Electrostatic Loudspeaker History

Rice and Kellogg had narrowed the field of “contestants” down to the cone and the electrostat.

In the late 1800s, 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 gramo-

phone couldn’t begin to reproduce all of the information on this new disc. As a result, further developments in loud- speakers 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 a 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 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 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 Kellogg’s enthusiasm, they devoted a considerable amount of time 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 at Bell Labs 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 Bell management to go with the cone. For the next 30 years, the electrostatic design lay dormant.

During the Great Depression of the 1930s, 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 1940s, 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.

16 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.