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Electrostats vs conventional drivers
Electrostats vs conventional drivers
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Old 18th February 2019, 06:17 PM   #181
bentoronto is offline bentoronto  Canada
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Electrostats vs conventional drivers
Quote:
Originally Posted by bolserst View Post
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 don't know enough except to add a practice note.

When I adapted a direct-drive Sanders-like amp, I used a large group of resistors as the load. The ESL panels were wired parallel but they had barely any impact on the load the amp saw. As folks have stated, ESLs are actually very efficient by themselves. That made the amp very happy.

Of course, a Sanders amp is a machine to make big voltages while using today's familiar audio amp is quite different. But the notion of resistors in parallel with ESLs panels......

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Old 18th February 2019, 06:18 PM   #182
kgrlee is offline kgrlee
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Originally Posted by bentoronto View Post
wouldn't it be nice to let the rest of us see what DBLT is all about
Double Blind Listening Test.

If I was a guru in my previous life, it was on using DBLTs to design speakers & other stuff.

But I've been a real beach bum for the last 2 decades so have problems buying AES papers too.
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Old 19th February 2019, 12:15 AM   #183
kgrlee is offline kgrlee
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Quote:
Originally Posted by bentoronto View Post
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.
I've been looking at "4 dimensions" for a very long time. I was instrumental in persuading John Wright to develop the "off-axis waterfall" which is a bell / whistle in Stereophile & and other hi-falutin reviews.

In another thread/forum (?) someone was dissing my suggestion that he should xover at a higher frequency with his selected units and posted an "off-axis waterfall" to show how good his speaker was. Actually it showed terrible off-axis behaviour which would have improved with a higher xover.

We now have much better tools .. some of which I helped develop.

But the knowledge and experience to interpret them is still thin on the ground.

John Atkinson has probably looked at more 'waterfalls' (KEFplots cos KEF invented them as their CDS) than any other person alive.
But in the early 80's I sat down with him over a couple of pints of Tetleys to explain what da wriggles meant in terms of speaker sound.

Quote:
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.
I've been a real beach bum for the last 2 decades so have no commercial axe to grind. Today, I don't have to be politically correct either so I can call BS if I see it.

But to get back to 'matching directivity' .. there are 3 factors.
  • Response AND directivity of lower unit near xover and for at least 2 8ves on either side
  • Response AND directivity of high unit bla bla
  • Xover itself and the resulting acoustic response
It's the care over the whole implementation which gives good 'matching' and good Room Interface Profile.

I'm sorry if people thought I meant the directivity of the 2 units have to match EXACTLY at xover.

And there are those who believe brickwall xovers will give good sound. I was involved with early experiments to do just that with DSP at Essex U. Guess what they sound like.


If I keep harping on about the SOUND that's cos I still think making your product sound better helps you sell more. We were very successful with this strategy in da previous Millenium. Perhaps this is naive today as it is almost impossible to get to hear stuff properly in a real shop ... so people rely on 'reviews'.

One thing you find out VERY quickly if you do DBLTs is how many reviewers are deaf ... so there's no point designing stuff to suit their ears. Instead you tell them, loudly & clearly, that your stuff is hand-carved from solid Unobtainium by Virgins.
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Old 19th February 2019, 12:46 AM   #184
kgrlee is offline kgrlee
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Quote:
Originally Posted by bolserst View Post
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.
Thanks for this bolserst. Soon after that, Kellog left the horny handed fields of audio to create his cornflake empire.

Chester Rice went on to make further advances in ESLs though nothing as earth-shattering as his invention with Kellog.

Quote:
Originally Posted by kgrlee
Da true ESL gurus will realise I'm being nearly as simplistic as bolserst. eg no mention of near field. I'm waiting for one to turn up on this thread.
My apologies to golfnut & bolserst who are of course true ESL gurus. I should've recognised this instantly and fallen on my knees in worship. Mea maxima culpa.

PS Do you guys have the facilities to wind the inductors for a Walker/Baxandall type transmission line ESL?
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Old 19th February 2019, 10:00 PM   #185
bolserst is offline bolserst  United States
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Quote:
Originally Posted by kgrlee View Post
…Kellog left the horny handed fields of audio to create his cornflake empire.
Chester Rice went on to make further advances in ESLs though nothing as earth-shattering as his invention with Kellog.
What…no Rice krispies?

Quote:
Do you guys have the facilities to wind the inductors for a Walker/Baxandall type transmission line ESL?
I don’t, although you can pick up sets for cheap on ebay from time to time. Speaking of LC transmission lines, Tim Mellow has been working on a similar segmented delay approach that seeks to emulate an oscillating sphere rather than a virtual point source. An oscillating sphere has uniform dipole radiation pattern at all frequencies. This approach also avoids the termination issues Walker wrestled with at the perimeter of the finite sized diaphragm when emulating the radiation from a virtual point source position a distance behind the diaphragm. The tricky part is that you need different delay values for each segment. Patent concept used digital delay and individual amplifiers, although now he has a working passive implementation. His AES and JASA papers on the topic are currently available for free download on his website. The sunflower inspired stator hole pattern is quite mesmerizing.

http://www.mellowacoustics.com/artic...r_45%20(2).pdf
http://www.mellowacoustics.com/artic...irectivity.pdf
Book & papers
Products page

US20120033834A1 - Apparatus With Directivity Pattern
- Google Patents


Quote:
Originally Posted by kgrlee View Post
…A 'nearly' perfect piston' operating across ka=1 sounds terrible.
If you can remember, what was approximate piston size, crossover frequency, and frequency of first break-up mode of the beryllium driver?

Can you elaborate on “sounds terrible”?
Do you feel it was related to directivity increase that rolls in for ka>1 with perfect pistons?
Was the terribleness noticeable only when listening to music in rooms? Or was it also noticeable as a “quality” to the sound of pink noise or test tones when measuring the driver in an anechoic chamber?

A lot of questions I know.
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Old 19th February 2019, 11:23 PM   #186
bolserst is offline bolserst  United States
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Originally Posted by bentoronto View Post
…the sound emanates from an extended surface, confusing the cancelation.
What you describe gives rise to directivity increase (ie “beaming”) and off axis lobing, but not relevant for this LF topic where wavelength >> piston size.

Quote:
And even more, the whole cancellation diagram looks even more like a big bowl of spaghetti when sound comes off the back wall.
I’d recommend not getting hung up on the word “cancellation” which doesn’t describe a dipole very well, and think in terms of the whole radiation pattern. As you said, mostly smooth broad coverage…with minor directivity index of about 4-5dB. Yes, the room can substantially affect the time-averaged sound reaching a listener, but that is not unique to dipoles; monopoles are similarly affected.

Quote:
Originally Posted by bentoronto View Post
Respectfully, it is evidence of the importance of evaluating the importance of directivity
I see that you feel it important to add an additional qualifier. Let me re-state and see if you still feel that way. Floyd Toole’s data showed that when people listen to loudspeakers in rooms, they prefer that the reverberant field have roughly the same spectrum as the on-axis response. With EMLs, I only know of one way to make this happen and that is to avoid large shifts in directivity when moving from driver to driver, and avoid operating a single driver over too large a bandwidth.

Was your additional qualifier to cover the possibility that what people are liking is not necessarily that the reverberant field and on-axis response are similar. But instead, the driver compliment needed to make this happen coincidentally (in every case) has some other quality they find desirable? If so, I guess it is possible but not probable considering the many different loudspeaker types and configurations that were tested all supporting the trend.
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Old 20th February 2019, 06:18 AM   #187
golfnut is offline golfnut  New Zealand
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Quote:
Originally Posted by bolserst View Post
What…no Rice krispies? :scratch
wrong Kellog - you're thinking of John Harvey and his brother = corn flakes, but no rice crispies, and no wanking, John Harvey Kellogg - Wikipedia
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Old 20th February 2019, 11:41 AM   #188
kgrlee is offline kgrlee
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Quote:
Originally Posted by golfnut View Post
wrong Kellog - you're thinking of John Harvey and his brother = corn flakes, but no rice crispies, and no wanking, John Harvey Kellogg - Wikipedia
Joke golfnut! Joke! Dun yus bloody Kiwis unnerstan 'joke'

... but Chester did get a couple of later patents on ESLs

Incidentally ... golfnut, I think I've got some PAFplots (not KEFplots. Their CDS are da present day 'waterfalls') of ESL63 done circa 1980 when only KEF & ourselves could do such hi-falutin stuff. It clearly shows the effects of the dustcovers on which you pontificate in another thread.

Last edited by kgrlee; 20th February 2019 at 11:55 AM.
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Old 21st February 2019, 05:08 AM   #189
Calvin is offline Calvin  Germany
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Hi,

so far I kept shut up and learned from the sheer mega brain powers discussing here

Quote:
But to get back to 'matching directivity' .. there are 3 factors.
Response AND directivity of lower unit near xover and for at least 2 8ves on either side
Response AND directivity of high unit bla bla
Xover itself and the resulting acoustic response
That is almost exactly what I did with my ESELs ... apart from the 2 8ves response (could just achieve 1 8ve) and guess what? .... they sound absolutely awesome with no audible transition between the branches

There´s just one point I tend to disagree .... and that is about the ESL63 and alikes.
Though brilliantly engineered their design concept seems vastly flawed to me.
The flaws beeing:
- that due to the quite small membrane area of each segment dynamics are seriously restricted
- that due to the small sized segment and the current steering the design becomes ridicolously high-ohmic, asking for insanenly high drive voltages (and hence stupidly high transformation factors of the audio trannies) that kill the very last bit of dynamics. I´m not at all surprised that the ESL63 sounds dull, muffled and slow.
- the concept of a pulsating sphere or a globe segment is only a theoretically good concept. In praxis -that is in a room- other directional characteristics like a strip line can be advantageous.

jauu
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Old 21st February 2019, 10:33 PM   #190
kgrlee is offline kgrlee
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Quote:
Do you guys have the facilities to wind the inductors for a Walker/Baxandall type transmission line ESL?
Quote:
Originally Posted by bolserst View Post
I don’t, although you can pick up sets for cheap on ebay from time to time. Speaking of LC transmission lines, Tim Mellow has been working on a similar segmented delay approach that seeks to emulate an oscillating sphere rather than a virtual point source.

http://www.mellowacoustics.com/artic...r_45%20(2).pdf
http://www.mellowacoustics.com/articles/Dipole_speaker_with_balanced_directivity.pdf
Thanks for this bolserst. I'm not after ESL63 inductors.

Like Mellow, I've got my own crazy idea for a segmented delay approach but to emulate something else. Being a horny handed speaker designer, my target is something much more mundane.

I've done some theoretical work on this but the inductors look like they need to be wound from Unobtainium by Virgins .. at least that's what Peter Walker said when I discussed it with him.

Quote:
…A 'nearly' perfect piston' operating across ka=1 sounds terrible.
Quote:
If you can remember, what was approximate piston size, crossover frequency, and frequency of first break-up mode of the beryllium driver?

Can you elaborate on “sounds terrible”?
Do you feel it was related to directivity increase that rolls in for ka>1 with perfect pistons?
Was the terribleness noticeable only when listening to music in rooms? Or was it also noticeable as a “quality” to the sound of pink noise or test tones when measuring the driver in an anechoic chamber?
I haven't forgotten this. I'm trying to remember details and I'm hoping to reply in more than a "mine is bigger than yours" fashion.

I've spent most of my working life looking at
  • what speaker distortions are audible
  • how to measure the important speaker distortion.
The PAFplots, KEFplots (waterfalls), Directivity waterfalls, Room Interface Profile are notable milestones in the 2nd quest as these 'measure' stuff that are AUDIBLE in DBLTs.

But there's a missing link between the oneD measurements like KEFplots ... & Room Interface Profile which is definitely a 3D phenomena.

Your query actually hits at this very question. More to come

Last edited by kgrlee; 21st February 2019 at 10:42 PM.
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