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Old 18th May 2011, 01:34 PM   #1
Atom66 is offline Atom66  Canada
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Default Building an Electrostatic Speaker

HI
Thought you guys may be interested in this step by step build of a very large curved ESL

Building an Electrostatic Speaker

Andy
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Old 18th May 2011, 01:48 PM   #2
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HI
Thought you guys may be interested in this step by step build of a very large curved ESL

Building an Electrostatic Speaker

Andy


Very cool link!
I will follow this. jer
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Old 18th May 2011, 07:04 PM   #3
beun is offline beun  United States
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I am actually the builder of this stat and the starter of the thread you mentioned. I built my first one more than 25 years ago (it's the large blue one that you can see it some of the pictures) and have recently been showing a smaller one at the Lone Star Audio Fest.

I do builds on spec but don't see a need to keep any secrets, I am willing to share all of my 'secrets' with anyone who wants to hear.
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Old 18th May 2011, 08:09 PM   #4
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I am actually the builder of this stat and the starter of the thread you mentioned. I built my first one more than 25 years ago (it's the large blue one that you can see it some of the pictures) and have recently been showing a smaller one at the Lone Star Audio Fest.

I do builds on spec but don't see a need to keep any secrets, I am willing to share all of my 'secrets' with anyone who wants to hear.
Hi,
I'm continually amazed by the ingenuity and workmanship of the DIY community and your project is exceptional. I can't wait to see the finished speakers-- any details of the build you care to share with us will be greatly appreciated. Have a great day!

Charlie
Savannah, GA
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Old 18th May 2011, 08:27 PM   #5
beun is offline beun  United States
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Charlie,

All details of the built will be laid out in the thread, if you or anyone else would like to hear additional information that is not mentioned of asked in the original thread, I will be more than willing to answer it here.
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Old 19th May 2011, 02:19 PM   #6
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...if you or anyone else would like to hear additional information that is not mentioned of asked in the original thread, I will be more than willing to answer it here.
Hello beun,

Your web page makes mention of using low resistance metalized diaphragms. Do you drive the diaphragms directly from the transformer like Beveridge and Final did? Or do you use a more conventional setup where the stators are driven by the transformers and the diaphragm is connected to the HV supply through a large value resistor.

The reason I ask, is that both Final and Beveridge had problems with the metalized coating being eaten away over time. Have you experienced any such problems?

Last edited by bolserst; 19th May 2011 at 02:21 PM.
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Old 19th May 2011, 04:00 PM   #7
beun is offline beun  United States
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Bolserst,

The setup is conventional, the membrane is connected through a high valued resistor (100Meg) and the stators are driven by the transformer. The oldest speaker was still playing fine after more than 20 years in service. Some small holes did appear in the metalization (not the membrane itself) which is caused by burning off dust and small gnats over time. The total metal area lost was less than 1% which does not effect the sensitivity in any way.
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Old 19th May 2011, 04:20 PM   #8
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Originally Posted by beun View Post
Bolserst,

The setup is conventional, the membrane is connected through a high valued resistor (100Meg) and the stators are driven by the transformer. The oldest speaker was still playing fine after more than 20 years in service. Some small holes did appear in the metalization (not the membrane itself) which is caused by burning off dust and small gnats over time. The total metal area lost was less than 1% which does not effect the sensitivity in any way.
That's good to hear.
I had always assumed it was the high AC current allowed by the capacitors bypassing the HV supply and high valued resistor in the Final and Beveridge designs that led to this problem.
I think 20 years of service proves the effectiveness of the 100Meg resistor for keeping the diaphragm current low, even during overload conditions.
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Old 20th May 2011, 02:33 PM   #9
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Default Aluminum Coating on Diaphragm

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That's good to hear.
I had always assumed it was the high AC current allowed by the capacitors bypassing the HV supply and high valued resistor in the Final and Beveridge designs that led to this problem.
I think 20 years of service proves the effectiveness of the 100Meg resistor for keeping the diaphragm current low, even during overload conditions.
Bolserst,
Audiostatic also had problems with the aluminum coating leaving the diaphragm on their ESLs a few years back. They used about +5kV on the diaphragm through 10.5M resistance.
A colleague of mine has suggested this is caused by ionization (ozone) in the gap and Aluminum having a valence of +2 being pulled to the negatively-charged stator. If so, making the diaphragm negative with respect to the stator should help. Reducing the field strength would also help.
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Old 20th May 2011, 03:08 PM   #10
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Bolserst,
Audiostatic also had problems with the aluminum coating leaving the diaphragm on their ESLs a few years back. They used about +5kV on the diaphragm through 10.5M resistance.
A colleague of mine has suggested this is caused by ionization (ozone) in the gap and Aluminum having a valence of +2 being pulled to the negatively-charged stator. If so, making the diaphragm negative with respect to the stator should help. Reducing the field strength would also help.
Huh. Interesting. I have worked on some Audiostatics that had degraded coatings.
However, all the Audiostatics I have seen used a high resistance coating on the diaphragm, not aluminum.
Do you know what models were involved?
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