| How thick for MYLAR??? - Click HERE for Original Thread |
| Dominick22 |
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 |
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| Calvin |
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 |
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| wrl |
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 |
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| michaelpage26 |
| Yeah their service is excellent. I live in Greece and I will be buying the ESL 3 kit from ER-audio, so I asked Rob if he could send me a small sample of the 3.8 micron diaphragm. Well he sent me for free 10 meters of it! :bigeyes: :bigeyes: :bigeyes: |
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| I_Forgot |
| quote: | Originally posted by wrl
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.
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How did you tension the film, and how did you measure the amount of tension?
Thanks,
I_F |
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| wrl |
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. |
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| I_Forgot |
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 |
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| wrl |
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 |
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| I_Forgot |
My experiece with foam tape is that it dries out and crumbles to dust in a about a year when exposed to air/light. Are you using some special tape?
What are your oldest panels that use that tape and are they still working?
Thanks,
I_F |
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| wrl |
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 |
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| I_Forgot |
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 |
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| homemade |
| 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. |
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| I_Forgot |
Can you provide part number for that tape?
Thanks,
I_F |
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| homemade |
| 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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| I_Forgot |
Good info! Thanks!
I_F |
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| Loris |
Hi Guys,
Do you know where the "urethane grade 2 sided tape(no foam)" can be found ?
I did some research, but the only thing I was able to found was the "Urethane tape Foam".
Thanks,
Loris |
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| furly |
Do you guys think that 0.045" is thick enough? That is relatively considerably thinner then 1/16" (0.0625"). What would be a safe max. width for a panel using this? or at what distance should extra support spacing be used?
furly |
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| dstockwell |
| I would think that would be enough spacing as long as your not trying to reproduce below 150 - 200 HZ. |
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| jmateus |
I use PVC material for spacers all the time.
It is imune to humidity, temperature, virtually imune to everything.
It's the best material for the spacers.
Want to buy some of it ? |
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| dstockwell |
| What do you use to attach the film when you use PVC spacers. |
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| Calvin |
Hi,
I used to use double sided tape made to glue carpets. The brand TESA manufactures a strong bond tape in a whitish-yellowish colour called ´universal´ (50mm wide, 25m long). Cut into half the width I used it on 30mm wide PVC with very good results.
jauu
Calvin |
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| el`Ol |
| quote: | Originally posted by Calvin
If You want to build a hybrid with lower mechanical tension You may use a film down to 1/8mil.
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Hello everybody! The talk about cylindrical ESLs in other threads lead me to this discussion about mylar thickness.
I am currently working on dynamic omnidirectional speakers. I am using fullrangers with a treble-dominated frequency response looking to the ceiling and no reflector. I made the experience that for the superior spatial image is essential to have the drivers on the level of my ears. My conclusion is that the most important point about omnidiredtionals is coherence of the direct part of the signal, not the fact that they show so much indirect reflections.
So I believe for a cylindrical ESL it is better to have many segments that are relatively narrow. A membrane with less tension may probably allow to manufacture this construction in one piece.
A good omni is worth any effort!
Greets, Oliver |
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| Capaciti |
Hi el'ol,
segmenting the cylinder has two disadvantages.
1. if you really want to come close to a cylinder you need to arrange a lot of small cells, which will suffer from a high frequency resonance. e.g.
a cell having 2" width will show a resonance @ about 400-800 Hz, even with low tension.
2. Cells which are angled to each other will show the venetian blind effect, which lead to significant interferences of higher frequencies, causing a lot of ripple in response. Could be that the omnidirectionality is ditributing those effects.
since 10 years the cylinder-ESL is in my mind . Maybe igonna try it. I am sure that the imaging will be breathtaking.
capaciti |
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| Capaciti |
hi folks,
regarding membran material, there is a new material called teonex, which is considered to outperfrom mylar.
Look here :
www.dupontteijinfilms.com/Teonex/Brochure/2.htm
Hi Calvin,
i read your post regarding your curvilinear panel. It would be interesting to see some frequency response measurements depending on the off-axis angle. I expect it to be very homogeneous between -10 and +10 °, with an significant loss of level @ larger angles.
my segmented panels are designed the same way. I intentionally try to have a good dispersion within +/10 °,which reduces at larger angles. imo too much dispersion is worse, since the first wave energy is reduced and wall reflexions are increased. As long you have sufficient dispersion in between the speakers base witdh, its OK. There is no need for further dispersion.
capaciti |
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| wrl |
From what I've read, segmented cylindrical panels will tend to suffer from a "venitian blind" effect. This makes sense when you consider how strongly traditional panels beam... especially in the high frequency. It would be difficult to get around this affect.
What angles were you looking to offset each segment?
-Wes |
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| Calvin |
Hi,
even with 2 of my curved panels placed side-by-side togeteher I can clearly hear and measure the venetian blind effect. With an array of flat panels it should be even more distinct. That leaves You with the problem of producing a truely 360° circular. How´s about a elliptical shape with two curved panels facing each other? The panels could be connected and the space between them be sealed by frame that holds both panels. The sound pattern would be changed from a dipolar cylindrical shape to a bipolar one. The ´cabinet´ could provide for some damping mechanisms as suggested earlier.
Still, I doubt that it´ll be possible to handle the reflection problem with the backside sound waves sufficiently. The lower the freqs the bigger the prob.
While a unidirectional speaker has its merits and friends, there are a lot of people -me included- who prefer a highly directive sound pattern. A cylindrical sound pattern is imo the best for a lot of rooms, because the nasty early reflections from the rooms sidewalls, ceiling and ground are minimized, thereby emphasizig on precize location of soundstage and fine dynamics (resolution of details). Of course is this concept less good for occasional istening, but on the other hand industry provides us with cheap dynamic speakers for ceiling or inwall use for this application :D A second advantage is the the more constant soundpressure over distance than with global patterns.
jauu
Calvin |
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| el`Ol |
| quote: | Originally posted by wrl
From what I've read, segmented cylindrical panels will tend to suffer from a "venitian blind" effect. This makes sense when you consider how strongly traditional panels beam... especially in the high frequency. It would be difficult to get around this affect.
What angles were you looking to offset each segment?
-Wes |
J thought about twelve 50mm segments.
Here are the frequency responses of a 50mm fullranger at 0 and 30°. Beaming doesn`t seem to be a big problem at that size. The problem that remains is to find a material with far less tension than mylar. I considered a nylon/latex compound in an other thread but I have strong doubts about linearity.
http://www.ejjordan.co.uk/drivers/jx53.html |
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| Capaciti |
Hi el' ol,
you cannot compare directivity of the 50mm jordan to that of a 50mm ESL-stripe. The jordan's effective sound radiating diameter decreases with higher frequencies, while a ESL-membran do not.
A 50mm ESL-stripe will start to roll-off at about 2000 Hz and should have a level drop of more than 20dB at 20000Hz (30° angled).
capaciti |
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| I_Forgot |
Bad link...
Try tinyurl.com
I_F |
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| Bazukaz |
Hi,
Today i have found a roll of film that is used to pack flowers.
I heard that it is made from Mylar.
It is about 16 μm thick , according to my calculations.
I would like to ask how big is the difference in sound , comparing 5 μm and 16 μm mylar ?
Lukas. |
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| furly |
Sorry about the dead link, but just copy and paste and it works fine.
furly |
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| Capaciti |
hi bazukaz,
16µm is a bad choice, since it will compromise high frequency response. To reach 20Khz, 12µm is the limit. Some people say, you will hear improvements the thinner the mylar. 4-6µm is a good compromise between lightweight and appropriate tension.
capaciti |
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| Lucius |
| quote: | Post #35
hi bazukaz,
16µm is a bad choice, since it will compromise high frequency response. To reach 20Khz, 12µm is the limit. Some people say, you will hear improvements the thinner the mylar. 4-6µm is a good compromise between lightweight and appropriate tension.
capaciti |
Further up this thread you list a new film "teonex". In the range you're talking they
have 12.7µm down to 1.5µm! Also I see the same manufacturer makes "Type C Mylar" also 12.7µm - 1.5µm! Type C is what Roger Sanders always advised to get but lamented that you could not buy below 12.7µm...But how to get in small amount?
Lucius
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| Capaciti |
Hi lucius,
there is no need for "C" quality. C is just a calibrated type with lower tolerance on thickness, but standard is not worse.
You can either use "Mylar" or the german brand "Hostaphan". its the same material.
Take a look at
www.shackman.de.
They sell Hostaphan in 3,5 and 6 and 8µm thickness. In ebay they offer the material for "high-end" pricing. Contact them directly and deal it out.
If you won't be successful you can contact me at
info@capaciti.de
regards,capaciti |
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| Bazukaz |
After i have made my ESL panel , i noticed that some parts of it play considerably loader than others , especially in higher freqencies. Is it a problem of non-uniform coating ? I use graphite.
Also i have found a very interesting HV switching supply.
It is used for luminescence lamps.
It uses 12 V at input and can be adjusted from 180 to 800V.
Costs only 15 Litas(~5 EUR).
Lukas |
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| dstockwell |
| Is 800 volts enough. |
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| Bazukaz |
| U can easily multiply with a diode/capacitor voltage multiplier. |
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| Capaciti |
Hi Bazukaz,
i guess that you have a problem with your coating. What you explain sounds typical. It is not easy to achieve a homogeneous coating by graphite rubbing. It is very important that you rub very strong. You did right if you need a shower after rubbing e.g. one square meter.
Capaciti |
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| Bazukaz |
Thanks for help.
I have read about the following method of coating :
Max. of fish line Nylon is dissolved in a boiling vinegar acid.
One drop of liquid soap is added to around 50 ml of solution.
It is then sprayed on mylar film.
However , i could not archieve uniform surface , even when spraying with a compressor.
Maybe it is because only 70% acid has been used.
Has anybody else used this method ?
Lukas |
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| dstockwell |
| you have a schematic of your hv supply. |
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| Bazukaz |
| Currently i am using the following : |
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| Calvin |
Hi,
we have a ESL-forum here in Germany. One of the members had very great difficulties with the nylon-coating. Under no circumstances did he get any good results, even though he tried several versions (doped/undoped etc.). His coating didn´t stick well to the diaphragm either (he used Mylar or Hostaphan so the material of the foil wasn´t the point). He eventually changed to a coating I suggested him and since then his ESL worked as supposed to. I´d regard to change the coating. There are several recipes to be found that seem to work flawlessly, even highly transparent ones (if that´s a decision criterium).
The only reason I´d use Nylon would be to rebuild a Quad with the original sound. In any other case...no!
jauu
Calvin |
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| MJ Dijkstra |
Hi,
There are many kinds of nylons (polyamids). Some will dissolve in formic acid, others need phenol to dissolve. Both are toxic, especially phenol. Phenol has very low LD50 and can be absorbed through the skin. (one gram phenol can be lethal!)
You should be aware of the properties of the chemicals you're using. If not, don't do it!
The use of soap is to lower the resistance. Pure nylon has a too high resistance for many esls. Unfortunately, the soap molecules tend to migrate to the surface and leave the coating.
There will be some more problems with the recipe you've mentioned, conclusion: not recommended.
Please check the audiocircuit (www.audiocircuit.com), go to electrostatic loudspeakers/materials/coatings.
Here you will find my EC-coating too! |
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| Lucius |
| quote: | Post #37
there is no need for "C" quality. C is just a calibrated type with lower tolerance on thickness, but standard is not worse.
You can either use "Mylar" or the german brand "Hostaphan". its the same material.
Take a look at
www.shackman.de. |
Capaciti,
Thanks for the site. A little difficult to get on and move
about but nice place to visit plus the foils they had.
In the meantime I can get a roll of 46 gauge (11.7)µm
400mm x 300m PVDC (saran) for a good price.
I'm thinking maybe my older ears won't value the thinner
films. Although I seem to be the only one looking like a
madman cupping my ears when an ambulance whizzes by.
Lucius |
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