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Old 4th November 2002, 04:10 AM   #1
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Default Yet another DIY Electrostatic Loudspeaker Design

As many of you know, I've been repairing Quad ESL's and other electrostatic speakers for nearly a decade now. I've always been wanting to build a set of ESL's from scratch that embody everything I want in a speaker system.

I've built a number of prototype panels and such, and I've finally gotten enough critical mass together to finally put together a system that is really working well.

If anybody is interested in it, I've got all the plans and construction details listed here:

http://quadesl.com/diy_esl1.shtml


Sheldon
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Old 4th November 2002, 04:50 AM   #2
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Default Re: Yet another DIY Electrostatic Loudspeaker Design

Sheldon,

Those look cool...

And welcome to the forum. It is very nice when we see members of your talents joing up.

dave
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Old 4th November 2002, 05:36 AM   #3
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Thanks

I'm glad to be a part of it.

Someday I won't be a Neophyte...

Sheldon
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Old 4th November 2002, 08:35 AM   #4
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Good work Sheldon.

I like when people show what they are doing with many good pictures.

Very nice wood work. How do they sound? I'm very curious. I own a Martin Logan SL3 which I'm quite pleased with.

Sheldon, have you checked the finnish guy?
http://www.ele.tut.fi/~artoko/audio/...rs/hybrid.html
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Old 4th November 2002, 01:04 PM   #5
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Very nice! I like the slides
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Old 4th November 2002, 02:56 PM   #6
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Default Re: Yet another DIY Electrostatic Loudspeaker Design

Quote:
Originally posted by stokessd


If anybody is interested in it, I've got all the plans and construction details listed here:

http://quadesl.com/diy_esl1.shtml


Sheldon
Very nice!

Are you using some specially formulated tape? All the polyurethane foam tape I have ever seen lasts about 6 months to one year, then turns to dust. It is even worse than the foam surrounds on some bass drivers, and exposure to ozone created by the high voltage in the speaker will only accelerate the deterioration. Also, when you stick a tensioned diaphragm to it the adhesive tends to get pulled into the speaker by the diaphragm, firmly sticking every piece of dust and dead bug that gets in there to the diaphragm right at the point where the stators, insulators, and diaphragms are closest together. I would expect a problem with arcing after only a few months of operation. Unfortunately, a vacuum cleaner won't help you clean it out because the dirt gets stuck to the adhesive.

As the adhesive gets pulled into the speaker, the tension on the diaphragm decreases. This may require that you drop the bias voltage (and so the speaker sensitivity) after a few weeks to keep the driver from oscillating.

I have found that contact cement bonds to the diaphragm and almost anything else you want to use for insulators. When the time comes to rebuild those drivers, you might want to give it a try. It is completely stable once it sets, which is a matter of minutes.

MR
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Old 5th November 2002, 03:09 AM   #7
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Peranders-

I'm very pleased with the sound. One of the problems I've had with the other hybrid ESL systems is integration and efficiency. As you are probably aware, you get a first order rolloff on the panel due to pressure feedback as the reproduced wavelength (1/4 of it actually) gets longer than the shortest panel dimension. With a passive crossover you really only have a couple options to deal with that. first, you could knock down the high frequencies so that they match the lowest used portion of the panel. But this leads to a fairly inefficient speakers. Second, you can roll off your woofer fairly shallowly and fill in that roll-off region with the woofer. but this leads to some odd blending and integration problems. I've gotten around that by using an active crossover, where I can actively compensate for that roll-off and make the panel flat from about 40 Hz on up. This means that there aren't any crossover elements turning my hard earned amplifier watts into heat. And I can drive my panels to very loud levels with my Heathkit W5M 20 watt amplifiers. It also means that I can cross the panels off low and sharply to minimize driver interaction. the active crossover also allows me to time align the woofer to the panel. This really isn't a huge deal with the wavelengths the woofer produces, but if I ever wanted to cross over higher, it may be an issue.

So you could say that I think they sound quite good.


MR-

The foam tape I'm using is a eurathane foam with an acrylic adhesive from 3M. So far it's been quite good at withstanding the shear forces and has held up nicely over time too. these panels are about 6 months old now, with essentially no change in resonant frequency. I haven't seen any adhesive creep, the edge of the foam tape is still square and the adhesive edge hasn't separated from the diaphragm.

When these panels go south, I'll be making some lexan spacers and using either epoxy or contact cement. I wanted to try the foam tape method. there are several ESL makers who are doing that (martin logan and innersound to name two). It's so easy, you can knock out a pair of panels in like 25 minutes.

Thanks for the info, I'll be waiting for the foam to turn to dust.

Sheldon
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Old 5th November 2002, 09:18 PM   #8
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Stokessd,

I just wanted to say that your speakers look great. If they sound half as good as they look you've got quite a pair of listening devices on your hands.



-Dan
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Old 6th November 2002, 06:48 PM   #9
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They do look excellent. Have you read the ESL Cookbook by Roger Sanders? If not he greatly promotes Transmission lines used with ESLs crossed over at about 400Hz. He is also the designer behind the innersound gear.
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Old 7th November 2002, 06:16 AM   #10
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Yes I've read the ESL cookbook. It's a very useful book for learning the ropes with ESL's. I do think that he is WAY too obsessed with extreme volume. I also think he's trying to kill the family pets with a sharing of the high voltage between speakers.

I am in violent agreement with Roger that TL enclosures are the way to go. But I think the 400-500 Hz is too high. Yes it's needed for absolute max SPL, but there is also a lot of musical information in that range, and frankly an ESL panel is more suited for any valuable musical information. So I am sacrificing SPL to get as little musical information on the woofer side of things. I also want the crossover point to be at a wavelength that is longer than the longest separation between the panel and the bass driver.

Sheldon
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