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Old 4th July 2012, 10:08 AM   #101
Legis is offline Legis  Finland
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Yep, the sparks are very evident with alumylar. I gave the weak spots generous coats of 2kV/mil conformal coating yesterday and after that I applied two more layers of urethane-alkyd all over.

The panels are these: Building an Electrostatic Speaker
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Old 16th March 2013, 06:54 PM   #102
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The more I read about coating mesh, the more I feel that Kynar wire staters may be an easier option to give good results. I like the look of mesh staters better than wire ones, but it is the sound quality that matters most.

What type of coating is on the MartinLogan staters? If they are selling them to the general public at the price they are, they surely are happy that their stator coating will be good for years, as they don't want people returning them all the time.
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Old 16th March 2013, 10:31 PM   #103
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Yes, I would like to give it a try as well!!!
A few have used it and say it works well.
I had tested the wire back when I built my first panels and it withstood at least 10Kv to 12Kv or so!!
At least it never broke down with the supply I was using.
I didn't use it because it was at the time when the price of wire just went through the roof and Radio shack was charging (and still do) a ridiculous price for a little roll of it.

In a search I have been able to locate a 1000' spool of it for about $30 to $50 and that is the best deal I could find so far.

The trickiest part about using mesh is properly sealing the sharp cut edges.
They just need to be buried deep in the silicone is all.
I will have to start a new thread sometime on how to use this method.
I would like to take it a step farther and do a electrically segmented version using the mesh method as well.

I am not positive, but, I think ML uses Powder coating on their stators.

Here is an excerpt from this post,

Best speaker to reproduce piano sound?

As a testament to how well the little black mesh ones sounded before I had a woofer system matched up to them,

"Before I built my first panels I had listened to some ML's and my very first panels were not any different as far as midrange and high frequency's are concerned and the sound quality is second to none IMHO.

They sounded so accurate that one time I was listening to a cassette recording of some rain and forest sounds and my dog would go to the door to watch the rain.
But she would not go outside for fear of getting wet when there was NO RAIN (ha,ha,ha).
She is now dubbed the Infamous Sadie in these threads."

Seriously it was not raining but she thought it was.
You see she is a Florida dog and it rained every day their and she used to love to sit and look out the screen door and watch it pour!!!

This was before I had a real amp and transformer's.
I was using a cheapy ole LXI 35 watt amp and a pair of 6V6 p-p output transformers.
They finally shorted out and then I didn't fire them back up until 2010.

My little black ones were double powder coated and that was it.
Until 2010 when I refurbished them and gave them quite a few coats of clear acrylic enamel.
And those are the infamous ones that took all of the extreme voltages.

jer

Last edited by geraldfryjr; 16th March 2013 at 10:37 PM.
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Old 16th March 2013, 11:01 PM   #104
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Kynar wire seems expensive here in the UK, but I can get .5mm^2 or .6mm^2 PVC coated wire pretty cheap. The PVC insulation is 0.3mm, which is about 12mills. PVC is said to withstand 500v per mill, so hopefully this should work well for a first prototype build
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Old 16th March 2013, 11:18 PM   #105
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Yep, That will work good.
My little one got to about 105db at 6Kv peak and 1 meter.
A larger panel will be much louder than this.
Figure about 6db for every doubling of the surface area.

This calculator will help you to get a better idea,

Electrostatic Loudspeaker (ESL) Simulator

jer
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Old 17th March 2013, 10:13 AM   #106
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Nice link
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Old 17th March 2013, 12:43 PM   #107
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Kynar is no good for the same reason as other fluorides/silicones: resistivity is too high - it will build up surface charge pretty quick. Moreover it has high piezoelectric effect so it should play without diaphragm, not too loud though...
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Old 17th March 2013, 04:07 PM   #108
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Quote:
Originally Posted by alexberg View Post
Kynar is no good for the same reason as other fluorides/silicones: resistivity is too high - it will build up surface charge pretty quick. Moreover it has high piezoelectric effect so it should play without diaphragm, not too loud though...
I seem to recall last time looking into Kynar wire insulation and the bulk resistivity was around 1e14 (ohm-cm), which is pretty much in the range of most PVC insulation compounds isn't it? Nothing like Teflon with bulk resistivity in the 1e18 to 1e20 (ohm-cm) range.

Interesting about the piezoelectric effect...
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Old 18th March 2013, 02:02 AM   #109
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Urethanes 10^11, PVC 10^12, PVDF 10^14, PTFE 10^18 carbon filled PVDF has 10^11 100 times IS substantially higher... tubing from fluoroelastomers collects dust like crazy Price of shrink Kynar is outrageous
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Old 18th March 2013, 10:26 PM   #110
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Quote:
Originally Posted by alexberg View Post
Urethanes 10^11, PVC 10^12, PVDF 10^14, PTFE 10^18 carbon filled PVDF has 10^11 100 times IS substantially higher... tubing from fluoroelastomers collects dust like crazy Price of shrink Kynar is outrageous
I am curious where your 10^12 number came from for PVC, did you measure it?
I am still working on a reliable way to measure bulk resisitivities in this range.

Internet searches for bulk resistivity values of PVC wire insulation yields range of 10^12 to 10^15 depend on the exact compound. Does this seem reasonable to you?
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