Thanks Steve. I would like to get Burnt's opinon on the merit of a spiderless driver.
I haven't made any recordings. My opinion on the sound is here.
If you don't fully understand the "physics and maths" of the patents, then you are in no position to accuse them of being "pseudoscience." In fact, many of YOUR baseless opinions are closer to pseudoscience than anything else.True, I did say that. I said, more I read NXT patents, I find them more like pseudoscience. It still does, but you have to keep on reading.I am not going into the physics and maths of their work.
Unless you have solid, hands-on experience of listening to a massive variety of speakers, and measuring them, or building good speakers of any kind at all, then you cannot go around making comments, especially regarding what YOU consider in your baseless opinion, on what is or is not a DML panel whether it's "wobbling or flapping" or not. Maybe you have to ask yourself if you are not far too vocal on this forum. Maybe it time for you to read things other than patents (that you do not understand anyway), instead of proving your ignorance every time you do make a comment.
And, this is from NXT, the Distributed Mode Loudspeaker (DML).
It is been considered that Henry Azima as the person, who brought the DM technology to the world, the father of the DML. None of the companies that bought what's left of NXT don't mention this at all. They keep mum, the standard business strategy. Also, who ever reads reportages on NXT, it was always Henry Azima. Well, he was the Chief Technical Officer, while he was there. And, when we read patents, in which he was one of the inventors, we always see Azima in the front, just because of the alphabetical order. When I started reading the NXT/Tectonic etc, documents/patents, it occurred to me that the brain behind all this is Dr. Graham Bank, the second person on the list. He also owns the rights to the BMR invention. The research on DM and BMR technology is still on-going, despite Henry Azima's departure and NXT dissolvement.
Anyway, for the radiator panel to become a fully fledged loudspeaker, its perimeter has to be secured with a resilient suspension, that is, because of the edge "problems"...
This matter of the perimeter suspension is mentioned in every patent/document I had read up to date, DE/GB/US and other foreign ones. The above quote is from a standard Azima patent. If anyone can give a link to a NXT/Tectonic patent, which states that the free open perimeter of the radiator panel is the preferred method for making a distributed mode loudspeaker, I'd be glad to study it.
It is been considered that Henry Azima as the person, who brought the DM technology to the world, the father of the DML. None of the companies that bought what's left of NXT don't mention this at all. They keep mum, the standard business strategy. Also, who ever reads reportages on NXT, it was always Henry Azima. Well, he was the Chief Technical Officer, while he was there. And, when we read patents, in which he was one of the inventors, we always see Azima in the front, just because of the alphabetical order. When I started reading the NXT/Tectonic etc, documents/patents, it occurred to me that the brain behind all this is Dr. Graham Bank, the second person on the list. He also owns the rights to the BMR invention. The research on DM and BMR technology is still on-going, despite Henry Azima's departure and NXT dissolvement.
Its interesting that Henry Azima left both companies working on the DM and BMR technology on the same day, 24th July, 2007. And, never continued on those technologies after he left. It simply points to the bottom line crisis, so the restructuring. The top management usually resign, and there is always a non-disclosure agreement. No more Azima patents afer July 2007 on DM technology. If anyone finds one, I'd be glasd to read it. Henry Azima went on to create his beloved product, amplifiers after leaving NXT and HiWave.
Anyway, for the radiator panel to become a fully fledged loudspeaker, its perimeter has to be secured with a resilient suspension, that is, because of the edge "problems"...
This matter of the perimeter suspension is mentioned in every patent/document I had read up to date, DE/GB/US and other foreign ones. The above quote is from a standard Azima patent. If anyone can give a link to a NXT/Tectonic patent, which states that the free open perimeter of the radiator panel is the preferred method for making a distributed mode loudspeaker, I'd be glad to study it.
So, the most important factor of a Distributed Mode Loudspeaker (DML), the radiator panel, for example the 5mm panel as in the post #8,945, has to be created, a composite with a very low density homogeneous core and two quite thin homogeneous surface skins, preferably of carbon fibre. The core is needed only because the very thin, like 300 micron, surface skins don't have the necessary stiffness. The core is actually a hindrance, but there's no way to do without it, physically. Anyway, a composite has more strength, more stiffness etc, than its components. Still, the core must be homogeneous, has the same stiffness in both directions. It could be cellular matrix or a honeycomb matrix, but not a corrugated matrix. Such a matrix contains a lot of air, but very stiff after the skins are glued on. One can use processed wood products such as paper or card for the matrix, which is the cheapest, but not long-lasting. Balsa wood was suggested in the Göbel patent, but that was dropped in the later products as plain wood or plywood is not homogeneous.
The preferred types skins are given in the patents, and the best being carbon fibre, better even if the weave is at 45 degrees. The skin is the most important element in the radiator panel, as it is on that surface the distributed mode bending waves happen, and the result depends on the physical characteristics of those skins. The information on that is given in the patents. There's quite a bit of maths and physics of the strength of materials are there, if one understands. The strength of materials is a separate section of applied physics. NXT was a lab of more than 40 engineers and scientists.
In the earlier days, NXT licensees used polystyrene sheets as the radiator panels for cheap PC speakers, or for toy speakers, but for the prototypes, NXT used better high quality composite panels. Armstrong, a NXT licensee, used very low density synthetic foam material for their CS1000, but that was quite weak loudspeaker.
Tectonic Audio Labs only use carbon fibre composite panel with carbon fibre skins for their DM loudspeakers. Sheet Control/DPK Sound now use very light aramid honeycombs as the structural element (core) and a special grade of paper as the skin.
As for transducers, both Tectonic Audio and DPK Sound make their own, and their placing on the panel is still a trade secret.
The preferred types skins are given in the patents, and the best being carbon fibre, better even if the weave is at 45 degrees. The skin is the most important element in the radiator panel, as it is on that surface the distributed mode bending waves happen, and the result depends on the physical characteristics of those skins. The information on that is given in the patents. There's quite a bit of maths and physics of the strength of materials are there, if one understands. The strength of materials is a separate section of applied physics. NXT was a lab of more than 40 engineers and scientists.
In the earlier days, NXT licensees used polystyrene sheets as the radiator panels for cheap PC speakers, or for toy speakers, but for the prototypes, NXT used better high quality composite panels. Armstrong, a NXT licensee, used very low density synthetic foam material for their CS1000, but that was quite weak loudspeaker.
Tectonic Audio Labs only use carbon fibre composite panel with carbon fibre skins for their DM loudspeakers. Sheet Control/DPK Sound now use very light aramid honeycombs as the structural element (core) and a special grade of paper as the skin.
As for transducers, both Tectonic Audio and DPK Sound make their own, and their placing on the panel is still a trade secret.
i just made 2 new recordings of the ply panel with dome on the left and the proplex with cling film on the right.
the panels are 2ft apart facing each other full range without subs , with me holding the phone between them.
this makes recording easier as i do not have to get the mixing right.
they are at the same volum level so similar efficiency , but i think the ply is brighter sounding ?
it is still too cold to do serious listening at the moment so will reserve my thoughts till i can have a proper listen.
but this will do for now , i think.
steve.
the panels are 2ft apart facing each other full range without subs , with me holding the phone between them.
this makes recording easier as i do not have to get the mixing right.
they are at the same volum level so similar efficiency , but i think the ply is brighter sounding ?
it is still too cold to do serious listening at the moment so will reserve my thoughts till i can have a proper listen.
but this will do for now , i think.
steve.
I'm not sure why you are so fixated on "homogenous". A "carbon fiber" skin actually is a composite of carbon fibers and epoxy, which is actually the antithesis of homogeneous.
That's almost true, but a strange way of looking at it. What we need for good efficiency is a stiff light plate, because that promotes a high bending wave speed. Bending stiffness of a plate is determined mainly by the plates thickness, and elastic modulus of the component closest to the surface, because the surface is the region that deforms (stretches or contracts) the most in bending. Hence, the preference for high modulus skins like carbon fiber epoxy composite (CF). A solid CF would be very stiff, but too heavy. Hence the need for a lightweight core. But just being light is not enough. The core has to have enough shear stiffness, otherwise the plate just acts like two thin skins rather than a unified plate in which opposite sides are in tension and compression as a bending wave traverses the plate. So to say the core is a hindrance is a bit misleading. It's role is pretty much as important as the skin.
And to clarify, CF/core/CF composites are not stronger or stiffer than solid CF would be. But what they are is much, much lighter and only a little bit less strong and stiff. So their "specific" strength and stiffness (i.e. normalized by weight) is higher, but not their absolute strength and stiffness.
That's actually not what homogeneous means. The same stiffness in (all) directions would be isotropic. But there is no need for the core to be isotropic, only for them to be light and have sufficiently high shear stiffness. But the shear stiffness need not be the same in both directions. In fact, honeycombs can often have different shear stiffness in both directions, but as long as it's stiff enough in both directions, it fine.
A corrugated matrix is certainly less than ideal. This would be a case where the shear stiffness in one direction is really much lower than optimal. It could be used, but is not ideal.
Never hear of anyone doing that. But the issue is that these are pretty heavy, not that they are not long lasting. You might consider plywood an example, and indeed the greatest deficiency of plywood is that it is on the border of being too heavy.
Goebel is the only one I ever heard that claimed that the 45 degrees was better, as far as I know. It could possibly be true for a particular shape or aspect ratio of panel, but if so, I don't think it's for the reason he claimed. In fact, he dropped the 45 degree orientation when he switched from FG skins to CF, which is evident from the images in the Goebel site you linked. People who are unfamiliar with CF may not realize this, but the diagonal lines across his CF panel are created by the weave of the CF fabric. The most common weave is a twill weave which creates such a pattern of diagonal lines while the fibers themselves are oriented at 0 and 90 degrees.
While he did drop the 45 degree angle thing, he actually didn't drop the balsa core. See below from the site you linked. Interestingly, his claim is that the inhomogeneity of the wood is a special feature. I view that as another of his dubious claims.
I'm curious where you got that information. I actually have a few of those Armstrong speakers. The panel on mine is not a synthetic foam, but rather a structure like the DPK panel, that is, an Aramid honeycomb core with special paper skins (but no coatings, at least none that are obvious).
Eric
I cover the holes with 3m acoustic thinsulate and wool felt. Not like bass reflex, like leaky sealed box or aperiodic enclosure.Maybe, you also employ the idea here, #8,733 as in this patent, for that? Fig. 5 description in page 64, right side, to get rid of the back sound? The two side rectangular holes would act like bass-reflex, enhancing the lows. NXT/Tectonic placed their ideas in many separate patents.
Attachments
There's so much wrong with this opinionated blabbering, but I'll comment only on this specific thumb-sore...:
Inhomogeneity, or the lack of it, is only applicable if the material is not a composite, and then only if the reflecting edges are equidistant—In other words, if you use a single, non-composite material, without laminated skins, and if you place your exciter exactly in the middle of a panel, then you might possibly consider homogeneity. But a composite laminate has more to do with isotropy or anisotropy, i.e. the material stiffness in different directions.
I am currently experimenting with an inhomogeneous lightweight polycarbonate material which is non-laminated and non-composite, but it has a (CORRUGATED!) structure that allows differing stiffnesses in different directions. This is a desirable characteristic in this specific case because of the high-ratio form factor. Obviously somebody who has never built nor experimented with DML systems himself could never hope understand the nuances of these problems and especially not their solutions.
Chdsl
You make us benefit (not to say impose) from what I understand to be your reading notes with your current orientation on the "how" (not on the why) from the patents of the companies in the field. This is your choice. A choice that I do not share without having in mind the specifications, the project objectives of the designers. So be it. A way of writing that suggests that there is no other way. What I do not share, neither the way of writing, neither the absence of other design choices. But in all this, what's new? New would be for example information on the methods of suspension of the Tectonic membrane or the way to add weights to it for example.
There must be a valid reason why they make their own purpose-made exciters for their own DML products, Tectonic, for example doesn't demand that their clients should repair the DMLs by themselves. They have a service for that, and the buyers pay good money for those speaker systems to tinker with them. The exciters freely available in the market might not be the same as mounted on those DMLs. Food for thought.
The commercially available exciters from any company are just a product to be sold. They are rarely returned by customers, if at all, either a replacement would sent back, or money refunded. For example,
Some patents describe the recommended transducers/exciters which must be used with the recommended radiator panels, to make a workable Distributed Mode Loudspeaker, sometimes in the same patent. Sometimes, you have to check a few patents. Some inventors give direct clues, some don't. There are quite a few inventors!
As for exciter placements, the standard
Why Tectonic? Here's why.
We will never know about those "certain assets" acquired by FLAT Audio Technologies, LLC, or the conditions of the acquisition, except of course, whatever patents/documents Tectonic Audio Labs care to publish.
We can, of course, make a clone of NXT Distributed Mode Loudspeaker, or Tectonic DML500 or its few variants. Or, you can make patent claim, or clone a patent to claim as some had done few years ago, then create the DML to that patent, or create the DML and make the patent later, or get someone else to claim the patent.
The commercially available exciters from any company are just a product to be sold. They are rarely returned by customers, if at all, either a replacement would sent back, or money refunded. For example,
The company is not inviting the buyers to buy this "another form of Transducers" to go make loudspeakers, but paste them on any rigid surface to create sound, for the surface to function as the speaker.
Some patents describe the recommended transducers/exciters which must be used with the recommended radiator panels, to make a workable Distributed Mode Loudspeaker, sometimes in the same patent. Sometimes, you have to check a few patents. Some inventors give direct clues, some don't. There are quite a few inventors!
As for exciter placements, the standard
is still considered as good enough, but there is no mention of any 2/5, 3/5 position as suggested by the-hanging-by-strings YT guru anywhere in the NXT/Tectonic patents. Neither NXT or Tectonic or any other company sold Distributed Mode Loudspeakers hanging by strings. Tectonic Audio Labs now have advanced to a different placement of a cluster of exciters, somewhat around the centre of mass of the radiator panel. But as,
any further development of Distributed Mode Technology depends on them. And, that's a trade secret.
Why Tectonic? Here's why.
We will never know about those "certain assets" acquired by FLAT Audio Technologies, LLC, or the conditions of the acquisition, except of course, whatever patents/documents Tectonic Audio Labs care to publish.
We can, of course, make a clone of NXT Distributed Mode Loudspeaker, or Tectonic DML500 or its few variants. Or, you can make patent claim, or clone a patent to claim as some had done few years ago, then create the DML to that patent, or create the DML and make the patent later, or get someone else to claim the patent.
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I use my on-going DML experiments in live stage sound while performing. And yes, I LIKE the omnidirectional sound from the back of the panels: It means that I can do away with separate monitors, AND I don't have to worry about microphone feedback, AND I can hear exactly what the audience hears without having to continually swop between FOH and monitor feeds, AND I can hear every instrument clearly without having to push its 'solo' button on the desk while I'm performing.
It's a win-win in every way.
It's called Market Pressures. Maybe you should do an MBA or something.
Do you ever keep silent for a few moments in the distant hope of LEARNING SOMETHING???
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If this is about 300microns and rest, maybe this question should be directed to Neil Harris, I suppose, former NXT Chief Scientist and the Director of Technology after Henry Azima left.
If this is about "Anyway, a composite has more strength, more stiffness etc, than its components.",
Have a look at a SIP panel for example. Also, did you notice the "etc," in the above sentence?
Homogeneous means there is the same stuff everywhere, isotropic means it has the same properties in all directions. A material can be isotropic with respect to one point or multiple points. If a material is isotropic with respect to multiple points, it will be also homogeneous.
About using paper honeycomb as the core? Yes, I know who had used paper honeycomb as the core, and paper as the skins.
Neither plain wood or plywood is good for the core. They are neither homogeneous nor isotropic. No two pieces of wood or plywood are the same. I spoke to a piano doctor on this matter. If you need a good piece of wood for the "sounding board' you have to get it done, and it'd consist of different pieces. And, it is expensive.
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The rest is not worth discussing. Neither Gobel or Armstrong tiles.
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Thanks for the link Steve. In those posts you talked about panel saturation. Can you please define that?
I just found and downloaded a book on Loudspeakers with information on those "add weights to the membrane" from the '50s in last century, before it was invented a decade or so ago. Reading it atm, and smiling.
True enough, but takes only a little math to realize that the 2/5 is really quite close to 3/7, 4/9, and 5/13.
And you only have to make one or two speakers of your own to realize that there is really nothing magical about any of those positions.