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Old 22nd April 2010, 12:50 AM   #381
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I had wondered if it could be diluted with a solvent to reduce the conductivity into a suitable range (say high meg ohms). Figured the tech dept would at least know what the appropriate solvent would be. No trouble to spray the contents into a clean glass jar and go from there. I have found that water based epoxy (usually acrylic) bond well to Mylar so perhaps a mix might work. Might be more effort than it is worth, still interesting.
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Old 22nd April 2010, 01:15 AM   #382
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Quote:
Originally Posted by moray james View Post
I had wondered if it could be diluted with a solvent to reduce the conductivity into a suitable range (say high meg ohms). Figured the tech dept would at least know what the appropriate solvent would be. No trouble to spray the contents into a clean glass jar and go from there. I have found that water based epoxy (usually acrylic) bond well to Mylar so perhaps a mix might work. Might be more effort than it is worth, still interesting.
As I recall, the Sprayon is over 90% volatiles so I would think its very thin when dry anyway.
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Old 22nd April 2010, 03:45 AM   #383
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Hi guys,here are some crude frequency response tests I did today.
Since this thread is for coatings ,I will only post these here once so as not clutter up or confuse anyone trying to read this thread.
When I get a more calibrated setup going, I'll start a new thread on the subject.
The main point is that the test do show some improvement on the exterem high end due to the different coatings and/or added thickness's and added mass.
The eq setting that I used was what I preceived to be flat and good sounding by listening to some music at a low comfortable level and not blairingly loud by any circumstance.
And by the results I am not that far off, suprizingly!
The eq settings were as follows 75hz cutoff high pass filter was on at all times to avoid any transformer saturation and amplifier issues.
#1 flat no eq.
#2 around 180hz mid boost at +6db and +9db 12khz highpass shelving.
#3 +9db 12khz highpass shelving.
The board picture shows a sample of the integrity of the signals and are as follows.
track #1 test sweep , 4hz to 20khz linear sweep for 30 seconds.
track #2 frequency response ,no eq,straight thru the board to sub master #1 and #2 of 8 into the computer.
I could have used an aux send as it they have a flatter response and don't have any high end drop off,but this is the way I have it setup for now.
track #3 test 1
track #4 test 2
track #5 test 3
The hump in the response in "open no eq" may be that of the micrphone response ,but I am not sure ,as i said these are crude real world tests.
Also the notch at 400hz to 500hz depicted in all of the charts could be refractions of reflections of the monitor and/or cubby holes on my desk.
I once did A test where I tried to elminate them as much as I could with room treatment and came up with a very flat response,I believe I posted that one on another thread.
The measurements were taken 1 foot away and off center about 1/3 up from the bottem and I am not sure what happend to the high end response of both panels depicted in th graphs ,but i asure you the highs were there and they sounded good
Feel free to ask any questions if there is any confusions, enjoy. jer
Attached Images
File Type: jpg testsetup for both.jpg (66.8 KB, 382 views)
File Type: jpg testsetup for one.jpg (51.2 KB, 370 views)
File Type: jpg open setup(new).jpg (53.3 KB, 367 views)
File Type: jpg board integrity.jpg (32.6 KB, 361 views)
File Type: jpg new.jpg (48.9 KB, 363 views)
File Type: jpg old.jpg (51.2 KB, 69 views)
File Type: jpg both.jpg (40.1 KB, 50 views)
File Type: jpg new eq'ed ,+6db 200hz,+9db 12khz.jpg (49.8 KB, 52 views)
File Type: jpg old eq'ed,+6db 200hz,+9db 12khz.jpg (49.5 KB, 51 views)
File Type: jpg both same eq.jpg (38.6 KB, 55 views)
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Old 22nd April 2010, 03:54 AM   #384
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One more, of course, as this is the one to compare them all to.
The sony speakers in the pictures were not hooked up and was only used as support for the panels and to view the effects of backwave cancelations. jer
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Old 21st June 2010, 03:06 PM   #385
Nevod is offline Nevod  Russian Federation
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Having reread the thread for probably 3rd time I thought that some sort of FAQ or at least summarization is required on this subject. Moreover, I think that this thread could be used to try to synthesize one or several modern and useful coatings together with methods of application.

There are few properties of the coating:
1) Surface resistance
2) Uniformity
3) Stability
4) Thickness
5) Water resistance
6) Ease of use
These parameters are influenced by three moments: surface preparation, coating composition and application method.

Surface preparation is what is actually more or less understood. The easiest method seems to use a tesla coil (build or borrow), and connect it to discharger - a sharpened steel liner, maybe a blade, something with long straight sharp edge. There are some chemical methods, but the chemicals required are not really obtainable and very dangerous.

Coating recipes vary greatly, but I've found probably two which are seemingly easy:
1) Water-PVA-Ink
2) Water - Water-soluble acrylic varnish - carbon from burnt sugar.
The second coating can be applied to obtain 0.1*m uniform thickness and lasts at least 20 years. Hovewer, it has not-so-high surface resistance - 2e8 Ohm, iirc. The first coating can give up to 1e12 Ohm resistance, but other properties are not known precisely, besides that it's not bad

Most coating recipes can be broken down to 3 primary components - the binder, which adheres to mylar, the base, which is the bulk of the coating, and the filler, which is the main conductor.
In the 1st coating, PVA is both base and binder, and ink is conductor, I suppose. In the 2nd - acryl is base and binder, and carbon is conductor.
Some recipes cite dissolving a permanent marker, which, I believe, contains binder agents. As such, I think that it can be safely added to the composition.
The problem with the 1st coating is PVA - in low humidity it's good, but it's hygroscopic and it conducts when mixed with water, so in high humidity SR may lower.
The 2nd coating just has too low resistance.
The answer, as it seems to me, is to exchange the components of the coating and use acrylic varnish with ink, with addition of permanent marker for better adherence.


Finally, the application method has also seemingly been narrowed down to using foam brush, which allows uniform application of thin coating layer.


I may have made mistakes on several points, particularly regarding materials' properties. Still, I think that some structurization of known information is required, and attempts to collectively synthesize the True and Proper Coating should be done.

Thanks.
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Old 21st June 2010, 11:44 PM   #386
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As Jonas told me here,ESL Diaphragm coating .jer
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Old 22nd June 2010, 12:02 AM   #387
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Please forgive me but I do not recall a compleat reciept for this formula.jer

" 2) Water - Water-soluble acrylic varnish - carbon from burnt sugar.
The second coating can be applied to obtain 0.1*m uniform thickness and lasts at least 20 years. Hovewer, it has not-so-high surface resistance - 2e8 Ohm, iirc. The first coating can give up to 1e12 Ohm resistance, but other properties are not known precisely, besides that it's not bad. "

From past experience the foam brush produces a smooth consistent even coating without bubbles which causes bare spots on the surface of the diagraphram without leaving any kind of lent, like tissue papper or cotten balls do.jer
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Old 22nd June 2010, 08:09 AM   #388
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Nevod, can you please tell us more about the "Burnt sugar Coating" ?

After Your post above, I put fire on some sugar and let it burn out. Then I scraped some carbon of the remains, crushed it to verrrrry fine powder, and mixed it with distilled water and acrylic varnish. The resulting coating was above 100 giga ohm, unable to measure resistance.

What did I do wrong?
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Old 22nd June 2010, 11:19 AM   #389
Nevod is offline Nevod  Russian Federation
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Sorry, have done some mistake. Sugar is not burnt, but pyrolised. Has anybody made an ELS headphone? - Post #71 here the coating is described.

Read some bits of the thread more precisely - Phil47 recommends using varnish + antistatic liquid. He measures 2.5 Gigaohm with it. This already seems a good idea, with more diluted luquid the resistance can be increased further.
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Old 22nd June 2010, 03:44 PM   #390
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Quote:
Originally Posted by Nevod View Post
Sorry, have done some mistake. Sugar is not burnt, but pyrolised. Has anybody made an ELS headphone? - Post #71 here the coating is described.

Read some bits of the thread more precisely - Phil47 recommends using varnish + antistatic liquid. He measures 2.5 Gigaohm with it. This already seems a good idea, with more diluted luquid the resistance can be increased further.
The most interesting thing would be the task of removing Sulphuric acid out of the reaction byproduct.
So it stays there holding water due to natural hydroscopicity.
It's also well known that acid water mixture conducts well - car battery for instance.
Be careful - wery exothemic reaction, sometimes with the flames. Concentrated acid is no fun either.
Alex
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