Electrostatic Speakers Vs. Horn/component Tweeter

I’m curious… when a horn or tweeter goes bad, it’s clearly obvious.  The driver is shot and the audio sounds clipped and distorted.  Electrostatic however, have massive surface areas and use static electricity to vibrate the material…. So when an electrostatic speaker goes bad, what actually happens to cause it to go bad, and does it go bad like a tweeter, where it goes from sounding fine to sounding like crap in a split second?  Or will an electrostatic speaker slowly decay over time, so you don’t notice it initially, and then one day, it just doesn’t sound as good as you remember it sounding?  If an electrostatic speaker goes bad, what causes it?  Is it torn material?  Is it something where you can replace a single small part?  Or do you typically have to replace the entire panel?

I’ve come across plenty of blown regular speakers in my life, but never a blown (if that’s even possible) electrostatic speaker.


Electrostatics can go bad, and yes, you can blow them up, too.   They can 'arc" between the panels, which sounds kinda like a gunshot or they can have other issues, all of which degrade the sound.  Depending on the failure, you may have to replace the panel, or perhaps, a part inside the unit if it is powered.   If you own an electrostatic speaker, then your manufacturer can tell you what you will need to do for repair.  I don't believe there is a "typical failure mode" for electrostatics in general, but certainly for a given manufacturer and model, they can have common failure mechanisms. 

I have some Martin Logan ESL’s.  I guess what I’m asking is.. if they get “damaged” from over or under powering them, should I expect catastrophic failure, or slow degradation of quality?

I had some issues early on with my receiver overheating while powering them and them clipping/sounding distorted.  It’s a surround sound receiver, and while high end, not intended for stereo.  I’ve since added a subwoofer and gotten my full surround sound setup going.  I’ve set them to small size in the receiver settings, so bass gets sent to the self powered sub, and reduces the strain on the receiver to power the speakers.  Obviously, that change means the speakers don’t sound like they used to.   Eventually, I hope to get a nice 2ch amp specifically to power this pair, but I’m just wondering if the reduced qualify is because I changed them to “small” in the receiver settings, or if I’ve already potentially damaged them.

Since I’m used to damaged speakers being blown, I’m wondering if these can be partially degraded without being destroyed, or if damaged electrostatic speakers are about as clear as regular speakers when they’ve been damaged.

Since I’m used to damaged speakers being blown, I’m wondering if these can be partially degraded without being destroyed, or if damaged electrostatic speakers are about as clear as regular speakers when they’ve been damaged.


Hmm, interesting questions. I think the people to ask are Martin Logan. 

My 2 cents:

Perhaps you should get an amp/receiver that can power your speakers properly.  You mention setting the receiver to 'small size'. Perhaps this be a workaround, but  a sub will only lessen an amps power demands if it is run with a high pass crossover (ala Vandersteen).-Perhaps this is what ' Small size' does, but it probably impacts sound reproduction.


I’m currently bi-amping it off a 4520CI Denon receiver, which meets specs per MFG standards, but realistically doesn’t meet specs for the speakers.  While ML says it will work, everything else I’ve read, states it can draw as low as 1 ohm, which is far more than the Denon receiver can put out, and I’ve heard the negative results first hand.  I’d love to get a good amp to power it, but with no current job, dumping months worth of money in bills into a single amp, so I can enjoy it before the power is shut off, doesn’t seem like an advisable solution ;)

I wasn’t asking how to fix clipping issues from the wrong equipment.  I was asking how to identify whether or not the wrong equipment has actually cause damage, since I’m used to it being crystal clear when a speaker is fine and and a speaker is destroyed.  Will she electrostatic speaker fail like a standard tweeter?  Or will it not instantaneously fail, but instead, degrade in quality after time?  I’m not asking advise on how to power it.  Only want to understand how it can/will fail/what the signs are.

The panels on ML speakers are hard to damage to the point of failure,  They do not suffer from arcing like Quads do, for example.  I know of only one instance where a friend’s ML panel failed.  The owner stored the speakers in a garage for several years in a high humidity climate.  The wire that charges the panel corroded at the point where the wire attaches to the panel. 

Ive had a pair of ML ESLs for a few years now... No problems... The panels crossover to the woofer at 500Hz... And the woofer goes down to 42Hz... I would set your AVR to a full range and cross over the subwoofer itself at around 52Hz... So if you are doing a "small speaker" crossover in your AVR your most likely doing things wrong... You can try to run the ESL at another ohm setting via your AVR 2, 4, 6 or 8 and see how that changes your thermal issues or add a 2 channel Amp... These ESLs will test your AVR or AMP diving into low ohm territory... Standard AVRs and AMPs will want to double power as ohms half and ESLs "map" opposite of standard speakers...  Are you bi-amping or bi-wiring???  Sounds odd to me if you are driving it all from an AVR...  If I were to bi-amp I would use tubes for the panel and solid state to drive the woofer...

BTY you can vacuum the dust off the panels... RTFM...

My receiver won’t utilize the subwoofer if the main speakers are set to stereo mode and large speakers. Setting them to small, tells the receiver to use the sub for low frequencies and thus reduces the draw from the speakers.  My receiver is biamping the speakers at 150w per channel x2 per speaker, but it’s only 8ohm stable.  It can do 6ohm above 1k frequency.  I think these speakers can pull as low as 2ohm, so it’s just too much for the receiver to handle.  This is why I need to eventually get a new amp when I can afford it.

It might help if you clarify which ESLs you have...  I have the original Motion ESLs...  Did drive them with a Yamaha AVR...  No thermal issues...  Now drive them with a small McIntosh MC152...  No problem with those autoformers...  You might want to find an AMP that "maps" to your ESLs and does not just double as ohms dip...  As those ESLs will dive into the lows ohms at high frequencies, unlike orthodox speakers which dive towards low ohms at low frequencies...

Ok... So, crossover between panel and woofersx2 at 400Hz... I don’t think I would try and bi-amp with an AVR like that... You could be pushing 150 watts x 4 just for RMS... And when panels dive to 2 ohms your pulling 150 x 2 per channel (std) for the woofers and 150 x 3 (8, 4, 2 ohms with a doubling AVR/Amp) per channel... Ouch!!! No wonder you would have a thermal problem and clipping... Wonder what the total wattage output of that AVR can handle is... Spec is 150 watts per channel in _Stereo mode_ I read that as 2 channel... And I don’t see anything about multichannel mode... Also not sure how you would drive 2 left and 2 right stereo channels to bi-amp from an AVR like that... And how would driver time alignment work out... Speaker placement and time alinement is critical with these ESL hybrids... Hoping you have your room acoustics in order and use something like REW to get your speaker placement and room right...

The receiver is a 9 channel receiver with 9x150w 8ohn channels.  Designed to do a 9.1 or 9.2 setup.  Instead of doing front left and right and front high left and right, there is an option to bi amp the left and right which is what I’ve done.  Since the speaker nominal power is something like 320w RMS (I don’t recall exactly, been a while since I looked it up), it gives the power, and it says you can run it at 8ohm, but we all know that a speaker will suck down every bit of juice it can, and if a speaker can run down to 2ohm, it will try to suck that out of your receiver, whether the receiver can handle it or not.  I don’t have the clipping issue since I added the sub, however, there has definitely been a degradation of quality.  I believe it to be because of the limitation of setting the speakers to “small” and having the receiver apply it’s own filters/crossovers as it sees fit with no ability to manually adjust those.  That said, there isn’t much I can do to avoid clipping otherwise, unless I get a nice amp that will cost thousands I don’t have atm until I can get a reliable source of income.  You work with what you’ve got!  On the bright side, I don’t have a piece of crap Arcam receiver to ruin my day with constant failures ;)

ML suggests a power amplifier in the 20 to 400 watt range... I think they should do just fine with 150 watts... Although the ESL X are rated at 6 ohms which will cause your AVR to run up 190 watts per channel... Again more than enough to properly power your ESL Xs...

Back to you initial question about how your speakers may be damaged... The mylar may decompose with age, sun, dust... There is no voice coil like in a cone speaker which may deform or melt in an overpower situation...

I would be curious how the ESLs sound running as a vanilla 2 channel with out that extra subwoofer and set as large speakers in the AVR... You may be able to connect that subwoofer to other left and right channels or even tap directly to the standard left and rights... There is no reason to run them as anything less than full range speakers... You could then crossover your subwoofer in your subwoofer, given it has the capability to manage its own gain, crossover and phase or polarity...

My current setup is how ML recommended I configure it until I can get a dedicated amp.  Set to large mode, there is no need for a sub.  They sound incredible and have plenty of bass.  But when turned up, my receiver overheats on heavy bass songs and starts clipping.  Since this room is used more for movies than music, I need the sub to handle the various surround modes, but an also using it to reduce the workload on the receiver until I get a dedicated 2 channel for the speakers.  Then they will be set to large again :)

There is a wealth of information on ESL's at diyaudio.com under the Planars & Exotics forum.  The technical guru's there are extremely helpful and generous with their knowledge for both the novice and the more experienced enthusiasts.  They have helped me with mine on several issues I've had.  The Martin Logan owners forum should also have plenty of info.

Now I am not technical, but I will give you my understanding of what can go wrong with ESL speakers:

Because a normal amplifier does not produce enough volts to properly drive an ESL, a step up transformer is used for this purpose... anywhere from 50 to 150:1 ratio.  If over driven, they can fail causing low output and distortion...kind of a crackling noise.  This happened to me one night on my left speaker while listening  to some very loud and dynamic music.  However, this was pilot error on my part since I wired the transformer for maximum output vs a lower safer output(I'm still mad at myself for this!).  I don't think Martin Logan's have this problem?

A bias power supply charges the diaphragm to a high voltage(2000-4000 volts!) so it can interact with the stators-the curved perforated metal on your speakers.  If the power supply fails, there will be less sound or hardly any sound at all.

The thin mylar diaphragm vibrates by being attracted to the + or - stator, producing music.  Over time, the conductive coating may lose its effectiveness or actually separate from the diaphragm. Dirt, dust, and bugs can find their way between the diaphragm and the stators.  Bugs at nighttime can be quite entertaining with a light show as they are electrocuted...but this may cause a burnt hole in the diaphragm. The ML's should be well insulated to prevent this?

The stators are usually trouble free, unless they somehow lose their insulation or bent too close to the diaphragm.

These are items that may go wrong but most likely will not.  Hope this helps a bit.  Look into the forums for the real experts, though!



Do the speakers sound good in stereo set to full range? If so you’ve obviously got no issue and it’s all in the crossover. Also, when income allows don’t get an amp — get a stereo integrated amp.  Getting the Denon’s preamp outta the picture for stereo listening is at least as important as upgrading the amp if not more. The preamp section of your AVR sucks — they pretty much all do — and the preamp is crucial to get the best performance out of a system. Just my $0.02 FWIW.

This is always a good read when considering amplifiers for ESLs...


For stereo music a proper line stage preamplifier is always the best way forward...  And of course the proper paradigm amplifier for the type of speakers used...

Good luck in you choices...

All things suffer from entropy and degrade with time. E-statics are one of the more fragile designs in loudspeakers. The panels are plastic the electrical parts that energize the panels all break down a bit faster than in conventional dynamic designs they also attract dust another longevity killer they can arc causing burns in diaphragms and stators. If you want a timeless loudspeaker that can last generations look into horns. I have horn speakers from the 1940s that still meet the specs and work wonderfully. Or plan on repairs from time to time and enjoy your panels.

My receiver won’t utilize the subwoofer if the main speakers are set to stereo mode and large speakers. Setting them to small, tells the receiver to use the sub for low frequencies and thus reduces the draw from the speakers. My receiver is biamping the speakers at 150w per channel x2 per speaker, but it’s only 8ohm stable. It can do 6ohm above 1k frequency. I think these speakers can pull as low as 2ohm, so it’s just too much for the receiver to handle. This is why I need to eventually get a new amp when I can afford it.

@maverick3n1 The 1 Ohm impedance occurs at 20KHz where there is hardly any musical energy so your receiver will be fine. The speaker is higher impedance where there is more music energy, such as in the bass region.

When ESLs fail they have several symptoms. One is low volume which can be caused by a power supply failure. Buzzing and flapping is another due to tears in the diaphragm. Arcing (which might sound like a loud background hiss or actual sparking) is caused by too much power or excessive exposure to dust and moisture (possibly in the form of humidity); once that happens the panel can continue to arc, leading to failure of the membrane. They can degrade slowly or quite quickly depending on how they are treated. An underpowered receiver won’t be able to damage the speaker.