Why do ML panels die?

[Angela]

And on a final note, I question the appropriateness of one stat manufacturer using a competitors internet forum to espouse the virtues of their speakers and, by inference, criticizing the other manufacturer's speakers.

As I said in the beginning, I wish Roger and Angela the best but, with all due respect, it just doesn't feel right to me.GG

Hi Gordon, I totally understand and recognize your point and believe me that was not my intention here. I was asked direct questions and I was doing my best to answer them. I didn't start it, I just responded ... and then things just took off... and well...it keep rolling along... and I didn't know how to quietly step out without appearing to be avoiding the questions, so I hung in here and got sucked into more... you know how forums get from time to time... you keep thinking the topic is over, but it's not. I have tried my best to graciously bow out of this one.

Here's what I have learned about audiophile forums over the years - things can get what some people may refer to as "heated" or "passionate" or "emotional" ~ but the way I see it, that is how they should be. After all, I think what sets audiophiles apart IS the passion and emotion over the music and the equipment to recreate it...

The members of this site have been so supportive of Roger and his amplifiers and you guys are usually talking about some worthy topics. That is why I check in from time to time. I hope that is OK.

Cheers,
Angela

 

[FoxMulder]

That is why I check in from time to time. I hope that is OK.

Cheers,
Angela

Angela, as far as I am concerned you are always welcome here. I really enjoy reading what you have it say. I also feel that you and Roger make some wonderful product.

 

[westoz]

I started this thread to discuss the early death of many, not all, ML panels.
I have a pair of Requests and 2 pairs of SL3, one of the SL3 was re-panelled a few years ago and the other panels are near death.
I've since found out that the panels CAN be repaired and it is a matter of reapplying the conductive coating.
Since some panels die, others dont I think it is fair to assume that ML's quality control on the conductive coating application is suspect.
It is also probably fair to assume that they have been less than earnest in researching a better coating. And dont give me the lame smoking/humidity excuse because that is what it is- an excuse.
How many panels have been ditched because the mylar simply needed recoating?
What a waste and a poor reflection on ill-considered consumerism and recycling.
You dont know what you have till it is gone.
Anyway I have the materials to repair my ML's (and hopefully improve them) Will post results.

 

[Rich]

Angela, as far as I am concerned you are always welcome here. I really enjoy reading what you have it say. I also feel that you and Roger make some wonderful product.

Totally agree!

 

[Gordon Gray]

Sorry all,

I stand by what I said.

My comments / observations were honest, respectful and well intentioned.

Sorry that most folks seem to have missed my point.

Angela seems to understand.

Again Angela and Roger, my best wishes for your continued success.

Gordon

 

[tonepub]

As every other electrostatic speaker is damaged by smoke and humidity, I'll be curious to see how you've solved this issue.

 

[Rich]

As every other electrostatic speaker is damaged by smoke and humidity, I'll be curious to see how you've solved this issue.

Did you read the white paper Angela directed us to? It provides a little insight. Sounds like the main ingredients are the fact that the stators are not made of perf. metal like ML's but instead of a highly insulated material, and that the conductive coating is embedded in the diaphragm rather than just applied on top of it, which makes it tougher and more durable.

By the way, Soundlabs in their speaker faq states:

Because of the non-hygroscopic nature of the materials used in our speakers, humidity has no measurable effect on speaker performance. We have had speakers in the Far-East for years that are still performing well.

As long as the speakers are not abused like directly exposing them to water, sunlight, excessive heat, or other destructive environmental factors, or over-driving them, there is no deterioration with time. Properly cared for, your speakers should be considered heir-looms.

Perhaps it is just marketing hype, but on the surface at least it seems to belie your assertion that "every other electrostatic speaker is damaged by smoke and humidity."

 

[j beede]

Thanks, but that doesn't answer my question as to why the panels die- giving them a wash only helps in some circumstances, not every panel is resurrected by washing (and yes I did wash my Requests) I suspect that as far as the Requests go they have a definitive lifetime and once it is up that is it.
Again, this panel problem keeps coming up, and if it is not a case of needing a clean, what causes this problem?

I have continuously owned ESLs of one sort or other since 1976. I have had two panel failures in that period of time. One failure was due to leakage--a dc path that resulted in the bias on the diaphragm bleeding away. The other failure was stator separation due to failed two-sided tape.

Myself, I would not allow my ML panels to get wet. The foam two-sided tape and clear edge tape are already a questionable choice in materials in my opinion, and wetting them does not seem likely to extend their operating lives.

I have built basic ESL panels and interfaces from scratch. It was easy and entertaining. I know of no other type of speaker that I would attempt to build myself. FYI: I used graphite powder (lock lubricant) to achieve the desired high resistivity. I sprinkled the powder on the pre-tensioned mylar, rubbed it in thoroughly with lint free cloth then wiped the mylar with clean cloths wetted with naphtha or isopropyl alcohol until no residue was visible on a fresh cloth.

I'd consider rebuilding ML panels if I come up with some ideas on properly tensioning a curved panel.

 

[MPS]

There is nothing macigal about electrostatic panels, well maybe the sound, lol! They are quite old concept of speaker element and one of the most simple ones in principle.
It all comes down to three main issues:

- conductivity, as what kind of treatment or material is being used and how its applied

- insulation, how to prevent any leak current from bringing down stator voltage. High voltage sources attract all kinds of elements and particles which over the time will do their damage. High insulation break point between the stator and diaphgram is relevant. Smoke and grease _will_ eventually create current path unless the whole unit is sealed from enviromental conditions.

- mechanical integrity, well quite obvious but also diaphgram tension plays a role here and will change over the time..

 

[j beede]

Well I checked out Rob McKingley and he can supply materials to resurrect ML panels, funny thing is he only lives 300km from me.
Very much looking forward to doing this- seems such a waste to ditch old tired panels- frankly I amazed that someone in the US isn't supplying materials.

The materials are easily available worldwide and very inexpensive. The problem is properly tensioning the new diaphragms. On a flat ESL tensioning is less complicated and can be successfully done by the DIY'er. The segmentation of the ML panel is the showstopper for me. I don't really care about the resistive coating durability. If I devise a means for tensioning the ML panels I would be experimenting and replacing the diaphragms fairly often anyway--it is part of the hobby for me.

I have stated before that ML's policy of replacing panels versus rebuilding is a puzzle. The ML coated stators are very durable and are excellent candidates for rebuilding. The diaphragm material, spacers and insulators are easily available and very cheap.

 

[Tosh]

Myself, I would not allow my ML panels to get wet. The foam two-sided tape and clear edge tape are already a questionable choice in materials in my opinion, and wetting them does not seem likely to extend their operating lives.

I agree. I suspect that people who hear a difference after showering their panels might in fact be hearing the effect of clean wire connections rather than a difference in the showered panel. (So if one is going to try showering the panels, before detaching the panels, first re-make the wire connections, and listen again. Then if the speaker sounds different after showering, at least you have ruled out dirty connections as a reason.)

Quote from Nelson Pass' 1980 paper on speaker cables:
"Copper and aluminum oxidize quickly and oils from our fingers find their
way to the conductor surfaces, causing poor contact; so on more than
one occasion the dramatic improvement provided by an exotic cable has
merely demonstrated the extremely poor quality of the previous cable's
long neglected connections. Wire connections can age, and anyone
wishing to accurately evaluate the newer cable's improved quality
should first renew the contacts on his current set."

 

[j beede]

There is nothing macigal about electrostatic panels, well maybe the sound, lol! They are quite old concept of speaker element and one of the most simple ones in principle.
It all comes down to three main issues:

- conductivity, as what kind of treatment or material is being used and how its applied

- insulation, how to prevent any leak current from bringing down stator voltage. High voltage sources attract all kinds of elements and particles which over the time will do their damage. High insulation break point between the stator and diaphragm is relevant. Smoke and grease _will_ eventually create current path unless the whole unit is sealed from enviromental conditions.

- mechanical integrity, well quite obvious but also diaphgram tension plays a role here and will change over the time..

A couple comments: The diaphragm is coated or processed to slightly reduce its resistivity. I would not describe film with sheet resistivity of megohms per square as "conductive". When I have treated diaphragms with graphite I measured the resistance by setting two pennies on the treated diaphragm an inch or so apart. Using a DVM I look for >10 MOhms. This is after cleaning the graphite off until the mylar looks clean and clear. Higher resistivity is better. Dirt or dust or smoke or other contaminants lower resistivity and increase leakage. How does treating the diaphragm with some liquid raise the resistivity? Have failed panels had their resistivity measured? If not, how do you know if the resistivity is too high (unlikely) or if you have a leakage path between the diaphragm and the stator(s)? Washing the diaphragm could remove resistivity lowering containments or diaphragm-to-stator leakage paths--but in the case of ML curved panels you run the risk of accelerating the failure of the 2-sided tape and edge sealing tape. Stator voltage is dynamic, the front stator is 180° out of phase with respect to the rear. The diaphragm voltage is static.

NOTE: Aiming a heat gun at a mylar diaphragm can change its tension and resonant frequency (best case) or melt holes in it. I suggest you avoid the heat gun unless you have experience tensioning this way or understand the potential outcomes.

 

[j beede]

There probably is a reason that we are not aware of.

In addition, the revenue stream for panel replacement is, for all practical purposes, totally insignificant for a company of this size.

GG

I wonder what assumptions you are making with respect to cost of sales and margin for a set of CLS replacement panels for $1500. I would have guessed that ML does a pretty healthy replacement panel business. Most ML owners seem to have replaced their panels or plan to do so. Assuming that the fixturing is fully depreciated and that ML does their stator coating in house--I would estimate the materials cost to be about $50 per panel. If the manufacturing is done in Kansas I would assume a burden rate around $25 per hour. If two hours of labor per panel is required that puts us at $100 per panel. If my estimates are close, the replacement panel business has a very nice ROI.

 

[MPS]

I would not describe film with sheet resistivity of megohms per square as "conductive".

Diaphgram sheet is nonconductive to start with and needs to be treaded to become conductive. When this treatment fails, there will be "dead" or "cold" sections in the panel where by there is no acoustic output as has been reported in several cases. Recent (~10years or so) panel have improved treatment which is supposed to be more stable over the time.

 

[Beakman]

I wonder what assumptions you are making with respect to cost of sales and margin for a set of CLS replacement panels for $1500. I would have guessed that ML does a pretty healthy replacement panel business. Most ML owners seem to have replaced their panels or plan to do so. Assuming that the fixturing is fully depreciated and that ML does their stator coating in house--I would estimate the materials cost to be about $50 per panel. If the manufacturing is done in Kansas I would assume a burden rate around $25 per hour. If two hours of labor per panel is required that puts us at $100 per panel. If my estimates are close, the replacement panel business has a very nice ROI.

Add in the financial scheme used to pay for the process equipment and the product price increases.

side question - would replacement CLS panels have the benefits of the latest ML technology, i.e. improved diaphragm life?

 

[robertawillisjr]

side question - would replacement CLS panels have the benefits of the latest ML technology, i.e. improved diaphragm life?

I reently received an e-mail from ML that the mylar in the replacement panels is more robust. Should last longer. they also said that new technology stats and electronics are simply not available.

 

[Beakman]

I reently received an e-mail from ML that the mylar in the replacement panels is more robust. Should last longer. they also said that new technology stats and electronics are simply not available.

Then that's as well as can be expected. I'll keep saving my pocket change. Thanks.

 

[amey01]

Slightly OT, but still interesting, I have not yet heard of any failed new-gen panels. Would anyone care to correct me?

We have certainly had much discussion on an apparent lowering of QC on the new-gen panels, wrinkling, etc. But no outright fails. Correct?

With the oldest of these speakers coming up to six/seven years, that is a looking better than the older ones - which would have had at least a few failures in that time.