1/2 mil Mylar for ESLs

My current situation: I've finished my first pair of ESLs and ready to build another pair as a gift (as well as another pair for myself). I've got all of the neccessary parts ready to go, except the Mylar. I've tried repeatedly to get in touch with Barry Waldron, the supplier for my first batch, but have had no luck. He has not returned my emails for the past month, so it looks as if I'm going to have to look elsewhere. I've looked online for suppliers (thomasregistry.com) but have only found companies ready to sell industrial size rolls. I only need 20' and I don't want to pay for 150'. Does anyone know where to get a 20' length of Mylar? Anyone selling some from personal stock? If not, I'll have to just suck it up and blow $100 more than I want to.
Thanks.
-Dan
 
Jakeh,
The Mylar you've pointed me to is about 10 times too thick. I need 1/2 mil, but maybe the Kapton Mylar would work. Of course, it is a $75 test... Thanks for the link, though.

Petter,
I haven't tested any of the other films, but I don't see why they wouldn't work. As far as I can see, the only parameters of the membrane that affect sound quality are tensile strength and weight/density. The membrane doesn't need to have any electrical qualities (as far as I can tell). But, as far as construction goes, the Mylar's heat-shrinkability helped alot. Imperfections in my construction were whisked away with a wave of the heat gun. Magic.

dufre,
I've been to Barry's new page, but his email has not changed since the summer and my first order. I don't see why I am having trouble finding him. Thanks for the DIY-ESL forum. I will definitely try to find Barry there. It seems that he's recently made a post. Hope abounds.


Thanks everyone
-Dan
 
Thank you, Jakeh. What a wonderful supply. Have you checked out the Hollytex and Dartek that they sell? I asked them to send me some samples of the material to see what mysterious properties they contain first-hand. But, I'd still rather get my Mylar from Mr. Waldron, simply becuase I've heard it in action and I'm satisfied with the results. I'm also not sure if Barry sells Mylar "D". DuPont apparently makes all sorts of different types of Mylar, complete with different properties, however subtle. Most 1/2 mil Mylar that I see being sold is Mylar "D". Is this the same stuff that Barry is peddling? I can't find out simply because I still can't get ahold of him. Catch-22.

-Dan
 
12 or 10 my Mylar film

I have got two rolls of mylar film that can be used for electrostatic loudspeakers.
None of them can be stretched with heat though.
But it's better if you can control the stretching instead of make final adjustments with a heat-gun which will give a very uneven tension.

I'm dropping my electrostatic project and if anyone is interested I will sell both rolls at a low cost.
Each of them contains around 100000 meters of film.

/Janne
 
Hedlund,
What type of Mylar are you selling? Is it 1/2 mil DuPont made Mylar? Or another type of PET film. I haven't heard of DuPont Mylar that doesn't heat-shrink, but there is alot that I don't know. "100000 meters"?? I don't think that my house is large enough for that. How big are these rolls? And how much are you willing to let the go for? Perhaps I can buy just 30 meters.

As for the heat-shrinking, I've found it the easiest way to tension my speakers. The Mylar that I bought from Barry was accidentally pre-shrunk in the mail (I had bought the stuff in the middle of summer). I tried the stretch and tape method of tensioning, but a large crease ran down the middle of the film. I simply could not pull hard enough to get the crease out. This crease was complete with loose spots around it that would not comply to audiophile standards. It looked hopeless. To alleviate the problem I sloppily glued the Mylar in a frame that was just a bit larger than my stator. I waved the heat gun over the Mylar till the crease had dissappeared. The entire surface became tight and even. Coating with graphite was a cinch. Glueing required no effort, just apply epoxy and lay the stator/spacers on the film in the frame. The speaker came out beutifully. Afterwards, I used the heat gun again to make sure everything was even. Here's the beuty of it: the Mylar only shrinks to a certain tension, then stops. While I have no control over said tension, it is even as can be, over the entire speaker. The resonance of the speaker turned out to be ~120 hz, low enough to make me happy. I suggest this same technique to anyone who is discouraged by the stretch and tension method.

-Dan
 
Dan,

It's normal polyester film = Mylar which I bought from Rifa (the capacitor producer). The products name is Hostaphan and works very well for electrostatic loudspeakers.
The surface seems to be pretreated for metallization, and this makes it very easy to apply the conductive liquid, or graphite powder you use to make the film conductive.
The thickness is given in my = 1/1000 of a millimeter which equals 1/25400 of an inch. My film is as said 10 or 12 my which will be 10 or 12/25400 inch = (approx) 0,00043 inch which I assume is 0,43 mil if I understand your measuring standard correctly.
Let me know if I don't, cause I'm a millimeter man myself.

30 meter mylar costs 15 cents which equals $20 US including my work and shipping from Sweden.

>How big are these rolls? And how much are you willing to >let the go for? Perhaps I can buy just 30 meters.

They weights around 40 Kg each. 30 meters is OK as long as you accept the price above.

I think you will get a better result if you don't use shrinkable mylar. Just use/build a good tensioning rig.

/Janne
 
Hedlund,
How is this PET film pretreated for metalization? Does that mean that it is metalized? How wide is your roll of film? Yes, you are close enough in your conversion from metric to imperial measurements. 12um = 48 guage = .48 mils ~= 1/2 mil film.

What rig do you use to stretch your film? I've had difficulty with the stretch and tape method (see above). Are there any drawbacks to the heat-shrinking method other than overall evenness? Durability? Longevity? Because I feel that the heat-shrinking method is even enough, unless I'm proven otherwise.
Thank you very much for your input.
-Dan
 
Well,
Due to time constraints I am forced to abandon my idea of finding the heat-shrinkable mylar that Barry sold me over the summer. Instead, I have plain ole' PET film, which is the generic version of DuPont's Mylar. I will swallow my pride and build a tensioning rig, but I'm not sure exactly how to do it.
Let me throw out this idea for a tensioning rig to see if anyone can point out any flaws or suggest anything. I plan on laying out the mylar and glueing some steel unistrut (big-boy "erector set" pieces that I have lying around) to two opposite edges. I will then drape the film over a rigid piece of metal. Then, I can add weight to both unistrut pieces (which are now hanging down on the sides) until I am satisfied with the tension of the film. Glueing on the stators will be a cinch. The tension will be the same for each panel, as the weight will not change between the construction.
An obvious problem with this is the tension is only in one direction, not both. But, I cannot see why this would be such a bad thing.
Anybody have other suggestions/comments for me? Please respond.
Thanks
-Dan