That depends on which sort of stator you have in mind. I've bought perforated steel from McMaster-Carr, and lincaine-style perforated aluminum at local hardware stores (for building prototypes). Wire for wire-based stators can be purchased from Digi-Key, Mouser, Newark, Allied...or surplus suppliers if you can find what you're after.
WRT coatings: I used black epoxy spray paint to coat the perforated steel quite a number of years ago. I've used the aluminum uncoated, just relying on the anodized surface as insulation. Wire, of course, comes "pre-coated."
WRT coatings: I used black epoxy spray paint to coat the perforated steel quite a number of years ago. I've used the aluminum uncoated, just relying on the anodized surface as insulation. Wire, of course, comes "pre-coated."
Hi,
Properly coating perforated steel it very difficult to do at home.
Surface tension of paint makes it very difficult to get a thick layer of coat at edges of holes. You must keep in mind that coating should withstand voltages of around 10kV.An option is powder coating , however , the coat must be around 0.5mm thick , and not all types of powder are suitable.
Thats why wire stators are popular. The base material for wire stators is usually light louvers. The wire may be standard PVC insulated wire or double insulation 200C class magnet wire.
Regards,
Lukas.
Properly coating perforated steel it very difficult to do at home.
Surface tension of paint makes it very difficult to get a thick layer of coat at edges of holes. You must keep in mind that coating should withstand voltages of around 10kV.An option is powder coating , however , the coat must be around 0.5mm thick , and not all types of powder are suitable.
Thats why wire stators are popular. The base material for wire stators is usually light louvers. The wire may be standard PVC insulated wire or double insulation 200C class magnet wire.
Regards,
Lukas.
I got my perf aluminum for cheap at a metal surplus place. I think I paid about $2 per sq foot for my 20" x 48" stators. I mechanically mounted eyelets onto each stator and had them powder coated. The powder coating cost me $150 if memory serves me right. The combination of the cheap stators and powder coating added up to what I would have paid for simply painted metal from mcmaster carr.
My prototype panels were painted with several coats applied with a roller. I could shock myself if I tried with the painted ones, but not the powder coated ones.
Sheldon
My prototype panels were painted with several coats applied with a roller. I could shock myself if I tried with the painted ones, but not the powder coated ones.
Sheldon
If you don't have a good source for surplus metal (I haven't seen too many places like the one in Albuquerque), then based on my searching a couple years ago, McMaster Carr is the best source. That's for truely perf metal, in the stereotypical sense. You can build panels cheaply with lincain at a hardware store.
I'd consider wire stators before lincain though.
Sheldon
I'd consider wire stators before lincain though.
Sheldon
These speakers are not only being built for their sound quality but for their ascetics so wire stators are out of the question. I am hell bent on perf metal stators. I have a good source for mylar of any size/weight. My only remaining problems are the transformers and the stators.
This is my first build and I would love to have some curved statorsas, but as always I am a bit ambisious. I have been steered off of that for my first build. I have been told that this is extremely difficult to do, much less for a first build.
I have always lived by the motto "Go big or go home". I guess this time I will compromise and just go with some flat stators. I am just worried about the directionality of them. They will be in a rather large room.
This is my first build and I would love to have some curved statorsas, but as always I am a bit ambisious. I have been steered off of that for my first build. I have been told that this is extremely difficult to do, much less for a first build.
I have always lived by the motto "Go big or go home". I guess this time I will compromise and just go with some flat stators. I am just worried about the directionality of them. They will be in a rather large room.
I've been listening to a pair of large panels (about 19" wide and 6' tall) for a few years now. The directionality has become an issue for me, and in fact that is one of the reasons I'm designing a new version. Nonetheless, I certainly don't regret making the first pair. I've gotten many years of very enjoyable use out of them. I do agree that starting with something flat and relatively simple improves the odds of having a successful outcome. You can then listen to them while working on the inevitable "new and improved" model a year or three down the road.
Have you had a look at ...
the number of wire stator designs out there? Some nice looking stuff here http://esl.hifi.nl/index.htm not to mention Final ESL's which are wire. However the ML look is cool to so what ever works for you is the important thing.
Regarding flat panels and directionality. If you plan to run powered subs (good idea) then narrow flat panels not only look excellent as tall line source monoliths but they will also give you a fairly wide listening area while at the same time being directional. This (directionality) is actually one of the strong points of line source dipoles. Just as a dipole ribbon microphone ony hears what is within the figure of 8 polar patern so too the dipole ESL only radiates inside that figure of 8 polar patern. This means that you can project the sound where you want it to go and have the least amount of room interaction. Less room reflections means cleaner sound at the listening position along with fewer room resonance's to have to listen to and deal with.
An active diaphragm area of 6 - 9 inches wide by 7 feet tall can play very loud. You can make a nice set of tubular frames (sand filled) and even include three spaced apart vertical tubes on the rear side of the panel to diffuse the back wave. This can not only look good but will stiffen the frame and make speaker positioning easier too. Perf metal with an open area of about 35 - 40% should yield you the highest possible output while offering more structural integridty that higher open area metals. Depending upon your stator spacing you might want to consider a central vertical spacer to insure diaphragm stability. Don't let this worry you as the panel will act as if the spacer were not there. Good luck and have fun. Regards Moray James.
the number of wire stator designs out there? Some nice looking stuff here http://esl.hifi.nl/index.htm not to mention Final ESL's which are wire. However the ML look is cool to so what ever works for you is the important thing.
Regarding flat panels and directionality. If you plan to run powered subs (good idea) then narrow flat panels not only look excellent as tall line source monoliths but they will also give you a fairly wide listening area while at the same time being directional. This (directionality) is actually one of the strong points of line source dipoles. Just as a dipole ribbon microphone ony hears what is within the figure of 8 polar patern so too the dipole ESL only radiates inside that figure of 8 polar patern. This means that you can project the sound where you want it to go and have the least amount of room interaction. Less room reflections means cleaner sound at the listening position along with fewer room resonance's to have to listen to and deal with.
An active diaphragm area of 6 - 9 inches wide by 7 feet tall can play very loud. You can make a nice set of tubular frames (sand filled) and even include three spaced apart vertical tubes on the rear side of the panel to diffuse the back wave. This can not only look good but will stiffen the frame and make speaker positioning easier too. Perf metal with an open area of about 35 - 40% should yield you the highest possible output while offering more structural integridty that higher open area metals. Depending upon your stator spacing you might want to consider a central vertical spacer to insure diaphragm stability. Don't let this worry you as the panel will act as if the spacer were not there. Good luck and have fun. Regards Moray James.
Hi, jzh797s.
Go with Mcmaster-Carr for the perforated material. The prices are reasonable and they will ship small orders to DIYers. Plus, you've got your choice of materials, thicknesses, hole sizes, and open area.
Regarding the high frequency beaming of ESLs, it's going to be there. The narrower the panel, the higher the frequency that the beaming starts. If you can, divide your stators into narrow, wide, and maybe wider sections and low-pass filter the wide and wider sections with series resistors.
Transformer selection is limited unless you've got a large budget. I_Forgot found some toroids that look like a good choice if you want to give it a try without a lot of cost. See this thread. I got mine from JustRealMusic.com.
Moray, can you give us some details? IMHO, positioning is one of the most important elements of ESL use.
Go with Mcmaster-Carr for the perforated material. The prices are reasonable and they will ship small orders to DIYers. Plus, you've got your choice of materials, thicknesses, hole sizes, and open area.
Regarding the high frequency beaming of ESLs, it's going to be there. The narrower the panel, the higher the frequency that the beaming starts. If you can, divide your stators into narrow, wide, and maybe wider sections and low-pass filter the wide and wider sections with series resistors.
Transformer selection is limited unless you've got a large budget. I_Forgot found some toroids that look like a good choice if you want to give it a try without a lot of cost. See this thread. I got mine from JustRealMusic.com.
Moray, can you give us some details? IMHO, positioning is one of the most important elements of ESL use.
depends...
on the size of the panel. This idea was used by Roger Sanders. Roger used a single pipe that he called a "beam splitter". I have used multiple (smaller usually three) pipes of the plumbing variety as they are cheap and easy to get in various sizes (can be loaded with sand) and one large and two small will break up the rear wave off of the panel making the wave diffuse rather than being identical to the front wave. This helps make placement easier to do and also helps keep direct reflections form making their way back to the panel too. Regards Moray James.
on the size of the panel. This idea was used by Roger Sanders. Roger used a single pipe that he called a "beam splitter". I have used multiple (smaller usually three) pipes of the plumbing variety as they are cheap and easy to get in various sizes (can be loaded with sand) and one large and two small will break up the rear wave off of the panel making the wave diffuse rather than being identical to the front wave. This helps make placement easier to do and also helps keep direct reflections form making their way back to the panel too. Regards Moray James.
I've played a bit with curved panels, and I keep coming back to flat ones. With curved panels, you get a bit more dispersion, but nothing like a monkey box speaker. And when you curve the panel, the insanely great dynamics go away. My solution is to have a set of competent bookshelf speakers to use when not seriously listening.
Sheldon
Sheldon
Hi,
I´ve played a bit with flat panels, and I keep coming back to curved ones or flat segmented ones.
With flat panels You have to fix Your listening position to a tiny little spot. Those are al- or-nothing machines. The hardly noticeable advantage regarding high-freq-dynamics -and only there! and there are other factors with which You can influence the dynamic character far more!- costs in ease of handling and flexibility of listening position and so on.
My solution is to spare the money for additional bookshelf speakers but have a panel with some dispersion first hand.
jauu
Calvin
I´ve played a bit with flat panels, and I keep coming back to curved ones or flat segmented ones.
With flat panels You have to fix Your listening position to a tiny little spot. Those are al- or-nothing machines. The hardly noticeable advantage regarding high-freq-dynamics -and only there! and there are other factors with which You can influence the dynamic character far more!- costs in ease of handling and flexibility of listening position and so on. My solution is to spare the money for additional bookshelf speakers but have a panel with some dispersion first hand.
jauu
Calvin
The dynamics of flat panels, as mentioned by Sheldon, are of particular interest to me. I think they were the first thing that struck me when I got my first pair of big flat panels working. I've long wondered what the origin of the effect is---they sound almost horn-like in that respect. That had me wondering whether the acoustic impedance match between the air and diaphragm, or perhaps the small diaphragm displacement, might somehow be responsible (since horns and large ESL panels share those characteristics).
As I design a new pair of ESLs, and consider using wire stators so that I can make the directivity less frequency dependent, I worry that I might lose some of those dynamics that I've gotten so used to. They're not something I want to give up. Sheldon, you've clearly heard more than your share of the original Quads, with their segmented panels. Do they give up some of the "snap" or dynamics that you hear in your single-wide-panel design? If so, might there be a cause other than the panel segmentation?
Sorry, I just realized this is a bit off the stator material thread, but it follows from the most recent posts.
As I design a new pair of ESLs, and consider using wire stators so that I can make the directivity less frequency dependent, I worry that I might lose some of those dynamics that I've gotten so used to. They're not something I want to give up. Sheldon, you've clearly heard more than your share of the original Quads, with their segmented panels. Do they give up some of the "snap" or dynamics that you hear in your single-wide-panel design? If so, might there be a cause other than the panel segmentation?
Sorry, I just realized this is a bit off the stator material thread, but it follows from the most recent posts.
Hi,
if You do things well, the difference between a segmented wire stator and a completely driven stator -wether curved or flat doesn´t make a noticeable difference- is marginal and could just be heard by direct comparison. Differences in frequency linearity, HV-supply and other parameters affect the sound of the panel far more.
jauu
Calvin
if You do things well, the difference between a segmented wire stator and a completely driven stator -wether curved or flat doesn´t make a noticeable difference- is marginal and could just be heard by direct comparison. Differences in frequency linearity, HV-supply and other parameters affect the sound of the panel far more.
jauu
Calvin
The quads have a midrange naturalness that is the equal of any ESL I've heard. However, they do not have the dynamic impact of larger panels, segmented or not. They also lack the frequency extension that makes them lack weight, and actually in the case of the 57 actually makes midrange stand out even more. They are very polite speakers, and very gentle speakers, which make poorly recorded material listen-able. I don't feel that the quads are as good as my simple perf-metal one piece ESL speakers, but they are good enough that I would not hesitate on living with them if I didn't have my DIY speakers. There's a very short list of "livable" speakers that are not DIY for me.
I think Calvin is onto something with his mention of the segmented stators. I strongly suspect that if the segments are crossed over just short of beaming, then the dynamic impact you seek and the better dispersion can be had. I need to build some wire stators.
I built perf-metal stators due to the ease of construction and likelihood of success. But I do think that a well-done set of wire stators will make a better sounding and more versatile speaker that would allow segmentation and segmentation changes. I did try to build a long narrow ESL panel with perf metal, and a slightly wider one. The resonances within the strip were insanely bad. Segmentation can really only be done with wire stators, or with some method to hold the perf metal that doesn't create a cavity, and electrically separates the two stator sections.
Sheldon
I think Calvin is onto something with his mention of the segmented stators. I strongly suspect that if the segments are crossed over just short of beaming, then the dynamic impact you seek and the better dispersion can be had. I need to build some wire stators.
I built perf-metal stators due to the ease of construction and likelihood of success. But I do think that a well-done set of wire stators will make a better sounding and more versatile speaker that would allow segmentation and segmentation changes. I did try to build a long narrow ESL panel with perf metal, and a slightly wider one. The resonances within the strip were insanely bad. Segmentation can really only be done with wire stators, or with some method to hold the perf metal that doesn't create a cavity, and electrically separates the two stator sections.
Sheldon
Thanks for the responses Calvin and Sheldon. By the way Sheldon, when you wrote "The resonances within the strip were insanely bad" does this refer to diaphragm resonances because of the way it was clamped (a long narrow strip) or to cavity resonances set up by the structure surrounding the diaphragm? I assume insanely bad means lots of peaks and suck-outs in the frequency response plot.
Few said:
I think the problem was cavity related, rather than film resonances, but I'm not 100% sure. Neither the cavity resonance calculation or the film tension resonance calculation exactly matched what I measured. It was really honky and not good sounding at all.
It was bad enough that I bailed on trying to EQ it. And I realized that even if I could EQ it, I've still got diffraction and other problems with segmenting using perf metal. I had a frame built that held each section which meant that there was nearly 2" of dead space between the mid panel and the tweeter strip. That would hose up radiation pattern way more than the laser beam of sound was a problem (if that makes sense).
The way to segment in my mind is to use wire stators and one big piece of diaphragm that is driven differently in different parts be differing signals on the wires. I just don't see a reasonable way to use perf metal and not have big gaps between driven parts (it's possible, but kludgy). Quad 63's use fiberglass circuit board material and etch away portions to establish different driven regions. The 57's used conductive paint on plastic.
The way DIY ESL's shake out in my mind is:
perf metal: Easiest, most likely chance of success. Cheap, and quick, particularly if you aren't too worried about insulation. All one driven area which produces laser beams of sound. Hope you like to sit still. Tremendous dynamics.
Wire Stators: Hard, labor intensive, and may not be as flat or precise as perf metal. Chance of success is more closely tied to skill of fabricator. Less potential issues with cavity resonance. Flexible, can be segmented, or not, segments can be varied as part of the voicing process. Can be more ugly, but doesn’t have to be (see audiostatic for beautiful wire stators). Typically more bulky panels, requiring a larger frame structure to mount.
Exotic Methods: Circuit board material: Easy to build (like perf), free from shock hazards, can be segmented, can have wild segmentation (concentric circles, etc). Expensive! Mesh screening: like wire stators, but often harder to get flat and rattle free.
Anything I forgot?
Sheldon
That's quite a bit already. Thanks very much. I too tried the segmented perforated metal approach, albeit just in prototype mode. I didn't have any more success than you did coming up with a way to avoid the gaps or cavities that you mentioned. I eventually bailed and just went with large laser-beaming panels. They sound great when you're in the hot seat, but I find that I log more hours out of the hot seat than in it, especially since the speakers are used for home theater applications as well as music.
The potential for easier segmentation is what has been causing me to lean toward wire stators, even though they're clearly trickier to put together than perf metal. I agree that they really provide the most practical way to provide segmentation without some sort of awkward resonance-supporting framework keeping the segments in position. I've been planning on using the same approach you described---segmented wire stators with the diaphragm treated as one large piece. If others have alternative approaches, I'd love to hear about them.
Few
Hi,
imo one of the reasons for heavy resonances of a panel is due to lacking damping. You will certainly experience standing waves that depend on the physical dimensions of the panel. These can be minimized if the horizontal and vertical dimensions of a segment (or a complete panel) are chosen appropriately. Most panels don´t account for damping of the standing waves, since the diaphragm is pulled taut and fixed on hard spacer-material. The absence of damping at the edges and the big difference in mechanical impedance leads to heavy resonances. Using foam tapes helps a bit, as well does some damping material at the segment´s circumference. If You add some spots to account for the 1:70-1:100 rule (regarding the d/s) use some soft material (Audiostatic uses silicione-drops along the middle line of the membrane, ML did it with horizontally orientated foam-strips). My finding is that curved panels exhibit a bit less standing wave related resonances. Maybe because of the inherent higher stability of the metal sheets, maybe the bent membrane is less prone to this effect, I´m not sure. But I can´t measure the often to find resonance around 1kHz (~ 17cm wide panels) in my panels.
So I´d suggest to build curved panels in case You want a fullsize-diaphragm panel, or a segmented wire stator in case You want some dispersion.
jauu
Calvin
imo one of the reasons for heavy resonances of a panel is due to lacking damping. You will certainly experience standing waves that depend on the physical dimensions of the panel. These can be minimized if the horizontal and vertical dimensions of a segment (or a complete panel) are chosen appropriately. Most panels don´t account for damping of the standing waves, since the diaphragm is pulled taut and fixed on hard spacer-material. The absence of damping at the edges and the big difference in mechanical impedance leads to heavy resonances. Using foam tapes helps a bit, as well does some damping material at the segment´s circumference. If You add some spots to account for the 1:70-1:100 rule (regarding the d/s) use some soft material (Audiostatic uses silicione-drops along the middle line of the membrane, ML did it with horizontally orientated foam-strips). My finding is that curved panels exhibit a bit less standing wave related resonances. Maybe because of the inherent higher stability of the metal sheets, maybe the bent membrane is less prone to this effect, I´m not sure. But I can´t measure the often to find resonance around 1kHz (~ 17cm wide panels) in my panels.
So I´d suggest to build curved panels in case You want a fullsize-diaphragm panel, or a segmented wire stator in case You want some dispersion.
jauu
Calvin
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