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Old 17th November 2018, 05:12 PM   #1081
misterdog is offline misterdog  United Kingdom
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Quote:
I have seen that Quad used an oven for applying the Elvamide coating on the original ESL. Anyone any idea how they used the oven in the original ESL process?
I think the oven was used as part of the tensioning process, though it may have been to dry/cure the coating.
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Old 17th November 2018, 05:23 PM   #1082
Discopete is offline Discopete  Canada
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Why not use airless paint spray equipment?
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Old 17th November 2018, 05:29 PM   #1083
misterdog is offline misterdog  United Kingdom
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Quote:
Originally Posted by tatas View Post
Hi David


What are you referring to ?
could you provide a link ?
ER Audio sell a conductive coating, though I have not used it, maybe Sheldon has and might comment.

Step Up Transformer

Hope this link works.
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Old Yesterday, 02:47 AM   #1084
stokessd is offline stokessd  United States
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Quote:
Originally Posted by misterdog View Post
I think the oven was used as part of the tensioning process, though it may have been to dry/cure the coating.
I'd heard the tensioning hypotheses a lot, and I'm not convinced. Sure, it will heat shrink the mylar a bit (some mylar types shrink more than others), but I don't think that was the primary reason. Quad LOVED (and I mean loved) thermoset glues, they are all over all the quad speaker designs.

My guess is that the oven is used to melt the glue to bond the diaphram to the stator. But that's just a guess.

Sheldon
quadesl.com
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Old Yesterday, 03:05 AM   #1085
stokessd is offline stokessd  United States
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Quote:
Originally Posted by misterdog View Post
ER Audio sell a conductive coating, though I have not used it, maybe Sheldon has and might comment.

Step Up Transformer

Hope this link works.
Rob at ER has had a couple coatings over the years, and they have all been good. I'm 99% sure that he is only selling the water based one now (so as not to poison his customers and allow easy shipping). If I understand his coating, it's pretty similar to mine, which uses modern conductive materials which are also used in anti-static coating products. There's a whole world of anti-static powders that get mixed into resins to form conductive coatings. The resistivity is varied (typically logarithmically) by varying the concentration of the powder in the resin.

I use a water based polyester resin which bonds really well to mylar. I also use a dispersant and a little bit of wetting agent. There's a bit of chemistry involved to make sure the pH is right and the particulates don't clump etc, but it's really pretty simple (chemistry isn't my bag). It wipes on and self levels and then dries. In my testing it seems to not change conductivity with humidity level. And so far it lasts 20 years (that's the oldest rebuilt panel I've got using it).

Using a shockingly cheap and crappy surface resistance meter from eBay, I measure 10^7 ohms/sq on the original ESL63 diaphragms, and I've tuned my coating to give me the same resistivity when measured with the same meter. I don't trust the absolute values from that meter, so I do relative measures between diaphragms.

I don't sell my coating, and I point people to ER audio for Rob's coating. It will work well for you. Actually I do sell my coating, but you only get a little of it, dried onto rebuilt quad panels.

Hope that helps,
Sheldon
quadesl.com
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Old Yesterday, 02:31 PM   #1086
alexberg is offline alexberg
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Yep, if one looked at water soluble polyester and additives even @ Google, one finds zillion appropriate products often offered as a samples. Who cares though, just
buy ready to use industrial products.
Cheers
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Old Yesterday, 07:58 PM   #1087
misterdog is offline misterdog  United Kingdom
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Quote:
Originally Posted by stokessd View Post
Using a shockingly cheap and crappy surface resistance meter from eBay, I measure 10^7 ohms/sq on the original ESL63 diaphragms, and I've tuned my coating to give me the same resistivity when measured with the same meter. I don't trust the absolute values from that meter, so I do relative measures between diaphragms.


Hope that helps,
Sheldon
quadesl.com

Strangely I ordered one of these last week.

GM3110 Capacitance Ohm Meter Capacitor Circuit Tester Resistance Measuring | eBay

YouTube

As I have a neighbour who is a retired Prof of pyhsics I thought I could have it's accuracy checked against proper test equipment, and also thought that so long as it has repeatable measures it will suffice.

I have bought a pair of 'broken' 63's to play with and a set of panels from someone who had a full Quad rebuild.
I run 989's which I bought after a Quad rebuild only to find that they only replaced the panels which had failed.

So a few months later I had to embark on the 'how to rebuild broken Quad ESL's' merry go round.

So I have the following panels on which to test.

Early 63's which had the 2 part sprayed coating

Later 63's with a one part sprayed coating

Original 989 panels

3 year old 'new' Quad panels

Test results to follow, though as the meter is on a slow boat from China it could be Jan/Feb.

Last edited by misterdog; Yesterday at 08:01 PM.
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Old Yesterday, 10:34 PM   #1088
stokessd is offline stokessd  United States
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Quote:
Originally Posted by misterdog View Post
So a few months later I had to embark on the 'how to rebuild broken Quad ESL's' merry go round.

So I have the following panels on which to test.

Early 63's which had the 2 part sprayed coating

Later 63's with a one part sprayed coating

Original 989 panels

3 year old 'new' Quad panels

Test results to follow, though as the meter is on a slow boat from China it could be Jan/Feb.

I bought a set of 2912's for a song because 5 of the 12 panels had gone bad. These are 4 year old speakers...
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Old Yesterday, 11:08 PM   #1089
misterdog is offline misterdog  United Kingdom
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Therein lies a whole new question, completely off topic.

The 2912's weigh twice that of the 989's and have all 'mil spec' components.
So do they sound better ?

Many quote that the 57's are better than 63's which are better than Chinese production 9 and 12 series.

I must listen to some 12 series.

Shame that Grantham is in New Hampshire and not Lincolnshire UK. though I believe you have heard this before

I listen to my 989's naked with supertweeters and DSP subwoofers monoblocked with chip amps.

0.00012 % THD

Parallel-86: High-power composite amplifier achieving 0.00012 % THD.
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