The Lamar register., 1923-01-24
RADIO
PRESERVING TONE
IN LOUD SPEAKER
How This Can Be Done and the
Maximum Amount Of Ampll-
ficati0n Obtained.

The loud speaker ls tho ultimate aim
OF every radio novice, as with one of
these Instruments greater range OF the
received signals In obtained and the
necessity Of wearing the head phones
in eliminated The loud speaker also
permits n greater number Of people TO
hear the concert. Ms with head phones
the number hearing the concer Is
limited to the supply OF head phones,
Will. with the nmplihcstion the mum
her Of people hearing the concert Is
limited to the range OF the device,
There are several problems involved
In obtaining the maximum amount OF
amplincation. and yet at the same tim"
preserving the original tone so that 1t
viii retain Its pleasing qualities
Most OF these problems are involved
IN the maintenance Of the quality of
the received tone, as IL is q compara-
lively simple matter 10 amplify the
received signal sufficiently.
In order to eliminate or minimize
loud speaker distortion, IL is necessary
TO know the causes involved. The
source Of the trouble may be In the
amplificr. In the loud speaker itself
or In both.
Ampliner distortion may be caused
by unequal voltage transformations in
the coupling transformer nj different
radio frcaueucies by the operation OF
the Ampllner tube at the wrong point
OF its characteristic and by overload
ins the tube 10 the point Of saturauen.
For good amplincstion Of telephone
signals, tho interstaSe transformer
should he capable Of giving a uni
form transfer OF voltage from about
20 20 S,eo cycles per second, 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
tssc applied TO the smplifcr tube there
is corresponding value OF negative
grid voltage which should he spoiled
in order 70 operate upon . straight por'
don of the characteristics curve and
thus secure uniform amplincatien-
For connecting TO the loud speaker.
especially when using . power tube
Tor the las; stage. 10 10 preferable 10
usc an intermediate transformer with
the proper constants. instead OF plac~
ing the loud speaker directly In the
tube plate circuit This keeps wind
ms and prevents the prlartzinE effect
that Il would have upon the dis
phragm-
twe-s,sge ampliner will general
ty sive enough intensity 10 operate 8
loud speaker in an oniinAry living
rcon. while the loud speaker mechan-
ism Itself may he 0f the head tele
phone type with suitable horn. some
recelvers operate very well At M sder~
ate intensities, but when very strong
signals arr applied TO them they vi
hrste - violently that the disphrsgms
hIt the pole pieres and prcduce harsh
sounds instead " god reproduction
~ the original signals T>o handle the
proper amount % eaersS. therefore,
the Construction must he such thsi re-
soaShly strong vibrations will no;
torSV the diaphragm TO its limit ot
travel The material and shape % the
diaphragm are also Important IN de-
tcrulnlns the resultant tone qualities.
since whatever natural pevieis ot vi
hra;iOa 0; may have vii bring out GER
tain tones IN sreater ProPN-;ioa than
they should Re "a the Tt'1aAintns tones
% uuScSl seleciioa.
The sire share and material ~ the
horn are likewise important factors
ia the dnal result TIE high nsturs.
period - 6 small horn vii tend 70 sc
,rntpate the higher tones to the ex,
clusiSn % the lower saes- TIE ms
terisl from which the horn is made
should Se sSue substance which vii
not viA-ste and prcducs rStilins
salndS
Thus ne sex that IN o-se- 70 pro
duce . comhinatiOn o: Ampli6e- and
Icaa speaker which s1n g!ve pleasing
results Il Is necessary to choose The
various parts with cSrr AID assemble
theu - that they wfu give rros -
pro6ncsisa 81 the original sicasls
Tsss soz-er fsr crsstal csseStsr Set