Reviving older ESLs - burn-in required?

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If the speakers truly come to life at higher volume then they should not sound bass heavy. Sound bass heavy one reason is the panel output is weak.

Despite being bass heavy and listening carefully at the volume just when the panel comes to life. If you think panel sonics are greater compared to previous. Then you need to adjust the placement. Placement close to the corner and wall in front of the listener can make the overall sound bass heavy.

In my opinion try adjust the following:

Placement
. After I felt placement was optimal with my ML hybrids. The resulting sonic in my spartan room can be described as understated bass, open clear midrange and clear dynamic treble.

Listening position.

Run them in
minimum time a month. Observe improvement in panel sonic.

Listening room is not overcrowded with sound absorbers such as sofa, cushion, curtains, main carpet and small rugs.

If after adjustments the sound is still bass heavy, recommend new panels. For peace of mind namely - 5-year warranty, longevity, fault free craftsmanship recommend electrostatic industry leader, Martin Logan.
Thank you. I know that placement ist critical. My listening room is certainly not over-damped, and it is rather large, although I have to use the shorter side of the room for practical reasons (it is also our living room, and it is all glass on one side).

The sound seems very different to yours - OVERstated bass, recessed and not very clear midrange, slightly thin treble. And the speakers do not "disappear" at all, although this may be caused by the placement.

This can't be it...
 
What are the upgrades. I could be better caps, resistors or point to point wiring rather than multi traces on the board.
I would seriously consider converting them to a Active Crossover/bi-amped scenario. There are several threads on here (one linked below). Now while I have no doubt that Martin Logan has been genuine in the pursuit of seamless integration of the hybrid ESL/Woofer designs since their inception, we have to remember that low-cost digital filtering was NOT an option until relatively recently. Also, when looking at the current upper-end ML models, they are effectively doing EXACTLY this... a built-in Class D amp for the LF, and using whatever high-quality amps the speaker owners might be able to bring to bear on the panels.

https://www.martinloganowners.com/threads/how-to-active-bass-section.19237/

BTW - the current version of the Crown amp is now the XLS1002 (I think). You would need one of them to power both LF systems on the Aeons, and whatever amplification you were looking at (for the whole speakers) to drive the panels.
 
They also recommend some upgrades to the crossovers - which seen already high quality, to me at least.

Any advice on this?

Crossover is designed keeping characteristics of electrostatic or electromagnetic drivers in mind. If the German electrostatic driver is not an exact copy of the original. Meaning among other differences, at a minimum, perhaps different from original panel lower frequency cut off point. Then you will have to adjust or tweak the original crossover to match with the new electrostatic driver. The existing crossover is in good shape, not requiring adjustment if you buy a new panel from ML. I may be mistaken but changing the electrostatic panel and modifying the crossover may mess with the new electrostatic panel and original woofer integration.

Conclusion:
If the price is the same not substantially less then why not buy from the company that has designed the crossover and woofer to match the panel. Like someone said “you can take a horse to the river but not be able to make it drink water.”
 
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My view is more concerning or say realistic.
But if you only can hear the difference unless inban A/B test does it matter - meaning possible not? I.e., unless you don't enjoy what to hear. I find the discussion about how much cable A is beter than cable B ( costing 10 fold), yet not realising the panel is dead long time ago, even before the room corecton increase to +10dB - makes me wonder. Anyway, whats sounds good to someone sounds good - but worth to consider if you waste your money if this is really the case (though psykologicaly you might be happy having this purple coloured cable lifted 2" from your floor).
 
The weird thing is that the panels are not defective per se. It´s more like the frequency response seems off - upper treble is there, lower treble is lacking, as is lower midrange. And it sounds slightly lifeless, as Doug033 mentioned.

I just spoke to the guys who do the refurbishment in Germany. They say that usually 1) the coating starts to deteriorate, lowering the output overall and 2) those "divider strips" (don´t know how they are called correctly) lose their elastic properties, causing all kinds of resonances and cancellations between the segments of the panel.

That sounds quite plausible to me. I think I'll go with them. They replace everything but the metal parts, so it is not a "repair". They are also a licensed ML dealer and could source original parts, but prefer their own refurbishments. And they can do it in a couple of weeks, not months, which is a nice bonus.

I'll report back ;-)
Please report back, would love to hear how it goes. Their prices are great for larger panels (which ML charges a lot for), not so great for smaller panels since I assume their cost is mostly labor which isn't all that different for different panel sizes. The price they quoted me for the Aeon i is only slightly cheaper than ML, but for the Summit it was about half if I remember correctly.
 
Hello all,

panels are back, results are in 😉
  • Hifi Zenit did a great job – seems like really good craftsmanship, and the process was flawless. Yes, the panels are “just” refurbished, but they look and feel brand new. So a thumbs up from my side - not cheaper than ML, but much faster!
  • That said, it seems like the old panels were not all that tired. Yes, the sound has improved somewhat, but its not a huge step. Midrange resolution got better, the soundstage is now widened, and integration with the bass seems better now.
  • BUT: the bass is still slightly overpowering. There is still a slight lack of energy in the treble. And the speaker still only comes alive at higher volumes. Thinner, brighter recordings sound great, “warmer” recordings sound dull.
  • Overall, you get a glimpse of “ESL magic”, but is all a bit dull and subdued. I expected a lot more sparkle from those speakers – something I had experienced earlier at dealer demos with other ML models.
Just to make sure it wasn´t due to other factors: I used a different amp – no change. I changed sources – no change. I compared to the only other speaker I have at home (a vintage, but fully refurbished B&W Matrix 802, which is not known to sound overly bright, other than newer B&Ws) – and the Aeon sounded darker/duller. When I went to the Munich High End Show last weekend, almost every system I heard was clearly brighter than mine – so it is not just me.

To be clear: I don't think there's anything really broken – the speakers sound alright (even great, sometimes), levels are equal left and right, the entire panels are working. But I was expecting more than just “alright”.

Maybe these are just not for me (and this was a very expensive learning experiment)? Or am I missing something? Any ideas?

Cheers

Ingo


For reference: I am using a Musical Fidelity M6i Integrated amp, Denafrips Ares II DAC, a Scheu Cello/Roksan Nima/Dynavector 20X2/Dynavector P75 turntable, Kimber Interconnects, reson Solidcore speaker cables (bi-wired)
 
Hello all,

panels are back, results are in 😉
  • Hifi Zenit did a great job – seems like really good craftsmanship, and the process was flawless. Yes, the panels are “just” refurbished, but they look and feel brand new. So a thumbs up from my side - not cheaper than ML, but much faster!
  • That said, it seems like the old panels were not all that tired. Yes, the sound has improved somewhat, but its not a huge step. Midrange resolution got better, the soundstage is now widened, and integration with the bass seems better now.
  • BUT: the bass is still slightly overpowering. There is still a slight lack of energy in the treble. And the speaker still only comes alive at higher volumes. Thinner, brighter recordings sound great, “warmer” recordings sound dull.
  • Overall, you get a glimpse of “ESL magic”, but is all a bit dull and subdued. I expected a lot more sparkle from those speakers – something I had experienced earlier at dealer demos with other ML models.
Just to make sure it wasn´t due to other factors: I used a different amp – no change. I changed sources – no change. I compared to the only other speaker I have at home (a vintage, but fully refurbished B&W Matrix 802, which is not known to sound overly bright, other than newer B&Ws) – and the Aeon sounded darker/duller. When I went to the Munich High End Show last weekend, almost every system I heard was clearly brighter than mine – so it is not just me.

To be clear: I don't think there's anything really broken – the speakers sound alright (even great, sometimes), levels are equal left and right, the entire panels are working. But I was expecting more than just “alright”.

Maybe these are just not for me (and this was a very expensive learning experiment)? Or am I missing something? Any ideas?

Cheers

Ingo


For reference: I am using a Musical Fidelity M6i Integrated amp, Denafrips Ares II DAC, a Scheu Cello/Roksan Nima/Dynavector 20X2/Dynavector P75 turntable, Kimber Interconnects, reson Solidcore speaker cables (bi-wired)

I was considering having Hifi Zenit rebuild my Summit panels but your review has me worried. New panels from ML should sound perfectly blended with the woofers, with a sparkling and crisp high end.
 
Forgot to mention, that sounds about the results I got with Russ Knotts restoring my panels as well. They work but don't sound the same as new, and also some woofer imbalance.
 
Forgot to mention, that sounds about the results I got with Russ Knotts restoring my panels as well. They work but don't sound the same as new, and also some woofer imbalance.
From what I read, Russ Knott actually repairs the panels (recoats, replaces divider strips...). Hifi Zenit replaces everything except the metal parts, you can clearly tell. So there should be a difference, which is also reflected in the price.

I will ask them for advice.
 
From what I read, Russ Knott actually repairs the panels (recoats, replaces divider strips...). Hifi Zenit replaces everything except the metal parts, you can clearly tell. So there should be a difference, which is also reflected in the price.

I will ask them for advice.
Ah yes, you're definitely right, I remember it now.

I'm just quite surprised that the Hifi Zenit rebuilt panels doesn't sound perfect. Is there an ML dealer near you where you can have a listen to compare?
 
I'm just quite surprised that the Hifi Zenit rebuilt panels doesn't sound perfect.
So am I - hence the question what I could be missing. Hifi Zenit is also an ML dealer - they should know what it is supposed to sound like

There is an ML dealer around here, but they only carry the "big boys" - and comparing to a 15a will not really help ;-)
 
they should know what it is supposed to sound like
I'm pretty sure they tested them before returning them to you, and they measured to spec.

I'm pretty sure your issues are due to room acoustics, so please provide a picture of the deployment and describe where they are in relation to the listening position. Also, describe what's behind the main listening position and how far away.

Big (relative to an 802) dipole line arrays behave very differently in terms of coupling to the room.

Do you have REW to measure the setup?
 
I'm pretty sure they tested them before returning them to you
That´s what they said, and I have no reason not to trust them.

so please provide a picture of the deployment
I will provide a drawing with dimensions. The room is good sized, but far from ideal, that's for sure. But I am really limited as this is our living room, not a dedicated listening room.

Also, describe what's behind the main listening position and how far away.
That may well be the culprit for the somewhat bloated bass response - about 2 ft. behind the listening position is a solid (brick) wall. with two pictures acting as acoustic panels.

Sorry for this (probably dumb) question - but how do room acoustics influence high frequency response? Bass and imaging are obviously dependent on the room - but treble?

Do you have REW to measure the setup?
I do (and a calibrated mic), but I've never used it to measure room response, just near field stuff.

Thanks

Ingo
 
A lot of moving parts here. IMO re-paneling and burning in are both oversold here, except burning in not so much with ESL panels. It's possible the diaphragm tension isn't quite right. Burning in is going to lower the tension, lower the resonant frequencies and probably, cause the bass to be even more overwhelming. The room you are listening in also has a huge effect. Subjectively, the increased bass may account for the impression of less sparkle. For what you pay ML for replacement panels, I might expect you get tighter control of the tension than with a third party refurbisher.

Comparing one model ML at a hi fi shop with another in you home has, as I say, too many moving parts to draw any conclusions.

Also, as others have suggested, changing to active crossover could give you much better control of woofer/panel blending and frequency response.
 
That may well be the culprit for the somewhat bloated bass response - about 2 ft. behind the listening position is a solid (brick) wall. with two pictures acting as acoustic panels.
Ah, yes, cause #1 for bloated bass is that you are sitting close to a (very) solid wall, and bass frequencies build up there. Depending on room dimensions, that build-up can be massive. REW measurements will show you. I bet you are +10dB out of balance relative to 1KHz.

This could possibly be EQ'd out with a switch to an active crossover.

Sorry for this (probably dumb) question - but how do room acoustics influence high frequency response? Bass and imaging are obviously dependent on the room - but treble?
It's a combination of overwhelming low-end boost and possibly some destructive high-frequency reflections causing the tilt.

As a dipole speaker, where the rear wave of the speaker hits and then reflects in the room is a major part of balancing an ESL. More often than not, it is HF reinforcement, but depending on layout and surface reflectivity (say, cement walls) then it can problematic.
 
A lot of moving parts here. IMO re-paneling and burning in are both oversold here, except burning in not so much with ESL panels. It's possible the diaphragm tension isn't quite right. Burning in is going to lower the tension, lower the resonant frequencies and probably, cause the bass to be even more overwhelming. The room you are listening in also has a huge effect. Subjectively, the increased bass may account for the impression of less sparkle. For what you pay ML for replacement panels, I might expect you get tighter control of the tension than with a third party refurbisher.

Comparing one model ML at a hi fi shop with another in you home has, as I say, too many moving parts to draw any conclusions.

Also, as others have suggested, changing to active crossover could give you much better control of woofer/panel blending and frequency response.

I couldn't agree more, Leporello. Your comments are thoughtful and on point, in my opinion.

I would like to expand on your points a bit, if I may. Although my experience is mostly building wire-stator ESLs, I recently refurbished a Martin Logan panel, which was a learning experience for me.

Assuming adequate diaphragm conductance, a panel's treble response and tonal quality are predominantly determined by the step-up transformer and diaphragm thickness. Transformers with high winding ratios (>100:1) typically give poorer treble response. Hybrid ESLs with closer d/s (diaphragm-to-stator gap) can use lower ratio transformers (typically 75:1), which give better treble response.

Assuming perfect transformer response, a 12-micron diaphragm will start rolling off the treble significantly lower than a 6-micron diaphragm. In any case, you're just not going to get flat response to 20kHz with a 12-micron diaphragm.

No doubt, ML opts for a 12 micron diaphragm because it's robust, they tension it quite high, and a thinner diaphragm could easily tear on installation, which would slow the manufacturing flow.

Most people can't hear 20hHz anyway, so if the diaphragm rolls off the highs at 12k, very few would notice. Still, you do get a bit more treble accuracy and sparkle with a thinner diaphragm.

I would doubt any refurbisher who claims better than factory response, but if everything else is done right, a thinner replacement diaphragm could be a valid basis for such a claim.

Also; ML has a specific, repeatable process for tensioning the diaphragm, which they don't share, and it would be difficult for an inexperienced refurbisher to exactly reproduce the factory tension.

The diaphragm tension is a big deal because it determines the diaphragm's drum-head resonance, and ML will have tailored the crossover filters and spacing between spars to accommodate that specific resonance frequency. If a refurbisher is off on the tension, the resonance won't sync with the crossover or spar spacing, and won't sound as ML designed it.

That said, a refurbished panel with a correctly tensioned diaphragm, should sound wonderful.

I particularly agree with Leporello's observation that a bass-heavy response or tuning, will make any panel sound comparatively muffled and lifeless.

Replacing the dividers (ML calls them spars) should not affect the sound in any way, but it might create some problems if replacement spars are not correctly bonded, such that gaps exist between the spars and stators, or the front stator spars and diaphragm.

The only reason you might want to replace those spars is if they were damaged or dis-bonded during panel disassembly. BTW, those spars are clear, hard, non-elastic polycarbonate plastic bonded to the stators and diaphragm with a 5-mil double-sided adhesive tape.

Finally; I would never use a passive crossover in a hybrid ESL. A passive crossover is at best a power-robbing, phase-altering, non-tunable compromise to allow the speaker to be driven with a single amp.

Manufacturers use passives because it makes business sense, as the lion's share of buyers want an inexpensive plug-n-play speaker that doesn't require bi-amping.

If I owned a ML speaker with a passive crossover, I would bypass the crossover entirely and bi-amp it with a DSP crossover. Not only will the bass tighten-up considerably with the amp directly coupled to the woofer, but phasing errors disappear, the full sonic spectrum sounds more alive with greater punch, and the tuning capabilities are infinite. BTW; it's easier to do than most people imagine.

My 2 cents...
 
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My new Prodigy panels did.
Zenit may be fully competent to rebuild ML panels. I don't wish to disparage any rebuilders, just pointing out the pitfalls.

Matching the tension would involve measuring it directly on an intact panel, or inferring it from measuring the resonance of an intact panel, and then tensioning the new diaphragm to the same resonance. Once the tension is accurately determined, it's not that difficult to reproduce it if you have a method to measure and verify it before bonding the new diaphragm in-place.

When I rebuilt the Theater panel I posted about a few weeks ago, I measured the diaphragm's drum-head resonance before dismantling the panel, using a frequency generator, microphone and real-time analyzer.

I was also able to measure the diaphragm's tension directly, using a deflection gauge on a still-intact area of the diaphragm, after removing the front stator. I then had a method to tension the new diaphragm to the same measured deflection before bonding it in-place.

I also measured the drum head resonance on the rebuilt panel, and found that my method had reproduced the original resonance almost perfectly. The owner was very happy with the refurbished panel.

There is a company in Australia (ER Audio) who sells highly regarded ESL kits, and they also sell rebuild kits for some ML models. Their refurbishing method involves tensioning the diaphragm by applying a specific pull-force in the longitudinal direction, and a specific pull-force in the perpendicular (curved) direction. Their rebuild kit includes a spring-scale and coupling to measure the applied tension. No doubt, ER Audio had the know how to determine the necessary pulling force to match ML's designed diaphragm tension.

At issue is whether a typical DIY'er or inexperienced refurbisher would know how to determine and reproduce ML's designed diaphragm tension, or just wing it and hope for the best.
Even if the tension were off, overall output would increase and the highs would sparkle again.

Positive customer reviews for a reputable refurbisher would ease my concerns.
 
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