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Old 11th March 2013, 07:05 AM   #51
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This open area calculator might help.

Calculation of open area - RMIG

Here is one for wire mesh my material of choice,

http://www.wirecloth.com/cwc/percent.htm

jer

Last edited by geraldfryjr; 11th March 2013 at 07:16 AM.
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Old 11th March 2013, 08:43 AM   #52
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I just used the online calculator to work out the open area and it gives 35.4%

This would be ok wouldn't it?
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Old 11th March 2013, 09:20 AM   #53
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By the time you get a good coating of about 15 to 20 mil your open area is going to be more into the 20% range.

You want to be no less than about 40% after the coating has been applied.

jer
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Old 11th March 2013, 09:40 AM   #54
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Ah, never thouht about the open area decreasing after applying paint etc. Good point

I may go down the wire method instead, as the only reason for thinking about using the perforated sheet was the fact I can get hold of this for nothing.
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Last edited by portreathbeach; 11th March 2013 at 09:46 AM.
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Old 11th March 2013, 10:09 AM   #55
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Here is a picture of the material I made my very first panels out of.
It has 2.5mm holes on 5mm centers and has a open area of about 22.7%.
By the time I got a good coating on them of about 10 mil or so my open area had dropped to 12%.

They worked but the sound was restricted quite a bit and didn't get very loud at all.
It was just too restrictive.

Then I made a identically sized panel using wire mesh and my open area was about 4X that of my first panel.
What a big difference it made as far as the quality and especially the sensitivity.

The third panel I made used an even better coating material (powder coating) and this allowed for on even greater open area and higher voltages as well.
What a difference this made!!!

Your material has bigger holes and this will help a great deal compared to what I used.

That was when I got the idea of trying wire mesh as this gave me higher concentration of holes per area while still giving me a large open area.
The thin wires allowed enough room for a decent thickness of insulative coating as well.
This also allowed for a more uniform highly concentrated static field across the panel than what larger holes would allow.
Not to mention the cost difference between the two materials as I couldn't afford metal panels at the time.

jer
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File Type: jpg ESL material rs.jpg (95.2 KB, 124 views)

Last edited by geraldfryjr; 11th March 2013 at 10:31 AM.
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Old 12th March 2013, 09:27 PM   #56
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I've been doing a bit more research and looking at various ESL builds and I really want to make curved mesh speakers. I prefer the look of them over the wire ones and making them curved will give a wider listening angle. At work we have a sheet metal roller and I can get the mesh powder coated locally. Just need to find some mesh with a larger open area. What would you think the open area of the mesh I showed in an earlier post would be after powder coating?

Also, I think the metal sheet roller at work can only accept sheets up to 2 1/2 feet wide. Would a panel 2 1/2 feet high and 1 foot wide be OK for 400Hz and up, or would it be better to have two panels per channel?

Here is an interesting blog I found on making curved ESLs:

https://sites.google.com/site/eslarr...roject-history
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Last edited by portreathbeach; 12th March 2013 at 09:55 PM.
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Old 12th March 2013, 10:04 PM   #57
Bazukaz is offline Bazukaz  Lithuania
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Quote:
Originally Posted by portreathbeach View Post
I've been doing a bit more research and looking at various ESL builds and I really want to make curved mesh speakers. I prefer the look of them over the wire ones and making them curved will give a wider listening angle. At work we have a sheet metal roller and I can get the mesh powder coated locally. Just need to find some mesh with a larger open area. What would you think the open area of the mesh I showed in an earlier post would be after powder coating?
Hi,

Take a small sample to coat and you can measure.If they can do it right(which I doubt) it will eat quite a lot of open area depending on hole size as coating should be up to 0.3-0.5mm thick. In case of just 0.1mm thick typical polyester open area will not drop as much, but the coating will act only for cosmetic and rust prevention purposes. And yes I have(and perhaps other) tried this. Even then the speaker could be quite usable with limited drive voltages, providing that membrane coating has sufficiently high resistance, and no one is allowed to touch both sides simultaneously. For example the treble element of quad 57 has had no insulating barrier between stator and diaphragm.

There is an interesting info about proper coating in this post :

wire stator design

As I wrote earlier, there is no such a general rule as "no less than 40% open area". Manufacturers have used as low as 20% with high success.

Edit : IMO the widest listening angle is possible with a segmented wire ESL when width of treble segment is small (2-3cm).

Last edited by Bazukaz; 12th March 2013 at 10:22 PM. Reason: Extend
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Old 13th March 2013, 12:56 PM   #58
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Thanks Bazukaz. 2-3cm, that is narrow! So instead of a curved panel, you could use several segments instead of one large one? Do you know of anyone who has made a curved wire stator, and if so, was it successful?

Wire or mesh, I still don't know what to use! but at least I know the schematics for the ESLs. I like the design that Jazzman uses:

Jazzman's DIY Electrostatic Loudspeaker Page: The Electronics Package

The only thing I would need to change on the design is the way T3 is connected. In the UK we use 230v, not 115V, so I would wire the 6v side of the transformer in series, not parallel like he did.
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Old 13th March 2013, 01:35 PM   #59
Bazukaz is offline Bazukaz  Lithuania
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Hi,

I have read some people tried(or had an idea) to make a curved wire stator over here. Do not know if they were successful.
Basically there is no need to make a curved wire stator as a flat segmented panel can have very good dispersion compared to a non-segmented one. So making a curved wire stator is a difficult and a bit pointless task.
Before making a decision between using perforated/mesh vs insulated wire stators it is wise to do some experiments. It is relatively simple to build a test panel that even sounds good on-axis. However it is really difficult to build a reliable speaker that :
1) is free from buzzing/rattling noises of the film or mechanical resonances of the structure(i.e flat steel sheets)
2) does not arc at high levels
3) has wide listening angles
4) has a good freq. response curve
5) provides similar sensitivity to hi-fi dynamic systems

And there are other factors including multiple resonance modes of the diaphragm.

Regards,
Lukas.

Quote:
Originally Posted by portreathbeach View Post
Thanks Bazukaz. 2-3cm, that is narrow! So instead of a curved panel, you could use several segments instead of one large one? Do you know of anyone who has made a curved wire stator, and if so, was it successful?

Wire or mesh, I still don't know what to use! but at least I know the schematics for the ESLs. I like the design that Jazzman uses:

Jazzman's DIY Electrostatic Loudspeaker Page: The Electronics Package

The only thing I would need to change on the design is the way T3 is connected. In the UK we use 230v, not 115V, so I would wire the 6v side of the transformer in series, not parallel like he did.

Last edited by Bazukaz; 13th March 2013 at 01:40 PM.
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Old 13th March 2013, 02:51 PM   #60
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So basically I should get the parts together to build the power supply and also the step-up transformers for the stators and experiment with panels? Sounds fair.

Is the schematic that Jazzman uses a good one to use? It seems simple enough to build and I'd rather use this type of circuit than a switch mode type.

Another quick question. I can get the mylar from eBay no problem, but wanted to know what the best coating to use on it is. There are several different sprays and compounds, like graphite etc. people are using, what is a good coating to start with, nothing too expensive or hard to work with would be preferable.
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