People talk about the Weathers FM pickup often. It's was a legend in its own time in terms of sonic quality. According to the late J. Gordon Holt, this pickup was one of the best phono cartridges he had ever heard. Unfortunately few, if any, have survived the ravage of time. Aside from a picture of it in the VE's cartridge database, I've never had the good fortunate of ever using one nor have I ever seen one in person.
The Stax CP-X with the POD-XE Oscillator/Demodulator, is a stereo unit said to be similar to the Weathers in operating principle. According to the info available from the Stax website, the first Stax designed electrostatic cartridge, CP-20, a mono unit, appeared in 1952. A stereo unit, CPS-40 came out in 1962 and the CP-X came out in 1970. The CP-X was upgraded to CP-X/Type 2 in 1975. In 1977, Stax introduced a new model CP-Y using a permanent electret element with an IC built into the body of the cartridge. Shortly afterwards, the CP-X was discontinued.
I acquired my CP-X System in 1976. It had to be imported directly from Japan as there were no distributors in the US at the time. I limped along with the skimpy instructions in Japanese that came with the unit. Eventually I wrote to Stax for Help. They were nice enough to send me a copy of a hand-written instrcuction manual in Janpanese with English translations. Only then was I able to set up the unit half way decently.
CP-X stayed in my system for quite a while. I liked it so much I actually made a tubed 10db voltage amp to replace the fet/bipolar one in the POD-XE, as I had and probably still have a fixation in wanting to keep my audio chain as "solid-state free" as possible.
The CP-X was out of storage the other day for photos. Afterwards, I actually set it up in the Panasonic SP10 and listened to it through the ARC SP8/Cary 805C/Quad 63. I was amazed at how wonderful it still sounded. A few hours later I found myself still playing records. I had to pratically force myself to quit. Nothing had generated quite so much excitement for me in audio recently.
The Stax CP-X sounds drastically different in character from magnetic cartridges. Sonically the difference between the CP-X and the magnetic cartridges is closely parallel to the difference you hear from the electrostatic headphones/loudspeakers and their dynamic counterparts.
Published specifications of the cartridge:
Freq. Response: 10-40kHz; 10-50kHz for Type2
Channel Separation: 22db(1kz); 24db for Type2
Effective Tip Mass: 0.3mg
Compliance: vetical - 10
horizontal - 20; 15 for Type2
Optimum Tracking Pressure: 1 g.
Stylus shape: 0.2 x 0.8 mil; 0.3 x 0.8 for Type2
Vertical Tracking Angle: 15 degrees
Weight: 9.5g; 8.5g for Type2