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Old 4th April 2010, 08:23 PM   #1
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Default Help needed with ESL

Mavric and I just assembled his stat panels in my garage and there is a problem-- they play but the output is very low. We plugged Mavrics panels into my speakers' electronics and used my amps for the test, so we know the problem isn't with the electronics.

The panels went together perfectly: The diaghragms are beautifully stretched to 1 1/2% elongation, D/S spacing is 1/16", diaphragm supports are almost exactly @ 70x d/s spacing and the stators are 51% open perf with .141 diameter holes. Accordingly, they should be efficient and play loud.

Coating thickness on the stators is about 10 mils overall except along the periphery edges which are thicker because double coats were applied to the edges to prevent arcing (up to 20 mils on periphery edges). The coating material Mavric used on the stators is a two-part gray primer that's used under Rhino lining, which I believe is a polyurethane but I'm not sure.

What we could not do (because we don't have a Megger) was check the resistance of the diaphragm coating before we assembled the panels. When I built my ESL's two years ago I had purchased two bottles of a proprietary coating solution from Just Real Music, which has worked wonderfully on my speakers. I had one unopened bottle left and we used it on Mavric's diaphragms.

The diaphragms are very taught and it doesn't appear they are being pulled into the stators and bleeding off the bias charge.

I don't see any trash between the stators and diaphragms that could cause a short or bleed off the bias charge. The bias charge is applied via a periphery copper foil charge ring that runs down the centerline of the 1" foam tape on the panel periphery. Also, the outermost 1/4" of diaphrams' peripheries were masked off before we applied the diaphragm coating.

The panels play with no arcing or other indication of a problem but the output is very low. I can only think of these remaining possibilities:

1) Diaphragm not conducting sufficiently. The coating solution used is at least two years old -- don't know if it has a limited shelf life.

2) Bias charge is somehow bleeding off.

3) The stators are over-insulated. Rhrino lining primer is unknown quantity. Perhaps it is too thick... how much coating thickness is too much?

QUESTION:

Is there anyone here with a Meggar that can check the diaphragm resistance?
Mavric can mail out a sample piece of coated diaphragm material to anyone can help with this.
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Old 4th April 2010, 08:57 PM   #2
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Here are some photos I took after assembly. Mavric will be posting some made before assembly when he gets home this evening.
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File Type: jpg 010.jpg (486.2 KB, 158 views)
File Type: jpg 011.JPG (648.4 KB, 152 views)
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Old 4th April 2010, 10:13 PM   #3
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3. Over insulated stators is unlikely (you'd need one **** of an insulator)
2. You can check this with a blinker light combo (neon || capacitor + series resistor)
1. the most likely candidate, bad coating. I can check the resistance but I'm sure you can find someone else closer by. If not send me a pm.
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Old 4th April 2010, 10:25 PM   #4
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Quote:
Originally Posted by CharlieM View Post
QUESTION:

Is there anyone here with a Meggar that can check the diaphragm resistance?
Mavric can mail out a sample piece of coated diaphragm material to anyone can help with this.
The following post has some suggestions for using a charging indicator to determine if the panels are charging up properly, have a short, have a poor coating, or bad connection to the coating.

ESL technical questions


Also, this post describes how to use the charging indicator to test if the coating is conductive.
ESL technical questions


Good luck, and let us know what you find out.

Last edited by bolserst; 4th April 2010 at 10:28 PM.
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Old 4th April 2010, 10:43 PM   #5
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I would bet on #1 -- some of the special coatings do have limited shelf life in the bottle, but once applied & dried last "forever". The one I got from MJ Dijkstra did, anyway (but for me it worked fantastic because I applied it right away)

Best of luck,
Kenneth
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Old 5th April 2010, 01:07 AM   #6
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Yeppers, it was the diaphragm coating...

That unopened bottle of coating solution I purchased in March 2008 went bad sitting on the shelf. I know this because I just took one of the panels apart and recoated the diaphragm with a liquid hand-soap containing sodium laurel sulfate and now it sounds wonderful and rocks the house.
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Old 5th April 2010, 02:11 AM   #7
mavric is offline mavric  United States
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some more pics
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File Type: jpg P4040313.jpg (332.6 KB, 109 views)
File Type: jpg P4040314.jpg (524.7 KB, 106 views)
File Type: jpg P4040315.jpg (430.9 KB, 34 views)
File Type: jpg P4040316.jpg (418.9 KB, 31 views)
File Type: jpg P4040317.jpg (346.5 KB, 32 views)
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Old 5th April 2010, 02:25 AM   #8
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Hi Mavric,

It's great to know that the ESLs are performing well now. I think it would be better if you could post these pictures in your own thread. It would be very much easier for us all to follow up on your progress that way.

Wachara C.

Last edited by chinsettawong; 5th April 2010 at 02:27 AM.
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Old 5th April 2010, 02:26 AM   #9
mavric is offline mavric  United States
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some more pics of of pics
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File Type: jpg P4040319.jpg (396.5 KB, 33 views)
File Type: jpg P4040320.jpg (446.9 KB, 34 views)
File Type: jpg P4040321.jpg (337.7 KB, 30 views)
File Type: jpg P4040322.jpg (507.4 KB, 30 views)
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Old 5th April 2010, 02:28 AM   #10
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Hi CharlieM,

The coating using liquid soap might not last very long - that's what I've heard anyway.

Wachara C.
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