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Thread: CLS Heat Treatment Tweak

  1. #1
    MLO owner/operator TomDac's Avatar
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    Default CLS Heat Treatment Tweak

    Posted by vtech007 (A) on March 01, 2003 at 21:17:21 (from Audio Asylum Forum)



    I contacted Jim Power, the service manager at Martin Logan, when my original CLS's developed a buzz coming form the bass sections of the panels. Below is copied the e-mail train explaining a procedure he recommended. It REALLY, REALLY WORKED, saved me from spending $900+ on replacement panels! Give it a try AS A LAST RESORT!!!

    "My guess is that something is no right with the panel itself. You can confirm this by swapping the circuit box from the back of the speaker with the other speaker. If the symptom remained with the same panel, then the panel itself is definately the problem. There is a remote chance that the panel would recover from a routine "heat treatment". I would say that since we have nothing to lose, we should try it before spending any money. I will include a detailed description of the process at the end of my email. I have a 'canned' bit of text covering the matter. Worst case scenario, should it not work, then yes; new panels would be in order. New panels are $890/pair plus shipping. They are UPS-able so shipping would only be about $25. They are reasonably easy to replace. Instructions are included. We accept most major credit cards. First, lets try the easy stuff. Here is my notes on heat-treatment.

    -------------------

    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.

    CAUTION!!!!
    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

    Hi Jim,
    Thank you very much for the heat treatment procedure. The short of it is...IT WORKED BEAUTIFULLY!!!
    I performed three of the passes of the hair dryer on each panel as you described. Then the listening test...all of the resonance was gone except for a very faint amount. Then three more passes...all of the resonance was then completely gone. Not a trace. I will keep this in mind for future use. Do you mind if I share your info with other audio enthusiasts? If you don't mind, I would like to quote you word for word on the Audio Asylum web site. I will give you full credit (and praise) mentioning your name and title, unless you mind.

    THANK YOU AGAIN! All is well with the family music system again, thanks to you and your kind, expert advise! If we ended up needing new panels, it was going to have to wait a very long time until we could afford it.

    God bless.

    Warmest regards, Excellent! I'm glad it worked.
    No I don't mind sharing the info. My only concern is that everyone needs to understand how easy it is to melt a hole in the film. Once that happens, the panel is toast. That being the case, I usually only recommend the procedure when you have nothing to loose. I do think that it is a pretty detailed procedure and if it is followed to the 'T', it should be ok. Happy listening!
    jp

  2. #2

    Default never in the center

    NEVER IN THE CENTER,
    or the mid section inside of the bass side sections.
    If you heat any of this area, even by accident you will shrink this section thus causing the membrane to tighten AND THEN YOU WILL HAVE A BUZZ AND DISCHARGE SOUND which is almost impossible to remove.

    If you have done so [applied heat] and have now got a major discharge sound [crackle and hiss] the only way to cure is to temporaraly increase the bend in the panel and hope you have stretched the mylar enough, PROBABLY NOT.

    Your panel is now no more.Say good-bye to beautiful sound.

    I have tested the above on a panel and believe me it will happen.

    I have also tested heating the side bass panels only when there is a buz and this does work.

  3. #3
    Senior Member
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    Default

    Thats almost exactly what I need to know for my Sequel panels!
    They've lost a bit of tension; there's a slight wrinkle in the top left corner of the membrane on one. I knew that would be the solution, but now I know exactly how to go about it! Thanks for sharing!

  4. #4
    Newbie Hifiasylet's Avatar
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    Default But...

    Only remember to never, ever, ever use a heating gun as a replacement for your missing hairdryer...



    I am now playing my music of a new set of replacement stators
    Damn the heating gun and my lack of patience...
    | | | | | |
    ( @ @ )
    -----oooO---O---Oooo-----

  5. #5
    Super User C.A.P's Avatar
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    Default

    This tweak does work . It helps the Mylar re tension. Especially with a big panel like the CLS ! Its the only panel that actually has formed mid section in one panel. It has separate bass and mid all in one panel. You can see this with the crease in the metal panel and that they are physically connected there too.

    Only do the outside bass area . It may take several attempts . Don't rush or you will be out $900 fast. The mylar and the verticle stator areas are prone also to Kazooing. With hand tension and a bit of heat you can fix that too. Heat the area with a hair dryer angling in towards the outside edge, but as to get the spar too. it needs to re heat the glue and shrink the mylar and hold it all at cooling. Use a pressing of the two panels with one hand on each side pushing together right after you heat it. It works best if you have 2 people , one heating and the other compressing.
    Martin Logan... Odyssey...Krell KSA 100s...Krell KRC3 Pre Amp...Krell Connect Media server/DAC
    My system here

  6. #6
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    Default

    First of all I want to thank you for this very good and informative forum. As a ML new-be its a great help reading all the comments from experienced ML users.

    Secondly I would like to ask you if you can recomend the Heat Treatment Tweak also to a pair of Aerius?
    Would I have to follow the same pattern (not in the center) as with the CLS´s?
    I would think "no" as they are not producing low frequentier, am I right?
    Could this Treatment also make some improvement to the Sound of the MLs? After I washed the Panels I dried them with a hair dryer and a room blow heater and I hear an improvement of the Sound and wonder if the drying process also influenced the improvement.
    When washing the Panels I observed the the Panel sanwich has slightly separated in one side (middel part but no wrincles) and this Panel has a very slight blurr which is only audible when I put my ear Close to the Panel.

    Please let me add a comment or possibly a question: As far as I know (I am working in the plastic industry since 30 years) PET will not melt before heated up to app. 260° C. Therefore I cannot really understand the warning that one should be able to melt the diaphragm with a hair dryer (without holding the hair dryer right up to the foil for quete some time). I do though understand the warning not to use a hot air blower, as they do heat a lot more.

    I would very much appreciate to receive your Feedback.




    Quote Originally Posted by TomDac View Post
    Posted by vtech007 (A) on March 01, 2003 at 21:17:21 (from Audio Asylum Forum)



    I contacted Jim Power, the service manager at Martin Logan, when my original CLS's developed a buzz coming form the bass sections of the panels. Below is copied the e-mail train explaining a procedure he recommended. It REALLY, REALLY WORKED, saved me from spending $900+ on replacement panels! Give it a try AS A LAST RESORT!!!

    "My guess is that something is no right with the panel itself. You can confirm this by swapping the circuit box from the back of the speaker with the other speaker. If the symptom remained with the same panel, then the panel itself is definately the problem. There is a remote chance that the panel would recover from a routine "heat treatment". I would say that since we have nothing to lose, we should try it before spending any money. I will include a detailed description of the process at the end of my email. I have a 'canned' bit of text covering the matter. Worst case scenario, should it not work, then yes; new panels would be in order. New panels are $890/pair plus shipping. They are UPS-able so shipping would only be about $25. They are reasonably easy to replace. Instructions are included. We accept most major credit cards. First, lets try the easy stuff. Here is my notes on heat-treatment.

    -------------------

    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.

    CAUTION!!!!
    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

    Hi Jim,
    Thank you very much for the heat treatment procedure. The short of it is...IT WORKED BEAUTIFULLY!!!
    I performed three of the passes of the hair dryer on each panel as you described. Then the listening test...all of the resonance was gone except for a very faint amount. Then three more passes...all of the resonance was then completely gone. Not a trace. I will keep this in mind for future use. Do you mind if I share your info with other audio enthusiasts? If you don't mind, I would like to quote you word for word on the Audio Asylum web site. I will give you full credit (and praise) mentioning your name and title, unless you mind.

    THANK YOU AGAIN! All is well with the family music system again, thanks to you and your kind, expert advise! If we ended up needing new panels, it was going to have to wait a very long time until we could afford it.

    God bless.

    Warmest regards, Excellent! I'm glad it worked.
    No I don't mind sharing the info. My only concern is that everyone needs to understand how easy it is to melt a hole in the film. Once that happens, the panel is toast. That being the case, I usually only recommend the procedure when you have nothing to loose. I do think that it is a pretty detailed procedure and if it is followed to the 'T', it should be ok. Happy listening!
    jp
    Last edited by HiFiFuchs; 11-09-2016 at 05:46 AM.

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