Panel life?

[zinda]

I keep reading about how ML panels need to be replaced after 15 years? What exactly happens to them at that point? What should I be hearing if they are older than 15 years or maybe 30 years?

When I hear need replacing, I have to wonder exactly why that is or what happens to the sound that would be the reason for sut ch a claim?

I have owned JansZem panels form 1959, 1967 and 1971 and they had remarkable sound. I did a DIY build that used 28 JansZen panels and made my own bass integration with them and after much time testing during covid I had a fantastic sounding 2-way set up using an active crossover. What I found was their is a need for the woofers to overlap the panels. My tests showed the little 5x5" panels were able to play as low as 660Hz and I mixed the woofers at 600Hz to 800Hz with fantastic undetecable results.

Overall sound was 24Hz to 24kHz at reference level with less than 3db difference. Unfortunately they were melted in a fire and I've been looking for a replacement. I had about $1300 involved in last set and had to do some power supply repairs, I was fortunate with the woofers since I have a huge amount of drivers that I've stored up over the years.

So I'm familiar with electrostatics and the magic they can do when they're properly set up and configured.

That brings back to the question of this 15 year limitation that's constantly being mentioned. I noticed that ML uses a very basic type design with perforated plates as stators where others use wires strung across the panels. I figured that was to make the curve easier but wires can do that with a bridge like a guitar.

When I'm listening to MLs what signifies their end of life? This has never been explained, it's like it's said as some type of rule that everyone is supposed to take as gospel and needs to be unquestioned without any explanation of exactly why this is?

What if I find a pair that sound fine and they're over 20 years old and never have had anything done to them? What about 30 years old? Should they be considered to be worthless even if they are still working? This confuses me when this rule is in place.

The reality is they shouldn't wear out, especially when there's nothing that's moving enough to cause wear and wear would appear as a tear in the membrane. Since they don't use wires there's no arcing possibilities or burnt wires causing an open circuit.

The only other thing that could happen is the membrane glue would break down or allow slippage? But why aren't others having these problems with glue especially from 1959? You'd think that glues now will be far more advanced.

Please explain this so it makes sense? Is it simply something that ML has thrown out there so owners will buy new panels, is this ever mentioned at time of purchase?
It seems that ML is the only one that's putting a time limit on their panels.

Are panels even available for older stuff? When did they discover that the panels only last 15 years? There has to be a bunch of obvious problems for owners to report a problem and what were they reporting? It's hard to recognize a slow loss in overall sound and without obvious popping or vibrations I doubt people would be able to tell if the sound has made much change. This is typically only noticed when something has a drastic change in a very short time. Like its no working at all. (Power supply) or a rattling noise at certain frequencies or a dramatic loss in sound volume yet I don't see anything posted as symptoms to look for.

Ty for reading and I'll come back to see what you all have to say on this.

 

[Jazzman53]

I have a theory about what causes some ESL panels to fade over time, which I will share with you.

The old Acoustat panels seemingly never die, although their electronics sometimes burn out. I attribute their panels' longevity to the carbon-black based diaphragm coating. That coating is heavy and opaque, so not suitable for a ML panel which needs to be transparent for aesthetic reasons.

Other brand ESLs have used nylon or vapor deposited indium tin oxide or various other proprietary diaphragm coatings, and some probably hold up better than others.

I'm not sure what ML uses for the diaphragm coating but we know that ML panels can fade over time, and some fade faster than others.

ML alledgedly "fixed" the fading problem by adding a music sensing circuit that de-energizes the HV bias supply when no music signal is detected, whereas previously the bias supplies were energized 24/7 (as long as the AC power cord was plugged into a wall outlet).

ML's "fix" implies that the high voltage bias charge on the diaphragm degrades the conductive coating over time. It then follows that panels with more accrued playing-time should degrade sooner than panels with less playing time.

So; it's not necessarily calendar age, but accrued playing time that determines panel life, at least for ML panels.

 

[Robert D]

I have a theory about what causes some ESL panels to fade over time, which I will share with you.

The old Acoustat panels seemingly never die, although their electronics sometimes burn out. I attribute their panels' longevity to the carbon-black based diaphragm coating. That coating is heavy and opaque, so not suitable for a ML panel which needs to be transparent for aesthetic reasons.

Other brand ESLs have used nylon or vapor deposited indium tin oxide or various other proprietary diaphragm coatings, and some probably hold up better than others.

I'm not sure what ML uses for the diaphragm coating but we know that ML panels can fade over time, and some fade faster than others.

ML alledgedly "fixed" the fading problem by adding a music sensing circuit that de-energizes the HV bias supply when no music signal is detected, whereas previously the bias supplies were energized 24/7 (as long as the AC power cord was plugged into a wall outlet).

ML's "fix" implies that the high voltage bias charge on the diaphragm degrades the conductive coating over time. It then follows that panels with more accrued playing-time should degrade sooner than panels with less playing time.

So; it's not necessarily calendar age, but accrued playing time that determines panel life, at least for ML panels.

Another factor would be related to the membrane bein on 24/7. Being charged, the panels attract dust, because of the static charge. That attracts dirt etc.

One big influence on how long a panel lasts I think is the environment the speakers are played in. Air that's dusty and full of pollutants wears the panel, and then humidity does too..

 

[waynecar]

Another factor would be related to the membrane bein on 24/7. Being charged, the panels attract dust, because of the static charge. That attracts dirt etc.

One big influence on how long a panel lasts I think is the environment the speakers are played in. Air that's dusty and full of pollutants wears the panel, and then humidity does too..

Yes, I agree with Robert's assessment. Much of the panel "deterioration" seems to be connected to environmental conditions. Vacuuming the dis-charged panels
seems to prolong life as well. My 1998 SL-3's needed new panels in 2015, but my manufactured in 2000 Prodigy's are still going strong. YMMV.
Wayne

 

[Jazzman53]

I think I'll stick with my theory on this one.

I also believe that a 20 year old panel that exhibits little or no apparent loss in output is perfectly fine to buy, as there is no reason to believe it will suddenly fade in the near future, just because it's aged.

However, I would never buy a 10+ year old ESL without first checking it, and if a used hybrid ESL sounds even a little bass-heavy, I'm not buying it.

Consider that the bias charge is an electrically corrosive plasma coupled to the diaphragm coating.

High voltage plasmas are used in industry to etch surfaces for adhesion ('corona treating') or even machining metal (EDM).

In an ESL the charge/plasma is dispersed across the diaphragm, and only slowly degrades whatever it touches, over time. However, the surface charge immediately shunts to any shorting paths it finds, and the resuling concetrated arc can burn a hole in the diaphragm (not a big problem) or burn through the insulating coating on a stator (big problem).

Some coatings, like the old Acoustat brush-on carbon-black-in-a-binder coating, are so robust that they last for 30+ years. Other coatings do not.

The bias charge also attracts any dust or other particulate matter in the surrounding air, which can combine with humidity to create shorting paths (to a stator) that drains away charge, resulting in reduced output. In this case; vacuuming and/or shower cleaning can restore output.

However, once a diaphragm coating has been degraded by the corrosive plasma, vacuuming and shower cleaning can't restore it.

 

[mfotiou]

I believe the question was what are the symptoms of a degraded panel? Is it sensitivity loss (eg it becomes quiet?), is it frequency response (eg loss in highs) or both?

 

[Brewnoser]

I believe the question was what are the symptoms of a degraded panel? Is it sensitivity loss (eg it becomes quiet?), is it frequency response (eg loss in highs) or both?

In my experience it was a degradation of highs and detail. Akin to how I know when to retune my amp. A decrease in emotional enjoyment results in me listening less. And when I retune my time spent in front of the stereo returns. The panels I replaced were 17 at the time and the change was very noticeable. They came to life. Anything that degrades slowly is difficult to pin down. To recognize because you become used to it and the aggregated change isn’t jumping out at you. And it’s not like you have a backup set of panels to A-B it.

 

[Brewnoser]

In my experience it was a degradation of highs and detail. Akin to how I know when to retune my amp. A decrease in emotional enjoyment results in me listening less. And when I retune my time spent in front of the stereo returns. The panels I replaced were 17 at the time and the change was very noticeable. They came to life. Anything that degrades slowly is difficult to pin down. To recognize because you become used to it and the aggregated change isn’t jumping out at you. And it’s not like you have a backup set of panels to A-B it.

Retube. Not retune.

 

[DanR]

The big factor I have not seen one person mention here is this. If you find a pair of lets say Ascent-i speakers that are 20 years old and you’re thinking of buying them so you go listen to them and you say wow those sound great why would the panels need to be replaced? Well here is my point, when you listen to the 20 year old speakers you DO NOT HAVE A PAIR OF NEW PANELS to compare the 20 year old panels to, and from everything used I’ve listened to there is a discernible difference the vast majority of the time, my 20 some year old Odysseys were definitely that way. Yep they sounded good with the original
panels, but with the new panels they sound friking superb! A large noticeable difference. I know nothing about the theories as to why they wear out but they do from everything I’ve heard. My Odysseys had one speaker with just slightly less volume output than the other, new panels installed perfect balance. I totally respect Jazzman’s comments he’s put countless hours in with building, researching and understanding electrostatic speakers. This is just my 2 cents worth. Take it for what you will.

 

[Jazzman53]

I'm reminded of my number one beef with ESL manufacturers. That is; they don't make the diaphragms accessible for servicing. This is doable but would complicate assembly a bit (from their perspective; not worth it).

The diaphragm needs to be bonded to one stator (typically the rear stator) but there is no functional necessity for bonding the front stator to the diaphragm-- it only needs to be held in intimate contact, which could be accomplished mechanically by the surrounding speaker frame.

If the diaphragm were accessible, a faded panel could be easily restored to full output by merely cleaning and recoating it.

 

[Jazzman53]

I believe the question was what are the symptoms of a degraded panel? Is it sensitivity loss (eg it becomes quiet?), is it frequency response (eg loss in highs) or both?

Yes, that was the original question which seems to have been lost in the ensuing discussion.

I think Brewnoser's point about needing a reference for A/B comparison is well taken.

A fading panel will have lower output, which may be more noticeable in the high frequencies (remember back in the day when receivers had "loudness" buttons to boost the highs/lows at lower volume?).

A small loss in output can easily be overlooked without a reference, especially in a full range ESL.

In a hybrid ESL, a more noticeable symptom is a bass heavy sound because the woofer overpowers the faded panel.

 

[Daniel M]

I keep reading about how ML panels need to be replaced after 15 years? What exactly happens to them at that point? What should I be hearing if they are older than 15 years or maybe 30 years?

When I hear need replacing, I have to wonder exactly why that is or what happens to the sound that would be the reason for sut ch a claim?

I have owned JansZem panels form 1959, 1967 and 1971 and they had remarkable sound. I did a DIY build that used 28 JansZen panels and made my own bass integration with them and after much time testing during covid I had a fantastic sounding 2-way set up using an active crossover. What I found was their is a need for the woofers to overlap the panels. My tests showed the little 5x5" panels were able to play as low as 660Hz and I mixed the woofers at 600Hz to 800Hz with fantastic undetecable results.

Overall sound was 24Hz to 24kHz at reference level with less than 3db difference. Unfortunately they were melted in a fire and I've been looking for a replacement. I had about $1300 involved in last set and had to do some power supply repairs, I was fortunate with the woofers since I have a huge amount of drivers that I've stored up over the years.

So I'm familiar with electrostatics and the magic they can do when they're properly set up and configured.

That brings back to the question of this 15 year limitation that's constantly being mentioned. I noticed that ML uses a very basic type design with perforated plates as stators where others use wires strung across the panels. I figured that was to make the curve easier but wires can do that with a bridge like a guitar.

When I'm listening to MLs what signifies their end of life? This has never been explained, it's like it's said as some type of rule that everyone is supposed to take as gospel and needs to be unquestioned without any explanation of exactly why this is?

What if I find a pair that sound fine and they're over 20 years old and never have had anything done to them? What about 30 years old? Should they be considered to be worthless even if they are still working? This confuses me when this rule is in place.

The reality is they shouldn't wear out, especially when there's nothing that's moving enough to cause wear and wear would appear as a tear in the membrane. Since they don't use wires there's no arcing possibilities or burnt wires causing an open circuit.

The only other thing that could happen is the membrane glue would break down or allow slippage? But why aren't others having these problems with glue especially from 1959? You'd think that glues now will be far more advanced.

Please explain this so it makes sense? Is it simply something that ML has thrown out there so owners will buy new panels, is this ever mentioned at time of purchase?
It seems that ML is the only one that's putting a time limit on their panels.

Are panels even available for older stuff? When did they discover that the panels only last 15 years? There has to be a bunch of obvious problems for owners to report a problem and what were they reporting? It's hard to recognize a slow loss in overall sound and without obvious popping or vibrations I doubt people would be able to tell if the sound has made much change. This is typically only noticed when something has a drastic change in a very short time. Like its no working at all. (Power supply) or a rattling noise at certain frequencies or a dramatic loss in sound volume yet I don't see anything posted as symptoms to look for.

Ty for reading and I'll come back to see what you all have to say on this.

It would seem to me that the environment in which the speakers are used, stored or exposed to would be the biggest factor on the longevity of panels. Seems no one here has taken that into consideration the climate of the HT room. IE Dry vs humid climate , dusty or clean, dog, cat or animal dander, smoke cigar etc. the use of air purifiers . et all...I will have a large air purifier going in my HT room once its complete. Just to be sure I will protect my ML- ESL 11A s, C .and REL 1205s. especially being on the floor. I live in a humid and very warm Houston climate.