Very nice rebuild and thanks for sharing!
I use a similar technique for measuring resonance, mic close to the membrane, run some rta software and tap it. However for larger membranes (Audiostatics) I prefer running a slow sweep on a conventional box speaker nearby, while looking at the reflection of a light source in the mylar. When it hits resonance the amplitude increases quite noticable. You'll need quite some volume and sometimes some experimentation with placement to get good results.
I use a similar technique for measuring resonance, mic close to the membrane, run some rta software and tap it. However for larger membranes (Audiostatics) I prefer running a slow sweep on a conventional box speaker nearby, while looking at the reflection of a light source in the mylar. When it hits resonance the amplitude increases quite noticable. You'll need quite some volume and sometimes some experimentation with placement to get good results.
Externally similar, but this is where their similarity ends, because the electrostatic membrane is controlled over the entire area by a uniform electrostatic field, and the drum will have zonal resonances.
In the photo where you showed the peeled off second film from the first, apparently they made it insulating, that is, they applied a conductive coating to the main film and covered it with another one on top, all this is strange.
When I tried sweeping a tone on a speaker I also tried bouncing a laser off the diaphragm to watch the line it put on the wall. I figured that at maximum amplitude it was resonant, but I was never sure if the diaphragm was just following the speaker or if what I was seeing was the diaphragm resonance. I also found that the line on the wall would rotate depending on where on the diaphragm the laser bounced.
I understand that the driver behavior is going to be different when bias and signal are applied. But when they aren't, two same-sized drivers tuned to the same resonance should behave the same when bias and signal are applied.
I understand that the driver behavior is going to be different when bias and signal are applied. But when they aren't, two same-sized drivers tuned to the same resonance should behave the same when bias and signal are applied.
There are 3 methods for electrostatic charging:
- Charging by friction
- Charging by conduction
- Charging by induction
- Option 1, not an option in an ESL
- Option 2, used by most, the simplest method
- Option 3, the Peter Walker method used on the high panels of the original ESL and used on all panels on the 63
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The gray coating on the diaphragms is conductive and it is on the side that contacts the metal strips on the grid on the back side of the driver.
I'm always surprised that talking about an electroSTATIC speaker there is always only talk about surface resistance and conductivity.
I am aware that people are doing their measurements on the graphite layer.
I am aware that people are doing their measurements on the graphite layer.
Who said it wasn't. Your conclusions from those facts are different from mine.
Yes, this is also new for me, and you raise an interesting subject with this subject of inductive loading. Thanks to your your input I now even have been diving a bit into the theoretical basics of induction, thus refreshing my physics, thank you for this very special kind of induction 🙂.
But I have to admit that I still cannot precisely understand the mechanism of induction within an ESL63. I would really need some kind of "... for dummies ..." how-to about the way this specifically functions within an ESL63, and therefore I would greatly appreciate if you could elaborate about the subject. For the sake of a deeper understanding of these marvellous 63's.
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I have never "held in my hands" the
Therefore, it can be assumed that the membrane worked due to "friction", that is, nylon was applied to the lavsan, forming a tribo-pair. I did it this way, so this is a working option, the whole problem is in the recoil, it is weak and in general the whole problem with electrostatics is in their efficiency.
Then I have a question for more experienced users: over the entire history of the ESL 57 and ESL 63 models, which of them failed more often?
wout31, you wrote that the inductive bias option does NOT require contact, but MarkRehorst writes that there is still contact, how to understand this?
QUAD
speakers, but I have come across information on the Internet that the first ESL 57 required a long charge, literally 0.5 hours, some even suggested never turning off the bias.Therefore, it can be assumed that the membrane worked due to "friction", that is, nylon was applied to the lavsan, forming a tribo-pair. I did it this way, so this is a working option, the whole problem is in the recoil, it is weak and in general the whole problem with electrostatics is in their efficiency.
Then I have a question for more experienced users: over the entire history of the ESL 57 and ESL 63 models, which of them failed more often?
wout31, you wrote that the inductive bias option does NOT require contact, but MarkRehorst writes that there is still contact, how to understand this?
As I wrote, there are 3 different charging methods, so I guess he didn't use method 3 like Peter Walker did.
They both failed, but both with very different reasons as the construction is also completely different.
The 57 failed on the high panels arcing due to the extremely small air gap of 0,5 mm, the bending and construction of the panels. Please note there was no protection in the early 57 model and they were designed with the 15W Quad II tube amp in mind, not for 100+ watt SS amps. In later productions a clamp board was installed to limit the voltage to the vulnerable high panels. The clamp boards are now often retro fit. The bass panels hardly ever fail, they only loose efficiency due to deterioration of the Nylon coating. The air gap and the bias voltage on the 57 bass panels is quite different from the high panels. 10x the air gap (which is not all free movement of the diaphragm) and 4x the bias voltage.
The 63 (and all later models up to the current ones) mostly failed due to poor glue strength that holds the stator to the plastic grid. The stator would come loose from the grid and touch the Mylar or cause arcing due to reduction in stator - stator distance. It destabilises the system and when not fixed, results in other problems to occur. Combined almost 100K units of these speakers were sold over the years.
You have a vivid imagination. Can't imagine how that would work, but that could just be me. There has to be contact and friction between 2 opposite tribo materials to charge like that. Next you have to separate the 2 to hold the charge.
Never turn off the bias is the best way to go IMHO.
Depending on how you charge the diaphragm, what coating you use and the (remaining) quality of the coating, it can take quite some time (or not) to FULLY charge the diaphragm.
The fact that the speaker produces sound doesn't mean it is fully charged. You can establish that with measurements.
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So, after all, the film that peeled off from the main membrane with the black coating applied in the photo above - what material is it made of, nylon or the same mylar as the main one?
As for IMHO, this is correct, because I, for example, would never do this, because in this case the membrane attracts dust to the membrane around the clock, and the membrane is STILL, that is, it does not “shake off” the dust as happens during operation.
That is why there are dust covers on ALL Quad ESL models. No other brand has dust protection. Mylar by itself attracks dust because it is very easily positively charged. Look at old dust covers and you know.
I'm not interested in the black coating layer. I'm interested in the electrostatic coating layer. What that is? That is the million dollar question and why there are threads about coating living 17 years on this forum. Can't be Mylar IMHO.
That thread is 17 years long because... audiophiles.... There's always someone who is trying to assert their superior knowledge of the smallest of minutia. They know more than you, they can hear better than you, and their system is better than yours. Ignore it.
People who actually build and/or repair ESLs use what works and don't need to argue about it for 17 years. Who cares what the factory used? The factory used crappy glue for the diaphragms and the stators. Do you want to duplicate that, too, or improve it?
Back in the day, the arguments against Licron were "ooh, the mass! it's going to lower the resonance of the panels..." when no one was measuring the resonance anyway. I measured it. 1 Hz. I'm not worried about it.
While others argue and fret over the exact formulations and processes the factory used, and they'll probably continue for another 17 years, I enjoy my speakers.
People who actually build and/or repair ESLs use what works and don't need to argue about it for 17 years. Who cares what the factory used? The factory used crappy glue for the diaphragms and the stators. Do you want to duplicate that, too, or improve it?
Back in the day, the arguments against Licron were "ooh, the mass! it's going to lower the resonance of the panels..." when no one was measuring the resonance anyway. I measured it. 1 Hz. I'm not worried about it.
While others argue and fret over the exact formulations and processes the factory used, and they'll probably continue for another 17 years, I enjoy my speakers.
Forget the tribo electric story. Tribos means rubbing and unless you are willing to take the ESL apart, rub the Mylar with a cloth and quickly reassemble it, it makes no sense. Induction would be like putting a kind of plate capacitor in series. Cant see any benefit in doing it that way. Likely to loose voltage in a rather unpredictable way.
By the way nice pics of the quads. I got a 57 waiting for repair and it seems lots of horror and surprises are waiting for me. They look so clumsey made.
By the way nice pics of the quads. I got a 57 waiting for repair and it seems lots of horror and surprises are waiting for me. They look so clumsey made.
@MarkRehorst As do I enjoy my Quad ESL 57 and ESL-63, for over 40 years now.
Rebuilding Quad ESL's for over 10 years now. Measuring every single piece we deliver back to the owner and testing on new developments. Seeing differences and small and larger improvements that can be made over the years as we learn is an ongoing process
Nothing audiophile and no superior knowledge about it, just technically curious and challenged why Peter Walker made some choices and if I understand them correctly or at all. I DO care what the factory used, to understand if it was a technical choice, a commercial choice, a manufacturing choice (could it be made fast and cheap), a strong compromise choice. Nothing on these speakers is by accident. Still more questions than answers after all these years. But still working on them every day with the greatest joy. Never saw any comment on Licron being heavy and influencing resonance. It is applied so thin it can have only very little weight influence. And as you questioned yourself, does the resonance matter?
Rebuilding Quad ESL's for over 10 years now. Measuring every single piece we deliver back to the owner and testing on new developments. Seeing differences and small and larger improvements that can be made over the years as we learn is an ongoing process
Nothing audiophile and no superior knowledge about it, just technically curious and challenged why Peter Walker made some choices and if I understand them correctly or at all. I DO care what the factory used, to understand if it was a technical choice, a commercial choice, a manufacturing choice (could it be made fast and cheap), a strong compromise choice. Nothing on these speakers is by accident. Still more questions than answers after all these years. But still working on them every day with the greatest joy. Never saw any comment on Licron being heavy and influencing resonance. It is applied so thin it can have only very little weight influence. And as you questioned yourself, does the resonance matter?
Not clumsy.
Fifties made. Manual labour, no CNC, no computers, in an audio market in which the phrase High Fidelity was not invented yet.
And very British like the cars of the era. If a British car didn't leak oil, there was no oil in it.
Probably Google didn't translate it clearly enough, what is this sandwich?
I suppose that even without a million dollars you can figure out that this is graphite on mylar covered with nylon.
Why did it peel off? Because it was specially not welded tightly to create a triboelectric effect.
I wrote above - I did it this way, only I baked nylon varnish on mylar at a temperature close to the melting point of mylar, this has been working since 2010 on the monsters that I made then, this is on bass panels where the mass is even preferable to a very light membrane, but the varnish was only a couple of microns thick, if the membrane is 12 microns, then with varnish 15 microns.
Next, how to check the reliability of the coating for its flying off, after all, in the bass register the amplitude of the oscillation and frequency are quite critical for an incomprehensible sandwich, but in this case I checked it the Soviet way, adhesive tape (transparent) is glued to the finished membrane, and then with a sharp movement it is torn off the membrane, if the coating remains on the adhesive tape then... then you are a loser😀.
This is essentialy why I refurbished mine. To try to understand.
And I really would like to understand your finding about the charge induction into the specific charge carrier layer. E.g. what is the surface resistance of this stator-sided layer, then? And also, an unanswered question of mine - what is the layer you call the "bonding" good layer? Obviously to bond something. But bonding what? I already asked for an answer but unhappily got none until now.
As I peeled off the sandwich, I maybe I peeled off one of these mystery layers from the mylar. Either the "bonding" layer, or the electrostatic charge carrier layer as you preconize. As today, I don't think it was yet another sheet of mylar, despite it's similar strength.
@Daihedz Sorry I can't answer all you question instantly. I have to think how to formulate my answers. In audio there is never a simple answers, as everything is connected and I don't have all the answers, still learning and testing every day as mentioned.
My thoughts about the bonding layer is simple. Try to stick graphite to Mylar. You can't, it wont stick. So you need an adhesion layer.
The surface resistance of the electrostatic layer is around 200 Gig Ohm per square on samples I was able to measure. But these were diaphragms taken from old panels. So was this like it was new? I don't know? My guess is, it is nylon like on the 57. As you found out and mentioned, you can peel that layer off as one film.
More important than the square resistance is that the stator side layer is completely isolated from the plastic frame, it floats to prevent leakage. It can only leak to the air and the Mylar. Resistance of Mylar is 10^16, so most likely only leakage to air.
Please note before any comments, these are my findings after many years and many dozens of sets of Quad ESL's rebuilds. Am I right, am I wrong? This is just a discussion, not trying to make any statement.
My thoughts about the bonding layer is simple. Try to stick graphite to Mylar. You can't, it wont stick. So you need an adhesion layer.
The surface resistance of the electrostatic layer is around 200 Gig Ohm per square on samples I was able to measure. But these were diaphragms taken from old panels. So was this like it was new? I don't know? My guess is, it is nylon like on the 57. As you found out and mentioned, you can peel that layer off as one film.
More important than the square resistance is that the stator side layer is completely isolated from the plastic frame, it floats to prevent leakage. It can only leak to the air and the Mylar. Resistance of Mylar is 10^16, so most likely only leakage to air.
Please note before any comments, these are my findings after many years and many dozens of sets of Quad ESL's rebuilds. Am I right, am I wrong? This is just a discussion, not trying to make any statement.