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Topic: Electrostatic speaker myths (Read 14676 times) previous topic - next topic
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Re: Electrostatic speaker myths

Reply #25 –
Quote from: Kees de Visser on
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 –
Quote from: ajinfla on
Quote from: old tech on
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 –
Quote from: Lighton on
Quote from: Kees de Visser on
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 –
Quote from: Arnold B. Krueger on
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 –
Quote from: ajinfla on
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 –
Quote from: Kees de Visser on
Quote from: ajinfla on
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 –
Quote from: Kees de Visser on
Quote from: ajinfla on
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 –
Quote from: Arnold B. Krueger on
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 –
Quote from: Porcus on
Quote from: Arnold B. Krueger on
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 –
Quote from: Arnold B. Krueger on
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 –
Quote from: ajinfla on
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 –
Quote from: Porcus on
Quote from: Arnold B. Krueger on
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 –
Quote from: Porcus on
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 –
Quote from: htnut3 on
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.