Page 7
Stylos User's Manual
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
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 electro-
static tweeter element ready for commercial production.
This new tweeter soon created a sensation among
American audio hobbyists. Since Janszen's tweeter
element was limited to high frequency reproduction, it
often found itself used in conjunction with woofers, most
notably, woofers from Acoustic Research. These systems
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 on
electrostatic loudspeaker design in
Wireless World, a
British electronics magazine. In these articles Walker
demonstrated the benefits of the electrostatic loud-
speaker. 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 fre-
quency 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 ESL. This
speaker immediately set a standard of performance for
the audio industry due to its incredible accuracy. How-
ever, in actual use the Quad had a few problems. It could
not play very loud, it had poor bass performance, it
presented a difficult load that some amplifiers did not like,
its dispersion was very directional, and its power han-
dling was limited to around 70 watts. As a result, many
people continued to use box speakers with cones.
In the early 1960's Arthur Janszen joined forces with the
KLH loudspeaker company and together they introduced
the KLH 9. Due to the large size of the KLH 9, it did not
have as many limitations as the Quad. The KLH 9 could
play markedly louder and lower in frequency than the
Quad ESL. Thus a rivalry was born.
Janszen continued to develop electrostatic designs. He
was instrumental in the design of the Koss Model One,
the Acoustech, and the Dennesen speakers. Roger West,
the chief designer of the JansZen Corporation became
the president of Sound Lab. When JansZen Corporation
was sold, the RTR loudspeaker company bought half of
the production tooling. This tooling was used to make the
electrostatic panels for the Servostatic, a hybrid electro-
static system that was Infinity's first speaker product. Other
companies soon followed; each with their own unique
applications of the technology. These include Acoustat,
Audiostatic, Beverage, Dayton Wright, Sound Lab, and
Stax to name a few.
Electrostatic speakers have progressed and prospered
because they actually do what Peter Walker claimed they
would. The limitations and problems experienced in the
past were not inherent to the electrostatic concept. They
were related to the applications of these concepts.
Today, these limitations have been addressed. Advance-
ments in materials due to the U.S. space program give
designers the ability to harness the superiority of the
electrostatic principle. Today's electrostats use advanced
insulation techniques or provide protection circuitry. The
poor dispersion properties of early models have been
addressed by using delay lines, acoustical lenses,
multiple panel arrays or, as in our own products, by
curving the diaphragm. Power handling and sensitivity
have been increased.
These developments allow the consumer the opportunity
to own the highest performance loudspeaker products
ever built. It's too bad Rice and Kellogg were never able
to see just how far the technology would be taken.
