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Old 8th June 2004, 12:24 AM   #21
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Am such a turkey! i burst out laughing like a child at first, but as i read on, it kind of had a theory behind it, maybe a its all BS but its sounds ok, i mean the theory. I know that NXT shares are worth alot on the stock market! i promise if i had money i would invest it in them, BS or not there making money and am not with my conventional woofers, makes me feels sick. I would really like to speak to Dr. Shelley Katz about the design, if anybody knows who they are! get them on this forum please, I am always interested in a new way of making a transducer, i think it could have something in it, Its only a few generations old and am sure the first speakers made in the early 1900 were not all that great, so lets cut them some slack and see what happens!
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Old 8th June 2004, 02:52 AM   #22
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Quote:
Originally posted by 7V


As far as I can tell, Diaural are selling some sort of crossover technology. I've never heard it and I don't use the things anyway so it's not of much interest to me. There doesn't seem to be much information on their web site so I can't even offer an intellectual critique.

There is some info on Diaural crossover technology on their patent.

Just go to www.uspto.gov, download one of the freeware image viewers, (I use Internetiff), fill patent number 6115475, and there you are.

For some reason, that Patent Office link works better if you write it out rather than clickong on the link.

They call it a capacitorless crossover. They use a resistor in place of a capacitor in some way.

Here is the 2 way version:
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File Type: gif diaural crossover 2way.gif (2.4 KB, 396 views)
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Old 8th June 2004, 02:56 AM   #23
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Here is the 3 way version, for those interested.

I leave it to the reader to decide if this is an advance or overhyped guff. I would guess that using a resistor in place of a capacitor might have beneficial results on the phase response.

Just by glancing it at it, I don't know if this makes it possible to have symmetrical second order crossovers without having to reverse the polarity of one of the speakers.

At any rate, it might have value if you can eliminate the necessity of using electrolytic capacitors for drivers that cross over low in frequency.
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File Type: gif diaural crooosver 3 way.gif (4.5 KB, 350 views)
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Old 8th June 2004, 09:29 AM   #24
sreten is offline sreten  United Kingdom
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Well the obvious thing with both circuits shown is you have
8R in parallel with the bass unit at low frequencies, which
is chucking away half of the input power, not good at all.

The only effect of the 8R resistor is to reduce bass unit
treble levels by ~ 6dB, less so if inductance is high (2 way).

Analysis of the "3 way" is highly amusing.

Utter guff IMO, you'd struggle to call it proper 1st order.

sreten.
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Old 8th June 2004, 09:36 AM   #25
7V is offline 7V  United Kingdom
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Quote:
Originally posted by Paradise_Ice
... I would really like to speak to Dr. Shelley Katz about the design, if anybody knows who they are! get them on this forum please...
I've met Dr. Katz - he came round to my house 3 days ago to hear my speakers and he brought some of his NXT toys. I haven't yet been able to evaluate the Layered Sound approach thoroughly but what I've heard has interested me enough to look further. That's why I originally started this thread.

I suspect Shelley Katz might be too busy to get involved with a DIY forum, as in addition to his work in this field he is a professional musician and concert pianist of some repute.

It was as a result of his conducting that he became interested in this field. When the orchestra used early acoustic instruments, such as harpsichords, he became frustrated by how difficult it was to keep the things in tune for any length of time. So Dr. Katz used electronic keyboards in their place. However, he couldn't replace his Steinway with electronics. He found that the best electronic piano played and felt exactly like a Steinway. It even emulated the waveforms precisely. But it didn't sound like the real thing.

Dr. Katz went to hi-fi dealers and borrowed their 'top' loudspeakers in an attempt to get an electronic piano to sound real but he had no joy. Then, one day he was experimenting with an NXT panel and he discovered that if he used it in combination with a conventional moving coil loudspeaker (but at a lower volume) the piano sounded real to him.

I'm interested to see if this combination technology has a use in hi-fi. The possibility of combining the dispersion characteristics of NXT and moving coil speakers is very interesting to me.

Anyway, well done Paradise_Ice, you've broken through. I must admit that when I originally asked
Quote:
Has anyone experimented with NHT 'exciters' and different panel shapes, sizes or materials?
I was hoping for answers other than "Don't bother, they're no good".

Well, DUH!

I know they're no good. Dr Shelley Katz knows they're no good. The relevant questions are, "how good could they be?" and "could they be any use?"

PS: My advice would be to stay away from NXT shares. Apparently, they're the real turkeys.
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Old 8th June 2004, 11:32 AM   #26
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Quote:
Originally posted by sreten
Well the obvious thing with both circuits shown is you have
8R in parallel with the bass unit at low frequencies, which
is chucking away half of the input power, not good at all.

The only effect of the 8R resistor is to reduce bass unit
treble levels by ~ 6dB, less so if inductance is high (2 way).


sreten.
I was wondering about that, too. Unless this is designed to be used specially with high inductance speakers, or something.

I note that this crossover made it's appearance a few years after all the amplifier manufacturers started emphasizing extra current as one of their major design goals.

I don't think the public, as well as a fair portion of the audio world, understands the correlation between impedance and efficiency yet.

Who knows, maybe it sounds good, and the public might think, "It sounds good, all it requires is some extra current, but my amp has it", not really understanding that it is lowering the speaker's efficiency by perhaps 6 dB.
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Old 8th June 2004, 12:48 PM   #27
SineEra is offline SineEra  United Kingdom
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Default NXT panels

My experience, following the HiFi World review is with the TDK S80 tremor design. The were designed by NXT not by a licensee.
I heard the Misson's mentioned and agree with you on their performance.
The TDK's NXT panels have an altogether much better sound (the sub is truly awful) It is better than my Sennheiser HD580's in their frequency range 250Hz up. They have a limited output, which is fine for PC use when tried in my living room 24ft by 14ft it became a problem even for moderate volumes.
One day when I have time I will be making a proper speaker with them as I feel that these have tremendous potential.

Simon
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Old 8th June 2004, 01:00 PM   #28
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Hi Steve
Its fascinating the theory, I have heard Missions attempts at the NXT for hi-fi and it was the wrong time, As the marketing people promised to much, I believe this technology has the potential to be better once again in theory then a cone and coil, I donít care what anybody says, no matter what amp or source is used the transducers make the greatest effect on the sound and the enclosures, more than any cable or circuitry people get carried away with tweaking and reinventing the same old formula again and again,
A chip is a chip; wither its round or crinkled or straight,
A woofer is a woofer, sure with different tones characters
But basically the same, I have become so disillusioned with the world of Hi-fi for its lack of vision, I hope this technology gets more refined and improved upon year after year leading to more designs! I donít want to be making subwoofers in 20 years time!, I want something more advanced for better or for worse, R&D into transducers is very low and the progress is almost static
The Shed people are a rare breed now days, spending hours making there own concoctions, thatís one of the greatest things about Britain, but a new way of making music will not e made in a shed, just as brain surgery was
Not refined in a kitchen, I hope! The big companyís need to invest and encourage new ideas and new people, there is elitism from the big wigs to the boot straps, so why would anybody put themselves up to be mocked, Am glad you started this thread, I needed to be slapped into eating a humble pie, I may even turn my hand to the NXT and see what I can do with it?
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Old 8th June 2004, 03:33 PM   #29
7V is offline 7V  United Kingdom
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Quote:
Originally posted by johnnyx
I read that if you buy a license from NXT, you get CAD software with it so that you can design speakers. It's probably difficult to design a flat(ish) response speaker without it, finite element maths & other such stuff. Theile & Small won't help you.
Quote:
Originally posted by Paradise_Ice
The Shed people are a rare breed now days, spending hours making there own concoctions, thatís one of the greatest things about Britain, but a new way of making music will not e made in a shed, just as brain surgery was
Not refined in a kitchen, I hope! The big companyís need to invest and encourage new ideas and new people, there is elitism from the big wigs to the boot straps, so why would anybody put themselves up to be mocked, Am glad you started this thread, I needed to be slapped into eating a humble pie, I may even turn my hand to the NXT and see what I can do with it?
I'm told that the CAD software is a long way from perfect. With building NXTs you can choose material, size, thickness, shape, number of exciters, etc. I'd be very surprised if software could accurately model the whole caboodle.

Which means we're back in Paradise_Ice's shed. Great.

I say "Go for it". I visit this forum from time to time when I'm in a designing space because I find it inspiring. I remain convinced that with the skill, knowledge, creativity and experience we have here, members could do better than the big boys anyway.

And remember this, if we're using the panels in a combo application (Layered Sound), they don't have to be perfect. They're about 4dB to 6dB down on the moving coil main speakers anyway and that's enough to mask some of the evils.

PS: I've never had a problem with putting myself up to be mocked (as regular, long-term posters will know).
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Old 8th June 2004, 03:54 PM   #30
1audio is offline 1audio  United States
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Default NXT, Capacitorless Xovr and AR Magic

As is common here one question forked into three threads.

First, the layerd concept is very similar to the AR Magic Speaker from many years ago. The core concept then was to control the room sound by swamping it with a controlled sound adjusted to NOT interfere with the primary direct sound. AR did it with a delay (before digital delays were easy) and an EQ to compensate for the room.

I have worked on a project with large NXT panels and have mixed feelings. Used as surrounds or as the room drivers in an AR Magic type installation they have a lot of promise. However the lack of phase coherency limits their performance as a stereo speaker. They may be perfect for MP3 and other ultracompressed audio formats with their innate ability to mask some artifacts. Extended bass is not likely to come from them anytime soon.

Somehow the capacitorless crossover/ series crossover patent turned up. I think its very narrow since 1) The big Sonus Faber used a similar technology before the patent was filed and 2) series crossovers are not new. The novel aspect is the combination, and that requires remarkably good drivers to work. I don't find the errors of capacitors so much more egregious than inductors that I would ban them. More likely the opposite.
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