Martin Logan CLS panel distortion

Dear Audiophiles,
My original Martin Logan CLS speakers developed harsh distortion at higher spectrum of frequencies (mostly audible at high pitched soprano voices). Distortion disappears at low volumes of sound. Are my panels getting too old (they could be 10 years old, I am a third owner)? Is there a way to clean/tighten them (the panels, not owners ;-)? Your comments and suggestions will be appreciated. Thank you.
There are several threads on this subject if you do a search for Martin Logan.

It is possible that the panels need to be replaced. This is about the expected life, but my Quests are about the same age and still doing OK. You may be able to solve the problem by unplugging the panels and letting them sit for several hours. Then vacuum them. Humidity or smoke can also cause problems.

Good luck and write me if you can't find what you are looking for in a search.

Happy listening.
If you e-mail Jim at Martin Logan he will send you back an E-mail describing the use of a hair drier passed quickly over the panels in an attempt to tighten them and remove distortion. It would be worth trying since you would have nothing to lose if you had to replace the panels anyway (about $800).
are you shure it's not your amplifier?
I a re-posting Jim Power's advice which I think is already in the archives - see below. You can ruin the panel...but it is already broken you may have nothing to lose. Also, you can call ML, give them the serial # on the panels and they can tell you when the panels were built.

There are a couple of possibilities that may be occurring. One would be that the panel is simply resonating because it has perhaps lost a bit of tension. The other possibility is that the clear 'damping strips' have come loose from the backside of the panel. There is a difference in performance between the two.

A resonating panel will only buzz on certain notes and at somewhat higher volumes.
A loose damping strip will buzz at almost any frequency and at any volume.

From your description, I believe that you are hearing a resonance. We fondly refer to the phenomena as "Kazooing" because it sounds like a kazoo. This can usually be improved by heat treatment. All CLS panels are heat treated initially before they leave the factory. Some times with age, they will stretch themselves slightly loose. They need heat to re-tension them. There is a very specific technique to heat treatment. If you wish to try it, Here are the instructions.

There certainly is the risk of damaging the panels by melting a hole through the membrane. Bad thing. If you are careful however, I think you will do just fine.

The heat can be applied with a strong hair dryer. A heat gun may be too extreme. I recommend starting with the heat source about 12 inches away from the speaker. Complete the entire procedure and if it has no affect, move the heat source about 2 inches closer and repeat the entire process. Patience is required.
The heat must be applied ONLY to the side portions of the panel, never in the center zone indicated by the horizontal spars or ribs. The side sections are the 'bass' sections that are about 6 inches or so wide and run from top to bottom on each side of the panel.
The heat must be applied from a constantly moving heat source but at a very slow steady rate of movement. Specifically, start applying heat from the dryer at the top of the panel along the edge of the wood frame moving toward the bottom. Keep the heat source moving at the rate of 1 foot per 3 seconds. Next start at the top again but this time, move inboard just slightly, about 2 inches and make another slow downward pass. Repeat until you are near the vertical spar defining the beginning of the center section.
If you first treated the left bass zone, now do the right bass zone.
If you have a good light source on the membrane, you may be able to determine if it is receiving enough heat to have a good effect. You should be able to see a slight shimmer of the membrane directly under the heat if light is so that you can see the reflection of the light. As you move the heat past, the area that was shimmering will draw tight. I hope this helps.
If all else fails, you can purchase new panels and receive an new 5 year warranty on everything. New panels are $890 including shipping within the US. We accept Visa, MC. Call me if you have any questions or need new panels. (785) 749-0133.

Happy listening!
Jim Power
service manager
Here's a related question - I just bought a pair of used CLSII, they were advertised as new panels, but when I called ML, I discovered that the panels were built in 1989.

I'm also getting distorion, but not sure if the problem is low power, old panels or a combination of both (I'm using 80 watt mono GTA tube amps, this is the low end of ML recommended 80-200 watts). Not sure if I want to invest in both new amps and new panels...any recommendations for inexpensive amps that I could try out with the old panels before upgrading them? or should I just go ahead and replace the panels? Jim at ML said that very few panels of that age are still in use...which might be a good argument for replacement?
Hello Tonnesen - thank you for your answer and forwarding of Jim Power's e-mail. I will attempt "tightening" of the panels in few days.
I will also test my amplifier - need to borrow something more powerful. I am using VAC Renaissance 70/70 so our problem could be related to not sufficient power supply.
Try to examine tubes in your amplifier. If it's old than upgrade or replacement of passive components should probably take place to bring your amp back to tolal balance.
Any opinions on the Anthem Amp 2 200w/channel hybrid for the CLSII? These are available for about $1k (I'm looking for a higher power amp to try out the CLSII).

Tonnesen, definitely try another amp before giving up on the panels. I've been driving my IIZs hard for 11 years, 9 of those with an Aragon 4004 and have had no panel distortion issues, just a flattening/hardening of the sound when I push the amp too hard. Just this week I've been auditioning amps to upgrade the Aragon and discovered that the 150W VTL couldn't even begin to drive the CLSs-- major distortion in the upper mids at moderate listening levels. Too bad since the VTL otherwise sounded pretty wonderful.
Those speakers can really drop in impedance at certain frequencies. So, like others have said - check your amp. You may want to check with Martin Logan to see where those dips occur,(if you don't knwo already) and see if that's where your problem is.
Golden ears,
they can dip and jump to increadibly high impedance.

The best successfull way to deal with them is to bi-amp using OTL that realy cares less about high impedances and beefy SS on the bottom certainly with active crossover.

All tube stuff is also possible having beefy VTL on the bottom and some 25...30wpc OTL at the top.

I actually heard many of Martin Logans speakers and no setup I realy liked with them and than they have one of the most complexed impedance characteristics on earth.
Martn logan pannel are just like airfilters they remove airborn particals from the room ,you will be lucky to get 7 years out of the pannel before dust dirt and grease from cooking loads them up .Even if they are away from kitchens and fireplaces.I got so sick of failing pannels in my many martin logans glad I moved on .
Yeah, seven years can realy try a man's patience. BTW, I've had near-new panels for five years. I guess the problems will be forthcoming. Maybe I should set up a wok near the speakers to expedite this. LOL. I seriously doubt that you have ever owned these speakers.
BTW... all CLS 1's,later serial # CLS II's and all CLS IIa's "power down" if no signal is received after 20 minutes. So the "air filter" theory goes out the window.
Jim when they are running they filter the air ,and yes I have owned CLS2Z and many other martin logans could care less if you believe me .Ever here of electrostatic air filters?Ask any HVAC instaler.Also cooking grease travels the the air the speakers can have problems even in another room . I feel sorry for you that you are so uptight .Take care and happy listening .JK
Yes, electrostatic precipitators are in fact a widely used air pollution control device fine particulate matter...and whenever my house mate cooks stir fry it sends me into a panic, it does fill the air with a huge amount of aerosol that quickly moves through the house....please, no more stir fry!!

Let me get this straight...on another thread you claim that 5 of 8 ML speakers you've owned have "failed". I have not known 5 *owners* who have had these kinds of problems, (within a reasonable time frame -- let's say several years), let alone 5 times with *one* owner. The math just doesn't seem to work.

I am also curious as to why you suffered with 8 pairs of speakers to get 3 pairs that didn't fail. Am I missing something essential to your speaker preferences and decision making process?

BTW my listening room happens to be around the corner from my kitchen (crappy afterthought)*and* I fire up a wok 3 to 4 times a week (Thai food -- even though I am "falang"). Add L.A. air polution and I still do not have problems. Same goes for the Quad ESL 57's when they are in service.

Again, I'm not buying it. Not because I am "uptight" -- and I am just as a matter of course -- but because the facts do not jibe based on real world experiences. Mine and most others. ML's are far from perfect, but your other posts on this site where you state that there are "lots of problems with ML's" simply are not consistent with reality. These things are damn near indestructable notwithstanding normal wear and tear.

If I am mistaken and you have actually had 5 of 8 pairs of ML's fail, you should run for your life. For you are cursed. ;-)
Of the 8 systems ,5 gave me trouble I have owned M/L for over 14 years .Most where problems with the pannels wrinkled diaphrames ,missing parts, non funtioning woofer,cosmetic issues .Buzzing pannels.My Prodigy was the worst had 2 wrinkled pannels ,missing 8 screws had damaged trim was missing the nuts that hold the binding posts on they just spun.Also 1 of the second pair of replacement pannels where wrinkled.M/L took care of the problems but I had to repair the prodigy in my home .Took 3 months and many calls to sort it out .My dealer ended up returning this prodigy back to M/L .Then I purchased the odessy and descent sub both I had no problems with .Maybe you are so in love with M/L you can not bear to hear the truth from a long term owner .JK
My other post states , reliability problems with M/L? asking if others have too ,also I did not say failed but wrinkled and buzzing pannels are not usable.You might allready have reduced the hi frequincy responce of your pannels due to build up ,happens slowly so is hard to notice unless you hear a newer logan.If you look up the posts for martin logan you will see others have had problems with there pannels.I have had lots of experiance with M/L.I have a few friends that still use there speakers.My good friend is the local dealer .Just giving you the facts as I have experanced them, stay indenial if you will .JK