Martin Logan ElectroMotion ESL Manuel De L'utilisateur page 20

Due to Rice and Kellogg's enthusiasm, they
d e v o t e d a c o n s i d e r a b l e a m o u n t o f t i m e
researching the electrostatic design. However,
they soon encountered the same difficulties that
even present designers face; planar speakers
require a very large surface area to reproduce
the lower frequencies of the audio spectrum.
Because the management considered large
speakers unacceptable, Rice and Kellogg's work
on electrostatics would never be put to use for
a commercial product.
Reluctantly, they advised
the management to go
with the cone. For the next
30 years, the electrostatic
design lay dormant.
D u r i n g t h e G r e a t
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 experienced 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.
In 1947, Arthur Janszen, a young Naval engineer,
took part in a research project for the Navy.
The Navy was interested in developing a better
instrument for testing microphone arrays. The test
instrument needed an extremely accurate speaker,
but Janszen found that the cone speakers of the
period were too nonlinear in phase and amplitude
response to meet his criteria. Janszen believed
that electrostats were inherently more linear than
cones, so he built a model using a thin plastic
20
These developments
allow the consumer
to own the highest
performance loudspeaker
products ever built.
diaphragm treated with a conductive coating. This
model confirmed Janszen's beliefs, for it exhibited
remarkable phase and amplitude linearity.
Janszen was so excited with the results that he
continued research on the electrostatic speaker
on his own time. He soon thought of insulating the
stators to prevent the destructive effects of arcing.
By 1952, he had an electrostatic tweeter element
ready for commercial production. This new tweeter
were highly regarded by all audio enthusiasts.
As good as these systems were, they would soon
be surpassed by another electrostatic speaker.
In 1955, Peter Walker published three articles
regarding electrostatic loudspeaker design in
Wireless World, a British magazine. In these
articles, Walker demonstrated the benefits of
the electrostatic loudspeaker. He explained that
electrostatics permit the use of diaphragms that
are low in mass, large in area and uniformly
driven over their surfaces by electrostatic forces.
Due to these characteristics, electrostats have the
inherent ability to produce a wide bandwidth, flat
frequency response with distortion products being
no greater than the electronics driving them.
By 1956, Walker backed up his articles by
introducing a consumer product, the now famous
Quad EM-ESL. This speaker immediately set a
standard of performance for the audio industry
soon created a sensation
a m o n g A m e r i c a n
audio hobbyists. Since
Janszen's tweeter element
w a s l i m i t e d t o h i g h
frequency reproduction,
it often found itself used
i n c o n j u n c t i o n w i t h
woofers—most notably,
t h o s e f r o m A c o u s t i c
Research. These systems