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Electrostats vs conventional drivers
Electrostats vs conventional drivers
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Old 18th February 2019, 11:16 AM   #171
Bill Coltrane is offline Bill Coltrane  Netherlands
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Quote:
Originally Posted by MJ Dijkstra View Post
In a loudspeaker handbook I have seen pictures regarding cone breakup and resonance effects.
What can happen is that some parts of the cone move forward and some move backward.
So this resonance is less likely to appear in the output as it cancels. (unless you apply some very local laser doppler measurements?)
But it is resonance energy which needs to be fed from the input signal. As cones are relatively heavy this means you take away energy (information) from the beginning of the exciting signal. So a nearly perfect piston (if it would excist) would avoid this [problem.
Acceleration equals force divided by mass.
So if you have more mass, apply more force to get the same acceleration.

Pistonic behavior or not, has to do with stiffness and internal damping of the speakercone/membrane.
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Old 18th February 2019, 04:34 PM   #172
bolserst is offline bolserst  United States
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Originally Posted by kgrlee View Post
... loadsa good stuff though some of it is perhaps too simplified.
Indeed, intentionally simplified to focus on query concerning how impedance matching relates to EML & ESL.
Very easy to get lost in the weeds otherwise.

Quote:
In fact you want a diaphragm which shrinks in size & mass with frequency…ESL needs the refinements of Walker/Baxandall to achieve flat on-axis response
Agreed, and this is exactly what many current DIY builders are doing thanks to golfnut’s AES paper on segmented ESL line sources, and a few software tools.
AES E-Library >> Wide-Range Electrostatic Loudspeaker with a Zero-Free Polar Response
experiences with ESL directivity?
Segmented Wire Stator ESL simulator (esl_seg_ui)

Of course there are still tradeoffs between bandwidth, polar/power response, and sensitivity.
Example measurements: Glue for wire stators
Example trade-off trends: experiences with ESL directivity?

Quote:
…no mention of near field.
Already covered by golfnut in Post #117.
ESL driven with voltage source will have flat response in near field.

Quote:
Originally Posted by kgrlee View Post
…ESL63 midrange & treble is only OK. The reason is the dustcovers. Fig 6 in Peter Walkers AES article is without dustcovers. Response is MUCH more ragged with.
Pic of ESL-63 dust cover and ragged response posted here:
All Acoustat panels can give
Comparison of measurements vs theory for the effect of dust covers was posted here:
All Acoustat panels can give

The modeling method used is based on techniques described in one of the papers golfnut mentioned in Post #138.
http://www.aes.org/e-lib/browse.cfm?elib=18782
Superb article on HF ESL phenomena (IMHO)
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Old 18th February 2019, 04:38 PM   #173
bolserst is offline bolserst  United States
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Originally Posted by bentoronto View Post
Sure, for hours on end you can name ways drivers - of all sorts - can match or mismatch as woofers, mids, or tweeters. Yes, there are good and bad drivers. But I can't say as I've ever heard an empirically verified thought on the subject of matching.
The Toole book provides years of acquired data supporting subjective preference for smoothly trending power/polar response. This highlights the importance of considering directivity when matching up drivers for a system.
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Old 18th February 2019, 04:38 PM   #174
bentoronto is online now bentoronto  Canada
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Electrostats vs conventional drivers
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Originally Posted by bolserst View Post
...Only at 90 degrees off-axis from an ideal dipole piston will the pressure from the front and rear of the piston be equal and opposite and cancel. At all other angles, the different propagation path distance results in the phase difference being something less than 180 deg for low frequencies and will not cancel....
Even in the pure ray diagrams, the cancellation is remarkably slight over a large forward angle, as you've illustrated.

But all freq face cancellation albeit at the fluctuating freqs of music (in the pure ideal situation, that can be diagrammed looking like a comb... which is meaningless for shifting tones in music and whether apropos a dipole or off the side walls).

And more, the sound emanates from an extended surface, confusing the cancelation.

And even more, the whole cancellation diagram looks even more like a big bowl of spaghetti when sound comes off the back wall.

B.
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Old 18th February 2019, 04:41 PM   #175
bolserst is offline bolserst  United States
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Originally Posted by golfnut View Post
…Although the ESL itself is efficient, it forces the amplifier to be very inefficient and dissipate high powers.
Can’t remember if I had mentioned it before, but Edward Kellogg received a patent for the use of LC transmission line in 1934 to minimize amplifier dissipation when driving ESLs. I’m sure Figure 3 looks mighty familiar as the same concept is used in the Quad ESL-63 and decedents. Note also the inverted configuration (for which FINAL was awarded patent US7054456 in 2006) is shown in Figure 1.
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File Type: pdf Kellogg_US1983377.pdf (288.5 KB, 14 views)
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Old 18th February 2019, 04:45 PM   #176
bentoronto is online now bentoronto  Canada
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Electrostats vs conventional drivers
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Originally Posted by bolserst View Post
The Toole book provides years of acquired data supporting subjective preference for smoothly trending power/polar response. This highlights the importance of considering directivity when matching up drivers for a system.
Respectfully, it is evidence of the importance of evaluating the importance of directivity for your setting as illuminated by results in his setting. In any case, not directly speaking to matching.

BTW, I've been re-examing my youthful exuberance about Toole's studies particularly when intact manufactured speaker systems are used. Specifically, as in medical studies where those folks who eat fish 5X a week seem better than those who eat none. Those two groups of folks differ in many ways, with the parameter nominally under question being only one.

If Toole tested speakers anechoically for, let's say, "clarity" or "airiness", perhaps some of his human preference results would seem to validate those parameters as core to quality as polar results did in the past?

B.
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Last edited by bentoronto; 18th February 2019 at 04:49 PM.
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Old 18th February 2019, 05:41 PM   #177
kgrlee is offline kgrlee
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Quote:
Originally Posted by MJ Dijkstra View Post
In a loudspeaker handbook I have seen pictures regarding cone breakup and resonance effects.
What can happen is that some parts of the cone move forward and some move backward.
Yup. But what do you think happens on an ESL diaphragm, even a CCESLpWB ?
Quote:
So this resonance is less likely to appear in the output as it cancels. (unless you apply some very local laser doppler measurements?)
But it is resonance energy which needs to be fed from the input signal.
It's NOT a resonance. I've spent a lot of time with our SCAnned Laser Plots (we were the first to do animated laser doppler stuff on speakers) & FEA trying to optimise this behaviour with some success.

What you see is travelling bending waves in the cone which cancel out. The 'pistonic' part, which doesn't cancel out, has 'bulk' waves where the speed of sound is much higher. In a well behaved cone, this part shrinks nicely with frequency.
Resonances give stationary bending waves and you can sometimes see these on simple impedance plots too. The waves have to be terminated properly.

That's with a good sounding engineered plastic cone.

Ted Jordan had several 1960 & 70s (?) articles in Wireless World about this. His ideas were sorta right but his detail was seriously wonky. He didn't have laser Doppler velocimetry & FEA.

The breakup behaviour of a good sounding paper cone is very different though you still have this shrinking central 'pistonic' part.

Quote:
So a nearly perfect piston (if it would excist) would avoid this [problem.
A 'nearly' perfect piston' operating across ka=1 sounds terrible. We tried this with Berillium and also a ceramic material. It's only useful in certain treble units. I still prefer a soft dome ... though we designed some of the best hard dome trebles in large scale production.

Good sound in a speaker is more than some fashionable buzz word like 'pistonic', ESL, directivity, Room Interface Profile bla bla. In the end, you need to 'measure' the sum of all da bits to see if you get 'good sound'. You do this with DBLTs
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Old 18th February 2019, 05:52 PM   #178
bentoronto is online now bentoronto  Canada
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Electrostats vs conventional drivers
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Originally Posted by kgrlee View Post
...Good sound in a speaker is more than some fashionable buzz word like 'pistonic', ESL, directivity, Room Interface Profile bla bla. In the end, you need to 'measure' the sum of all da bits to see if you get 'good sound'. You do this with DBLTs
Say kgrlee, wouldn't it be nice to let the rest of us see what DBLT is all about even if we don't want to pay $30 for the treat as per your earlier link? Your cherished method seems to have escaped the attention of the rest of the world, at least so far.

You allude to a speaker business. Without fussing about mixing subliminal marketing and pleasure at this website, it would be helpful to learn just what products you are so very proud of?

Please do not mistake my flippancy for anything but sincere interest in the research and results you talk about.

B.
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Old 18th February 2019, 05:54 PM   #179
kgrlee is offline kgrlee
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Originally Posted by bentoronto View Post
Respectfully, it is evidence of the importance of evaluating the importance of directivity for your setting as illuminated by results in his setting. In any case, not directly speaking to matching.
What is your point Ben? Are you claiming matching directivity across a xover is unimportant? Are you one of those who believe speakers (& stereo) will sound so better in anechoics?

The BBC have tested both these points since the early 70s or even earlier. Wanna guess the results?

I have serious reservations about how the false prophets Floyd & Olive conduct DBLTs. But at least they reference & confirm our work on AUDIBLE SPEAKER DISTORTIONS
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Old 18th February 2019, 06:07 PM   #180
bentoronto is online now bentoronto  Canada
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Electrostats vs conventional drivers
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Originally Posted by kgrlee View Post
What is your point Ben? Are you claiming matching directivity across a xover is unimportant?
As a sort of summation of his book, Toole argued that excellent polar plots (in 3D!) are very important to good SQ. Who could argue with that, at least in the abstract?

And maybe "matching" is an unhelpful term. Maybe "what tweeter should I buy, all things considered" is a better term. In that sense, all kinds of things might occur to the builder with dovetailing polar plots being only one. Not that there is any indisputable way to define "dovetailing" of two fuzzy curves families (in 4 dimensions because you have to count freq), a fact that kgrlee seems to overlook.

But to someone who is a commercial partisan, sometimes only one leading patentable feature like matching dispersions at the crossover point might seem to matter.

B.
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