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Old 24th April 2004, 04:52 PM   #21
SY is offline SY  United States
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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.
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Old 24th April 2004, 09:31 PM   #22
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Quote:
I haven't seen free-standing film as thin as 0.00015- I can't see how you could handle it. What's the material?
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
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Old 24th April 2004, 09:38 PM   #23
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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?
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Old 24th April 2004, 11:16 PM   #24
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Default The Gap

Most fall between 0.0625 and 0.125 inches. More gap, more potential travel and SPL, but the higher the drive requirements.
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Old 24th April 2004, 11:31 PM   #25
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Okay, yeah, that was pretty much what I was thinking.
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Old 25th April 2004, 01:41 PM   #26
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SY, is this home brew formula of yours shootable in a spray gun?
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Old 25th April 2004, 01:54 PM   #27
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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.
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Old 25th April 2004, 03:50 PM   #28
extremy is offline extremy  United States
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Gap:
Quote:
Most fall between 0.0625 and 0.125 inches. More gap, more potential travel and SPL, but the higher the drive requirements.
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
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Old 25th April 2004, 04:25 PM   #29
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Default 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.
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Old 25th April 2004, 08:34 PM   #30
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Quote:
Originally posted by SY


you probably would want a high structure factor carbon black (like a channel black) rather than graphite, though, because the goal is a uniform HIGH resistivity.
hmm, printer toner comes to mind. what about that? What comes to mind is to use a shrinkable plastic, dust with printer toner before shrinking and then let the heat 'set' the toner on to the plastic. Would that even stick?
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