New mylar on Sequel II - Project description - diyAudio
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Old 21st June 2012, 06:30 PM   #1
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Default New mylar on Sequel II - Project description

Hello all,

Since I posted my last thread about mylar tension on the Sequel IIs, I have finished applying new mylar to both panels. Here are some pics and descriptions of what I did.

1. Take off ripped mylar and old double-sided foam
tape. A heat gun and a plastic or nylon scraper works great on the foam tape. The plastic scraper won't damage powder coating.

2. Clean old panel. I used AutoTech Quick-n-Easy Specialty Adhesive remover from McMaster-Carr. Use only in a well-ventilated area. This also will not damage powder coating or paint.

3. Apply new double-sided foam tape, but leave the backing on the mylar side until it's time to mount the mylar. I used Scotch foam mounting tape cut into trips across the stators. I used 3M double-sided foam tape from McMaster-Carr. This stuff is strong enough that glue is not needed.

That's it for cleaning and prep.
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Old 21st June 2012, 07:19 PM   #2
49 - for the 18th time
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Waiting to see sum audio porn photo's of naked speakers and your fix 'em up scheme...

Ahhhhhhhh - I just found your other post on the subject - Thank you for posting.

Perhaps this should be combined into one thread where people can find all of the information in one place?
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Last edited by c2cthomas; 21st June 2012 at 07:24 PM.
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Old 21st June 2012, 07:26 PM   #3
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Yeah, I though about that after I posted....

Moderator, can you move all four posts into one thread? Sorry, I should have thought this put better.
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Old 22nd June 2012, 01:52 PM   #4
cfb is offline cfb  United States
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Perhaps this was covered earlier but what are you planning on using for the conductive coating on the Mylar? It was my understanding that Martin Logan used a proprietary formula but what is known about their process is first a chemical mix based on indium tin oxide otherwise known as ITO and other undisclosed compounds are applied via CVD, chemical vapor deposition, onto the Mylar film. Then a graphite slurry is applied or rubbed in, to fill in any micro breaks in the coating after the Mylar is tensioned. Did you obtain ITO vapor deposited Mylar or were you planning to just use a liquid Nylon mix like the Quad ESL?
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Old 23rd June 2012, 11:58 PM   #5
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Hi cfb,

I'm using Licron Crystal spray this time. I have cleaned and re-coated ML panels with ER Audio's coating in the past which worked well. Jazzman, a frequent poster on this forum, uses the Licron Crystal spray exclusively in his custom designs and it works very well.

I also switched the mylar from 12 micron to 6 micron. I'm not sure why ML used such thick mylar on the Sequels; it may have had something to do with the assembly process twenty years ago.
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Old 26th June 2012, 08:17 AM   #6
Calvin is offline Calvin  Germany
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Hi,

the reason is far simpler......cost.
The ITO sputtered film (sputtered, not chemically treated, no additives, apart from the final slurry treatment) is availably in quantities off of the shelf, since this film Is used in the manufacture of TFT-Displays. A second reason is that the sputtering process introduces heat into the film. Thinner films simply would crinkel because of too much heat. ITO sputtered films (of the supplyer) come in two resistance ranges, around 0.5MOhm˛ and 1.5MOhm˛ which is a rather low value (see threads about THD vers. ohmic value). So, the main reason to use this kind of pretreated film is cheap, cheaper, cheapest production cost.

jauu
Calvin
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Old 26th June 2012, 06:18 PM   #7
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Calvin,
when building curved ESLs, do you find it easier to achieve the required uni-directional diaphragm tension with thicker diaphragm material? thinner? doesn't matter?
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Old 26th June 2012, 06:46 PM   #8
Calvin is offline Calvin  Germany
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Hi,

apart from the ability to stretch thicker films harder and as such to achieve higher resonance frequencies, no matters.
A weakly wimp might find the higher tensioning forces less easy though

jauu
Calvin
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Old 26th June 2012, 06:56 PM   #9
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I was thinking more about the requirement for minimal side to side tension rather than the large top to bottom. I thought perhaps the thicker films used by Martin Logan might be easier to work with since even minimal side to side tension might cause thinner films to pull toward the rear stator.
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Old 27th June 2012, 07:32 PM   #10
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I ran into a tension problem on the first try. 5kgs was too much; the mylar was pulled into the rear stator. 4 kgs worked well. The curved panels also have those foam strips running across the stator about 3-4" apart that helps keep the mylar away from the stator. 5 kgs compressed the foam strips too much.
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