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DIY Electrostatic Speakers

Joined
May 15, 2019
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#1
Hi all,
I built my 'beam splitter' speaker eleven years ago, and it's electronics and stat panels have evolved quite a bit in the years since. Originally it had perf-metal stators, then more efficient micro-perf stators, then segmented welding rod stators, and now state of the art segmented wire stators that electrically curve the wave front. The links below explain it all, with build photos, and If anyone is interested; I am happy to share my CAD drawings. Enjoy!

Jazzman's DIY Electrostatic Loudspeaker Page
Video of the new "Audi" speaker at Carverfest 2017

Beam Splitter.jpg
 
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andreasmaaan

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Jun 19, 2018
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#2
Hey, I've come across your design online before. Very impressive, and thanks for sharing :)

I'm curious about the use of highly reflective wood (the housing for the transmission line) apparently just a few centimetres behind the electrostatic panel. I would have thought the effect of this would be to reflect forward the backwave from the panel, which would then recombine with the front wave (with a short delay). Do you consider this a feature or a drawback, and if the latter, how do you try to deal with it in the design?

I also wonder if you've published any measurements of the current design anywhere?
 
Joined
May 15, 2019
Messages
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20
#3
I had the concern that you described before committing to the build. I did some listening tests with and without the beam splitter behind the panel and I couldn't hear anything objectionable; only a change in the room ambience; which also was not objectionable. I suspect the beam splitter adds a bit of impedance, but the bounce back is apparently being deflected to the side rather than back to the diaphragm. I was amazed that it didn't seem to have an adverse affect. And the speaker does sound pretty incredible.

The beam splitter turned out to be an elegant solution to the problem of where to stuff all that box volume, and for years afterward I had thought it was my original idea-- until I saw a drawing of an ESL built 30 years ago by the Shackman company in Germany. The Shackman speaker was smaller with two woofers, one on top and one below a V-section beam splitter, and the ESL panel in front of the splitter was curved!!!! Assuming the back wave's direction of travel is normal to the diaphragm, a curved diaphragm would be much closer to parallel with the beam splitter's surfaces, and I figure that had to result in some bounce back and standing waves between them. Whereas, a flat panel would not be parallel to a V-section beam splitter behind it.

I would love to post some measurements but I don't have the measurement gear or the know how to use it. It's an old dog, new trick thing.... I read up on the Room EQ software but it just made my brain hurt.
 
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