These developments allow the consumer to own the highest performance loud- speaker products ever built.

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 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 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 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 ESL. This speaker immediately set a standard of performance for the audio industry due to its incredible accuracy. However, in actual use, the Quad had a few problems. It could not be played 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 handling was limited to

around 70 watts. As a result, many people continued to use box speakers with cones.

In the early 1960s 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 electro- static 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 electrostatic 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. Advancements 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 also 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.

Electrostatic Loudspeaker History 17

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MartinLogan CLS IIz user manual Electrostatic Loudspeaker History

CLS IIz specifications

The MartinLogan CLS IIz is a sophisticated hybrid electrostatic loudspeaker that exemplifies the brand's commitment to innovation and exceptional audio performance. This model is a continuation of the legendary CLS design, which has garnered a loyal following among audiophiles and music enthusiasts alike.

One of the standout features of the CLS IIz is its electrostatic transducer design. Unlike conventional dynamic speakers that rely on moving coils and cones, electrostatic speakers use a thin, electrically charged diaphragm sandwiched between two stators. This design allows the CLS IIz to produce sound with extraordinary clarity, speed, and precision, making it particularly well-suited for accurately reproducing the nuances of vocal performances and acoustic instrumentation.

The CLS IIz also integrates a new, more advanced version of the brand's Curvilinear Line Source technology. This innovation provides a wider and more consistent sound dispersion pattern, resulting in an expansive soundstage that immerses listeners in their favorite recordings. The speaker’s tall, slender design further enhances this effect, allowing for an impressive imaging capability that places sounds precisely within the listening environment.

Another key characteristic of the CLS IIz is its frequency response. The speaker is capable of reproducing frequencies from an astonishingly low 38 Hz to a remarkable 25 kHz. This wide frequency range ensures that music and audio content are delivered with great depth and richness, fully capturing the lower bass notes while maintaining the sparkling clarity of high-frequency sounds.

In terms of build quality, the CLS IIz features a sturdy yet elegant cabinet that minimizes resonance and vibration, allowing for pure audio reproduction. The speaker's sleek aesthetic is complemented by high-quality finishes, ensuring that it looks as good as it sounds, making it an attractive addition to any audio setup.

Additionally, the CLS IIz boasts versatility in its setup, allowing for positioning flexibility that accommodates various room sizes and acoustic conditions. This ensures that enthusiasts can achieve optimal sound quality regardless of their environment.

In summary, the MartinLogan CLS IIz is a marvel of modern audio engineering that combines cutting-edge technologies with a commitment to high fidelity sound. With its electrostatic design, advanced dispersion capabilities, wide frequency response, and elegant build, the CLS IIz stands as a testament to MartinLogan's dedication to providing an unparalleled listening experience.