Dissipative polyester film, time for a change?

It´s time to think big.
No more coating, no more resistivity variations, or variations with humidity.
There is some companies making dissipative polyester film with resistivity 10^8
I have been in contact with a seller, and he will come back next week.
Can´t wait :p
My requirement is 3um and 8um and a surface resistivity around 10^8 on both.
3um for QUADs and 8um for something else..


2004-03-25 2:43 pm
Den Haag
would be verry helpfull. BUT, as in a quad 63 there are sections where there is no coating. and there is no coating for a reason, leakage to the frame for instance since the screws go trough the panel into the aluminum frame.

so i could imagine it is usable for some ELS's and would be great, but not for a quad 63 :( i wish it was different since im getting sick of the coating debate :)
Wrine x you are right.. But.
If we remove the way for the charge to go from the film to the screws. And then to the stators. Maybe to use screws in polyamide PA 8 (nylon with glass fiber)

that would be an idea, but what to do in the middle sections ? where the screw is to connect front to back stator. they leave a circle free of coating. But maybe it is possible to get rid of the conductivity ? that would be awesome just clean the spots you dont want to be conductive :)

anyhow you can count me in for a group buy! you prob need to buy allot and im willing to buy allot if needed. if we know more about the product thickness and stretch-ability and how it behaves ofcourse :)
so we might need some samples. looking forward to his reaction.
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2009-10-01 2:25 pm
What is your experience then? With the material itself and not the claims in DS. I believe there's a company that utilize metalized film, actually two, sandwiched (glued) metal inside plastic outside. PET is transparent to gases - that's why wine bags are heavily metalized and coated with polyolefines.
If this would work in a wery large dipole for low frequensies 30-100 Hz I would be happy. A concern is that even though the surface resistivity is high maybe the middle layer metal film will gets charged as well and generate distortion. A low distortion membrane should have very high resistivity as we know. I guess the middle metal foil will be charged from the edges, where the different layer meets... bad bad. I know that Beveridge (Beveridge 2 SW 2 ) solved this and used high conductive metalized foil. I theink they sound very good every where in the room. But when switching over to the QUAD´s the staging is superior... Distortion vice the Beveridge is extremely good, so how did he get away with this? The answer is the different driving principle: http://ansaht.com/uv638jed4/BeverigdeIISW_sch.JPG
inverted esl ? audio on foil. HV on stator. ? but thats not the way to go. distortion wise.

Btw Quad esl 63 has a low resistance. although everyone tells otherwise. every panel i measured i get reading of few Meg 2-5 . thats not enormous and not in the range to counter migration if you ask me. you can even measure it with a crappy multimeter.
dont even need a megger.
I'd be concerned with charge migration through the very conductive central layer. That would make the panel displacement non-linear.

Also good modern coatings are largely unaffected by changes in humidity.

I keep the coating away from the corners and short edges of the panels in the 63's. I also have a small ring of un-coated diaphragm around the support pillar holes in the diaphragm. You need to leave a bit of space around the mounting holes to prevent the shorting of the diaphragm, but that can be a fairly small area.