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Old 23rd June 2012, 12:30 PM   #11
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Join Date: Feb 2008
Location: Jackson,michigan
Make sure that there are no sharp edges or burrs were you had drilled out the rivets.

Maybe deburr the holes edges with a fine grit round tipped grinding stone, But do this by hand.

It looks like those panels are anodized but the bare metal from where the rivets were drill may be your culprit.
Some Clear acrylic spray may be a good choice to reseal those areas and is the best cheapest material that I have found to use so far.

I don't have any experience with the 57's are any commercial model for that matter, But I have spent lots of time researching on the best and cheapest methods to contain high voltages on my DIY ESL's.

I use aluminium window screen for my material of choice and I have had my issues with it.
All have been documented here and there in other threads.

I would also suggest that you use a thin coat of red oxide primer first as well thin a few coats of some clear on those bare spots.
Use the red oxide type as this has lots of Talc in it and is a great electrical insulator.
Do Not use the gray stuff as it has Titanium Dioxide and this stuff conducts especially at high voltages!

I have found the the clear will flow and a uneven thicknesses will develop if you don't use a primer.
This may or may not be relevant in your situation.

This can be done using a small paint brush as not to mess up the rest of the panel by capturing some paint from the can into a small cup.

Here are the links to some photos I have done using the spray acyrlic paint coatings,

High strength Dielectric Coatings, fact or fiction

High strength Dielectric Coatings, fact or fiction

High strength Dielectric Coatings, fact or fiction

As you can see I had my work cut out for me and sharp edges were the final demise of my little panels,

ESL woofer- anybody game?

I have gotten results has high as 2200Volts per mil using these materials.

Before you go and reassemble everything, it would be a good idea to check the panel by energizing it with the bias supply and scan it very closely with a ground probe of some sorts, I usually just use a grounded screwdriver or even just a piece of wire.

As long as it is insulated and it is on the grounded side of the power supply there is little chance of getting zapped.

In the picture of that large arc I was holding the wire with my bare fingers.

FWIW

jer

Last edited by geraldfryjr; 23rd June 2012 at 12:39 PM.
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Old 24th June 2012, 02:09 AM   #12
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Join Date: Oct 2010
Ok I have made some progress, but still have leakage on the bottm of the panel. I even removed the screws in this area but it did not help. As I said this panel has always has an issue and it was replaced in the 80s by Quad so I am wondering if this was the panel's real problem all along. Whatever it is I need to get to the bottom of it. Anyway thanks for the tip looking for bit of metal in the holes from the drilling as i found 3 or 4 in area i marked as having issues and no longer have so I really think I am making progress. However I dont know why I am still getting leaking along the bottom edge, any thoughts?
I have cut back slightly the foil strip were it is too near the holes but it has not really helped much. I am going to have another go at cleaning out the holes, but IMO they are fine. The only other thing I can think of is there is a current leakage between the two diaphram charging points and the stator (the ones that go to the two central rails). I would imagine that they should be well insulated from the panel?
Regards
Chris
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Old 24th June 2012, 02:29 AM   #13
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Join Date: Oct 2010
Also I am wondering can diaphram coatings go off? I got mine some years ago from ER audio ( blue fluid) and I am wondering if the lack of zest and sparkle could be due to it being old. When I opened the panel again I gave another light coat of fluid as diracted but this should now be a bit too much and things have improved. Maybe I am barking up the wrong tree.
Regards
Chris
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Old 24th June 2012, 03:29 AM   #14
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Join Date: Feb 2008
Location: Jackson,michigan
As I had mentioned I would test the integrity of the stator by sweeping it with a ground probe.
There could be a small scratch or pin hole in the coating.

They can be so small that the can be very difficult to see even with a Magnifying Glass.

I had one spot on the little panel of mine, after I had fixed many, that I just couldn't seem to get sealed properly.
For the most part it worked great until one time I decided to push it harder and then that one spot gave out and it burned up before I could back it back down.

If you do find some bad spots doing the tests then I would think that a few coats of clear acyrlic should take care of the problem.
Now I know what it means to try and keep them in their original coniditon but they aren't working properly in their current condition.

If the leakage is along the edges then may be a layer or two of some polyester tape might solve the problem as well.
Or even if it just a spot in the middle some where.

Many others use this method for sealing the edges as well and works good as long as there are no sharp edges anywhere.

When I first made my panels I used clear Silicone sealer to seal the sharp edges of the wires this worked excellent.

Then when I pulled it all out and tried to reseal it with some acrylic then it became a nightmare and was very hard to deal with until I finally got an adequate thickness built up.

In their original state they were just fine, But I was trying to push the voltages much higher and the acrylic paint was not sealing properly to the silicone sealant where the met and was arcing around it through any weak spot it could find to the stator.

Had I had an adequate stator coating thickness when I first made them this would not have been an issue.
But this is something that I did not know when I made them 9 years ago.

In the pictures of the burned panel one of its problems started as it had gotten damaged and the screen was torn and I did my best to patch that spot but it was still the weakest point that made it fail.

The other main problem that I had that actually started the chain of events was like you had suggested, was that, I had the charge ring a little to close to one of the through bolts and it would arc and leak around to the other side.
This was the start of my issues as I was trying to push the voltages higher, and was before any micro cracks in the coating started to occur.

I take it that those panels are made of aluminium, some times the material can start to corrode a little underneath the coating and question the integrity of the coating as well causing pits and/or micro cracks when it gets flexed after so many years.
At least that has been my experience, as mine are made by powder coating aluminum wire mesh.
As I said they were 9 years old before they had developed any problems at all.

This is just an explanation of what happened in my case and I was pushing voltages in excess of 8Kv to 10Kv and more.
But the leakages weren't from the very high bias voltages but in fact was caused from a very high music peaks the that punctured the weak section of the stator coating.

Although I knew the sounds that you were describing because I would get those same sounds as I turned up the bias voltage until I got a good coating thickness on the stators to contain the voltage.

I don't expect you to have the same kind of issues that I had gone through as from what I do know about the 57's by reading about them.
But I don't think the voltages are nearly as high as what I was trying to do.

So, with that in mind I can understand wanting to keep them in there original condition but I think that a couple of good coats of clear acyrlic to the inside of the stators could quite possibly fix the problem very easily.

But first do the test that I had described as it may be just spot or two that you will have to contend with.

Good luck !!

jer
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Old 24th June 2012, 03:38 AM   #15
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Join Date: Feb 2008
Location: Jackson,michigan
I don't have any experience with ER's coating so I wouldn't be the one to be able to answer that.
But I can say that it may be possible that a second coat may help.

I use Licron as my choice of coating and in the past I sometimes have had to add a second coat with both formula versions (but not so much with the Crystal formula) in order to get a good surface coating.

This because as you know nothing sticks to mylar very well and sometimes it is hard to get it wetted properly and the coating will bubble and bunch up into little droplets before it has a chance to dry or cure.

jer
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Old 24th June 2012, 04:56 AM   #16
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Join Date: Oct 2010
The Quad stators are plastic with a metal / conductive coating on the outside covered with grey paint. On the inside it is just bare plastic with a foil perimeter and two maybe carbon tracks that un up the center. These carbon tracks are connected to rivets that must be insulated somehow from the rest of the panel or you would have a dead short. The stator is connected via similar rivets but the paint is missing in this area to allow connection. My areas of fizzing are these connections that charge the diaphram and this bottom edge although I have vastily improved things. If these connections to the diaphram are fizzing there has to be a short in this area so I even tried with a dremel too to make them an island incase the rivet is shorting but this has not helped. I thought of painting but the leak seems to be coming from a couple of bolt holes. Maybe I could try painting in the holes themselves.
Is there and problem with recoating diaphrams?
Wont the resistance get lower and will this cause issues?
Sorry for the daft questions but I am learning as I go with these speakers.
Right now the panel has bass but lacks the mid elements unlike the other panels, any thoughts if this is coating or not?
Regards
Chris
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Old 24th June 2012, 11:23 AM   #17
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Join Date: Feb 2008
Location: Jackson,michigan
Yes I would try painting the holes as even a 2kv to 3kv potenial can conducted a small gap of just a few millimeters I don't remember off hand what the Bias voltage is on the 57's is but I believe it is in the 2.5kv to 5kv range.

Even if you don't see any arc's there is most likely little finger's of corona reaching out to the other conductor and is what is causing the fizzing sound.

They are very hard to see at the lower voltages.
But as I was experimenting around at 13.8kv these little fingers could clearly be seen and grew longer as the ground wire came closer to the HV terminal.
Until of course it was close enough to draw a constant arc or even just a snap.

Yes, A second coat may lower the coating resistance a bit, But I doubt that it will lower it by any significant amount using your nylon based material.

Even with the Licron that I use it took a very heavy coat with a thickness in the order of almost 1mil total thickness using .25mil mylar to get into the 100k ohm range in order for my Multimeter to measure it.
This was about 3 or 4 coats and is much thicker than the coating you are using.

I have even messed around the the PVA glue coatings as well and their resistances never got low enough for my meter to measure no matter how thick it was.

It has been shown that if the diaphragm coating resistance happens to be on the low side (very low) then the THD at the lower frequency's can increase some due to charge migration but won't cause the panel to not operate.

There has been another recent discussion of this, where ones panels were made with aluminized mylar and he replaced the mylar and used a high resistance coating and found it to have a significant drop in the THD's at frequency's from about 250Hz and lower.

If you are testing it with the original connections of where they go the loss the highs maybe due to the built in crossover of the system.
This what the resistors are for as they form a low pass filter with the capacitance of the panel itself.
Try connecting the panel to the Mid panel's connections and see if your highs comeback as they should.

Since you are getting sound out of them the coating appears to be working however it has been shown that it is possible to have a lower output as well if the coating has to high of a resistance,But this would have to be a very very very high resistance though.
It has been known that coating of this type can take as long as a few days to reach their full charge and hence a full output level.

The only time that I have ever noticed a drop of highs due to the coating is when I had it one of them exteremly thick and it was because of the extra mass that is added to the diaphragm.

I was not able to measure this at the time but it was only noticeable with my two identical panels in a A and B test of the two Licron formula's Regular and Crystal as the regular was quite thick and the Crystal formula I could not measure its thickness with a micrometer even after three coats.

Because of the extra mass it was the high end details that suffered more so that any actual loss in the level.

I too have switched to a carbon base charge strips and was what got to close to that bolt when my panels started messing up because this was a feature that I didn't account for when I first made them and was added later.

Should you feel the need to fix them or need to be touched up or has peel off, my formula is very simple.
I use about 6 to 8 parts water to 1 part PVA glue (white glue) and heavily dope it with some powdered graphite.
Then add a few drops of liquid dish soap ( I use Dawn over here in the states) as a wetting agent this keeps it from beading up.
Then just tape off your area if you need to and paint it on the surface.
It will dry to a thin conductive surface that has a high resistance and can be measured with an ohm meter if its range is high enough.

This whole thread has a wealth of info and deserves a good as it is quite long, But here are a few excerpts of the things that I have just described,

ESL Diaphragm coating

ESL Diaphragm coating

ESL Diaphragm coating

ESL Diaphragm coating

ESL Diaphragm coating

Here is a couple of excerpts from a past and more recent discussion of coating resistance and THD,

Asymmetric construction induced distortion in electrostatic speakers

Asymmetric construction induced distortion in electrostatic speakers

Don't sweat any about your questions, If you have any Please Do Ask!!
I as well as many others are very glad to help with what ever we can.
Asking is very essential to learning about these things even as simple as they are, Their operations are quite complicated until you learn as to what exactly is going on with them.

Remember like an ole' boy told me once "it is easy when you know son ,it's easy when you know how!! " He,he,he

jer

Last edited by geraldfryjr; 24th June 2012 at 11:37 AM.
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Old 24th June 2012, 11:26 PM   #18
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Join Date: Oct 2010
Thanks so much!! I will have a good read I will for sure learn a lot. I have just been sitting back with a cuppa looking for inspiration and I have noticed a difference between this newer panel and the rest apart its paint being in better condition. The area in the bottom center of the panel were there is no paint were the power to the stator is applied (a wire is soldered to a rivet) is MUCH lower down the panel that on any other panel. This exposed conductive area is maybe an inches higher on all my other panels so I wonder if this is were the panel is leaking as the stator charge strip is very close to this point. I have just applied paint to this area and into the holes in the stator here so when the paint dries I will see if it helped.
Another question. How much does diaphram thickness make a difference?
Regards
Chris

Last edited by cafe latte; 24th June 2012 at 11:40 PM.
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Old 25th June 2012, 04:50 AM   #19
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Join Date: Feb 2008
Location: Jackson,michigan
I have used every thing from .25mil mylar to model airplane covering like MonoKote to the thinnest Ultrakote material that I could find.

I also have some .06mil polyester stuff that is only 3" wide.
I have only used that stuff once on a micro ESL driver intended for some headphones.
I made that one out of some old gift credit cards from Xmas.
And it worked great as well but I never pursued it any further from the one driver as it is on my things to finish list.

As far as the its sound quality it was very good and was crystal clear with lots of bass without the sound even the slightest bit boomy.
At first I thought that it lacked some highs and thought that it may have been caused from the holes being too tiny.
But as it turned out that the YouTube recording of Jimi at Woodstock the long version was to blame and had no decent highs but everything else I listen to sounded great.

Budget ESL

I have yet to try the .06mil stuff in a regular ESL design as it is just a bit too narrow for the 3.25" wide frames that I already have.

They are all a PET films each with its own variables of characteristics.
They all worked just fine.

I first started out using the model coverings because it was so easy to use and I had plenty of it and still do.
It is hard to beat the iron on glue for ease of construction.

However even after washing off the unneeded glue backing, It is still quite thick and can be anywhere between .75mil to as much as 1.25mil and even 1.5mils thick depending on the grade that you use after heat treating it.

But this was a total thickness using the original formula licron as a coating, as it is quite thick (as much as .3mil to .6mil per coat).

I described the differences in the threads that I have posted and in the next link as well.

I only used it until I got my technique down pat as not to waste what little bit of .25 mylar that I do have as it is hard to find here in the states, And for as cheap as I got it when I did in 1991.

So I haven't done much research as to how much difference it makes in SQ other than what I have stated.
Many others seem to have the same views as I, As it seems that the thinner the material the more finesse and seems to have and more detail in the higher end than does a thicker material.

I have read in the past of many redoing there 57's with some .5 mil mylar and ended up changing the whole thing or at least the mid panel back to .25 mil mylar.
Some has said that they notice no difference at all.

The difference is so slight you really have to be very critical and know what you are looking for in order to hear the difference.

Except in the case of one of my examples were the diaphram was so soiled with dirt and sand and such that it did make a big difference and that just washing the diaphram off brought back its resiliency.
Many have stated this on there ML's and Acuostat planels as well.

Exactly like the difference in the sound quality of an old dull and tarnished cymbal and a nicely polished one.
I have heard and seen this difference and I was just amazed when it was demonstrated to me.

I believe Acuostat used .5 mil mylar and they are considered to be one of the caddilac's of ESL's.

The biggest factor that I have found is that when I built my first wider panels ( 8.5'' wide like the Acuostat's) it was harder to get enough tension with the .25mil mylar to be mechanically stable and not suck in to the stator on a low frequency peak.

Had I used a thicker material such as .5 mil or so I am sure that this would not have been an issue.
Although I did get them to finally work well.
I never had this problem with my 3.25" wide panels.
I use the heat treatment method of tensioning.

Also some PET Films are not tempered and the will keep stretching a bit until it gets to a certain point and then it doesn't stretch any more.
We try to use the tempered version and is what is more commonly available anyhow, But some of the model coverings are not.
I really haven't had much of any issues about this.

Acoustat panel angles? 8" vs 9" panels?

here are a few more links to some great discussions,

A possible new method for ESL construction

This one is the beginning of another great thread,

How to construct a cube louver (Acoustat)



jer

Last edited by geraldfryjr; 25th June 2012 at 05:18 AM.
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Old 25th June 2012, 06:17 AM   #20
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Join Date: Feb 2008
Location: Jackson,michigan
Quote:
Originally Posted by geraldfryjr View Post
I have used every thing from .25mil mylar to model airplane covering like MonoKote to the thinnest Ultrakote material that I could find.

I also have some .06mil polyester stuff that is only 3" wide.
I have only used that stuff once on a micro ESL driver intended for some headphones.
I made that one out of some old gift credit cards from Xmas.
And it worked great as well but I never pursued it any further from the one driver as it is on my things to finish list.

As far as the its sound quality it was very good and was crystal clear with lots of bass without the sound even the slightest bit boomy.
At first I thought that it lacked some highs and thought that it may have been caused from the holes being too tiny.
But as it turned out that the YouTube recording of Jimi at Woodstock the long version was to blame and had no decent highs but everything else I listen to sounded great.

Budget ESL

I have yet to try the .06mil stuff in a regular ESL design as it is just a bit too narrow for the 3.25" wide frames that I already have.

They are all a PET films each with its own variables of characteristics.
They all worked just fine.

I first started out using the model coverings because it was so easy to use and I had plenty of it and still do.
It is hard to beat the iron on glue for ease of construction.

However even after washing off the unneeded glue backing, It is still quite thick and can be anywhere between .75mil to as much as 1.25mil and even 1.5mils thick depending on the grade that you use after heat treating it.

But this was a total thickness using the original formula licron as a coating, as it is quite thick (as much as .3mil to .6mil per coat).

I described the differences in the threads that I have posted and in the next link as well.

I only used it until I got my technique down pat as not to waste what little bit of .25 mylar that I do have as it is hard to find here in the states, And for as cheap as I got it when I did in 1991.

So I haven't done much research as to how much difference it makes in SQ other than what I have stated.
Many others seem to have the same views as I, As it seems that the thinner the material the more finesse and seems to have and more detail in the higher end than does a thicker material.

I have read in the past of many redoing there 57's with some .5 mil mylar and ended up changing the whole thing or at least the mid panel back to .25 mil mylar.
Some has said that they notice no difference at all.

The difference is so slight you really have to be very critical and know what you are looking for in order to hear the difference.

Except in the case of one of my examples were the diaphram was so soiled with dirt and sand and such that it did make a big difference and that just washing the diaphram off brought back its resiliency.
Many have stated this on there ML's and Acuostat planels as well.

Exactly like the difference in the sound quality of an old dull and tarnished cymbal and a nicely polished one.
I have heard and seen this difference and I was just amazed when it was demonstrated to me.

I believe Acuostat used .5 mil mylar and they are considered to be one of the caddilac's of ESL's.

The biggest factor that I have found is that when I built my first wider panels ( 8.5'' wide like the Acuostat's) it was harder to get enough tension with the .25mil mylar to be mechanically stable and not suck in to the stator on a low frequency peak.

Had I used a thicker material such as .5 mil or so I am sure that this would not have been an issue.
Although I did get them to finally work well.
I never had this problem with my 3.25" wide panels.
I use the heat treatment method of tensioning.

Also some PET Films are not tempered and the will keep stretching a bit until it gets to a certain point and then it doesn't stretch any more.
We try to use the tempered version and is what is more commonly available anyhow, But some of the model coverings are not.
I really haven't had much of any issues about this.

Acoustat panel angles? 8" vs 9" panels?

here are a few more links to some great discussions,

A possible new method for ESL construction

This one is the beginning of another great thread,

How to construct a cube louver (Acoustat)



jer


P.S. I just found the link to better pictures of that tiny driver using the .06mil Polyester film.

Material for ESL

Jer
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