MartinLogan Sequel II, Руководство пользователя

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Page 6 Sequel II User's Manual
History
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 conven-
tional cone loudspeaker drivers that we know today.
However, Lodge had no intention for his device to repro-
duce 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, Bell Telephone Laboratories made the decision to
develop a complete musical playback system consisting
of an electronic phonograph and loudspeaker to take
advantage of the new recording medium. Bell Labs
assigned the project to 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 that Bell Labs had been 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”.
Bell Laboratory’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 the
membrane of a pigs intestine that was covered with fine
gold leaf to conduct the audio signal.
When Rice and Kellogg began playing the new electri-
cally cut records through the electrostat, they were shocked
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.
Due to Rice and Kelloggs enthusiasm, they devoted a
considerable amount of time researching the electrostatic
design. However, they soon encountered the same difficul-
ties that even present designers face; planar speakers
require a very large surface area to reproduce the lower
frequencies of the audio spectrum. Because the manage-
ment at Bell Labs considered large speakers unaccept-
able, Rice and Kelloggs work on electrostatics would never
be put to use for a commercial product. Reluctantly, they
advised the Bell management to go with the cone. For the
next thirty years the electrostatic design lay dormant.
During the Great Depression of the 1930's, consumer audio
almost died. The new electrically amplified loudspeaker
never gained acceptance, as most people continued to
use their old Victrola-style acoustic gramophones. Prior to
the end of World War II, consumer audio saw little, if any,
progress. However, during the late 1940's, audio experi-
enced a great rebirth. Suddenly there was tremendous
interest in audio products and with that, a great demand
for improved audio components. No sooner had the cone
become established than it was challenged by products
developed during this new rebirth.