Janszen Speakers - help

A friend of mine inherited some Janszen Electrostatic speakers. I want to help him set them up. He doesn't have any stereo equipment, so I am wondering what sort of amp would be needed to drive them. I can't find any information about these speakers. Some pictures are here and here.

They are big, about 15 inches square and 50 inches tall. The top black part just lifts off of the bottom, and is connected by a plug and socket, and some dowels that align the socket. The close up is of the bottom of the speaker.
I should add that it looks like there is a 12-volt input on the bottom of each speaker, as well as some sort of knob that is very hard to turn. Thanks for your help!
There needs to be some sort of power for the electrostatic tweeters. Usually, Janszen built that into them and one only needed to connect them to an AC outlet. These seem to need an external transformer or PS. Do you have them? Can you post a picture of the bottom?

There is one external transformer, like wall-wort style. Also the second link up in the original post is a picture of the bottom. Thanks Kal!
Ah. Well, you will have to get another wall-wort, of course. The control is probably the level control for the tweeter.

In principle, all you have to do is plug in the PS, connect the terminals up to an amp, and listen. I urge caution since these are old and may be faulty. (I have had on and off problems with old Janszen tweeters.) So, first plug the wall-wort into the AC by itself and see what is on the output and if it is stable. If so, connect it to the speakers and listen for noises. Good els elements will be quiet but may make very, very soft crinkly noises as they power up. After that, use your voltmeter to insure there is no DC or AC on the main speaker terminals before you connect it to a good amp.

Good luck.

I owned a pair of these back in the early 80's. They were nice speakers, though it was easy to bottom out the woofer on loud bass material.

Kr4 is correct. The control adjusts the balance between the electrostat tops and the cone bottoms. As I recall the crossover between the cone and electrostat elements was around 800 hz, and the nominal impedance of the speaker was 6 ohms. Nominal power handling was 100 watts, though I used more powerful amps than that without ill effects.

Each speaker had a 12v (DC I believe) wall wart power supply. I don't recall the polarity of the plug. I left them powered at all times. They draw almost nothing from the ac line.

The woofer boxes contain the audio step up transformers for the electrostat tops. The speakers provide a fairly reactive load, but I successfully drove them with a Sony integrated in 1983. They are not very efficient.

I think most amps with high end pretensions (e.g. Adcom, Hafler, Aragon, as well as more expensive brands) in the 70-150 watt range capable of driving a 4 ohm load should work. A lot of mid-fi receivers could fit this bill as well.

Let us know if you get them working, and enjoy!