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.
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.
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.
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.
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.
http://www.diyaudio.com/forums/planars-exotics/153773-esl-technical-questions.html#post1958015
Also, this post describes how to use the charging indicator to test if the coating is conductive.
http://www.diyaudio.com/forums/planars-exotics/153773-esl-technical-questions.html#post1962273
Good luck, and let us know what you find out.
Last edited:
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
Best of luck,
Kenneth
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.
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.
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.
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:
Hi CharlieM,
The coating using liquid soap might not last very long - that's what I've heard anyway.
Wachara C.
The coating using liquid soap might not last very long - that's what I've heard anyway.
Wachara C.
Hi CharlieM,
I'm very interested in your diaphragm stretcher. Can you show us how you build it and how you use it?
Wachara C.
I'm very interested in your diaphragm stretcher. Can you show us how you build it and how you use it?
Wachara C.
Wachara C.
this will permanent if all is well. I am not sure if Charlie used a combination of the original coating and soap as well. I guess time will tell. iam very thaknful for everyones input, i wish there was something to make sure these will last for years, this is not something i wish to rebuild as the coating is the issue.
His (Charlie) was apllied two years ago and works fine, would dillition be a factor of the coating?
should the they stay apart untill i can obtain the correct coating? Ger suggest Licron, tech spray high gloss, can anyone please give us some assistance or suggestion as they are DONE, but need to be disassebled and re coated without diagphram damage. i am all ears and ave two weeks to get thi right. thanks for any information on this. Mavric
this will permanent if all is well. I am not sure if Charlie used a combination of the original coating and soap as well. I guess time will tell. iam very thaknful for everyones input, i wish there was something to make sure these will last for years, this is not something i wish to rebuild as the coating is the issue.
His (Charlie) was apllied two years ago and works fine, would dillition be a factor of the coating?
should the they stay apart untill i can obtain the correct coating? Ger suggest Licron, tech spray high gloss, can anyone please give us some assistance or suggestion as they are DONE, but need to be disassebled and re coated without diagphram damage. i am all ears and ave two weeks to get thi right. thanks for any information on this. Mavric
Hi Mavric,
Just use the ESLs as they are now. Time will tell how long they will last. If they fail in the future, they can be redone easily anyway.
Wachara C.
Just use the ESLs as they are now. Time will tell how long they will last. If they fail in the future, they can be redone easily anyway.
Wachara C.
Yes, when I get home from work today, I will take some photos and post the tensioning procedure.
Charlie, just got in a checked voice mail, call or i will call you as soon as can my wifes phone, sorry, i hate cell phones, she does though. So licron?
I knew this would be a learning experience, and there is no way things can work perfect in an unperfect world, dissapointed, but with custom comes anomolies, and i have learned something new, something i can apply later on in other projects of this nature.
thank you everyone for quick response time and over all helpfullness, many thanks.
I knew this would be a learning experience, and there is no way things can work perfect in an unperfect world, dissapointed, but with custom comes anomolies, and i have learned something new, something i can apply later on in other projects of this nature.
thank you everyone for quick response time and over all helpfullness, many thanks.
My stretcher jig is made of MDF board sized 1" (25mm) larger than the stator panel on all sides and the height is 2" (50mm). All edges are rounded over to a .25" (6mm) radius. I applied 1" wide polyester tape along the top edges and waxed the tape so that the diaphragm won't snag on the MDF and break. The The bicycle tube is size 27" x 1 1/8" (700 mm x 32mm) and you want a tube with a Schreader valve (not a Presta valve). Note the photo showing the underside of the jig and the MDF board routed out to allow access to the tube valve.
The tube is positioned even with the top surface of the jig. The film is wrapped around and secured on the underside of the jig using double backed foam tape as shown.
Before I stretch the film, I use a felt pen to place two reference marks exactly 6.00" (150 mm) apart. Now comes the never racking part: Slowly inflate the tube to tension the diaphragm (and hope it doesn't snag and break). When the distance between the reference marks reaches 6.090", the film is then properly tensioned to 1.5% elongation. I use a small wooden stick trimmed to 6.090" length placed next to the reference marks to measure the elongation.
Attachments
- Status
- Not open for further replies.