I was able to sell my Theater i for about $650 if I remember right. Definitely made sense to me to sell. I used that toward the $3000 for a new Focus.
Panel rebuild guide?
- Thread starter Jazzman53
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Based on ML lack of any support for the Theater center channel speakers there will likely be a market for a refurbishing service. I don't think I'm that person, however, I'd be willing to inquire some details of how to diy directly from ML if they are willing to play ball since they won't take on the responsibility themselves. I suspect there's a decent market for this with most of these speakers at 20+ years old by this point.
This could be a means for an experienced diy-er to find a niche market and make a few bucks on the side. I'm probably not that person having zero experience with electrostatic builds/refurbishment, but based on Jazz mans input, it seems like something that can be done and with practice attain results nearing 100% equivalent of a new panel. The centers have a lot of double sided tape that needs to be studied for geometry, material, and purpose/intent. The means to attain appropriate "tension" would also need some study and guidance, preferably directly from ML design "drawings". A method to safely disassemble an old panel without ruining the parts needed in the rebuild would also be necessary.
If we could get a few old panels that have already been replaced back when ML still supported replacements, that would be the key to figure this out as it'll take a couple of iterations at a minimum to work out the kinks (figuratively and literally).
Again, I'm not the right person for the job, however I do think a team of a half dozen people bringing resources and knowledge together could achieve the intent, which would be to develop a process and tools to rebuild ML centers no longer supported by the company.
Now, the hard part....finding someone who's willing to take this on and lead the effort. It's no small task.
Thin stators could easily be damaged (bent) by prying them apart. But if the panel is dead anyway, there is little to lose.
Rather than prying the stators apart, I would attempt to saw thru the adhesive bond lines using 80-pound braided fishing line strung on a bow. I would start at a corner and saw perpendicular to the curvature.
If the panel edge-spacer/adhesive is urethane foam tape only, a string saw will cut thru that easily.
In addition to whatever type of edge spacers are used, I see in photos of the Theater panel [at least] two clear plastic horizontal spars in the center of the panel. These bond lines are no doubt a clear non-foam adhesive tape that would be not as easy to cut thru with a string, but since they are not very wide, perhaps it's do-able.
If the panel edge-spacers/adhesives are hard shims sandwiched between non-foam type adhesive tapes, those bond lines would be about 1" wide and difficult to cut with a string saw, but perhaps do-able.
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Since I stuck my foot in my mouth by starting this thread;
If someone wants to send me a Theater panel, I will attempt to disassemble and rebuild it, and document the process. Just PM me.
If the rebuild is not successful (i.e. damaged stators or panel doesn't play at full volume after rebuild) there will be no charge other than shipping.
If the rebuild is successful (i.e. panel plays at full volume), the owner agrees to reimburse actual cost for the materials used, plus return shipping. If the required materials happen to be materials that I already have on-hand (6-micron Mylar, 1/16" foam tape, Licron Crystal ESD coating) I would donate those at no cost.
There would be no charge for my labor in any case-- call it my contribution to the cause.
I have no desire to go into business rebuilding panels, so I will only agree to rebuild one Theater panel, and post the results.
Rather than prying the stators apart, I would attempt to saw thru the adhesive bond lines using 80-pound braided fishing line strung on a bow. I would start at a corner and saw perpendicular to the curvature.
If the panel edge-spacer/adhesive is urethane foam tape only, a string saw will cut thru that easily.
In addition to whatever type of edge spacers are used, I see in photos of the Theater panel [at least] two clear plastic horizontal spars in the center of the panel. These bond lines are no doubt a clear non-foam adhesive tape that would be not as easy to cut thru with a string, but since they are not very wide, perhaps it's do-able.
If the panel edge-spacers/adhesives are hard shims sandwiched between non-foam type adhesive tapes, those bond lines would be about 1" wide and difficult to cut with a string saw, but perhaps do-able.
***********************************************************************
Since I stuck my foot in my mouth by starting this thread;
If someone wants to send me a Theater panel, I will attempt to disassemble and rebuild it, and document the process. Just PM me.
If the rebuild is not successful (i.e. damaged stators or panel doesn't play at full volume after rebuild) there will be no charge other than shipping.
If the rebuild is successful (i.e. panel plays at full volume), the owner agrees to reimburse actual cost for the materials used, plus return shipping. If the required materials happen to be materials that I already have on-hand (6-micron Mylar, 1/16" foam tape, Licron Crystal ESD coating) I would donate those at no cost.
There would be no charge for my labor in any case-- call it my contribution to the cause.
I have no desire to go into business rebuilding panels, so I will only agree to rebuild one Theater panel, and post the results.
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Update April 1, 2024:
Not an April Fool's joke...
Someone took me up on my offer, and I've just finished rebuilding a ML Theater panel. I will be posting a step-by-step procedure shortly so stay tuned.
Not an April Fool's joke...
Someone took me up on my offer, and I've just finished rebuilding a ML Theater panel. I will be posting a step-by-step procedure shortly so stay tuned.
I eagerly await the guide! My Theater has been sitting on a shelf unused for the past few months awaiting its fate. A rebuild could be in its future!
At this time, I'm not interested in doing this as a business but i'm happy to share the know-how. I can't post the Theater panel rebuild-guide here apparently, so I may add it to my speaker blog (Jazzman's DIY ESL Page) and post a link to it here.
The first attached photo shows me verifying the diaphragm tension using a simple shop-made beam & cantilever deflection gauge. The second photo is testing the rebuilt panel's output level using a 1kHz test tone.
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Oh, I would be doing it myself, but only if a guide existed showing it can be done. I don't dare tear that thing open without the having everything I need to rebuild in hand. I'll go look up the post on your page. Thanks!
As promised... the rebuild guide is posted here:
https://www.martinloganowners.com/t...nter-channel-panel-rebuild.19972/#post-212648
https://www.martinloganowners.com/t...nter-channel-panel-rebuild.19972/#post-212648
Mark F
Active member
Jazzman, you seem pretty knowledgeable about ESL panels and rebuilding them. Do you understand root cause of sound degradation in older panels? Is it due to accumulation of dirt / dust on the old mylar or from the conductive coating burning off over time?
My question is really how complex it would be to rebuild tired Sequel II panels. Speakers are from 1995 and still functioning with original panels except for loss of acoustic transparency and lower panel efficiency. Lots of posts discuss removing Cu electrical contacts, replacing spars, updating film, etc. My question is if one were to successfully separate the top and bottom stators without damaging the film, would it be possible to just clean the existing mylar and simply re-coat with licron crystal spray? Current panels are only held at top and bottom edges and it looks feasible to cut the adhesive tape with an exacto knife to separate the stators without damaging the film.
Am I underestimating the complexity of such a project?
My question is really how complex it would be to rebuild tired Sequel II panels. Speakers are from 1995 and still functioning with original panels except for loss of acoustic transparency and lower panel efficiency. Lots of posts discuss removing Cu electrical contacts, replacing spars, updating film, etc. My question is if one were to successfully separate the top and bottom stators without damaging the film, would it be possible to just clean the existing mylar and simply re-coat with licron crystal spray? Current panels are only held at top and bottom edges and it looks feasible to cut the adhesive tape with an exacto knife to separate the stators without damaging the film.
Am I underestimating the complexity of such a project?
Mark F
Active member
Hi Mirolab, Did you ever find a home for your tired SL3 panels? I'm considering starting a science project to try and rebuild my tired Sequel II panels. Are the SL3 panels just tired or is the mylar film damaged?
Hi Mark,
I've built quite a few flat-panel ESLs but my experience with curved panels is limited to the one Theater panel I recently refurbished, so keep that in mind when considering any advice from me.
If the panel still plays, but it's volume decreased slowly over time, you can rule out the bias supply and transformers.
The reduced output could result from shorting paths draining charge off the diaphragm faster then the bias supply can replenish it, and/or the diaphragm coating has lost conductivity over part or all of the panel's area.
If the loss is due to shorting paths from dirt buildup, and there is no degradation of the coating otherwise, shower cleaning can partially or completely restore output.
If the diaphragm coating has lost its conductance, restoring output will required a fresh conductive coating.
If the diaphragm is intact after disassembly, cleaning and re-coating it, and then replacing the periphery charge ring, will completely restore output.
If the diaphragm must be replaced, it's possible to save and re-use the underlying spacer/adhesive.
The rear stator spacer-tape will be pristine & tacky after ripping off the diaphragm, and easily reusable.
The front stator spacer-tape will likely be contaminated with fingerprints and residue from the charge ring, but can still be reused by wiping with IPA and, if needed, applying a layer of 4-mil double-sided tape, as I did on the Theater panel.
The 4-mil clear tape that bonds the front-stator spars to the diaphragm will probably be damaged by dis-assembly, and will have to be replaced. I also applied a layer of 4-mil d/s tape on the front stator spacer-tape to restore it's tack (for re-bonding the panel).
I would build a jig to support the rear stator in contoured condition, when tensioning the diaphragm film. My jig and method are explained in the Theater panel rebuild thread here:
https://www.martinloganowners.com/t...nter-channel-panel-rebuild.19972/#post-212648
Mark F
Active member
Hi Jazzman,
Thanks for the quick and articulate reply. You mentioning the need for "build(ing) a jig to support the rear stator in contoured condition, when tensioning the diaphragm film". Suppose that's the part I was hoping to avoid.
Are you suggesting disassembly of 29 year old panels will likely result in damage to the film or that the film would have lost tension over time such that replacing and/or tensioning the current mylar will be necessary? Is double sided adhesive used to secure the front stator to the film at several points or just at the top and bottom of the panel? I was hoping the front stator would lift cleanly from the mylar once adhesive at the top and bottom of the panel is cut with an exacto knife.
Cleaning and re-coating the current mylar is within my abilities but replacing / re-tensioning new film is pushing the limits of my skill set.
Thanks for the quick and articulate reply. You mentioning the need for "build(ing) a jig to support the rear stator in contoured condition, when tensioning the diaphragm film". Suppose that's the part I was hoping to avoid.
Are you suggesting disassembly of 29 year old panels will likely result in damage to the film or that the film would have lost tension over time such that replacing and/or tensioning the current mylar will be necessary? Is double sided adhesive used to secure the front stator to the film at several points or just at the top and bottom of the panel? I was hoping the front stator would lift cleanly from the mylar once adhesive at the top and bottom of the panel is cut with an exacto knife.
Cleaning and re-coating the current mylar is within my abilities but replacing / re-tensioning new film is pushing the limits of my skill set.
I don't know what you have.
If you deem your panels unusable as-is, then there is not much to lose by dis-assembling one to find out what it needs for restoration. No one can advise you on that... it's your call.
On the Theater panel, the stators were bonded together around the entire periphery, which was necessary because the Theater panel is not enclosed within a frame-- it attached with velcro on the backside. Your panels may or may not be bonded around the entire periphery.
Separating the periphery bond lines is not too difficult.
It's likely the front spars are bonded to the diaphragm, and this is the risky part of trying to save the diaphragm.
You may get lucky and the front stator just pops off when you start prying. Otherwise, you will have to use a string-saw.
There's a fair chance of saving the diaphragm if you get the string inserted and cutting lengthwise on the panel, between the diaphragm and front spars.
I always assume the worst case, though, which would be having to replace everything but the stators.
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I'm over 70, retired from building ESLs and have moved on to other things. I was happy to post the Theater panel rebuild but I don't want to make a business of it.
Mark F
Active member
Current Sequel II panels are in use but 29 years old such that efficiency is lower then woofers. Have ordered a Crown 1002 amp to allow biamping and powering woofers separately to help balance bass with panels. If this fails, will need to either purchase new panels or service / improve sound of my panels.
Already had them in the shower which helped acoustic transparency but didn't do much for efficiency.
During disassembly for showering, it was noted that panels are only attached at the top and bottom. Left and Right edges seem to separate easily although they were clamped during shower as my intent was not to have them come apart during cleaning. Could disassemble again but my gut says the front stators are not attached to the mylar except at panel top and bottom edges. Assuming this to be the case, I envisioned using an exacto knife to cut adhesive foam at top and bottom and the front stators would fall off.
Perhaps I'm being optimistic? String saw is a good idea.
Might reach out to ML and get lead time on new panels. Doesn't seem like re-coating is a sure thing and one should be prepared to purchase replacements if rework goes wrong.
One last question... Would you remove the current coating before applying fresh Lycron Crystal? If so, will ethanol remove the ML conductive coating or is something more aggressive needed? Can the ML conductive film just be left near the copper contact strip or is it necessary to remove the strip and replace as part of the re-coating process?
As a weak panel loses output over time, there is a tendency to compensate by cranking up the amp. If pushed hard enough, the transformer will short-out, and possibly take out the amp with it.
A string-saw made from 50-lb braided fishing line will cut thru an acrylic adhesive glue-line with efficiency.
I've seen photos of some ML panels with a copper foil charge ring, but the Theater panel's charge ring was some kind of fabric tape impregnated with aluminum powder. When I separated the stators, part of the charge ring stuck to the font stator tape and part of it remained stuck on the rear stator. Scraping the remnants of the charge ring off the front stator tape left a lot of powdered aluminum residue that reduced the tackiness of the spacer tape. The portion that remained on the rear stator came off with the diaphragm (I replaced the diaphragm).
If your panel has a copper foil charge ring, it can be peeled off the diaphragm in one piece. If it's the powdered aluminum stuff, you will need to wipe it off with acetone or IPA (assuming you save the diaphragm).
If you can save the diaphragm, you might try acetone on a corner to see if it will remove the coating. If not, it can stay on, just solvent clean it with IPA before applying the Licron.
Also; before applying the Licron, you will want to mask off about a 3/16" width of the diaphragm's periphery because we don't want it to conduct out to the stator edges. You will also want to mask over the spars-- a 1/2" wide strip of blue painter's tape centered over each spar will be about right. Masking over the spars would prevent charge finding a leak path to a stator via the spar edges (dust buildup there) and also prevent a higher charge concentration there (because charge moves to areas closest to the stator).
There is a video on my website showing me applying the Licron coating on one of my wire panels.
The charge ring goes over the Licron coating. The bias supply wire would be soldered to the copper foil, and the foil would then be applied with its conductive adhesive side contacting the diaphragm coating.
If you want to give it a go, and you end up having to replace the diaphragm, send me measurements of your panel (length, point-to-point width, and depth of the curve -- to enable me to reproduce the curvature in CAD) and will draw you a jig like the one I used, which worked perfectly.
Then all you have to do is reproduce the same diapragm tension (which you will have measured by deflection before stripped off the old diaphragm). I will give you a sketch of my simple deflection gauge, which is pretty easy to make.
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Mark F
Active member
Hi Jazzman,
Thanks for all the guidance and narrative for ESL panel repair. Will remove my panels and inspect whether the front stator is attached to the mylar with 2 sided tape at the spars or if the front stator is only secured at the top and bottom. Think its the latter.
One more question... If mylar is taped off as you describe, it would create "islands" of of Licron static coating isolated by non-coated areas. Am I understanding that right? If so, how does the charge find its way to the islands?
Cheers,
Mark
Mark F
Active member
Hey Jazzman, Just found your webpage. Should have looked there first, lots of good information within. Will need to disassemble the Sequel II panels to understand if the copper foil covers the perimeter of the mylar. Its only visible at the single contact point so my one dimensional brain couldn't envision it along the entire edge.
By the way, nice pic with Mr. Carver. I live in WA state near Lynwood where he used to manufacture. Have an old M-500t amp and C1 preamp but it doesn't have long enough legs to drive electrostats. But his "new" Sunfire stuff definitely does.
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Cheers, Mark
By the way, nice pic with Mr. Carver. I live in WA state near Lynwood where he used to manufacture. Have an old M-500t amp and C1 preamp but it doesn't have long enough legs to drive electrostats. But his "new" Sunfire stuff definitely does.
.Cheers, Mark
Yes, you would have coated islands connecting to the charge ring on both sides, as shown in the sketch below.
Note that the spars are unevenly spaced to breakup the diaphragm's drum-head resonance into multiple smaller peaks. When you are measuring the deflection to gauge the diaphragm tension, pick one window and measure the deflection in the middle of that window. It doesn't matter which window one you choose, only that you measure the same window when tensioning the new diaphragm (if you have to replace it).
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The sketch shows how the diaphragm was coated in the Theater panel. I understand why ML did it this way, and I would guess most panels are configured this way. There's no real loss of output where the coating was omitted because the diaphragm is anchored and can't move at the spars. The omitted area also acts as a fire-break, preventing charge from reaching the spars and finding a leak path to a stator, which might otherwise happen if there were a dust buildup along the spar edges.
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