New CLS Owner

MartinLogan Audio Owners Forum

Help Support MartinLogan Audio Owners Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
May 4, 2023
Messages
8
Reaction score
7
Hello MLO Members,

I just picked up my first pair of Martin Logan's. My new-to-me early CLS's appear to be in great shape, and worked when I demo'd them at the PO's. However, after carefully plugging everything in at home, there is nearly no sound from either channel. Drat!!! Let the fun begin!!!
 
Are they fully charged?
I've had them charging for the last 8 hours. There is quite a bit more sound, but not a lot, coming from them compared to when I first tried (1 hour charge). I typically have KEF 107's hooked up.

I am currently using a Nakamichi CA-7 preamp and PA-7 power amp. How long should it take for the panels to be fully charged?

Thanks for your response,

MnM
 
I've had them charging for the last 8 hours. There is quite a bit more sound, but not a lot, coming from them compared to when I first tried (1 hour charge). I typically have KEF 107's hooked up.

I am currently using a Nakamichi CA-7 preamp and PA-7 power amp. How long should it take for the panels to be fully charged?

Thanks for your response,

MnM

If the panels are not dusty then need to play music through them daily 2 to 3 hour for 2 to 5 weeks. The volume level will gradually increase. Notice a improvement after 2 weeks and greater improvement after 5 weeks of daily playing music through them.

I hope you are using not defective power cable for CLS.
I use CLX stock power cable.

lmpression 11a stock cable may be adequate too. And less expensive. In addition with age and use I find spades provide tighter connection than bananas. If the speaker cable connection to CLS is not tight the result will be weak sonics or less volume. Loudspeaker cable has a major impact on overall loudness. When I switched from DH labs T14 to Nordost blue heaven the overall dynamics and finesse improved.

Please read my last post kmanusa system CLS. Volume level will increase with proper set up.

To conclude with CLS 1 any weakness in the audio chain and set up ( room placement, toe in, rake angle ) gets reflected as poor sonics. Keep operating them daily and they will after maximum 2 months sound just like they were at PO. 2 months is a conservative estimate.
 
Last edited:
RAH,

Thank you for your response. I'll try it. I use D'Addario power cables on most of my stuff, nothing fancy, but reliable. I am using bananas, but will swich to spades.

Should I keep the panels constantly charged?
Should I limit the amp power going to the panels during this period?

I read your information posted to kmanusa's thread. Once I get some additional sound out of them, I'll dial in the placement. Since your post, I have seen a slight improvement in volume in their current location.
 
I do not remember the exact time duration. Panels get fully charged after time ranging from 5 to 15 minutes. Assumption is panel is not defective. No need to keep the panels constantly charged because they are going to attract dust when charged. When not listening to music better to switch of power to panel and cover panel. Dust and sunlight both cause harm to panel.

Vacuum panel after 2 weeks. You will notice increase in volume level immediately after vacuuming. If you do not notice improvement in volume level then next time vacuum after three weeks.

Though the panels are old should treat them as new when considering the amp power going to panels. New panels need less amp power compared to old panels to produce a specific decibel level. Old panels produce less volume compared to new ones. To get same volume level like from new panel may overfeed amp power to electronic module and may cause failure of parts inside. Therefore better to limit amp power going to panels during this period.

Do you have original CLS or CLS 1?

Have the panels been replaced?

I have some useful CLS info. obtained from ML service dept. I can email to you if you message RAH your email address.
 
Last edited:
When transporting the CLS Speakers to your home, were the interfaces (metal box on speaker) disconnected from speaker frame? If so, when reassembling the speaker did you reconnect the three wire connector from panel to the interface?

Be very careful when doing anything inside the Interfaces. Do not have power connected to wall outlet and more importantly do not have the speaker connected to the amp driving the speakers.

EDIT - OK read this wrong - "nearly no sound", I had thought "no sound"

As advised by others, let speakers charge...you initial listening audition may have been from an amp that has considerably more power than what you have. As the panels get older the SPL drops. The CLS are relatively low efficiency speakers when new (86db/watt?), and may need more power to drive them properly as they age...

What Amp are you using to power the CLS speakers?
 
Last edited:
Hello MLO Members,

I just picked up my first pair of Martin Logan's. My new-to-me early CLS's appear to be in great shape, and worked when I demo'd them at the PO's. However, after carefully plugging everything in at home, there is nearly no sound from either channel. Drat!!! Let the fun begin!!!
CLS series are still my favorites. But I can't imagine what happened during the trip that would effect both speakers equally (mine survived a trip in a pickup truck across almost the entire state of MA and on to Albany). Hopefully it's something simple you will be kicking yourself for when you figure it out (sure the receptacle you plugged them into is live, for example?). Wish I could be more helpful. They should charge and make music almost instantly, though people debate about how long it takes for the charge to distribute for them to sound their best.
 
When transporting the CLS Speakers to your home, were the interfaces (metal box on speaker) disconnected from speaker frame? If so, when reassembling the speaker did you reconnect the three wire connector from panel to the interface?
That's a good bet. They almost certainly would not have been transported fully assembled. Maybe they were just hooked up incorrectly. If you don't have the original owner's manual, they are all available from the ML web site.

The lower powered amp from the original demo is a longer shot. The difference between 20W and 200W is only 10dB.
 
Hopefully I'm wrong but I'm gonna say it: I think you're beating a dead horse.

And I'm wondering how many watts were being pumped into those speakers when you auditioned them.

I think it's very unlikely that both speakers would malfunction in transit, and low output is consistent with the diaphragm coatings being deteriorated to the point where huge input power is required to get any sound out of them.

A normally operating ESL should give adequate output within a minute, and with normal amp power.

I'm an experienced ESL builder but I've never attempted to disassemble a ML speaker. Maybe someone here has, and will chime in and tell you whether the front stator can be removed without damaging the diaphragm.

Assuming the diaphragm coating is bad and the front stator can be removed without damaging the diaphragm, re-coating it with one spray-on coat of Licron Crystal ESD coating will 100% fix the problem. Licron Crystal comes in an 8-oz aerosol spray and is easy to apply.

If you just want to verify the diaphragm coating was the problem before spending $60 for a can of Licron Crystal; apply a thin coat of any liquid dishwashing detergent applied with a coating ball, then reassemble and test. The dish soap coating is an excellent temporary conductive coating that will give full sound output.
 
Just make sure the Soap has Sodium Lauryl Sulfate...some soaps do not have this...

I have separated three sets of CLS panels many years ago. Two sets were destroyed...not easy, but can be done...
 
Just make sure the Soap has Sodium Lauryl Sulfate...some soaps do not have this...

I have separated three sets of CLS panels many years ago. Two sets were destroyed...not easy, but can be done...
Even guys like Russ Knotts , ESL Repair - Home, who does lots of panel repairs has trouble with some panels. He took a look at my Prodigy panels and told me that there was a very good chance that trying to separate them would result in damage to the diaphragm. So I chose to just keep the old panels as an emergency backup and bought new panels from Martin Logan.

Does Martin Logan still make new panels for the CLS?
 
Do you have original CLS or CLS 1?

Have the panels been replaced?

I have some useful CLS info. obtained from ML service dept. I can email to you if you message RAH your email address.
I purchased these from MLO member dougstrach. I believe they are CLS's, serial numbers 1078, 1079

I don't think the panels have been replaced.

Any info would be greatly appreciated. PM'd email address.

Already, after just a couple of days, volume has increased significantly. WOOHOO!!!
 
When transporting the CLS Speakers to your home, were the interfaces (metal box on speaker) disconnected from speaker frame? If so, when reassembling the speaker did you reconnect the three wire connector from panel to the interface?

Be very careful when doing anything inside the Interfaces. Do not have power connected to wall outlet and more importantly do not have the speaker connected to the amp driving the speakers.

What Amp are you using to power the CLS speakers?
The interfaces were disconnected, the panels were horizontal. I connected the plug, red dot up, to the interface for each speaker.

I have learned from past experience to be very mindful of potential hazards. Thanks for the heads-up. Do the interfaces completely discharge when not powered or should I wait a while before unlidding?

I currenly have them powered by a single Nakamichi PA-7:
https://www.hifi-classic.net/review/nakamichi-stasis-pa-7-439.htmlI have another PA-7, a pair of Luxman M117's, and an AR D-76 if another option might be a better match.
 
It's good to hear that the panels are starting to come alive...! I wonder if the power supplies would benefit from a recap? Still, it sounds as if the power supply caps are reforming, so you should be good for now.
 
Last edited:
That Nak Stasis has plenty to drive the panels - your good here...but should not take longer than a few hours to fully charge the panels... I would think...

Sux that ML never put in a Neon Charge lamp like the Quads have - shows the health of the panels...I actually built one from the schematics... place this thingamabob in series with Bias connection and the neon light flashes when panel gets a replenish charge ... should blink once every like 10 sec for healthy panels, while bad panels blink more rapidly...indicating a charge leak...

Just the standard neon lamp and a 47nf cap in parallel... you should already have that 10meg (or larger) resistor on your ML bias circuit...
 

Attachments

  • PXL_20230516_195305709[1].jpg
    PXL_20230516_195305709[1].jpg
    1.5 MB · Views: 0
  • Capture.JPG
    Capture.JPG
    25 KB · Views: 0
Last edited:
I was told the panels charge up very fast. Mine were off once for two weeks while we were on vacation. I unplugged everything. I plugged it all in when we got back from Italy and the speakers played music like they always do. They seemed to charge right away, and dont require much. I have Prodigy panels too, and they aren't small. I've even messed around and unplugged the power to the speakers and they play loud and clear for many minutes like they were still plugged in. The static charge holds.
 
If they charge quickly, its healthy panels...

You should know - by driving ESL speakers with bias disconnected & near drained, you risk destroying both your amp (driving a dead short) and / or step up transformers in interface...neither are a cheap fix...
 
If they charge quickly, its healthy panels...

You should know - by driving ESL speakers with bias disconnected & near drained, you risk destroying both your amp (driving a dead short) and / or step up transformers in interface...neither are a cheap fix...
Thanks for that. I only did it for a minute or so. I've been told by others that they play a lot longer than that. I figured it probably wasn't a good thing.
 
In order make sound an ESL needs AC drive voltages on the stators (from the amp / step-up transformer) and a DC biasing voltage on the diaphragm (from the bias supply) for the drive voltages to react against.

If the bias supply is faulty or its wire-to-diaphragm contact is corroded, or the diaphragm's conductive coating is deteriorated/not holding charge, or there is a shorting path between the diaphragm and stator(s) draining charge off the diaphragm--- then the drive voltage has nothing to react against to move the diaphragm and make sound.

In this circumstance, and especially if the sound is merely weak and not completely gone, the tendency is to crank up the amp power way beyond what would normally be required, which can drive the step-up transformer to saturation. The amp would see this as a dead short and possibly smoke itself and/or the step-up transformer.

Replacing the diaphragms and conductive coatings is home do-able if the required diaphragm tension is known and can be reproduced. The diaphragm material is available on Ebay for about $30 and the double-sided adhesive tape is available at McMaster-Carr.

ML uses 12-micron polyester film (Mylar C) for the diaphragms, and tensions them by applying a specific amount of stretch/elongation in the lengthwise direction (only). I'm told that ML uses very high diaphragm tension.

ML tensions their diaphragms using a simple clamping jig.

The rear stator is positioned convex face up in the jig. The diaphragm film is suspended above the stator and secured to the jig with clamps at each the end. The film is then stretched to a specific elongation and hand-pressed into the adhesive tape on the stator's spars and spacers.

Because ML panels are curved, the diaphragm must be tensioned predominantly lengthwise only, as any lateral tension tends to pull the film into the rear stator. The technician hand-applies only enough lateral tension to pull out any wrinkles in the film.

This would not be difficult to DIY if one knows the amount of elongation needed to achieve design tension, and it could be done with a simple home-made jig or by even by hand alone.

Note that the stator's horizontal spacers (ML calls them "spars") are unevenly spaced on the panel, from top to bottom. This arrangement breaks up the diaphragm's fundamental ("drum-head") resonance into several softer resonance peaks at different frequencies, as opposed to equal spar spacing which would produce a much louder resonance peak at a single frequency.

FYI:
Distributing the diaphragm's drum-head resonance into multiple peaks across a wider bandwidth gives the illusion of more mid-bass output, and uses the resonance energy to somewhat mitigate the dipole rolloff for a flatter response, and this also allows using a lower crossover point and/or avoid having to use a steep-sloped filter in the passive crossover. It is my understanding that ML purposely uses very high diaphragm tension (I'm guessing >200Hz resonance) for the reasons noted above.

Soundlab also uses the "distributed resonance" approach, and for their full-range designs which must play down low, there is no better option to mitigate the drum-head resonance.

I'm not a fan of this approach for hybrid ESLs, however, because the drum-head resonance is sound but not music.

A big advantage for a hybrid ESL is that the ESL panel doesn't have to play down low where the drum-head resonance occurs, and with the right setup it can be largely avoided.

I tension my diaphragms [probably] much lower than a ML does, in order to lower the drum-head resonance to around 90Hz, and then I avoid exciting it by setting the crossover frequency one octave higher, using a steep (48db/octave) digital filter.

Since I'm not then using the resonance energy to boost the mid-bass output, I offset the rolloff with additional panel area, and overlay a parametric EQ to flatten the response curve.

Back to your ML:
Since the diaphragm's tension / drum-head resonance(s) affects the frequency response, the crossover network may include one or more notch filters specifically tuned to tamp down resonant peaks, and will probably include a 6db/octave shelving filter to offset the dipole rolloff. And since the crossover filters are tailored to the diaphragm tension; matching the design tension becomes an important consideration.

In any case, it's better to tension the film high than too low-- else the diaphragm would be too-easily driven into a stator at moderate volume levels or, if very loose, pulled into a stator by the static charge alone, even with no music playing.

Matching the design diaphragm tension becomes less critical, tuning becomes much simpler, and sound quality is improved (IMHO) if using a DSP crossover with adjustable EQ's rather than fixed value passive filters :)
 
Last edited:

Latest posts

Back
Top