I've been in contact with a shop that can make me curved panels cut to size but the same week that I mailed in my order they went on vacation. 
Then I happened on a youtube clip with Sanders having a monologue about why he's building flat panels instead of curved ones.
Now, Sanders being somewhat of a reference when talking about esl's makes it kind of interesting.
I know Calvin is building curved panels but most other people seem to go for flat ones?
How would you describe your experiences when comparing curved vs. flat panels?
Myself I've already orderd my curved panels but it would be interesting to hear what you all think.
Then I happened on a youtube clip with Sanders having a monologue about why he's building flat panels instead of curved ones.
Now, Sanders being somewhat of a reference when talking about esl's makes it kind of interesting.
I know Calvin is building curved panels but most other people seem to go for flat ones?
How would you describe your experiences when comparing curved vs. flat panels?
Myself I've already orderd my curved panels but it would be interesting to hear what you all think.
I've been in contact with a shop that can make me curved panels cut to size but the same week that I mailed in my order they went on vacation.
Then I happened on a youtube clip with Sanders having a monologue about why he's building flat panels instead of curved ones.
Now, Sanders being somewhat of a reference when talking about esl's makes it kind of interesting.
I know Calvin is building curved panels but most other people seem to go for flat ones?
How would you describe your experiences when comparing curved vs. flat panels?
Myself I've already orderd my curved panels but it would be interesting to hear what you all think.
I've heard both and I agree with Mr. Sanders' assertion that flat panels project a superior image-- but that's only at their focal point. The physics of their differences makes this so. But there is a price to pay, as the same physics makes a flat panel's sweet spot very pronounced and only about as wide as the panel itself. The effect is a very focused image but the treble energy falls off a cliff within inches as the listener moves out of the sweet spot, where the sound then becomes bass-heavy. This makes flat panels all but useless for party speakers, as the sweet spot is only wide enough for one person (two if she's sitting in your lap). A curved panel trades off some of that magical imaging for a wider, less pronounced sweet spot and better frequency balance outside of the sweet spot.
I have flat panels myself and they sound great but I have to admit that whenever company comes over I find myself wishing for a wider sweet spot.
Unfortunately, there's no way to have it all.... there are only compromises and we must choose which compromises are less objectionable.
I think if you are going with curved panels, you could help mitigate the negative effects of their wider dispersion by placing sound absorbing materials where their first reflections would strike room surfaces-- as you would do with conventional speakers.
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Very interesting to see that you agree with Mr Sanders.
I was sort of expecting to hear it was just a sales pitch because flat is easier and cheaper to manufacture?
If indeed his thoughts have merit it's a choice of taste more than any thing else.
There is one thing I would like to adress a little bit extra though.
He claims the flat panel sound outside the sweet spot is on par with regular speakers but the sound in the sweet spot is so amazing that the percieved differece leads you to think the off axis sound is "bad".
I was sort of expecting to hear it was just a sales pitch because flat is easier and cheaper to manufacture?
If indeed his thoughts have merit it's a choice of taste more than any thing else.
There is one thing I would like to adress a little bit extra though.
He claims the flat panel sound outside the sweet spot is on par with regular speakers but the sound in the sweet spot is so amazing that the percieved differece leads you to think the off axis sound is "bad".
Yes,I have to agree with Charlie and Roger Sanders.
My first listen was a set of ML's and when I built my first panel's 9"X22" ,I also found that they seemed to be more detailed than the ML's that I had first heard.
Although I was quite impressed at first listen.
One thing that I did notice is that my smaller width panels seem to have less of the beaming effect than the wider panels did hence a wider sweet spot for the higher frequency's although without the more pronounced lower end that the wider panels had, for obvious reasons.
Once I get going I will do more of a A/B comparison with some measurements between my two original panel sizes,But for now I have alot to get done until then.
It is because of this I tend favor my little panels but we will see once I get the bigger ones rebuilt.
The wider the panel the narrower the dispersion angle as the frequency goes up, Hence the beaming effect.
There have been many many discussions on this and I am very curious to find out the effects of using a segmented stator compared to a non-segmented stator of the same deminsions.
I have three sets of tig wire stators made that would be a good canidit for such an experiment and I could very easily to whip up another set so that I have a pair of each.
Anyway keep the idea's comming I am off to work on those 8' subs at the moment!
Keep on DIYin' !!!! jer
My first listen was a set of ML's and when I built my first panel's 9"X22" ,I also found that they seemed to be more detailed than the ML's that I had first heard.
Although I was quite impressed at first listen.
One thing that I did notice is that my smaller width panels seem to have less of the beaming effect than the wider panels did hence a wider sweet spot for the higher frequency's although without the more pronounced lower end that the wider panels had, for obvious reasons.
Once I get going I will do more of a A/B comparison with some measurements between my two original panel sizes,But for now I have alot to get done until then.
It is because of this I tend favor my little panels but we will see once I get the bigger ones rebuilt.
The wider the panel the narrower the dispersion angle as the frequency goes up, Hence the beaming effect.
There have been many many discussions on this and I am very curious to find out the effects of using a segmented stator compared to a non-segmented stator of the same deminsions.
I have three sets of tig wire stators made that would be a good canidit for such an experiment and I could very easily to whip up another set so that I have a pair of each.
Anyway keep the idea's comming I am off to work on those 8' subs at the moment!
Keep on DIYin' !!!! jer
Is there a way to do what you want. The acoustic lens in front of a high-ESL. It works well. I've tested. Laser cutting of metal elements of the lens. Layout work.
I think Sanders' point is that a flat panel gives superior imaging precisely because it beams sound like a laser-- such that at the focal point the listener hears a single coherent wavefront. By comparison, a wide dispersion speaker sprays sound all over the room-- such that the listener hears only a small portion of the direct radiated sound from the speaker along with a large portion of reflected/time-shifted sounds bounced off room surfaces-- and it's these reflected/phase-shifted sounds that degrade the imaging, frequency response (comb filtering) and perceived transient speed.
Since it's wide dispersion and resulting room reflections that degrade the sound reaching the listener, it follows that placing an acoustic lens in front of a flat panel to widen its dispersion (like Harold Beveridge did) would indeed create a much wider sweet spot... but, again, at the expense of trading off some of the pristine imaging and fidelity you'd otherwise get from a narrow dispersion speaker.
The only way to fully realize what Sanders is saying is to place yourself at the focal sweet spot of a pair of flat panel line-source electrostats and experience their magical 3D imaging, stunning clarity and power. Admittedly, you're head's in a vise listening to flat panel stats but you just can't get that same level of fidelity from any other driver that I've ever heard.
And, again, I'd be wishing for a wider sweet spot when company comes over!
The acoustic lens can make the dispersion, so what you need.
CharlieM
Objection. Not wide dispersion, and that which is necessary, small. The acoustic lens is easily controlled. Аt the beginning meditate area "sweet spot", then just create a lens. Layout can make their cardboard, so as not to spend too much money. Dispersion achieved controlled too. Make small variance. To not use a vise, as in daggerotype photo to listen to the "sweet spot". The last argument by the allusion to the old joke - what more do you want, "the word" taxi "or drive a car?" Decide that you no longer like it - head clamped in a vise or some degree of freedom. All the energy that makes the speaker comes to you in the form of a narrow beam or a few dispersed in space. The lens adjusts the angle of radiation, as in optics. Make a simple experiment with plates made of cardboard, requires no money is spent only your mental energy and time. I think you're in a hurry. The experience that I offer worth the cost of mental energy. He, the experience is worth it.
Sorry for the clumsy English, the computer translates.
CharlieM
Objection. Not wide dispersion, and that which is necessary, small. The acoustic lens is easily controlled. Аt the beginning meditate area "sweet spot", then just create a lens. Layout can make their cardboard, so as not to spend too much money. Dispersion achieved controlled too. Make small variance. To not use a vise, as in daggerotype photo to listen to the "sweet spot". The last argument by the allusion to the old joke - what more do you want, "the word" taxi "or drive a car?" Decide that you no longer like it - head clamped in a vise or some degree of freedom. All the energy that makes the speaker comes to you in the form of a narrow beam or a few dispersed in space. The lens adjusts the angle of radiation, as in optics. Make a simple experiment with plates made of cardboard, requires no money is spent only your mental energy and time. I think you're in a hurry. The experience that I offer worth the cost of mental energy. He, the experience is worth it.
Sorry for the clumsy English, the computer translates.
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Greetings Kontra,
It would be interesting to see the lens you have in mind. I haven't seen your lens of course, and I assumed that it would work in a manner similar to the highly curved multi-element lens used by Harold Beveridge. The Beveridge lens creates a very wide dispersion-- much wider even than the dispersion from a Martin Logan curved panel.
To the extent that the lens deflects sound laterally and the speakers are near adjacent walls, there would be resulting reflections bounced off adjacent room walls, which would reach the listener delayed in time; thus confusing the imaging. I see no way around this effect when there is [both] wide dispersion and adjacent room walls to reflect delayed sounds to the listener.
Even so, there are studies that show that only the "early" reflections confuse the brain enough to destroy the spatial imaging perceived by the listener (I forget the exact number but I'm thinking "early" was defined as 2 ms delay or less). If that is so, I think wide dispersion speakers can sound still very good if placed far enough inside the room space (and away from adjacent walls) that "early" reflections would not occur.
I still believe flat panels sound better within their restricted sweet spot but I'm definitely not against curved panels or lenses. In fact, I am seriously considering building a pair of curved ESL's for myself. Then I could listen to my flat panel ESL's when I'm home alone and switch over to the curved panels when company comes over
(I'm not married so I don't have to worry about spousal approval for so many speakers in the room)
I had toyed with the beam splitter idea with some glass plates directly behind the panel with the apex touching the panel in the center and on the ends this seemed to work very nicely.
I have been thinking that a cylnderical refelction surface may give good or better results and a more even dispersion pattern than the two flat surfaces I had originaly tried.
I will explore this more once I get going and set up a measuring system outside to eliminate the room refelctions.
As my test were mono and while I was working on my drive electronics last year.
So I haven't done alot since July of last year.
So Stay Tuned,I am getting there but slowly !!!
jer
I have been thinking that a cylnderical refelction surface may give good or better results and a more even dispersion pattern than the two flat surfaces I had originaly tried.
I will explore this more once I get going and set up a measuring system outside to eliminate the room refelctions.
As my test were mono and while I was working on my drive electronics last year.
So I haven't done alot since July of last year.
So Stay Tuned,I am getting there but slowly !!!
jer
I think that Kontra is probably trying to describe the slanted plate acoustic lens as popularized by JBL.
See attachment #1 for an idea of how well it works, providing very uniform off axis coverage up to 10kHz.
Unfortunately design formulas are difficult to come by, although there is an AES paper on their design.
AES E-Library Acoustic Lens, Their Design and Application
In general terms, the lens provides an acoustic path length that increase as you move off axis.
This delays the sound and bends the projected wavefront. See Attachment #2
1) the spacing of the plates determines how high in frequency the lens will work.
2) the angle of the plates determines vertical dispersion limits
3) the cut out determines horizontal dispersions limits and variation with frequency. JBL research showed that the hyperbolic cutout shape gave the most uniform dispersion trends. Hard to argue, looking at the data in Attachment #1.
For ESL use, the slanted plates with hyperbolic central cutout would be placed from top to bottom of the ESL line source. The JansZen Z-40 used this concept.
JansZen Z-40 electrostatic speaker
The Soundlab minisat incorporates the lens into its grill frame. See Attachment #3
Looking at the Soundlab lense, you can see that they did not use the hyperbolic cutout that JBL and JansZen did. Rather, a simple 90 degree notch was used.
For your purpose, you could keep the flat panels you prefer for personal listening and build a lens/grill frame that you could attach when company comes over. When using the lens, you would need to EQ up the high frequencies since the lens takes what had been an on-axis flat response and spreads it out over more space. The result would be a drooping HF if you didn't correct it.
Attachments
Yes,I remember those and I have seen and heard the JBL ones that Ted Nugent used on his stage PA cabinets he used through the 70's,up close.
But that was way before I knew anything about speaker design.
I saw those cabinet's way back when they were built at Al Nalli Annex in Ann Arbor Michigan when I was about 14 to 16 years old.
I believe it was Technic's (I think ) used them on a set of home speakers aswell.
I have been wanting to try them on my panels aswell,But like you said the design info is scarce.
It would be great if anyone has acsess to a set to post the dimensions so that it could be tried on a planar tyoe driver such as an ESL.
jer.
But that was way before I knew anything about speaker design.
I saw those cabinet's way back when they were built at Al Nalli Annex in Ann Arbor Michigan when I was about 14 to 16 years old.
I believe it was Technic's (I think ) used them on a set of home speakers aswell.
I have been wanting to try them on my panels aswell,But like you said the design info is scarce.
It would be great if anyone has acsess to a set to post the dimensions so that it could be tried on a planar tyoe driver such as an ESL.
jer.
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L. D. Rozenberg "Sound focusing systems" Publishers of the Academy of Sciences USSR 1949 but sorry on a russian lang
flat hyperbolic lens
without any JBL
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I have found fomula for hyperbolic lenses - no need for AES $20 charge.L. D. Rozenberg "Sound focusing systems" Publishers of the Academy of Sciences USSR 1949 but sorry on a russian lang
flat hyperbolic lens
Later...
I think the real question is: how should a loudspeaker behave off-axis? Which brings in the aspect of psychoacoustics. Our hearing is quite an amazing system, ignoring it's properties in speaker design is a fatal error.
IMO, Sanders talk is indeed a sales pitch. All speaker manufacturers have one
IMO, Sanders talk is indeed a sales pitch. All speaker manufacturers have one
I found the paper on JBL's acoustic lens!
As well as radiating pattern to a driver size with respect to wavelength of the radiated frequency.
jer
ACOUSTICAL LENS
http://www.lansingheritage.org/images/jbl/reference/technical/inside-monitor/page02.jpg
As well as radiating pattern to a driver size with respect to wavelength of the radiated frequency.
jer
ACOUSTICAL LENS
http://www.lansingheritage.org/images/jbl/reference/technical/inside-monitor/page02.jpg
Curved panels can be great if well designed - e.g. Soundlabs
Hi - I'm new to this Forum but thought I would drop my 10c in.
I love ESL's. Had Quad 57's years ago.
I own and still love my Heil ribbon speakers (cone woofer, does Ok ish).
But I now own a pair of Soundlab M1's - they are very large !!! And curved.
Contrary to what someone said earlier in the thread, Soundlabs are not multiple cells. It is all one large diaphragm, stretched over multiple cells. The cells are arranged in an arc and the cells are varying in size to break up resonance peaks.
Big curved panels can give fantastic imaging and depth. I walk in and around mine just to enjoy the experience of walking up to the artist.
I love mine so much that I am upgrading to the biggest model the Majestic - 9ft tall !
Try to build a curved panel. The actual construction is the same if you look at how Soundlab have achieved it.
Another possibility is to make a multi-panel system ala Quad 57 - using a thinner esl panel in the centre, and two large curved panels on each side. So it would look like a Soundlab type panel but with a line source (wider) centre strip.
Have fun. If you build it, send me a message and a photo !
Peter from Perth in Western Australia
Hi - I'm new to this Forum but thought I would drop my 10c in.
I love ESL's. Had Quad 57's years ago.
I own and still love my Heil ribbon speakers (cone woofer, does Ok ish).
But I now own a pair of Soundlab M1's - they are very large !!! And curved.
Contrary to what someone said earlier in the thread, Soundlabs are not multiple cells. It is all one large diaphragm, stretched over multiple cells. The cells are arranged in an arc and the cells are varying in size to break up resonance peaks.
Big curved panels can give fantastic imaging and depth. I walk in and around mine just to enjoy the experience of walking up to the artist.
I love mine so much that I am upgrading to the biggest model the Majestic - 9ft tall !
Try to build a curved panel. The actual construction is the same if you look at how Soundlab have achieved it.
Another possibility is to make a multi-panel system ala Quad 57 - using a thinner esl panel in the centre, and two large curved panels on each side. So it would look like a Soundlab type panel but with a line source (wider) centre strip.
Have fun. If you build it, send me a message and a photo !
Peter from Perth in Western Australia
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