How thick for MYLAR???

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Dominick22

Member
2005-08-18 1:48 pm
The following is in regards to building a homemade ESL panel...

I have seen mylar from 1 mil to 5 mil thick and then I read an article that recomended 5-6 microns thick. What do I want to buy? On ebay they all appear the same, but on DuPonts website, they have coated and uncoated and a ton of other options. What is the best way to go???HELP PLEASE
 
Thickness

Hi,

choose the thickness after Your needs! It depends on what You want to achieve. If You want to build a fullrange ESL You may use up to 0.5mil (12µ). If You want to build a hybrid like ML (with very high mechanical tension) use a film between 1/4 and 1/2mil. If You want to build a hybrid with lower mechanical tension You may use a film down to 1/8mil. You want a Bass-Panel? You may use up to 1mil. Films with thicknesses of more than 1/2mil will have problems to perform up to (and over) 20kHz. The best compromise seems to be around 1/4mil. Here the strength of the film is already high enough to withstand even high mechanical tension, on the other hand it is so lightweighted that it performs well up to and above 20kHz.

jauuu
Calvin
 

wrl

Member
2003-01-07 11:01 pm
USA
Hello,

I purchased the mylar for my speakers from

www.eraudio.com.au

just check under "components". I think that I purchased the 3.8 micron and have so far been very happy with it. I can't remember the exact tension I applied (something like 4-5 lbs) during construction, but I use a hybrid set up with 8 inch woofers.

Although the company is from australia and shipping is more difficult than in the States, I have been very happy with their service. I'd email them and ask what they recommend. I'd have no reservations ordering more from them.

They even send me a Christmas (or I guess Holiday to be P.C.) card every year :)

Anyway, hope this helps... best of luck with your project.

-Wes
 

wrl

Member
2003-01-07 11:01 pm
USA
With an oversized piece of diaphram laying flat on my work surface, I attached a piece of packing tape to the excess boarder of the mylar. The other end of the tape was than attached to a formica sample piece (the smooth kind...not the bumpy kind) which was in turn attached to a 3 dollar fish scale from walmart. ;)

After pulling to the correct tension I removed the tape end from the formica and stuck it down to my work surface (essentially locking in the tension)

I started at each corner and then did the center of each side. Then I did the center of each new division until all of the wrinkles were out. Then I redid the corners. This mechanical tensioning is less troublesome for first timers than heat shrinking. I have made several panels this way and haven't had any problems so far. I used foam tape to attach the diaphram to the stators. I got this idea from Sheldon who has some good info on his site

www.quadesl.com

Anyway, hope this helps... if you need more info I can try and write up something more specific.
 
So after tensioning the film on the work surface, you apply foam tape to the stator/insulator and stick it down on the tensioned film?

What sort of foam tape are you using? Is the foam tape the only insulation between the stators? When did you first make the drivers this way? Do the first drivers still work?

What are the insulator thickness and bias voltage you are using?

What sort of conductive coating do you apply to the diaphragm?

Thanks,

I_F
 

wrl

Member
2003-01-07 11:01 pm
USA
1) I used the black conductive coating from ER audio.

2)Yep, I just placed the panel/tape assembly right on top of the tensioned mylar. I used 3M foam mounting tape that was 1/16 of an inch thick.

So it goes like Stator:foam tape:mylar:foam tape:Stator.

I think I got a large role (~50 ft) from misterart.com I used perforated aluminum sheet metal for the stators which I then coated with many many thick coats of rustoleum pain to provide some insulation. The foam tape is the only spacer/insulator between the diaphram and the stators other than the paint.

3) I'm not sure of the exact bias voltage I'm using becuase I made it adjustible from 0-4000V. If I had to guess I'd say its probably about 2000-2500V bias

4) The overall setup is similar to the hybrid setup provided in Roger Sander's "The electrostatic cookbook"

-Wes
 

wrl

Member
2003-01-07 11:01 pm
USA
I don't think the tape was anything special... just standard 3M foam mounting tape.

So far my panels are almost 2 years old and I haven't had any problems yet. I built them in New Mexico (very dry) and then moved them here to St. Louis (ridiculously humid) and it didn't seem to hurt anything. I haven't used them in a while though because I'm rebuilding the bass cabinets. The tape has yellowed slightly but appears to be in good condition otherwise.

In anycase, because the panels are removable from the frames it would only take a weekend to rebuild them. And I usually get enough new ideas to want to try something new with them every few years anyway.

-Wes
 
That tape is good for putting them together quickly and getting something working, but I don't like to have to repair things every year or two. When I make them, I want them to work for the next 20 years. That is why I have always avoided that tape (except for a friends science fair project I helped with). I have also always avoided woofers that have foam surrounds. You KNOW what happens to those...

I talked with an apps guy at 3M about 10 years ago and he sent me a sample of scotchgrip 4693 contact cement which is a low surface energy material. The surface of the polyester film is of a moderate surface energy so it needs a low energy glue to properly wet the surface of the film and form a bond. Most glues are higher surface energy than the polyester so the polyester doesn't get wetted and form bonds well.

I tested the cement before building drivers with it and found that the film tore before the glue let go. As far as I can tell, the stuff is permanent. Those 10 year old drivers are working fine with no apparent loss of the high mechanical tension I put on them using the pneumatic stretcher.

I am looking for a source for a small quantity of that glue. There is a thicker version of it called 4693H that comes in 5 oz tubes, but it is an industrial product and no one wants to sell less than a case of 36 tubes.

I_F
 

homemade

Member
2004-07-22 3:42 am
us
use automotive grade

There are several types of 2 sided tape. The stuff that I_Forgot says will crumble is most likely a lower grade without UV protection. I sell automotive supplies(to body shops) and the 2 sided 3M tape for this use is UV protected. I've had moldings and such attached with this tape for 8-10yrs and cannot remember it ever falling off. As far as for speaker use , I will tell you that I'm rebuilding a pair of Electrostatic Research speakers (built in 1996), and they were contructed with this type of tape(no spacers , just tape) and there was zero crumbling. In fact I needed to heat the stators just to get the glue to loosen up , and even than it was still intact. I'm only repairing them because of abuse from the 1st owner. If you are really anla about such things, purchase the urethane grade 2 sided tape(no foam). That should ease your mind. .062(1/16") works very well(either type). Between this tape method and LICRON spray , assembly is a snap. I used these items with Partsexpress Pro speaker grills, mentioned on this site some time back , to great result. I can now assemble a panel in less than a hour.
 

homemade

Member
2004-07-22 3:42 am
us
3M 2 sided tape

Foam tape (white) in 1/2"&3/4" X 1/16" are #'s 06453 & 06454. These are 36 yard rolls. Urethane type in 1/2" X .045 is # 06382. This is a 20 yard roll. They also have this in .030 , #06380. I have used the white foam 1/2" with good results , mainly because of the roll size. You would be surprised how much tape you go through when making ESL's. The speaker I'm rebuilding used this same type(10 yrs old). Hope that helps.
 
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