New to Martin Logan, but not to Electrostatic speakers

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Has anyone replaced the spring loaded binding posts on the Electromotion ESL model? I can't find a thread on that. The ones I found were replacing already nice banana binding posts.
 
I plan to create a new thread, adding some pictures and explaining why certain design decisions were taken. Mike Wright was a physicist and so he designed his speaker sort of like NASA would, not trying to be practical. This is probably the reason why financially the company never made any money. Anyway I read a few books on the subject, the Sanders book to name a few. From what I am seeing, there are certain design decision made by others that seem less than ideal.I will post the link here after i get started.
Hoping that the third set of bracket will arrive next week, but since going by post office and the July 4th weekend coming up,, I am not going to hold my breath.

You obviously have a passion for ESLs and I'm looking forward to your planned thread about the Dayton Wright design decisions.

I've read about the Dayton Wright ESLs but there aren't many around anymore so it's unlikely I would ever hear an original pair, but I might get lucky and someday hear a pair of the new the Hommage Dayton Wright speakers shown here: https://hommage.lemayaudio.com/en/hommage/

I'm not sure I could contribute much to a discussion thread, but I've devoted a lot of thought to ESL design and it's nice to know there are others who share the psychosis :)
 
I grew up in a suburb of Toronto. That city probably had many of the best audio shops in all of Canada. As a teenager, I had a nice University sound speaker system I put together from the plans published by that company. It had a 12 inch woofer with Alnico magnet (seems those were amazing magnets because the field is unaffected by the magnetic flux in the voice coil.) The system was a threeway and I had purchased their super-tweeter, that claimed a response to 40,000kHz. I used that using a calibrated signal generator to test my hearing which extended to 22kHz at that age. Since I had amazing hearing when I was young, I focused a lot on how badly all HiFi sounded in the upper octaves compared to live music. The first time I heard electrostatic speaker was at an audio show in 1968. I still remember they were playing the Dayton Wrights using a direct drive tube amplifier playing Abraxis. When I heard how accurate the sound of drums and how clear the other instruments were I decided after I graduate from college I am going to buy one of these speaker. Well I did, never realizing how much effort it was to maintain them. Anyways, thought the 70's and 80's it was the blossoming of HiFi. I heard Heil air-motion transformers, the Ohm speaker, the original Quads, the amazing Crown 2x10 hybrid electrostatic system. They were 10 Jantzen electrostatic panels with a acoustic suspension double 10 inch woofer cabinet, driven by the crown DC150. very clear sound but somewhat un-musical, because the transition between bass and treble panels was not so good. The panels also seemed too bright. The thing I remember about the Quads was they did not play that loud and when driven by the crown they had to be repaired a few times because people in the showroom played them too loud because they really sounded good. A few of the staff used to sit in front of them, play some Beatle albums and smoke weed. There was a turntable, I don't remember which one, but they were using a Goldring cartridge, which at the time was probably the best sounding out there. Another store demonstrated the Hill plasma air tweeter. The treble was amazing, but the practicality was not. There was tank of helium in the cabinet and it would have to be replenished. But for me the subtle hiss of the gas escaping the jet made them uninteresting.
At that time, the driving the Dayton Wrights were presented as a challenge to several famous amplifier designers in the US. The PhaseLinear 700 amp is one. After a few modifications it stopped blowing up. The transformers in the speakers were 1000VA 100:1 step-up and insulation rated at 20kV. the speaker terminals were those ceramic things you see on high voltage power lines, lol. The reason I mention it is that that transformer, no matter what amp you threw at would be unaffected by any amplifier destruction. Worst case it would blow the 7A slow blow fuse. The ideal amplifier at that time and I think even today, a good match is any of the Nelson Pass designs. The effective speaker impedance is a 4.7uF capacitance in series with 3 Ohms. One of the ML impedance graphs I had seen was similar, 2 Ohms in series with a 2uF capacitance.
 
Ok the brackets arrived and finally put them together. It got late so i have not hooked them up. I need to make up some other speaker cables since I cant use my Kimber Kable speaker wires yet. The speakers look great.
20240630_155901a.jpg
 
I can well imagine. The space between the outer diaphragms would form a distributed acoustic resonator, particularly as the half wavelength approaches the spacing. Not insurmountable, just complicated. At low frequencies, though, the three diaphragms would move approximately in unison, and the wide spacing would allow for large excursions, ideal for a separate bass panel, if one wanted to go that route. If you create the thread I'd be interested in following it.
I started the thread on it already. One thing to remember all the design criteria depends entirely on the use of SF6. The bias voltages were between 12 and 16kV. There was a reostat on the bias supply to lower the voltage on humid days and increase it on dry days. Even within the the mylar enclosed speaker, there was still enough ingress of humidity. The best thing it provided was preventing dust settling on the cells.
 
I got them connected and there is a problem with one panel. Bass speaker works fine, but hardly anything coming out of one panel. I am going to have to order one. It has been quite a while since theeir delivery on June11. Has anyone else had problems with damage when they were shipped?
 
I got them connected and there is a problem with one panel. Bass speaker works fine, but hardly anything coming out of one panel. I am going to have to order one. It has been quite a while since theeir delivery on June11. Has anyone else had problems with damage when they were shipped?
I ordered a pair of Prodigy panels and the shipping was great. They came in a box that seemed like what they use on new speakers. It was done very well.
 
I got them connected and there is a problem with one panel. Bass speaker works fine, but hardly anything coming out of one panel. I am going to have to order one. It has been quite a while since theeir delivery on June11. Has anyone else had problems with damage when they were shipped?
Just curious... do you see any physical damage (bent or dented stator, chipped stator coating, etc...) on the panel that hardly outputs any sound? If no physical damage is evident, you might want to hang on to that panel and rebuild it someday-- it might be easier than you imagine.
 
@Jassman53, If you look at the pictures that I posted near the top, every plastic bracket that holds the panel to the woofer was broken. They were shipped in the original manufacturer's boxes. On one side all three wires connecting the panel were ripped out of the junction block. Upon inspection I saw that where the wires go into the panel, the plastic was pulled out a bit, This is why I measured the capacitance of the panels. And when they were different I concluded something was wrong, but not knowing what the correct value is, I did not know if it was really damaged. From what I see, I think the panel is not getting any bias. The side that had the wires ripped off is working, so I think I swapped the broken panel to the other side. Going to switch them around. I don't really feel like I want to measure if it actually is getting 3kV.
When I ran my previous speakers in air, I used 9-10kV bias. Am I right that all MartinLogan panels use 3kV? Must have been a decision quite a while ago to lower the gap and reduce excursion capability. Every time you lower the frequency response you need double the excursion for the same volume.

I agree with you on keeping it. Certainly would take it apart to see how they maintain the diaphragm curved and pensioned. I do see little plastic strips across the diaphragm across the several places. To my mind is see parasitic capacitance everywhere. And of course it is hard to make base when the diaphragm cant move across the whole surface in unison.
I won't comment on the sound before I get both sides working. But just for the working side, I am not disappointed.
My reference for playback sound quality are high end Beyerdynamic ear speakers, with a high quality headphone amp driving them.
 
@Jassman53, If you look at the pictures that I posted near the top, every plastic bracket that holds the panel to the woofer was broken. They were shipped in the original manufacturer's boxes. On one side all three wires connecting the panel were ripped out of the junction block. Upon inspection I saw that where the wires go into the panel, the plastic was pulled out a bit, This is why I measured the capacitance of the panels. And when they were different I concluded something was wrong, but not knowing what the correct value is, I did not know if it was really damaged. From what I see, I think the panel is not getting any bias. The side that had the wires ripped off is working, so I think I swapped the broken panel to the other side. Going to switch them around. I don't really feel like I want to measure if it actually is getting 3kV.
When I ran my previous speakers in air, I used 9-10kV bias. Am I right that all MartinLogan panels use 3kV? Must have been a decision quite a while ago to lower the gap and reduce excursion capability. Every time you lower the frequency response you need double the excursion for the same volume.

I agree with you on keeping it. Certainly would take it apart to see how they maintain the diaphragm curved and pensioned. I do see little plastic strips across the diaphragm across the several places. To my mind is see parasitic capacitance everywhere. And of course it is hard to make base when the diaphragm cant move across the whole surface in unison.
I won't comment on the sound before I get both sides working. But just for the working side, I am not disappointed.
My reference for playback sound quality are high end Beyerdynamic ear speakers, with a high quality headphone amp driving them.

I see your point. The impact could have pulled apart the flimsy connection between the bias supply lead and thin foil charge ring.

In your photo I see a greenish coloration on the exposed ends of all three panel wires. Is that corrosion or merely an artifact of the lighting?

It's easier to replace a dead panel with a new one but a dead panel can be rebuilt if the stators are undamaged.
 
Further thoughts:

I think you're ultra-efficient Dayton Wrights have spoiled you :)

So glad you posted the DW photos:
Aside from DW's SF6 and ultra-high voltages, I immediately noted the ultra-small stator slots, making finely spaced conductors-- no doubt resulting in a uniformly dense and powerful electric field, and the stator edges are small and curve away to minimize stray capacitance.

In comparison:
Perf-metal ESLs like ML's necessarily have wide edge bands for mounting, which produce huge stray-capacitance that loads the amp without contributing to output.

They are cost-effective, sound wonderful, and can be curved to mitigate beaming, but they aren't an easy load or especially efficient.

On the ML theater panel I recently rebuilt, the front stator-to-diaphragm gap was only about 0.030" (adjacent to spars) , and this gap limits how much bias voltage can be used (<3kV I would think).

Most DIY'ers use standard 1/16" (0.063) spacer-tape to set the diahragm-to-stator gap (d/s) for hybrid flat panels, and set the bias voltage about 1/2 the breakdown voltage of air. The breakdown voltage of air is about 100V/mil so, for a 0.063" d/s the safe bias voltage would be about 3kV.

Segmented wire-stator ESLs can have almost zero stray-capacitance because [except for the small areas where the wire loops are anchored at the panel ends] the wires only occupy driven areas of diaphragm.

Wire diameter smaller than the d/s, with minimal .010 SRPVC insulation, and optimal 43% open-area spacing yield very high efficiency for an open-air ESL. Their downside is the labor involved.

The wire-panels' segmentation resistors rob a bit of power that would not be lost in perf-metal panels, but this loss is less than the power lost to higher stray-capacitance in perf-metal panels.

Another advantage of RC segmentation is that the load becomes predominantly resistive.
 
The Dayton Wright panels were far from efficient compared to my new ML ESL. The DW panels required at least 300W/channel into 4 ohm to produce reasonable volume, especially when used without SF6. I used them this way for last few years before most panels died. ML panels seem very efficient. I used temporarily a 100W/channel amp and they play nice and loud, even with just one panel going. Using 1/16 inch gap certainly rules out even remotely using the panels for even high bass., but it raises the efficiency 12dB over 0.25 inch gap. Each time you double the gap, you loose 6db driving force. So you need to double the electric field to gain it back. So 0.25 inch means 12kV bias roughly. I think there are no current ESL that run this because of the high expense in transformer insulation and cost of HV supply.
Using a 100:1 transformer the power amp output has to swing at least 120V peak to peak to get a good volume. My own design had +/- 70V DC supply. Using Mosfet output devices with their high gate voltage my supply for the drivers was +/- 80V. I have not used it since I don't know what the limit of the ML panels are before arcing. I also looked at the tiny step-up transformer and not sure at what power level it will saturate.
I ordered a single new panel today. My seller reimbursed me for all costs, so I good and learned how to take these speakers apart. When you buy new you really are reluctant to hack them.
 
Order has been accepted, but no shipping info yet? What has been others experience with shipping time? Eric said mine will come from Missisauga, Ontario, Canada.
 
Well after it arrived, the capacitance matches the panel that I thought was good. Got it all installed and been listening to various music. I am not quite there with my tweaking. I think the speaker sound a bit bright. I am using a solid state bipolar amp. An Acurus 100x3 amp I took out of my home theater. I am going to replace it with a Mosfet power amp. The one I designed and build seems intermittent. Turns out that the power switch is broken. For year i had it also in my home theater and it was remotely turned on with a relay. I also purchased another commercial Mosfet amp which should be arriving soon. To me Mosfet amps always seemed to be a better match to electrostatic speakers, because they clip/distort more gradually. I like to play my speakers at live levels when I can to experience the like you are there experience. Many SS amps have their protection circuits cut in and it makes the sound harsh and nasty. Of course not all the time. Now I have a RadioShack SPL meter on my table just to make sure i don;t overdo it.
 
The speakers are very revealing. A great test of a sound that everyone is familiar with is hand-clapping. Most people don't really pay attention to the sound in real life, but it is an outstanding test for how a speakers transient response is. That and hard strumming of a guitar. I have one recording where you can actually count the number of people clapping if you have a revealing sound system. To me these speakers pass the test. I have a large number of recordings that have high dynamic range and have the transients very well recorded,. Any of the CD by David Gruisin is at least for my "Sound Candy". The last cut on this CD has the clapping. The rest of it just sounds great on these speakers.
 

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