Repanelling ML Clarity's

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neil5m

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Re-diaphragm'ed Stators
This is what the Stators look like once the diaphragm has been stuck. Let them sit for a few hours on a jib before cutting them off using a hot knife or a soldering iron. Do not cut it with a scissor as it will tear possibly across the stator and ruin all the effort!

Then once cut, fold the remaining film behind the stator and stick it to the double sided tape. Be very careful when cutting the excess film off as it could rip!

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Once completed, stick on the front spars. In the picture below, the backing tape of the clear acrylic tape is red.

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neil5m

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Materials required:

Some of the materials were supplied to me by ERAudio. Rob from ERAudio has been wonderful and its because of him that I even attempted this rebuild.
1) Alcohol and cotton
2) Copper tape
3) Scotch removable tape (no need to cover the spars if you have a steady hand)
4) Anti-static solution to be diluted in distilled water in 1 solution : 0.5 water ratio
5) Connection blocks

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neil5m

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Placing Copper Tape on the Stator

Placing Copper Tape on the Stator

Procedure:
1) Clean the diaphragm with alcohol and cotton
2) Place the copper tape on both sides of the stator as per the picture. Let it run to the length of the stator and then fold it around the edges extending it about 6 inches more. The idea is to terminate the copper tape to the connection blocks at the back of the stator rather than the method of glueing/soldering used by ML.
3) This is Rob's design and seems better.
4) The copper tape has to be isolated starting from the edge of the stator to the back using Kapton or insulating tape. (See diagram). I missed taking a pic, so drew a diagram instead.

Earlier ML design
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Rob's design

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neil5m

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Coating the Panels

Coating the Panels

After diluting the coating, dip the foam brush in and with a continuous movement from left to right, spread the coating in one layer on the diaphragm, covering the adjacent copper tape. Coat it in strips
NOTE: Coat approx 4mm from each spar and also leave at least 4-5mm from the edge of the stator to prevent voltage leakage

Pictures of coated panel

If you look closely near the spars, you will be able to see the coating line. Leave it at least a day to dry after application. I taped the sides of the stator while doing the coating. I managed to avoid the spars owing to a steady hand!

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neil5m

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Joining the Stators

After allowing the coating to dry, I removed the backing tape of the front spars and a little VHB tape backing from the right and left edges of the stator. In case you want a permanent mating of the stators, then remove the entire VHB tape backing.

Press the front stator down after carefully matching the holes.

Sometimes, the front stator may not have the same curvature of the rear diaphragm'ed stator. In this case, use your thumbs to press the middle of the front stator while using your fingers to pull up the sides, effectively slightly flattening it out. Get a friend to help. After matching the holes, press the middle down to the exposed spar and then let the ends go and press down. Clamp the stators for about a hour/two (see the drawing below)

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I read that ML uses a proprietary vaccum process to mate the two stators. I created my own with Vacuum bags. Proved effective!
After about two hours, remove the clamps and leave only the middle rear bar (use a little tape). Put the stators in the vaccum bag (for clothes) and get all the air out. Leave overnight.

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neil5m

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The next morning, I mounted the stators in their plastic frames and switched on the system. The music quality was back. The thinner Mylar (actually Hostaphan) was brilliant and improved transients. Thank you Rob from ERAudio. I guess it will improve once broken in.

I have made a few videos of the process which I will upload to Youtube if anyone is interested in doing their own rebuild.

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neil5m

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Thanks Tosh! It took nearly a month to do. It was absolutely worth it though.
 
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Wildcat Rudy

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I have a similar recoating kit from Rob at ER Audio, but I discovered the mylar was torn in my panels and I have to redo them.

I really don't want to order another shipment from Australia due to the postage and the delay, so I am trying to locate a US source for the film. I can get all the 0.0005" film I can handle really inexpensively, but that would be 12.7 microns. (I believe ML's original spec on the Sequel II was 12 microns, but I know Rob likes the 6 micron film in the MLs.)

I did find some pull scales I can order through Amazon. But I did have another idea. Rather than use a scale, 2.5kg is equal to 5.5 pounds. Why not just make up a 5.5 pound weight, and hang that to get the tension needed? It would actually be more consistent, as you would not be pulling the scale to a target, but would have a repeatable weight to create an even tension, and it could be nudged slightly to even out wrinkles as needed.

The only thing I don't know about, from Rob's kit, is what he means by "diaphragm adhesive" as it is shown as being a 30ml bottle. I will be reusing the old spars.

The one task I am left with is separating the panels. I will have to figure out the rest.
 

neil5m

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That is impressive. It doesnt look overly complex, i think the biggest hurdle to overcome is taking a speaker apart.

Regarding coating the film, are there not films that are already coated which could be used?

I refer to the film for sale at shackman, see
http://reromanus.net/loudspeaker-repair-service/Martin Logan.htm
Yes it's not overly difficult, just time consuming. Separate the panels using alcohol. If you can get alcohol cheap, let the entire panel soak in it. Or soak sponges with Alcohol, plastic wrap it round the panels and give it some time. This will dissolve the glue on the foam tape holding the panels together. A little manual poking and prying apart will be required, but be careful not to bend the panels while pulling apart.

I checked the Reromanus website. None of the diaphragm films are coated. Some are corona-ised for coating to stick better and some are metalized. But none are pre-coated.

If the sheets are precoated, then they would allow the charge to leak on to the diaphragm from the areas that make contact with the stator.
 

neil5m

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It has been three and a half years of dust and humidity since I last coated my ML Clarity panels. The coating seems to have started to fail with very muffled to barely any sound in a humid environment, but a good bit of sound in a low humidity environment (with the AC on). Over the the last three years it worked quite well even in high humidity >65%, but over the last three months, not so. So I assume it needs a re-coat. This time I will use TechSpray Licron Crystal in an Aerosol can. Wasn't the easiest to work with, but i'll comment on it later. Licron Crystal is polymer based and works at all humidity levels (0-100%). Of course, humidity also affects the static charge buildup but there isn't much I can do about that.

Separating the Panels: This was easy as I had only attached a bit in the middle and the sides with double sided tape while leaving the rest of the tape backing on. I used 100% ethyl alcohol and a butter knife. Dripped the ethanol along the spars to loosen the glue so the stators would come off easily. Some of the spars came off, but its an easy fix once my clear acrylic double sided tape arrives.

Some of the mylar was wrinkled, so I used a hot air gun in a swooping motion to iron out the wrinkles. Worked very well, with barely a second of heat on the mylar.

Cleaning the panels: Used the ethanol , rubbed firmly, removed the loose spars. I removed the old copper strip and replaced it. This time I'll have pictures attaching the copper strip in a different way from how ML does it. This way was recommended by ERAudio.

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Spraying the panels: After cleaning, I used cellotape and kapton tape to mask the spars and the top. Mounted the panel vertically and sprayed it in two passes per between-spar-area and immediately kept it horizontal to let the excess drip off. The problem with the Licron Crystal Spray is that its runny and got cloudy in a few areas. I would've preferred a liquid and use the foam brush to spread across. So I kept it horizontal and let it run down the side. Used alcohol to clear the side up after.

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neil5m

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This is what the dry panel looks like. The only mistake I made was to try and clean the spars with alcohol while it was drying. In some areas, the coating had cloudy drip-lines. Otherwise, it dried clear with a slight grey tinge.

After the double-sided acrylic tape arrives, I will redo some of the yellowed spars, rejoin the panels and reattach the copper strip to the terminal blocks as earlier. I will attach pictures of the process in my next post

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neil5m

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So the tape finally arrived. I redid the front spars tape+spar+tape. I found it easier to lay each layer down directly on the panel rather than preparing the tape+spar+tape and then laying it down on the panel.

I then slowly lined up the stator holes together and then pressed them down. I found it easier to do on a glass table with paper on it with a lamp illuminating from below. The paper diffuses the light making it easier to see through the stators and line up the holes. Then I packed books on both sides of the stators and vacuum bagged them for a day. The vacuum bagging evenly distributes pressure on all parts of the stator so the double sided tape can stick properly.

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One the stators have stuck together, begin work on the copper strip. The copper strip goes around the rear of the panel from both the left and the right. The end of the copper tape is terminated to blocks which are then connected to the red wire. Make sure you use the kapton tape liberally to prevent any leakage to the stators.



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neil5m

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Connected the panels back to the speakers and turned it on. Sound quality was excellent, highs were strong. Tested it under normal humidity as well as with the AC on (low humidity). Both sounded good! Will give the coating some time to settle down. Lets hope it lasts!

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neil5m

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Ok its been a few days since I completed the recoating using Licron Crystal in a spraycan. The earlier coating was from ERAudio. Few observations:

1) The sound quality is good! Good highs, everything sounds much sharper, much more forward than earlier.
2) The left panel was about 2db lower than the right, but after a few days, the right panel is down 1db, so the difference is now 1db. No change on the left panel
3) With the ERAudio coating, the music seemed to come from the front as if the singer was large and in front of me. With the Licron Crystal, it seems different, as if the singer is behind somewhere. I have not moved the speakers at all, so maybe its all in my head.
4) There is a high pitched whistling sound coming from both panels if i go really close. I'm not sure what it is, possibly some of the anti-static liquid has come onto the stators causing leakage? Don't know...
5) The Licron Crystal coating is visually more transparent than the ERAudio coating which had more grey.

Overall the recoat was worth it, all back to normal
 
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neil5m

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A week later, all great! The speakers sound great, highs play strong, mids powerful and clear. No db drops anymore. The right panel has settled at 1db below the left panel. The whistling sound from the panels has gone, its quiet now.
The performance drop in a high humidity environment compared to a mid humidity environment is very low. Am very happy with the Licron Crystal Coating. Of course it has only been about 2.5 weeks, so will monitor and report after some time.
 

JonFo

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First, thanks so much for all the detail in this this thread. That's an impressive amount of effort put into preserving / improving your ESLs.

Good to hear the whistling sound diminished/went away, as it could be leakage.

Well done!
 

neil5m

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Hi JonFo, thank you very much for your kind words and apologies for the delayed reply. I've learned so much going through forum posts from you, Roberto, Tom, etc. which made it possible for me to at least try and improve my ESL's.
Unfortunately just last week, my toddler son proceeded to poke two holes through the Mylar, thankfully no damage to the sound or quality. A month on, the licron crystal coating works well with no loss of highs even in high humidity and wet weather.
 
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jacek-k-wawa

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Hi Cliff, yes I agree, I placed an order for 1.1mm thick 3M VHB 5952 tape. It has an acrylic adhesive and will suit both powder coated substrates (the stator) and low surface energy (LSE) substrates (the Mylar). The 1.1mm thickness should squish to 1mm.

For the spars, I bought 0.2mm thickness clear acrylic gel tape with PET backing for some rigidity. There were options of PVC and simply the acrylic gel, but they would squish. Rob suggested the PET for rigidity.

I managed to save all the rear spars, but just a few front spars. The rear spars are thick (I assume 0.6mm) when compared to the front spars at approx 0.2mm (i'm guessing). So I cut out a few replacement front spars from the front clear plastic cover of a bound presentation from work and will use these instead.
For the rear spars: acrylic tape + rear spar + acrylic tape = 0.2+0.6+0.2 = 1mm. If necessary, I will add another 0.2mm layer and press it to flatten it out.
For the front spars: This is a little confusing as it is just acrylic tape + front spar + acrylic tape = 0.2+0.2+0.2 = 0.6mm. I will add layers of acrylic tape till it touches the front stator.

I am awaiting the tensioner and VHB tape before I start the rebuild. All the rest of the materials have arrived!
neil5m,

Just wondering - as per above your orginal spars were 0.6mm (rear) and 0.2mm front and finally you used spars with more thickness (front spar 0.2mm -> 0.6mm).
What is the reason for this? As this triples stator-membrane distance I would expect some audible effect resulting in lower SPL. Can you please let me know how this sounds comparing to orginal ones?

rgds
-jacek
 
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