Radio Doings May 22, 1927 - AmericanRadioHistory.Com

18 Radio Doings May 21
Phonograph Reproducers
E. K. HAYES -V. M. BITZ*
Many queries are received as to the extremely slow vibrations, however, the
merit of the capacü type phonograph truest overall reproduction is obtained
reproducer which has recently been with a good electro magnetic pick up.
placed on the market, and as the writ- A very important thing the experimenters
have had the opportunity to give it er should consider before putting a caa
rigid test, a comparison will be made pacity pick up into operation is that
with the electro magnetic reproducer. the oscillator, the output of which is
There are three types of reproducers modulated by the pick up, specified by
offered to the public, the so- called "mi- the manufacturers of the unit, is workcrophone"
type, the capacity type, and ing in the broadcast range and will
the electro magnetic type. Inasmuch as cause plenty of squeals In nearby rethe
"microphone type" is much inferior ceivers.
to the others, it will not he discussed. The most undesirable feature of the
The extreme pipe organ range is from capacity pick up from the operator's
16 to 16,000 cycles physical pitch, approx- standpoint is that whenever the hand is
imately: therefore, the theoretically per- placed near the pick up, such as in
fect pick up would reproduce these fre- winding the machine, etc., or placed
gnencies. There are practical linilta- near the leads from the pick up to the
tihus, however, the range of the human oscillator, considerable distortion reear
and the fact that present -day ampli- sults, as the capacity of the body defying
equipment will not pass efficient- tunes the oscillator. As a laboratory
ly such a wide band. Successful recordings
of frequencies from 26 to 9000
cycles are now being made, so if our
pick up and amplifying equipment will
reproduce these sounds we are doing
very well. To do this, the pick up
must follow faithfully the grooves of
the record, and must be so designed mechanically
that it does not In itself
damp out any of the vibrations. Both
types of pick up follow the grooves
very nicely. The damping effect on
high frequencies is greater on the capacity
type and the electro magnetic
pick up does not do quite as well on the
t.ahoratmy of Radio St n ndards.
proposition, the capacity type pick up
has considerable merit, but the experimenter
and home constructor will obtain
much better reproduction with the
electro magnetic pick up In addition to
not filling the ether in his immediate
neighborhood with the "squeal" of an
oscillator.
SAVE MONEY!
I lave your old set rebuilt into a Fiee Tube
Combination Set
$25.00 Does It
FREMONT RADIO SHOP
7621 So. San Pedro St. Los Angeles
R -94 "A"
Power Supply
STERLING "A" POWER UNIT
FOR
RADIOLA 20 -25 -28
And Other 4 -Volt Tube Sets
NO TROUBLE - NO ATTENTION
Telephone UNiversity 3371 or write for demonstration in your
own home. Unlimited guarantee.
1939 E. 16th St.
LOS ANGELES
DETSCH & CO.
555 Turk St.
SAN FRANCISCO