be- some substance which viii
not vlbrate and produce rafting
sounds.
Thus we see. that in order to pro
duee n combination Of ampllfer and
loud speaker which win give pleasing
results. II Is necessary TO choose the
various parts with care and assemble
them so that they win give a true re-
production of the original signals.