Pickering manufactures or has manufactured the following equipment (click to expand models list):Electrostatic Speakers
Mike Mason (December 2002): Around 1960 I bought and repaired/refurbished 4 or 5 pairs of Pickering Isophase loudspeakers, and spent quite a bit of time working on the insides of the panels, and replacing the diaphragms. Buying replacement diaphragms took me to the Pickering factory in Oceanside New York, where the company president (I'm not sure if it was Norman Pickering or Walter Stanton) demonstrated the prototype of their full-range electrostatic for me; the model they were developing was actually a two-way all-electrostatic unit, consisting of the larger of the two electrostatic mid-high units Pickering made (which was designed for a -3 dB crossover point of about 600 Hz), and the prototype unit, which was a separate electrostatic woofer.
I'd be happy to share more details of the construction of the Isophases with you if you're interested. I was very attached to them (in fact while foolishly attempting an adjustment with power on, I was once almost welded to them). I eventually used two on each stereo channel, crossing over to AR1Ws, driving the combination for a couple of years with Marantz 9s, later with Macintosh 30s. I much preferred them to the four-element JansZen 130s I used when I could no longer repair the Isophases (due to a too-drastic effort I made to solve a grid-rattling problem).
As you probably know, Dr. Pickering is one of the audio greats, and now, I think, still contributes a great deal to the design-theory of stringed instruments (drums also, I think), and I noticed -- on the RPG Diffusor site -- that he has has assisted in the design of microphone placement techniques for recording stringed instruments in an experimental project for recording classical music in anechoic rooms.
I used to do experimental work with tape-loop composition, in the early-1960s, and some of the most extraordinary musical experiences I had was with music played through the Isophases. Extremely simple design with very potent results. I'm seriously thinking of buying a pair of the "0.3" electrostatic-hybrid kits listed on the The ESL Circuit site, in order to see how they compare with my memory of the Isophases. Mike MasonMassachusetts, US
Leo Malet (December 2002): The Pickering Isophase Electrostatic High Range Flat Speaker (approx. 1956) features the Model 401E divider (power supply and crossover) and original Pickering model 402 woofer network. The divider runs at 115 volts, 60 cycles, and 10 watts, and a phasing switch with adjustable phasing control, the woofer network is 16 ohms. The speaker measures h28"x w36"x d1 Â¾-3 Â½"(width varies) and sits on a solid wood base. The unit is capable of crisp, clear and smooth high end!
Yvon Massicotte (November 2002): Why is there basically no mention of the Isophase loudspeakers made by Pickering in the fifties?The "Audio Cyclopedia" (H. M. Tremaine, published by H. W. Sams) mentions them in both its first (1959) and second (1969) editions. There is also an article about them in the the "Journal of the Audio Engineering Society" (April 1956 issue), by their designer a "Mr. Theodore Lindenberg". It seems from that article that Pickering were offering two models one mid-high range unit (from 400 HZ up) and a smaller one (from 1 kHz up).
Surely there must be some old units still around or somebody still alive who has had some hands-on experience with them. The Philco units' pictures that are shown have a general shape like the one portrayed in the Lindenbeg article but seem otherwise different; the Pickering units are being offered as stand-alone units without any woofer, their general curvature seems less pronounced and their diaphragm a single self-supporting stretched film. Could anyone supply more informationand details?
Stephen Huey (November 2001): Pickering made 2 ESL tweeters, the Isophasic. More or less the same except size. Visual is a curved 3 feet wide by 2 feet tall array, with external X-over and HV supply. These were designed to be used with a 16 ohm woofer, I believe from 1,000 on down. I will find schematic and send pic later.
Mike Mason (December 2002): Dr. Norman C. Pickering, who founded the Pickering Corporation -- no connection to Philco, I'm quite sure -- was one of the group of engineers who founded the Audio Engineering Society (U.S.) in 1948. As I think I mentioned, he's an outstanding, innovative engineer, who now (I've learned from web searches).also works on design, theory, improvement of acoustic musical instruments (mainly violin family, I think).
The plate that talks Popular Electronics, September 1956. One of the first articles where the Pickering Isophase is described (PDF, due to size available on request).).