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19
In the late 1800’s, any loudspeaker was
considered exotic. Today, most of us take the
wonders of sound reproduction for granted.
It was 1880 before Thomas Edison had invented
the first phonograph. This was a horn-loaded
diaphragm that was excited by a playback
stylus. In 1898, Sir Oliver Lodge invented a
cone loudspeaker, which he
referred to as a “bellowing
telephone”, that was very
similar to the conventional
cone loudspeaker drivers that
we know today. However,
Lodge had no intention for
his device to reproduce
music because in 1898 there
was no way to amplify an
electrical signal! As a result,
his speaker had nothing to offer over the acoustical
gramophones of the period. It was not until 1906
that Dr. Lee DeForrest invented the triode vacuum
tube. Before this, an electrical signal could not
be amplified. The loudspeaker, as we know it
today, should have ensued then, but it did not.
Amazingly, it was almost twenty years before this
would occur.
In 1921, the electrically cut phonograph record
became a reality. This method of recording was
far superior to the mechanically cut record and
possessed almost 30 dB of dynamic range.
The acoustical gramophone couldn’t begin to
reproduce all of the information on this new disc.
As a result, further developments in loudspeakers
were needed to cope with this amazing new
recording medium.
By 1923, the decision to develop a complete
musical playback system consisting of an electronic
phonograph and a loudspeaker to take advantage
of the new recording medium – the project of two
young engineers, C. W. Rice and E. W. Kellogg.
Rice and Kellogg had a well equipped laboratory
at their disposal. This lab possessed a vacuum tube
amplifier with an unheard of 200 watts, a large
selection of the new electrically cut phonograph
records and a variety of loudspeaker prototypes
collecting over the past
decade. Among these were
Lodge’s cone, a speaker
that used compressed air, a
corona discharge (plasma)
speaker, and an electrostatic
speaker.
After a short time, Rice and
Kellogg had narrowed the
field of “contestants” down to
the cone and the electrostat. The outcome would
dictate the way that future generations would refer
to loudspeakers as being either “conventional”
or “exotic”.
Rice and Kellogg’s electrostat was something
to behold. This enormous bipolar speaker was
as big as a door. The diaphragm, which was
beginning to rot, was made of a pig intestine that
was covered with fine gold leaf to conduct the
audio signal.
When Rice and Kellogg began playing the new
electrically cut records through the electrostat,
they were stunned and impressed. The electrostat
performed splendidly. They had never heard
instrumental timbres reproduced with such realism.
This system sounded like real music rather than
the honking, squawking rendition of the acoustic
gramophone. Immediately, they knew they were
on to something big. The acoustic gramophone
was destined to become obsolete.
electrostatIc HIstory
Rice and Kellogg
had narrowed the
field of “contestants”
down to the cone
and the electrostat.
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