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Topic: Electrostatic speaker myths (Read 21172 times) previous topic - next topic
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Re: Electrostatic speaker myths

Reply #25
Can you please elaborate about the math ? Arny already stated F = MA
So what? It's a linear equation. If you have two speakers producing (roughly) the same sound and at the same volume, they've both got to be imparting similar forces on the air. I could be wrong but I imagine this is part of why electrostatics have poor bass, in order to achieve the same force in that range, A would have to be quite large, and it's going to be limited by the materials and presumably a bunch of other factors.

Re: Electrostatic speaker myths

Reply #26
I was thinking more about his general discussion around digital media, amplifiers, measurements, double blind vs sighted testing and so on.
Yes, he seems to be spot on there. It was just ironic that he repeated an audiophile myth about driver mass right off the bat. That claim is pure nonsense.

As I read my post, I said pretty much what you did, just up thread. I read your post as debunking the myth that minimizing diaphragm mass gives an insurmountable advantage. I agree. and said exactly that in my way with the comment about F=MA. Your comments about differences in radiation pattern were addressed by my posting of some radiation patterns for 'stats. Are we  agreeing noisily or what?



Re: Electrostatic speaker myths

Reply #27
Can you please elaborate about the math ? Arny already stated F = MA
So what? It's a linear equation. If you have two speakers producing (roughly) the same sound and at the same volume, they've both got to be imparting similar forces on the air. I could be wrong but I imagine this is part of why electrostatics have poor bass, in order to achieve the same force in that range, A would have to be quite large, and it's going to be limited by the materials and presumably a bunch of other factors.

Since people are not getting my intent. Please let me expand on the mass issue. Let's say that we have two speaker diaphragms, one with low mass and one with high mass. Either can be accelerated as desired by providing sufficient acceleration, or force. Either can have the same rise time or impulse response if enough force is available.  Coming up with enough force is simply an engineering problem, subject to the inherent properties of the materials involved.

Electrostatic drive in practice tends to be limited in terms of available force. Electromagnetic drive is also limited, but in the real world we observe that it is common to have far, far higher amounts of force available with electrodynamic speakers.  The ready availability of cheap good clean amplifier power helps. This shows up as much higher dynamic range. The ESL63 addresses some of the directionality issues with a novel diaphragm design but it is brutally limited on the dynamic range issue.  The highest dynamic range drivers are based on the so-called electrodynamic compression driver that is actually limited by the nonlinear compression of air at the extremes.

To expand on the electrostatic dynamic range limitations. Electrostatic diaphragms are like any diaphragm, they need to have working room to move. In an electrostatic, one obtains that working room by increasing the spacing of the diaphragm and drive elements. But increasing the spacing decreases the electrostatic field gradient and thus decreases efficiency. You can increase the electrostatic field gradient by applying more voltage but above about 10,000 volts you start ionizing the atmosphere that the speaker is operating in.

There was one attempt that I know of to address this problem of air ionization by putting the whole speaker into a gas chamber, and this was the legendary Dayton-Wright.  I don't know why they went out of business, but I'm guessing that the insulating gas (Sulfur Hexaflouride?) leaked away and when the speaker turned itself back into an air-dielectric speaker, it failed fatally.   

Reference: https://en.wikipedia.org/wiki/Dielectric_gas

It is possible that since one of the consequences of arcing in Sulfur Hexafluoride can be the generation of Phosgene, a well-known highly poisonous gas with possible military significance, safety concerns may have killed the Dayton Wright.

Re: Electrostatic speaker myths

Reply #28
The "problem" about "F = ma" ("in singularis", just one equation and just one force) is the simplification to one representative body.  For a dynamic-speaker cone, the forces at the outer rubber suspension are not the same as the forces at the point it is glued to the voice coil unless the cone is rigid. For an electrostatic, the idealized model would be expected to be much closer to the truth. If that matters.

To get from F = ma to something more realistic like a(x) = F(dx) / m(dx) (where x = location on the diaphragm) and then aggregating up, isn't witchcraft, but it surely isn't handwaving. And to get from there to actual sound at listening position? Not "sound or not", but "better or worse"? If you pretend that you are doing science, then don't show me the my high school spherical cow in the vacuum. Show me model-predicted reproduction vs actual measurement.



Re: Electrostatic speaker myths

Reply #31
The ready availability of cheap good clean amplifier power helps. This shows up as much higher dynamic range. The ESL63 addresses some of the directionality issues with a novel diaphragm design but it is brutally limited on the dynamic range issue.


The Sound Labs seem to solve this problem. They run pretty high voltages (I seem to recall about 10KV) and for many years they did have arcing problems. That seems to be solved with a new diaphragm material they call the 'PX technology' .

They do need a bit more power, but with 100 watts on them they seem to fill an average room easily enough.

Re: Electrostatic speaker myths

Reply #32
There is no "performance/accuracy"advantage to stats in the midrange due to F=MA, that is pure nonsense.
It's not that I don't believe you, but I was actually hoping for some links to papers, or formulas that show that the 800x mass difference (3mg ESL 63 diaphragm vs a 2.5g typical driver like your Audax Mms) is non significant.

Re: Electrostatic speaker myths

Reply #33
There is no "performance/accuracy"advantage to stats in the midrange due to F=MA, that is pure nonsense.
It's not that I don't believe you, but I was actually hoping for some links to papers, or formulas that show that the 800x mass difference (3mg ESL 63 diaphragm vs a 2.5g typical driver like your Audax Mms) is non significant.
Kees, here is the quote again:
Quote
Magnetic speakers simply cannot match the performance of electrostatics in the midrange because they are heavy so cannot be accelerated quickly and accurately at treble frequencies.
There is nothing for me to link or show. It's up to Sanders to back that claim that "Magnetic" speakers (he probably means moving coil/dynamic) can't match the "performance" of electrostats due to diaphragm mass.
What "performance"?
Loudspeaker manufacturer

Re: Electrostatic speaker myths

Reply #34
There is no "performance/accuracy"advantage to stats in the midrange due to F=MA, that is pure nonsense.
It's not that I don't believe you, but I was actually hoping for some links to papers, or formulas that show that the 800x mass difference (3mg ESL 63 diaphragm vs a 2.5g typical driver like your Audax Mms) is non significant.

Barring a reliable source substantiating that the entire ESL63 diaphragm weighs a mere 3 mg, I'll call BS! I searched, but I found no such thing. 3.5 mg per square inch, I'll believe. ;-)


Re: Electrostatic speaker myths

Reply #35
Barring a reliable source substantiating that the entire ESL63 diaphragm weighs a mere 3 mg, I'll call BS! I searched, but I found no such thing. 3.5 mg per square inch, I'll believe. ;-)

Yeah, 3.5 mg per square inch, that matches very well - assuming Stereophile's thickness figure is off by a factor of 10 (and I manage to get the number of zeroes right!).
According to various sources (e.g., like this) the ESL63 uses a 3.5 µm thick mylar film. (Stereophile's figure translates to ten times as much).  Googling a couple of sources for the weight of mylar:
http://www.pauzuolis-rc.com/rc-shop/building-materials/mylar-film/mylar-film-3-mk
http://www.homefly.com/reference/Covering%20Weights.htm

A 3.5 µm mylar film would be around 5 grams per square meter. ~5000 mg/m^2 * (2.54/100)^2 (in/m)^2 translates to ~3.2 mg/square inch. (Edit: corrected m and µ this line.)

Re: Electrostatic speaker myths

Reply #36
Barring a reliable source substantiating that the entire ESL63 diaphragm weighs a mere 3 mg, I'll call BS! I searched, but I found no such thing. 3.5 mg per square inch, I'll believe. ;-)

Yeah, 3.5 mg per square inch, that matches very well - assuming Stereophile's thickness figure is off by a factor of 10 (and I manage to get the number of zeroes right!).

According to various sources (e.g., like this) the ESL63 uses a 3.5 µm thick mylar film. (Stereophile's figure translates to ten times as much).  Googling a couple of sources for the weight of mylar:
http://www.pauzuolis-rc.com/rc-shop/building-materials/mylar-film/mylar-film-3-mk
http://www.homefly.com/reference/Covering%20Weights.htm

A 3.5 µm mylar film would be around 5 grams per square meter. ~5000 mg/m^2 * (2.54/100)^2 (in/m)^2 translates to ~3.2 mg/square inch. (Edit: corrected m and µ this line.)

In comparison, the mass of the diaphragm of a candidate tweeter is given as 0.21 grams.

https://www.madisoundspeakerstore.com/ring-radiator-tweeters/vifa-ot19nc00-2/3-ring-radiator-tweeter-4-ohm/

Re: Electrostatic speaker myths

Reply #37
In comparison, the mass of the diaphragm of a candidate tweeter is given as 0.21 grams.

About 86 times as much per area unit, in order to keep the diaphragm rigid. But that says virtually nothing about whether it is "rigid enough", whatever that means.

When it comes to just the quantitative stuff, it is about as efficient as the ESL63.

Re: Electrostatic speaker myths

Reply #38
There is nothing for me to link or show. It's up to Sanders to back that claim that "Magnetic" speakers (he probably means moving coil/dynamic) can't match the "performance" of electrostats due to diaphragm mass.
What "performance"?

I remember being intrigued by Sanders' articles in The Audio Amateur when he published the details of how to build his direct-drive amp and electrostatic speaker combo - but he has always seemed to have a rather tenuous grasp of theory.  Even then you could tell by the handwaving that he accomplished most of his designing by trial and error.

Somewhere on his site he gives a putative explanation for the higher instantaneous power capabilities of tube amps, and he describes the phenomenon we know as "space charge" around the cathode providing a huge current reservoir to the amplifier.  Right then I realized that he's just trying to pump up the audiofools.  I wouldn't take any of his claims about loudspeaker performance seriously unless I read them from someone with a little better grounding in physics.

Re: Electrostatic speaker myths

Reply #39
In comparison, the mass of the diaphragm of a candidate tweeter is given as 0.21 grams.

About 86 times as much per area unit, in order to keep the diaphragm rigid. But that says virtually nothing about whether it is "rigid enough", whatever that means.

When it comes to just the quantitative stuff, it is about as efficient as the ESL63.

I love people who cherry pick their facts. 

The use of "mass per unit area" is entirely misleading as there is no need for the ring  tweeter to have anywhere near the same diaphragm area as a comparable 'stat. 

The ring tweeter's small area is a well-known technical advantage.

Comparing the size, complexity and cost of the 'stat with the ring tweeter or typical speakers containing the ring tweeter would be instructive, but also devastating to the 'stat.  Are there any 'stats with comparable dynamic range and power bandwidth for less than $10K?   A speaker with a ring tweeter and suitable woofer could run less than $200.

Comparing efficiency and ignoring all of the other disadvantages of the 'stat, or if you will the cost of elaborate and expensive efforts to attempt to overcome the inherent disadvantages of stats, is another example of cherry-picking the facts.


Re: Electrostatic speaker myths

Reply #41
So you want to talk about F but refuse to talk about F*s, and then you speak about cherry picking?

Please expand on that. I have no clue about what you are trying to get at.

Re: Electrostatic speaker myths

Reply #42
I realise the thread is a bit old, but just in case someone was interested the http://massless.info site debates the use of the term with respect to plasma speakers, tweeters, ionophones that sort of thing.

Re: Electrostatic speaker myths

Reply #43
the http://massless.info site debates the use of the term with respect to plasma speakers, tweeters, ionophones that sort of thing.
The argument made there is very centered on how bad the inertia of everyday speakers is, as it creates a mass-damper system. For example

Quote
All of the above have a common issue - they use a solid mass to drive the air. As a result of this there will always be some distortion present as the solid mass acts as a spring-mass-damper system and never truly follows the original signal. Of course this distortion is of little consequence for a wide variety of uses, however if we are trying to approach perfect sound reproduction then it is an area that needs to be addressed.

What it fails to mention is that as far as I know most plasma drivers have some sort of horn, which encloses an amount of air, and therefore also create inertia, and a mass-spring-damper system. However, while in an electrodynamic transducer you can control the mass, spring and damper, the air in a horn has fixed properties.

Quote
Other advantages of having no speaker diaphragm include: the lack of resonant frequencies
But then the horn has resonances, which makes this point moot.
Music: sounds arranged such that they construct feelings.


Re: Electrostatic speaker myths

Reply #45
Hello!

I am reopening this topic because, having read it, it does not seem to me that the assertion of dynamic/cone inferiority (to ESLs) due to their being spring-mass-damper systems was addressed.

This page describes it well:

"Interestingly and importantly, the way an ESL converts an audio signal to sound is the exact inverse of how a recording microphone converts sound into an audio signal. In a microphone, pressure creates voltage, and in an ESL, voltage creates pressure. This contributes to the exceptional accuracy of ESLs. It is not the case for cone speakers, where electrical current supplies non-linear force to a multiple spring-mass-damper system.

...

The situation is very different with cone speakers. One generally hears substantial contrasts in tone when listening to different designs. A large part of the explanation for this is that a heavy, spring-loaded coil pushes and pulls the center of a high mass radiating surface. There are practical limits to how accurately the coil movement can follow an audio signal, and then to how well the cone movement can follow the coil movement.

A cone speaker's resulting lags, displacements and resonances alter the sound in several ways, and add sound that was not part of the original recording. These effects can be minimized, but not eliminated or even made inaudible."

It is a fact that all cone speakers do operate as spring-mass-damper systems, and also a fact that such systems inherently lose information.

Intuitively, this strikes me as a serious weakness; it is intuitively obvious that this characteristic is going to result in substantial loss of information vis a vis an ESL, even with their other advantages (no crossover, uniform drive) being left on the table. We can also suppose that the advantage of the super-light membrane is not really an advantage, for the reasons discussed here - i.e., that heavier mass simply requires greater force and thus there is no inherent advantage. (FWIW, there's still an advantage in practice there.)

Is there anyone present here who would take a stab at "debunking" this supposed critical weakness of cones, and thus advantage of ESLs?

Re: Electrostatic speaker myths

Reply #46
What counts as loss of information? How much of it is too much?
If there is an imperfection that can be near perfectly negated by some equalization, is that also loss of information?
I would trust measurements more than intuitive reasoning. Are there any such measurements to back up this argument?
a fan of AutoEq + Meier Crossfeed

Re: Electrostatic speaker myths

Reply #47
Is there anyone present here who would take a stab at "debunking" this supposed critical weakness of cones, and thus advantage of ESLs?
Sure. I'll start with a simple omission in one of the statements:

Quote
"Interestingly and importantly, the way an ESL converts an audio signal to sound is the exact inverse of how a recording microphone converts sound into an audio signal. In a microphone, pressure creates voltage, and in an ESL, voltage creates pressure. This contributes to the exceptional accuracy of ESLs. It is not the case for cone speakers, where electrical current supplies non-linear force to a multiple spring-mass-damper system.
This ignores that electrostatic speaker membranes are usually rather large. Microphone membranes are often less than a centimeter (roughly half an inch) in diameter, and with larger membranes one often sees a roll-off in the high frequencies. The size of the membrane matters, so one cannot say an ESL is a direct inversion of a microphone.

More in general: Sure, electrodynamic speakers are not perfect. Tuning a mass-spring-damper system is a compromise, that is correct. But in return, electrostatic speakers are large and thus deviate from the ideal point-source. The lack of a crossover actually works against electrostatics in this respect: the higher the frequency, the more the size of the driver matters. So, a two-way speaker system can use a small element to come as close as possible to a point source for those high frequencies that need it the most, while using a larger driver for low frequencies that have long enough wavelengths for the size not to matter too much.

As with most technologies, there is compromise. Just because one technology outperforms the other in one aspect doesn't mean it is better, as it might be flawed in another.

Finally: Almost all nearfield studio monitors, which are built for the sound production with the highest accuracy, are electrodynamic, not electrostatic. That is not a coincidence. You could also say: the recording you're listening too has probably been approved by the musician while listening to an electrodynamic speaker. There is no reason to assume electrostatic loudspeakers will be closer to the artists intent if that artist worked on the recording using electrodynamic speakers.
Music: sounds arranged such that they construct feelings.

Re: Electrostatic speaker myths

Reply #48
What counts as loss of information? How much of it is too much?
If there is an imperfection that can be near perfectly negated by some equalization, is that also loss of information?

By definition, lost information cannot recovered.

The amount of loss of information that is tolerable is subjective.

But the topic here is the supposed debunking of objective electrostatic advantages.

We are talking here, mainly, about fine detail - decay trails fading to nothing, atmospheric nuance, etc. - these things live entirely outside the domain of EQ, which exists mainly to correct frequency response anomalies.

I would trust measurements more than intuitive reasoning. Are there any such measurements to back up this argument?

Yes. They are very easy to find - almost any ESL has far lower distortion in the midrange than almost any dynamic cone speaker, typically by an order of magnitude or better, even when the dynamic speaker is far more expensive.

In addition to its (virtually literally) perfect time-domain performance, the ancient Quad 63 & derivatives are some of the very lowest-distortion transducers made, at any price.

https://www.stereophile.com/content/quad-reference-esl-2805-loudspeaker-measurements

Measurements show that the best (under ~$50K) dynamic speakers such as Wilson Sasha and YG are around .5% distortion (500-1000 Hz) while Quads are .05-.1% - around 10% as much distortion.

The best dynamic speaker I could readily find measurements for compared to the Quad:

https://www.stereophile.com/content/wilson-audio-specialties-maxx-loudspeaker-measurements-part-2

The Quad is still 10 dB better than the incredibly expensive Wilson "MAXX" in the critical midband (1 Khz), and much better at lower frequencies. (S-phile summed it well: "The Quad was always a low-distortion speaker—I remember being with Martin Colloms when he measured an ESL-63 and found that it produced 0.1% THD or less over most of the audioband!")

The only dynamic speaker I have found that measures as well as even that old Quad 63 in the midrange was an active (active drive has advantages in driver control, of course) ATC three-way - it got very close. IIRC that speaker was well over $50K.

---

These measurements reinforce what my ears tell me. I have been going back to the Quad 63/988/2805 after trying many other speakers over the last decade or so because none of them give that sense of extreme purity, especially in the midrange. (I think the lack of any crossover and the resulting almost perfect phase performance are important ingredients as well.)

Re: Electrostatic speaker myths

Reply #49
More in general: Sure, electrodynamic speakers are not perfect. Tuning a mass-spring-damper system is a compromise, that is correct. But in return, electrostatic speakers are large and thus deviate from the ideal point-source. The lack of a crossover actually works against electrostatics in this respect: the higher the frequency, the more the size of the driver matters. So, a two-way speaker system can use a small element to come as close as possible to a point source for those high frequencies that need it the most, while using a larger driver for low frequencies that have long enough wavelengths for the size not to matter too much.

As with most technologies, there is compromise. Just because one technology outperforms the other in one aspect doesn't mean it is better, as it might be flawed in another.

You are certainly correct that there is no perfect speaker.

(It is interesting that one can literally spend $100K on a speaker system and immediately notice many faults. Audio shows are good for this type of education.)

You are also correct that the dispersion characteristics of large panels are a negative. The Quad 63 & friends get around this with that ingenious delay system. Trade-offs there too? Certainly.

In any case, because I came across this thread and found it interesting, I wanted to see what people here had to say about the mass-spring-damper issue. The stated purpose of the thread was to debunk the notion that electrostatics are generally superior to dynamic speakers, yet what is assuredly the biggest weakness of the latter was not discussed.

Finally: Almost all nearfield studio monitors, which are built for the sound production with the highest accuracy, are electrodynamic, not electrostatic. That is not a coincidence. You could also say: the recording you're listening too has probably been approved by the musician while listening to an electrodynamic speaker. There is no reason to assume electrostatic loudspeakers will be closer to the artists intent if that artist worked on the recording using electrodynamic speakers.

One need only take a look at any recording studio to realize that using ESLs as monitors is completely impractical for physical reasons. :)

The active ATCs I mentioned previously are extremely popular in studios, and, as noted, they are literally the only dynamic speaker I have ever been able to find measurements for that can compete with even the 50+ year-old Quad 63 design in midrange distortion.

They - the ATC three-way actives in particular - are also extremely expensive.

And, to my ear, still inferior to even the original Quad 63. I've owned several pairs of ATCs, though not the active 3-way models, but I have listened to those extensively at shows. I'd also climbed the Wilson ladder up to Sasha, but they, for their charms, can't touch the old (properly rebuilt) ESLs for purity, transparency, and naturalness - IMHO. (And going higher up that Wilson ladder is big $$$ indeed.)

FWIW, if anyone is interested, this is what I have hit upon, what has proven unbeatable for me after 15 years of being deep in the audiophile hobby, owning over 50 pairs of speakers, from single-driver backhorns, to conventional multiway dynamics, to cones (including with field-coil motors) on open baffles, to - probably the most esoteric - front horns with field-coil compression drivers (Cogent):

Quads, positioned semi-nearfield (8') in a large room, actively crossed at 24 dB/octave to dual 15" sealed subs.

Again, for sure there is no such thing as any home audio/speaker system that is without flaws, but I cannot find anything better, at least for under six figures. And this can be put together for far less.

But, again, IMHO and YMMV. It's all quite subjective.