In the very early years of radio, headphones
was about all there was for sound reproduction. The horn speaker
became the norm in the late teens.
Most early horn speakers consisted of a sound magnifying horn
with a what was not much more than the sound element of a headphone
attached to the base.
When you purchased your new radio
in the early 1920's most of them did not have enough power to drive
a loudspeaker so headphones was how you listened. Many companies
offered one or two stage (some had three) audio amplifiers
that would amplify the weak audio sound enough to drive a load
speaker. These (amplifiers and loudspeakers) of any brand of could be attached to
the simplest of radio receivers (even crystal sets) so the whole
family could listen.
Loud speakers were
usually an option and if desired were purchased separately. Most all
permanent magnet speakers of the 1920's had an impedance of
around 2000 ohms.
All permanent magnet (2 wire type) speakers were compatible with
any radio of that era that could drive a loudspeaker. This applies
to both the horn and disc type speakers. The disc (or cone speaker)
were introduced in the mid late 1920's and were compatible (and proper for use) with any
brand 1920's radio. This applies
to either battery or the early AC sets. The exception was some of
the AC operated sets made in the late '20's required an
electrodynamic speaker (more on this type later). It was quite common to have a radio of one brand
and a speaker of another as many speaker companies did not make
radios and some radio companies did not make speakers. It is proper
and ok to use any radio - speaker combination of that era as few
sets came with a speaker unless it had one built-in or a combo pack
was offered. There were a few (very few) speakers designed
(cosmetically) to go
with a particular radio, an example was the RCA
Radiola 33
receiver that was sold with the
Radiola 100B
speaker.
Speakers with 3-4 or more wires were
usually designed electrically for a particular set and almost always had a
special plug that plugged in to the radio chassis. These type
speakers were not usually compatible with other radios.
You should never apply power
to a radio with a proprietary speaker (electric sets)
without the speaker connected. Doing so will almost always
result in damage to the radio's power supply.
These 3-4 wire speakers are "electro-dynamic",
that is their magnet is energized by a coil (this is called the field
coil) which is part of the power supply circuitry of the radio.
A good example of this type is the
Atwater Kent
55. Speakers with
only 2 wires will have a permanent
magnet.
I should mention that there were certain speakers that were
promoted but not included with the purchase of a particular Radio,
for example; the
Radiola 44 and
60 were both
promoted with the Radiola 103 speaker, these are shown on the "Radiola
Info"
page. The
Radiola Super-Heterodyne portable and the
Radiola IIIA were sold
with the
UZ-1320 0r UZ-1325 speaker.
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