I recall Sanders saying that the Mylar is heat-shrinkable. The stuff about spring-tensioning may have been for his curved cells? In any case, unless you're talking about some specialized pretensilized films, it is indeed heat-shrinkable, though it takes an industrial heat gun to do a proper job. I used some Clysar, which is much easier to shrink, but is more difficult to coat.
When I did my panels, I didn't pay much attention to the tension, I basically just pulled the films by hand until the big wrinkles were out. Sort of like Ginger Baker's drumskins. Doing the heat-shrink step turned them into taut little panels.
When I did my panels, I didn't pay much attention to the tension, I basically just pulled the films by hand until the big wrinkles were out. Sort of like Ginger Baker's drumskins. Doing the heat-shrink step turned them into taut little panels.
3.8 micron x 670 wide uncoated from ER Audio. I hope its not a mistake. I just figured microns to inch in a conversion calculator.
I'm hopng I can get it right with setting tension. I'd love to buy their book but I'm sure there's someone here on the forums who may have read it and hopefully will guide me.
So far I'll end up with a pair of 14" by 14" panels. The panels will sit inside a 2" border of marble, garnite, or ceramic tile. I priced 18" square tiles today, and the price is reasonable for something as solid. I plan to cut out the middle of the tiles, leaving a 2" rim. I'll use fiberglass for my spacers, I found some 1/8" thick strips of Electrical Grade Fiberglass. I can rout the thickness down as needed. I thought I'd rout away 1/16" so I can mount the diaphram within 1/16" of each stator. I believe I need the stators that close, from what I've read so far. Please correct me of I'm wrong. My Stators will be Stainless Welded Wire panels with 76% open area, and these are only around 1/32" thick. I have some white filter material film for a dust cover on each side. Sounds way cool. I'll need a nice method to stand up each 18" by 18" panel, with a place to hide the transformer.
Many thanks for your ideas!
GH
Well, a thing governing stator spacing is bias voltage.
It will play into how efficient the speaker is, and most likely how it sounds.
If you use a wider gap, you'll need a higher bias voltage, so a slimmer one does make it lower voltage.
Also, how much excursion do you want? A wider gap allows more excursion, but only to a point of useability though.
I think that there's a certain range of useful space widths for certain sizes of ESLs.
Does anyone care to mention what this gap range may be?
It will play into how efficient the speaker is, and most likely how it sounds.
If you use a wider gap, you'll need a higher bias voltage, so a slimmer one does make it lower voltage.
Also, how much excursion do you want? A wider gap allows more excursion, but only to a point of useability though.
I think that there's a certain range of useful space widths for certain sizes of ESLs.
Does anyone care to mention what this gap range may be?
I suppose it could be adapted for spraying; you'd have to drop the viscosity a bit and slow down the evaporation rate of the solvent with a retarder, but that's pretty easy to do with some toluene or similar solvent. I used a brush, which made things pretty simple.
Again, the trick to getting this to work was the surface treatment of the Clysar (or Mylar, if you choose to use that); you want a surface energy of 40 dynes or higher to ensure good adhesion. With bulk plasma treaters, you can easily hit 50 dynes and the treatment is stable for a week or two. With the smaller blown-plasma unit I used, you have to do the coating within a few hours of the surface treatment. I haven't tried this and it's quite hazardous, but I bet you could achieve the same results by treating the film with something like chromic acid.
Again, the trick to getting this to work was the surface treatment of the Clysar (or Mylar, if you choose to use that); you want a surface energy of 40 dynes or higher to ensure good adhesion. With bulk plasma treaters, you can easily hit 50 dynes and the treatment is stable for a week or two. With the smaller blown-plasma unit I used, you have to do the coating within a few hours of the surface treatment. I haven't tried this and it's quite hazardous, but I bet you could achieve the same results by treating the film with something like chromic acid.
Gap:
That's between 1/16" and 1/8". I thought I read wider gaps than 1/16" are for tweeters. Your reply makes it appear wider gap is needed for lower frequencies production. Actually on Mark Rehorst's paper he says "insulator thickness on full range is between 1/8" and 1/4", on what looks like fairly large panels. Since my actual panels will be 14" x 14", it makes me wonder what I should do.
Ever read how much a diaphram moves or oscillates? I can adjust the width of gap now before its all glued up.
I had thought about designing an adjustable spacer set. I can find some compressable rubber spacers that would allow from 1/16" up to close to 1/8" Only reason I forgot that was I'd have to have a major gap where bolts go through both stators to do the tightening. It a little more work now in the design phase...
Thanks again,
GH
That's between 1/16" and 1/8". I thought I read wider gaps than 1/16" are for tweeters. Your reply makes it appear wider gap is needed for lower frequencies production. Actually on Mark Rehorst's paper he says "insulator thickness on full range is between 1/8" and 1/4", on what looks like fairly large panels. Since my actual panels will be 14" x 14", it makes me wonder what I should do.
Ever read how much a diaphram moves or oscillates? I can adjust the width of gap now before its all glued up.
I had thought about designing an adjustable spacer set. I can find some compressable rubber spacers that would allow from 1/16" up to close to 1/8" Only reason I forgot that was I'd have to have a major gap where bolts go through both stators to do the tightening. It a little more work now in the design phase...
Thanks again,
GH
static humming panel beaters
Just the opposite. Electrostatic tweeters are no different than any other kind- they don't need much travel. Woofers and bass is where you've got to swing that film.
The difficulty with adjustable stators, I'll guess, is that they need to remain quite parallel and not have any tendency to move in and out with signal applied. Not impossible, but much harder than using solid, fixed spacing.
Just the opposite. Electrostatic tweeters are no different than any other kind- they don't need much travel. Woofers and bass is where you've got to swing that film.
The difficulty with adjustable stators, I'll guess, is that they need to remain quite parallel and not have any tendency to move in and out with signal applied. Not impossible, but much harder than using solid, fixed spacing.
Extremy
This may already be obvious to you, but in case it's not...
Your 14" panels will need to be subdivided by spacers to prevent the diaphragm from contacting a stator. The wider the gap, the greater inter-spacer distance you can get away with. With reasonably flat and stable stators, I've successfully used a 1/16" gap and about 3-4" distance between spacers. When testing prototypes I tried a 1/32" gap with very thin aluminum stators (of the type recommended by Sanders). With that construction I found a 3-4" distance between stators to be unreliable. Once the stator takes on a slight curve---or worse yet a slight wrinkle---it's prone to trouble, and the aluminum was hard to keep perfectly flat. I've found perforated steel stators to be easier to work with (and more attractive). Just something to bear in mind when handling and mounting your stators.
Best of luck.
This may already be obvious to you, but in case it's not...
Your 14" panels will need to be subdivided by spacers to prevent the diaphragm from contacting a stator. The wider the gap, the greater inter-spacer distance you can get away with. With reasonably flat and stable stators, I've successfully used a 1/16" gap and about 3-4" distance between spacers. When testing prototypes I tried a 1/32" gap with very thin aluminum stators (of the type recommended by Sanders). With that construction I found a 3-4" distance between stators to be unreliable. Once the stator takes on a slight curve---or worse yet a slight wrinkle---it's prone to trouble, and the aluminum was hard to keep perfectly flat. I've found perforated steel stators to be easier to work with (and more attractive). Just something to bear in mind when handling and mounting your stators.
Best of luck.
That may be the opposite of what you're saying. To hold a static charge, a material must be NONconductive.
An easy way to check is to make a Xerox copy of a short, fat, black line, preferably on a nonporous substrate (like an overhead slide), then see if the resistance is something measurable with an ordinary ohmmeter.
An easy way to check is to make a Xerox copy of a short, fat, black line, preferably on a nonporous substrate (like an overhead slide), then see if the resistance is something measurable with an ordinary ohmmeter.
The coating shouldn't be non-conductive so much as a really, really high resistance. Multiple meg. Witness the graphic rub technique. Carbon conducts, but has a really high resistance. Think in terms of the old telephone carbon mics.
I kinda like the toner idea. The idea of "printing" a membrane could start a whole new wave of ESL building...if toner turns out to have the right characteristics. I see nothing wrong with the idea of simply printing a black bar on a piece of paper and attempting to measure the resistance at, say, a quarter or half an inch. The resistance will quickly go beyond the upper limits of what an ordinary meter can read.
If I recall, toner is carbon powder in a fusible plastic base. If true, or perhaps I should say if still true (for all I know they've gone to analine dyes or something of that nature), then it might work well. The only drawback I can see to actually using a laser printer is that the heat might pre-shrink the membrane. On the other hand, you could still glue it to the frame.
If I remember, I'll try to measure the resistance of toner tonight when I get home.
Oh great...just what I need, another project...and me with something like fourteen projects lined up already.
Grey
I kinda like the toner idea. The idea of "printing" a membrane could start a whole new wave of ESL building...if toner turns out to have the right characteristics. I see nothing wrong with the idea of simply printing a black bar on a piece of paper and attempting to measure the resistance at, say, a quarter or half an inch. The resistance will quickly go beyond the upper limits of what an ordinary meter can read.
If I recall, toner is carbon powder in a fusible plastic base. If true, or perhaps I should say if still true (for all I know they've gone to analine dyes or something of that nature), then it might work well. The only drawback I can see to actually using a laser printer is that the heat might pre-shrink the membrane. On the other hand, you could still glue it to the frame.
If I remember, I'll try to measure the resistance of toner tonight when I get home.
Oh great...just what I need, another project...and me with something like fourteen projects lined up already.
Grey
Take a look at these DIY full range 8-footer ESL panels:
http://www.ele.tut.fi/~artoko/audio/speakers/fullrange_esl.html
Smaller hybrid speakers here:
http://www.ele.tut.fi/~artoko/audio/audioindex.html
You could contact the guy and ask for construction details.
http://www.ele.tut.fi/~artoko/audio/speakers/fullrange_esl.html
Smaller hybrid speakers here:
http://www.ele.tut.fi/~artoko/audio/audioindex.html
You could contact the guy and ask for construction details.
I just finished making some esl's after buying the mylar and coating off ER audio. Mine are only tiny compared to some (600mm x 150mm)
Tensioning i used masking tape and my computer desk and then pressing my esl panel over the top. I used double sided tape as the insulator so it stuck straight on.
I havn't tested them yet since I can't make the PSU till i get all the components.
Also... Even if you had an A3 laser printer, I think the esl may be to small. The ones i've made are propably going to be used as the rear speakers for a surround sound setup (good excuse to make bigger and better ones for the front ). And if you were thinking of breaking the toner open, i'm pretty sure the stuff causes cancer.
I'd keep with the graphite or buy some coating from ER. I got the more expensive stuff (sorta looks like ink to me, nasty black stuff) and it applied fine with very little effort at all.
Tensioning i used masking tape and my computer desk and then pressing my esl panel over the top. I used double sided tape as the insulator so it stuck straight on.
I havn't tested them yet since I can't make the PSU till i get all the components.
Also... Even if you had an A3 laser printer, I think the esl may be to small. The ones i've made are propably going to be used as the rear speakers for a surround sound setup (good excuse to make bigger and better ones for the front
). And if you were thinking of breaking the toner open, i'm pretty sure the stuff causes cancer.I'd keep with the graphite or buy some coating from ER. I got the more expensive stuff (sorta looks like ink to me, nasty black stuff) and it applied fine with very little effort at all.
alternatives...
hello, this is my first post...
i have been looking at esl speakers for a while now, and am interested in building a pair, and i was wondering if there are any alternatives to perforated metal, i noticed on the esl information page that several of the plans have rods...
i would like to keep this pretty simple...and if there aren't any easy alternatives (to perforated metal) where would i go about finding some? i would like to stay away from ordering it from the internet if at all possible..
hello, this is my first post...
i have been looking at esl speakers for a while now, and am interested in building a pair, and i was wondering if there are any alternatives to perforated metal, i noticed on the esl information page that several of the plans have rods...
i would like to keep this pretty simple...and if there aren't any easy alternatives (to perforated metal) where would i go about finding some? i would like to stay away from ordering it from the internet if at all possible..
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.