Repanelling ML Clarity's

[neil5m]

Hi Guys

I'm planning to repanel my ML Clarity's this month. I originally intended to separate the stators and recoat the Mylar as LeeThomas (Forum member) had done on his Sequel II. Unfortunately I ripped the Mylar on both panels, so now have to repanel them. I'm in touch with Rob of ERAudio and he's been very helpful. I wonder if anyone knows the thickness of the 3M tape holding the panels together. i.e. the tape on the front panel and the rear panel. Any ideas on how to measure the width? Would I have to buy a pair of callipers?

I intend to post pictures and youtube videos of the rebuild

Cheers!
Neil

 

[CLIFF]

Hi neil,get back in touch with rob at er audio, he has a good idea of the sizes,i think from memory it was 2 mm thick.width doesnt matter ,as long as it all fits in the space. Going to do mine in a few months, also got the kit from er audio dreading pulling them apart!!

 

[neil5m]

Hi Cliff, The black VHB tape (measured from the side) is 1mm. . it differs across diff models.

Separating the panels is not tough. Initially, I tried to pry apart the panels with a small knife while using small wedges to hold the stators apart. This resulted in the Mylar tearing. Following Rob's advice on the second panel, I used a cotton swab drenched in alcohol and squeezed it over the top edge of the stator onto the front stator tape. I made small shallow stabs along the edge of the from stator tape with a knife for the alcohol to soak into the tape and then after, through the stator holes onto the spars. The idea was to dissolve the glue holding the panels together. To my relief, the stators came apart very easily after. So its not tough to do! If your mylar is intact, just coat it, unless you want to rebuild.

I just finished making the jig today. I cut the headboard using a normal saw (that took time). Otherwise, putting it together wasn't tough. I'll send a picture tomorrow.

Neil

 

[CLIFF]

Hi neil bear in mind, if you are measuring existing tape on a just pulled apart panel, that there will be a certain amount of squish in the tape, it wont rebound back completly to its original size, if you get it wrong the mylar will hit the stator,
when i do mine i think i will sit each panel end in a tub of metho for a day each, before pulling them apart.
Another thing, i believe the mylar from rob is about half the thickness of mls,so keen to see if they sound faster ,or different to the original mylar .cheers cliff.

 

[neil5m]

Cliff, I though that would be the case so I measured the tape at the sides of the panel which aren't glued together (only the top and bottom are taped together). Since they weren't glued together, I assumed the squish wouldn't be there. Unless the panel frame does the squishing. The rear stator spars too are flush in line with the tape at 1mm. So I infered that 1mm is the width. What do you think. If I go with 1.5mm, it will definitely make a difference.

From Jazzman's DIY Electrostatic Speaker Page: Diaphragm/Stator Spacing & Span Between Support Spacers:

Minimal diaphragm-to-stator spacing (d/s) is desirable for highest efficiency because the electrical field strength decreases with the square of the distance. Thus, doubling the d/s spacing would require four times the power input to produce the same volume. For hybrid speakers, as little as 1/16" (about 1.5 mm) d/s spacing can be used but 1/8" (3 mm) or more spacing is needed for full range panels to accommodate their longer bass excursion.

The Cookbook guidelines recommend placing diaphragm supports at spans equivalent to 70-100 times the d/s spacing. I prefer to go conservative and set my limit at 80x d/s for added protection against bass driving the diaphragms into the stators. With 1/16" d/s and 80x max spacing, the span between support strips should not exceed (.062 x 80)= 4.96". Since my 12" wide panels have a span between the edge spacers of 10.5" and I'm adding two 3/8" wide vertical support spacers, I end up with three sections, each 3.25" wide, which is well within the limits, so there is no problem.

Now, Jazzman is talking about vertical spacers on his homebuilt speakers, not horizontal spacers (spars) like on the ML. Assume the logic is the same. Then 1mm d/s spacing x 70 should have a max value of 70mm spar spacing and 1.5mm d/s spacing x 70 should have a value of 105mm spar spacing. I measured the spacing between the spars on the Clarity and they are 66mm (spar2-spar1), 71mm (spar3-spar2),52mm,72mm,71mm,52mm,71mm,66mm (spar9-spar8). Most of the spacing falls closer/within the 1mm d/s x 70 value of 70mm spar spacing from which I infer that the stator spacing is most likely 1mm. True, the spacing also falls within the 1.5mm d/s x 70 = 105mm spar spacing, but nowhere as close as the 1mm d/s for a value of 70mm spar spacing.

What do you think? Rob isn't sure if it is 1mm or 1.5mm. I'll have to figure it out through trial and error!

Ok I thought Rob's Mylar is similar to ML at 6um. I read that the 12um is used for panels which can also output bass. There was an option of 3.5um but I felt it was too thin. Rob suggested 6um. Let's see how it works!

OK I tried to measure the Spar on the rear stator. It seems to be 1mm as well (in-line with the stator tape). See pics

 

[neil5m]

Cliff, this is the Jig I made. The head and footboards took time (didn' have a jigsaw so I cut it using a normal wood saw). The rest was a simple "glue and screw"! it seems stable with the extra screws. I will put a single sided foam tape on the curved edges to protect the Mylar while stretching.

 

[CLIFF]

hi neil,sorry for delay, someone else has played with tape thickness,on this forum.
he went too thin and got buzzing,went up a size or two it was sorted
the jig looks fine!! make sure the edge that the mylar is being streached over, is smooth, no sharp edges. your idea of foam tape, is a good way to go, quick and easy.
might upset your curve, unless you have made adjustments?? maybe??
keep posting ,very keen to see the results.
about to send my oppo of to jtli (joe rasmusson) for mods, next week and after it is returned, and after a good listen, will then repaint my panels,fingers crossed, there will be no rips.
neil, i would go with 1.5mm. its a good size to go up or down in thickness.
have a feeling the other dude, was at 2mm,but not sure,will have a go finding it ,will keep you posted,cheers cliff,

 

[Brad225]

Hi Neil,
The stretching frame good, you might want to put a diagnonal brace in though. Would hate to see you get almost finished and have the frame rack and create a wrinkle in the Mylar.

 

[CLIFF]

hi neil,after reading your main post more carefully,i would go with 1mm as per your spar thickness, for the tape, a little bit of squish might be benificial.
not sure how your panels are attached to the frame?? mine have a pressure strip you push into place. so with mine, the strip will tell me if i have the right, or close enough, tape thickness.
cheers cliff

 

[neil5m]

Hi Neil,
The stretching frame good, you might want to put a diagnonal brace in though. Would hate to see you get almost finished and have the frame rack and create a wrinkle in the Mylar.

Hi Brad, you mean fix little triangles at each corner to stabilise the frame? Or a long beam from headboard corner to the diagonal footboard corner? If its the first option, I will do that. If its the second option, then would I have to brace it like an X-shape with two beams? Wouldn't it block the panel from being inserted once the Mylar is tensioned.
I had assumed that using strong wood glue and screwing the long beams in a slant (see the screw holes in picture 3) would stabilise the frame. However you may have a point as on screwing into the long beam wood, I noticed it was soft and light and could possibly bend under tension.

 

[neil5m]

hi neil,after reading your main post more carefully,i would go with 1mm as per your spar thickness, for the tape, a little bit of squish might be benificial.
not sure how your panels are attached to the frame?? mine have a pressure strip you push into place. so with mine, the strip will tell me if i have the right, or close enough, tape thickness.
cheers cliff

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. (updt Mar2020: I've reverted back to 0.6mm as I learned the distance affects SPL)

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

 

[CLIFF]

neil,sounds like every thing is going real well.
you get your clear plastic spars ,wherever you find them . once fixed a dishwasher door release with a bit of ally mast of a toy ship.
i am thinking of using the 3.5mm mylar,just to see the changes?? figure i may loose some midrange ,but may gain some air perhaps? whats your guess on this?? at least i shouild be all smarted up enough, to replace it with 5mm-6mm,if it sounds crap,cheers cliff

 

[Brad225]

The brace at each corner would work fine. Make them as large as you can without blocking access to the jig. Run them on a 45deg. angle across the corner.
Look forward to more pics of the project.

 

[neil5m]

neil,sounds like every thing is going real well.
you get your clear plastic spars ,wherever you find them . once fixed a dishwasher door release with a bit of ally mast of a toy ship.
i am thinking of using the 3.5mm mylar,just to see the changes?? figure i may loose some midrange ,but may gain some air perhaps? whats your guess on this?? at least i shouild be all smarted up enough, to replace it with 5mm-6mm,if it sounds crap,cheers cliff

Hi Cliff, from what i've understood, using 3.5um mylar may not change the sound a lot. It may just sound sharper and quicker. I toyed with the idea of using 3.5um on half the panel and 6um on the lower half. Of course, it may not integrate well with the woofer (high crossover at 450hz).

I missed your earlier message about the panel to frame attachment. Mine simply sits in the frame and there are two long dull silver plastic pieces that I have to screw in several places to press the panel to the frame. If you see a picture of the Clarity, the frame has these silver plastic pieces on the left and right. So it doesnt fit into any groove like the older ML models.

 

[neil5m]

Coating

Regarding the Coating, I found a company called Shanghai HuZheng Nanotech on Alibaba and placed an order for the coating (min 1 litre).
The company rep Annie said it was similar to Techspray Licron Crystal which others have used on the forum. I had tried to buy the Licron Crystal online, but it couldn't be shipped internationally being classified as a hazardous good.
Huzheng said to dilute their coating 1:1 with alcohol and it would achieve a resistivity of E7 to E9 and dry to approx 2 microns thick. They said this was a new coating and would last for 10 years at least. I spray tested it on the undamaged portion of the old Mylar after cleaning and it seemed to stick on perfectly (see pics of the iridescent coating). Unfortunately I couldn't test it as the panels were separated. I tried scratching it with my finger, but it stuck on.

After consulting with Rob, I decided to go with his tried and tested coating. This is just a hobby and I don't see myself testing coatings and rebuilding the panels again. I want to do a one time fix and get done with it.

I'm still curious to know what the HuZheng coating is like, so I may use it on one or two strips of the rebuilt panels while coating the remaining strips with Rob's liquid. Do you think this would affect the sound in any way? What are your thoughts.


I have some of the Huzheng coating left, so could send across samples if anyone would like to test it. Let me know.

 

[CLIFF]

hi neil,what a interesting thought, top in 3.5 and bottem in 6. you would maybe run a slightly wider central spar??
i think going to 3.5 only, may stuff up the sound ,since ml uses 5 .the stat may not intergrate very well with the woofer,
but your idea may just allow you to get the best from both worlds!
rob may know where to place the change point between the two sizes,i will check with him when i do mine.
regards the coating, i think there is a chance the two different coatings may not get along, however,they just may be benificial to each other as well. if the chinese one comes off with metho, i say go for it,cheers cliff.

 

[neil5m]

hi neil,what a interesting thought, top in 3.5 and bottem in 6. you would maybe run a slightly wider central spar??
i think going to 3.5 only, may stuff up the sound ,since ml uses 5 .the stat may not intergrate very well with the woofer,
but your idea may just allow you to get the best from both worlds!
rob may know where to place the change point between the two sizes,i will check with him when i do mine.
regards the coating, i think there is a chance the two different coatings may not get along, however,they just may be benificial to each other as well. if the chinese one comes off with metho, i say go for it,cheers cliff.

Cliff, I picked this off the ML Learn page:

The ultra-light, 0.0005-inch-thick polyethylene terathylate (PET) diaphragm is plasma-deposited with a conductive coating in a $20-million, oxygen-free argon environment chamber. This ensures extreme consistency across the diaphragm surface and enables it to accept high voltages without danger of arcing.


The 0.0005 in thickness is 13um. They were describing the X-Stat panels in the article. I'm not sure if they were for the larger speakers, but still it was 13um. Where'd you get the 5um from? Were the smaller models 5um?

One more question: I was reading your older discussion posts on other topics. In one you mentioned tensioning the diaphragm to 2.5 pounds (lbs.). Rob says 2.5kgs. So is it 2.5kgs or pounds?

 

[CLIFF]

hi neil ,went back to the info rob gave me eight months ago ? you are correct ,it is 2.5 kilos .
also had it in my head that the film he gave me was thinner than the mls, this is correct ,and as you rightly pointed out mls is 13um. the film i recieved from rob is 6um,hope this clears it up for you??

 

[neil5m]

Hi, ok so after a hiatus, i'm back on the project.

Taping: I laid out the VHB tape on the stators and also positioned the spars. Taping is relatively straighforward. Similar to the tape when taken apart. I had measured the spar distance (see earlier posts) and positioned accordingly.

Spars: I have rebuilt the spars, sticking the clear acrylic glue tape on either side of the rear and front spars. 9 for each panel. the rear spars are thicker than the front.

Rear Spars: Tape+Spar+Tape = 0.2mm+0.6mm+0.2mm = 1mm
Front Spars: Tape + Spar + Tape + Tape = 0.2mm+0.2mm+0.2mm+0.2mm= 0.8mm
NOTE: When I took apart the panels, it seemed that the front stator was only 0.6mm away from the diaphragm. I took a chance at adding an extra 0.2mm layer of tape to make it a total of 0.8mm. On testing, it worked well, no problem. (updt Mar2020: I've reverted back to 0.6mm as I learned the distance affects SPL)

View attachment 18177

 

[neil5m]

Stretching the diaphragm: Unfortunately I didn't take pictures of the final tensioned diaphragm, but just pictures of stretching part of it. I intend to redo one and then repost this section.

I used 3M duct tape. Widely available and can be torn easily by hand. I put some foam tape on the edge of the jig to prevent the film from snagging and tearing. I used a mechanical weighing scale rather than a digital one. Dont' use a digital one as you can't hold the tension without the digits going crazy!

Procedure:
1) Tape the breadth of the edges of the film to be tensioned before cutting it from the roll. Cut along the tape line as this will prevent the film from tearing and wastage. The film tears so easily!
2) First tape the middle of the film breadth to the middle of the jig and from the other end, do the same while applying tension of 2.5kgs.
NOTE: Don't tape the film to the foam on the edge of the curved portion of the jig, but rather on the flat surface below. In case there are any creases, you could always stretch the film breadth-ways along the foam edge before proceeding with the next tape tensioning.
3) Do the same starting to the right of that middle tape, then tension from the other side
4) Now do the same from the left of the middle tape and tension from the other side
5) Tension the film, taping in a hand-fan shape.
6) To fine tune the tensioned diaphragm, try and pull near the corners of the diaphragm with some tape and see if the small creases go away.
7) Finally tape the remaining loose film along the length of the jig to the jig itself. Do not pull hard as its the longitudinal tensioning that is important and not the breadth-ways tensioning.
Note: The reason to tape the loose length to the jig length is that when lowering the tensioned diaphragm on the stator, it may crease like very tiny lengthways ripples from one spar to the next. Either tape it to the jig to maintain a light side tension, or ask someone else to manually lightly stretch the tensioned film breadthways while lowering it on the stator. I lowered the jig from one side, stretching the breadth on the top, middle and then bottom.