Paul,
Sounds like you and I are on the same page. I just got a pioneer DV-47Ai for multichannel hi-rez music. I'm currently lusting after a 950 to bring it all together which is why I've been lurking in these forums lately (that undefeatable bass summing on the 5.1 direct input really has me bummed though). I've never used a center channel either. The 2+2s fire down the long axis of the room and they image so well I've never felt shortchanged. Nonetheless, I'd still like to try a single panel on top of my RPTV. After I got the tube amps that freed up the interface modules from the 2+2s to use with the other panels I got. Have yet to hook any up yet though...I'm still working on some ideas for frames, grill cloths, etc. How do you have the 1+1s oriented for rear channels? Are they on the sides aiming fore and aft to yield a dipole pattern or do you have them more behind you and aiming at the listener? Lots of room for experimentation here! I would like to mount single panels to a pole (like a pole lamp) that would let me rotate or move them around the room easily. Being able to rotate the pole to control the radiation pattern might be useful when switching between movies and music.
I hope you find some transformers but don't rule out HV tube amps if you can swing it...they are worth it!
Happy Listening/Viewing!


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Tekdredger

Tekdredger,

I have the 1+1s aimed towards the listener (for music use) but for movie soundtracks, I would consider experimenting with having them face fore and aft.

I don't feel a pressing need for a center channel speaker but I am keeping the ideal alive in my mind.

I am toying with the idea of making a mosfet output stage power amp for the center channel. At work, I was asked to make a high voltage pulser (for piezo transducer use) with adjustable pulse height, adjustable rise and fall times, etc. I gave them a linear amplifier that accepts input from a pulse generator. They make the desired pulse adjustments to the pulse generator and the amp I made for them gives them a bigger (by a factor of 100) version of the input. The pulse amp output is from 0 to 500v.

I was thinking of perhaps making a version that had output from -250v to +250v and with more current output capability (a few 100s of milliamps or so) and getting interface transformers with a much lower turns ratio than what is the usual (50 to 150) for electrostatic speaker use. If I made a version of the amp that had differential output (so that I had +/- 500v available to the speakers, I may even see how much acoustic volume the Acoustat panel would put out with no interface transformers. Any equalization that would need to be done for the Acoustat panel (performed at the low voltage side of the interfaces) would have to be done at the input to the high voltage amp.

The mind boggles at the possibilities.

Or, in my case, the mind boggles.

Paul

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the 1derful1

[This message has been edited by Paul J. Stiles (edited March 02, 2003).]

Paul,
Your amp idea is close to an idea I was toying with a while back. Since direct drive amps are somewhat rare and expensive, I thought why not use a conventional push-pull tube amp and hook up the output transformer backwards. In other words, transform to a higher impedance load instead of a lower one. I never got out the calculator to see if the turns ratios would work out but my gut tells me it would be in the right neighborhood. Voltage rating on the windings would be an important consideration though. I seem to remember Plitron coming out with some toroidal designs intended for use with electrostatic speakers. I would have to research that one some more but one of their wide-band models might make a good choice to mate with your mosfet design.

Good Luck in your audio pursuits!

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Tekdredger

Soundhound,

Some reasonably priced polystyrene capacitors (non-audio jewelry prices) at Mouser electronics. Only rated for 50 volts though.

http://www.mouser.com/index.cfm?handler=...Number&x=15&y=9

Paul

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the 1derful1

Paul:

Thanks for the link! I've bought from them before, but didn't know they had polystryenes. That's great to know, since I won't use any other type in my filter designs.