These are Koss Model one electrostatic speakers with many modifications in custom enclosures that sound absolutely incredible. Please note pictures do not seem to download- please e-mail me and I will send pictures
Cabinets; custom manufactured solid maple cabinets with Birdseye maple surround on the bases. With this new configuration the soundstage and imaging are greatly improved in addition to the beautiful cosmetics.
Bias supplies; Koss had a battery and charging circuit that through an inverter supplied voltage for the bias supply and in effect did not need to be plugged in for the 7KV bias requirement. This was a very poor design with the audio input responsible for charging the battery- this entailed tying the audio input ground to the high voltage ground and was one of the reasons these speakers sometimes presented extremely difficult loads to the driving amplifier. This system has been eliminated with transformers supplying the initial AC voltage to the bias circuit. Each speaker now has an AC power cord. Further advantages with this system is now the audio ground is separate from the bias ground. Regulation applied to the bias supply output greatly improving clarity.
Other general modifications; The Koss have 5 bass panels 32-250Hz- I removed one bass panel (now 4). This makes the balance perfect- the 5th bass panel is installed, top left on one speaker, top right on the other speaker- they are electrically disconnected and can be considered as a spare. Each speaker has 4 bass panels, one midrange, two upper midrange and one tweeter panel. The stators in each of these categories are driven by a separate transformer with turns ratio’s relative to the frequency response requirement.
The result is an unequalled harmonic representation and a wide dispersion of the acoustic energy from a full rage electrostatic in beautiful cabinets. In addition an extremely stable and reliable speaker. I have the original owner’s manual and some reviews.
Auditions are certainly welcome and pick up is preferred. These speakers are 95LBS each so shipping would be your responsibility. Located just north of Toronto Ontario.
Some comment info; Ever since Koss managed to produce the worlds first electrostatic headphone in 1968, the Koss engineers have worked on the realization of the idea of the ”full-range” electrostatic loudspeaker, a concept that dates back as far as 1870. During these days the materials available and the level of audio technology prevented the realization of such a loudspeaker. An unachievable dream until now.
Now Koss has developed the electrostatic dream in the model one. This loudspeaker is so unique in its way, that its realization will set new standards in the evaluation of loudspeakers. While other electrostatic loudspeaker designs at the most use two- or three way systems, the Koss Model 1a will utilize a exceptional four way system, that has a frequency range from 32 to 20.000 Hz. + / - 2dB
By utilizing this special design Koss has developed the first electrostatic woofer that can reach concert hall sound pressure. Besides that a special panel was designed for the midrange frequencies to prevent room dependent disturbances that are usually associated with big loudspeakers. By doing this music instruments will sound according to their size and dimension. The panels for the high frequencies and ultra high frequencies are designed according to the combined frequency ranges.