Lol. Well the reason I'm looking to a curved design is for structural stability and the fact it will give a smoother off axis response will it not? My main listening point will be directly in front of the stage but for those movie nights a flat panel will be no good to those sitting about 1m each side of the centre?
I plan on coating the stators with a light coat of black spray. Nothing thick. Was looking at some insulating spray paint too, seems decent. I'll have a play around with some scraps of the metal I use.
I plan on coating the stators with a light coat of black spray. Nothing thick. Was looking at some insulating spray paint too, seems decent. I'll have a play around with some scraps of the metal I use.
There is a guy on here at AK Planer & Exotics that uses a truck bed liner product. It must be professionally applied though.
Stability is increased with curved panels. Dispersion is also reducing the SPL at any one single listening spot since the energy is being "dispersed". Nuthin's free.😀
Stability is increased with curved panels. Dispersion is also reducing the SPL at any one single listening spot since the energy is being "dispersed". Nuthin's free.😀
Hi,
the problem with thick sheets of punched metal is that each hole may look like a cylindrical thunnel. The more so the lower the relation between diameter and length becomes. If that happens each hole functions similar to a Helmholz-resonator. The sum of the holes in conjunction with the air volume incased between the stators then shows a bandpass behaviour. The upper bandwidth limit of this mechanical filter may fall into the audible range.
Measures against this are thinner sheets and a thick insulation layer which leads to a rounded, tapered shape of the holes.
Since we want a as efficient as possible panel, this asks for small d/s values, which again asks for small holes and hence thin sheets.
I wouldn´t go beyond 5mm hole diameter. 3mm is a nice compromise between hole-size, percentage of open-area, available sheet thickness and stiffness and practicality with regard to insulating, processing and handling. You may use 1.6mm thick sheets, but You should be aware of the bandlimiting problem and undertake the sheets a process of rounding the hole wands. This process alone can be very time consuming, complicated and expensive. Some mechanical processes like sandblasting may obscure flatness or the preciseness of curvature because the sheet may warp and bend. Some (electro-) chemical processes may work, are usually beyond DIYer´s skills and quite costly. Making the sheet thinner and applying soft grinding is a possible way to go. Too thin a sheet obsures stiffness and stability though. So a compromise needs to be chosen. After my experience for a panel of the suggested size 0.8mm-1mm thick sheets are a good choice.
Curving increases the structural stabilty alot. It also widens the sweet spot, but the effect is quite small. Curved panels still exhibit a high degree of directionality and if 2 or 3 persons shall enjoy the full sonic capabilities, their listening positions would rather be in a line one-behind-the-other, instead of a row side-by-side.
The choice of the coating and its application are a key factor to a well working panel and divides the ´men from the boys´. In other words, it makes the difference between a serious and safe panel and a potentially lethal toy. A light coat of black spray will prevent corrosion and may look fine, a decent functional coating certainly is something different.
@speedracer:
You know I regard Your Q not only OT but also off-sense in a certain sense, but I´d like to give an answer still. 🙄
When You design a panel Your choice should depend on good reasoning. The reasons will differ from case to case and designer to designer and are not necessarily communicated to the public. If one could simplify the production processes and/or reduce costs, he might e.g communicate this by saying that overall quality has been increased (which btw. leaves the nice option to increase pricing).
It seems to me that many DIYers judge sound quality of utmost priority. But this may only apply if effort, sourceability, ordering partys specifications, time-to-market, optics, or in general costs don´t play the prime role.
In other words: If I need to build a panel as cheap as possible, I´d definitely choose a flat wire stator design. If I want to use as much prefabricated materials as possible to reduce my own labour costs and time, I´d choose a flat stator, made from a polymer or PCB-similar material.
If I want highest sound quality and greatest dynamic range other stator designs may be a preferrable choice at the expense of higher manufacturing costs.
So I don´t wonder at all that Mr. Sander´s stator designs from his DIY-times differ from those of his commercial period. Changing paradigms requires a rethinking of the designs. I´d rather wonder if it were different.
jauu
Calvin
the problem with thick sheets of punched metal is that each hole may look like a cylindrical thunnel. The more so the lower the relation between diameter and length becomes. If that happens each hole functions similar to a Helmholz-resonator. The sum of the holes in conjunction with the air volume incased between the stators then shows a bandpass behaviour. The upper bandwidth limit of this mechanical filter may fall into the audible range.
Measures against this are thinner sheets and a thick insulation layer which leads to a rounded, tapered shape of the holes.
Since we want a as efficient as possible panel, this asks for small d/s values, which again asks for small holes and hence thin sheets.
I wouldn´t go beyond 5mm hole diameter. 3mm is a nice compromise between hole-size, percentage of open-area, available sheet thickness and stiffness and practicality with regard to insulating, processing and handling. You may use 1.6mm thick sheets, but You should be aware of the bandlimiting problem and undertake the sheets a process of rounding the hole wands. This process alone can be very time consuming, complicated and expensive. Some mechanical processes like sandblasting may obscure flatness or the preciseness of curvature because the sheet may warp and bend. Some (electro-) chemical processes may work, are usually beyond DIYer´s skills and quite costly. Making the sheet thinner and applying soft grinding is a possible way to go. Too thin a sheet obsures stiffness and stability though. So a compromise needs to be chosen. After my experience for a panel of the suggested size 0.8mm-1mm thick sheets are a good choice.
Curving increases the structural stabilty alot. It also widens the sweet spot, but the effect is quite small. Curved panels still exhibit a high degree of directionality and if 2 or 3 persons shall enjoy the full sonic capabilities, their listening positions would rather be in a line one-behind-the-other, instead of a row side-by-side.
The choice of the coating and its application are a key factor to a well working panel and divides the ´men from the boys´. In other words, it makes the difference between a serious and safe panel and a potentially lethal toy. A light coat of black spray will prevent corrosion and may look fine, a decent functional coating certainly is something different.
@speedracer:
You know I regard Your Q not only OT but also off-sense in a certain sense, but I´d like to give an answer still. 🙄
When You design a panel Your choice should depend on good reasoning. The reasons will differ from case to case and designer to designer and are not necessarily communicated to the public. If one could simplify the production processes and/or reduce costs, he might e.g communicate this by saying that overall quality has been increased (which btw. leaves the nice option to increase pricing).
It seems to me that many DIYers judge sound quality of utmost priority. But this may only apply if effort, sourceability, ordering partys specifications, time-to-market, optics, or in general costs don´t play the prime role.
In other words: If I need to build a panel as cheap as possible, I´d definitely choose a flat wire stator design. If I want to use as much prefabricated materials as possible to reduce my own labour costs and time, I´d choose a flat stator, made from a polymer or PCB-similar material.
If I want highest sound quality and greatest dynamic range other stator designs may be a preferrable choice at the expense of higher manufacturing costs.
So I don´t wonder at all that Mr. Sander´s stator designs from his DIY-times differ from those of his commercial period. Changing paradigms requires a rethinking of the designs. I´d rather wonder if it were different.
jauu
Calvin
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I'll go for the 0.55mm thick, 4.8mm hole sheet then. In your opinion, how would these speakers fair in a home theatre set up to people who don't really care how they sound? As I said, I'll mostly be used for music and games (i.e. Just me sitting and listening to them) but for the other drunk students I live with that couldn't give two ***** about how much justice these beauties will deserve, including my girlfriend will say "oh its very good" just to be nice and as long as it falls within the WAF category 😛, these things will go through a hell of a lot of movies. Comparing to a pair of super cheap open baffles using £5 car speakers. Which sound pretty decent for what they are.
I plan on using a small open baffle centre speaker and a pair of Linkwitz style Pluto tube rear channels.
I plan on using a small open baffle centre speaker and a pair of Linkwitz style Pluto tube rear channels.
Hi,
well, a transparent ESL panel seems to be fascinating anybody who realizes that this thing actually is the source of the music they can hear 😉
If the whole system is well executed the sound quality is far beyond anything a typical box can offer. Most of us, if not all, had become infected by the audio-virus at a certain point or event, as if someone had toggled a switch in the brain. My first listening experience with ESLs dated back to 1985 and from that very day on I was triggered to learn about and build ESLs. Maybe Your system could be of such appetizer-quality too...who knows? And if not, then kick Your other drunk students pinky butts out of the room, declare Your room an ignorance-free zone, snatch all the booze You can get and enjoy Yourself *lol*
jauu
Calvin
well, a transparent ESL panel seems to be fascinating anybody who realizes that this thing actually is the source of the music they can hear 😉
If the whole system is well executed the sound quality is far beyond anything a typical box can offer. Most of us, if not all, had become infected by the audio-virus at a certain point or event, as if someone had toggled a switch in the brain. My first listening experience with ESLs dated back to 1985 and from that very day on I was triggered to learn about and build ESLs. Maybe Your system could be of such appetizer-quality too...who knows? And if not, then kick Your other drunk students pinky butts out of the room, declare Your room an ignorance-free zone, snatch all the booze You can get and enjoy Yourself *lol*
jauu
Calvin
Lol, well put. I'll probably get going with building these sometime soon. I'll try put a thread up to show progress =]. Thanks!
I've come across this conductive coating for the diaphragm:
Rapid Electronics - Graphite 33 Spray
and this insulation spray for the stators:
Rapid Electronics - Protective transparent coating
I'm hoping to do a layer of black spray on the stators as well. I'll experiment on a bit of scrap metal first I think. Think it's worth trying this stuff? A couple layers between the paint should make it safe enough, and shouldn't come out too thick should it? Compared to powder coating (though this would be going slightly off budget and DIY-ability)?
looking at getting some 6 Micron mylar. Can't seem to find anywhere but ER audio that sell it. Anyone know of anywhere in the UK (or close) that sell it?
I've designed an 8 inch sealed woofer box 29cm*29cm*29cm with the top and back tapered so it's not cube shaped. Volume is about 18 ltr and I'll fit all the electronics inside, including amps and xover. Do transformers, capacitors, ect count as volume taken away from the inside of a box as far as a speaker is concerned?
Rapid Electronics - Graphite 33 Spray
and this insulation spray for the stators:
Rapid Electronics - Protective transparent coating
I'm hoping to do a layer of black spray on the stators as well. I'll experiment on a bit of scrap metal first I think. Think it's worth trying this stuff? A couple layers between the paint should make it safe enough, and shouldn't come out too thick should it? Compared to powder coating (though this would be going slightly off budget and DIY-ability)?
looking at getting some 6 Micron mylar. Can't seem to find anywhere but ER audio that sell it. Anyone know of anywhere in the UK (or close) that sell it?
I've designed an 8 inch sealed woofer box 29cm*29cm*29cm with the top and back tapered so it's not cube shaped. Volume is about 18 ltr and I'll fit all the electronics inside, including amps and xover. Do transformers, capacitors, ect count as volume taken away from the inside of a box as far as a speaker is concerned?
Hi,
forget graphit33. too low ohmic value and doesn´t stick well to the membrane film
A just thin insulative coating is not the path to Endor. It´s to understand that a thick coating doesn´t spoil efficiency as long as the open area if the panel remains sufficient, which should be somewhere >30%.
Thick coating layers improve safety and flashover treshold.
What works well is a multiple of thin layers (8 or more) of a PU-laquer. PU coatings are used as top coats for stair cases and boats. Use solvent based coating, which give a smoother and more surface even if it stinks like hell.
jauu
Calvin
forget graphit33. too low ohmic value and doesn´t stick well to the membrane film
A just thin insulative coating is not the path to Endor. It´s to understand that a thick coating doesn´t spoil efficiency as long as the open area if the panel remains sufficient, which should be somewhere >30%.
Thick coating layers improve safety and flashover treshold.
What works well is a multiple of thin layers (8 or more) of a PU-laquer. PU coatings are used as top coats for stair cases and boats. Use solvent based coating, which give a smoother and more surface even if it stinks like hell.
jauu
Calvin
You can buy the 6 micron film on Ebay:
/http://cgi.ebay.com/Electrostatic-speaker-membrane-Hostaphan-eq-Mylar-C-/230566091574?pt=Speakers_Subwoofers&hash=item35aecf5b36#ht_747wt_1139
The data sheet for that graphite 33 spray you referenced shows its resistivity is 1k-2k ohms; which is much too conductive. You want a higher resistance coating to minimize charge migration over the surface of the diaphragm-- at least several hundred kohms, I would think (Quad/Walker's white paper recommends 1 megaohm). There are some DIY glue coatings that are reported to work well but I have no experience with those. I use Licron Crystal ESD coating but it might not be available where you live. I can tell you for sure that a very light coating of any hand dishwashing liquid containing sodium laurel sulfate will work perfectly (I've tested it) but I don't know how long it would last.
Sanders' Cookbook says you can get by without a stator coating but I would definitely want a minimum of 10 mils of a good dielectric coating for safe operation. Powder coating is considered the best but a thick paint coating works OK too. My very first stators were coated with a latex house paint base coat with a black acrylic topcoat (not very pretty but it worked). My current speakers are coated with 14 mils of a 2-part automotive polyurethane clearcoat over a thin black basecoat, which looks very nice and works great (any autobody shop could spray them for you).
I recommend you read up on Calvin's postings on this forum before you start your build-- you can't go wrong following his guidelines, especially if you're going to build curved panels. I have some practical build info for flat panels on my blogpage here that might be helpful as well:
Jazzman's DIY Electrostatic Loudspeaker Page
Good luck with it!
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Thanks for the link to the Mylar film =]. I looked on ebay for all this stuff but didn't seem to find any.
The Licron stuff isn't available round these parts. I'm looking for other ESD sprays but most dont seem to show resistivity. Unless someone wants to stick some on ebay for those of us in merry ol' england [=, I may have to look at other solutions.
Nice blog by the way, I like your method of insulating the edges of the panel. I was thinking of just rounding the edges down and spraying them to stop arcing. Adding the tape folded along the edge looks like a very good idea.
About the insulation spray I mentioned, would a good 8 or 9 coats be good enough? I'd chuck a couple coats of paint in there. I'll be putting a speaker cloth sleeve over the whole thing anyway.
The Licron stuff isn't available round these parts. I'm looking for other ESD sprays but most dont seem to show resistivity. Unless someone wants to stick some on ebay for those of us in merry ol' england [=, I may have to look at other solutions.
Nice blog by the way, I like your method of insulating the edges of the panel. I was thinking of just rounding the edges down and spraying them to stop arcing. Adding the tape folded along the edge looks like a very good idea.
About the insulation spray I mentioned, would a good 8 or 9 coats be good enough? I'd chuck a couple coats of paint in there. I'll be putting a speaker cloth sleeve over the whole thing anyway.
Have you tried this:
Techspray 1756-8S Licron Crystal Permanent Static Dissipative Spray
or that:
Techspray Sample Request Form
Techspray 1756-8S Licron Crystal Permanent Static Dissipative Spray
or that:
Techspray Sample Request Form
Ohh, haven't come across that, I can order that stuff then. I also realised the mylar I want to order ships with some Elvamide. From what I understand, it's a pain to apply. Is it worth just going with the Licron spray?
Too scared to start poking around for samples. I don't have a company, well not a real one... 😛, I suppose I could order it to my university. Is it easy enough to just say, I want to try one... Give meh???
Too scared to start poking around for samples. I don't have a company, well not a real one... 😛, I suppose I could order it to my university. Is it easy enough to just say, I want to try one... Give meh???
A good old friend of mine used to entertain himself with the following sport - he called to whatever company just to see if he could solisit a free staff😉
EDIT: you'll need to be very particular with Elvamide. Licron, on the contrary needs just good degreasing: acetone first and isopropanol next.
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I think you can buy the Hostaphan with or without the Elvimide and I see that you're now found a source for the Licron Crystal too. Here's a link to Calvin's inexpensive DIY recipe, which uses a Tesla glue that's not available in the US (otherwise I would have used it) but it may be available where you live:
http://www.diyaudio.com/forums/headphones/132573-has-anybody-made-els-headphone-14.html#post1844005
(be sure to read the related threads too)
Since I haven't tried the paint you asked about for insulating your stators, I can't say for sure how well it would work but my guess is that 8 or 9 coats of it, as you mentioned, would probably work OK. I wouldn't be touching those stators while they're playing, though.
The polyester tape-wrap over the stator edges shown in my blog is one of many things I borrowed from Calvin's threads. In fact, most of what I've been able to learn about ESL's I learned from reading Calvin's and others' threads here on the Forum.
Keep us posted on your progress!
I want to go for a simpler process so may just get this licron stuff. I know it works and works well from reading all these ESL posts 😛.
I may give the Elvimide a go as I've now ordered the stuff with the film 😛. I don't plan on going anywhere near these things when their running. The HV circuitry will be isolated from ground with the transformers anyway, I'm also wondering is it's possible to get the current low enough to not actually be harmfull, in the order of nanoamps? Gigaohm resistance? I'm guessing too much voltage will be dropped across it if the stator/diaphragm air resistivity comes into play? Something tells me it wont be feasible but I thought I'd throw it out there =].
I may give the Elvimide a go as I've now ordered the stuff with the film 😛. I don't plan on going anywhere near these things when their running. The HV circuitry will be isolated from ground with the transformers anyway, I'm also wondering is it's possible to get the current low enough to not actually be harmfull, in the order of nanoamps? Gigaohm resistance? I'm guessing too much voltage will be dropped across it if the stator/diaphragm air resistivity comes into play? Something tells me it wont be feasible but I thought I'd throw it out there =].
100 microamps should be fine for the HV, unless there is a leakage path somewhere. If you put an appropriate current-limiting resistor right at the output of the HV module, the sensation of touching the HV will be comparable to an electric cattle fence.
The stators is where people might really get zapped. If they touch the back stator with one hand and the front stator with the other while music is playing, they'll start dancing 🙂 Seriously though, there's more than enough current available there to kill someone very dead, and in the above scenario, it would go right through the heart.
Just something to think about. The example might seem far-fetched, but then again people (especially layman guests) do strange things... 😉
So you mean the current from the amplifier that is put across to the stators is the harm full one rather than the current from the HV supply?
That's right.
A typical bias supply will have a 10-20 Mohm (or even higher) resistor at the output which limits the amount of current that can flow to the diaphragm to relatively safe levels. But you can't limit the amp's current to the stators in the same way or the speakers won't play and, as Kavermei correctly warns, the amperage across the stators can be lethal.
By the way, please don't let the safety concerns hold you back. Just be aware of what&where the dangers are. If a professional power coating job is not an option, there are other ways to make the speakers safe to the prying fingers of uninitiated guests. A grill cloth cover comes to mind. Or double perf metal panels for the stators (with the outer panels connected to mains earth). Or just be bold and build a working panel first, and later worry about building a nice WAF-approved & safe enclosure.
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