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Old 8th June 2004, 04:05 PM   #31
7V is offline 7V  United Kingdom
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Default Re: NXT, Capacitorless Xovr and AR Magic

Quote:
Originally posted by 1audio
... Extended bass is not likely to come from them anytime soon.
Just a quick add-on ...

I'm told that in a Layered Sound application the crucial frequencies are 500Hz to 5kHz.
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Old 8th June 2004, 04:55 PM   #32
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Default Critical frequencies

500Hz to 5000 Hz would fit into the original concept from AR. This also relates to the Haas window and more. Sadly many new discoveries and patents turn out to be rehashes of much older work that was forgotton. The web as a research tool should make it much easier to test the history of an idea but its still hard to know what has gone before.

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Old 8th June 2004, 06:21 PM   #33
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Default Re: NXT, Capacitorless Xovr and AR Magic

Quote:
Originally posted by 1audio
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've been looking up the old AR Magic Speakers and have found this. Fascinating stuff. They seem to have been designed to get around the negative effects of early side-wall reflections. By delaying a small portion of the overall sound and directing out at an angle to the side, they are supposed to give the impression that the room's side walls are 20 feet away, although the width of the soundstage and the amount of 'ambience' could be varied.

I'm not sure that the Layered concept is all that similar. As a matter of fact it's almost identical to the Kef Instant Theatre system discussed earlier. I think that the AR Magic speakers, together with the Kefs, the numerous omni-directional designs that have come out over the years (including the new B & O Beolab 5), the Bose 901, ambisonics, quadraphonics, Hafler mode, this Layered Sound approach and numerous others all attempt to address the problems inherent in moving coil stereo speakers playing in living rooms.

The NXT combo approach has advantages over the others and, as has already been pointed out, disadvantages but it does represent an interesting approach and is, in my view, a worthy attempt. It's certainly a simple approach.

I agree though, "There's nothing new under the sun" - not really new anyway.
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Old 8th June 2004, 07:01 PM   #34
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Quote:
"this Layered Sound approach and numerous others all attempt to address the problems inherent in moving coil stereo speakers playing in living rooms."
I agree there are problems but this is a very broad statement. Perhaps you can elaborate?
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Old 8th June 2004, 07:49 PM   #35
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Quote:
Originally posted by 1audio
I agree there are problems but this is a very broad statement. Perhaps you can elaborate?
It's a tricky area and one in which far greater minds than mine have failed to find agreement. Still, I'll throw out some thoughts and see who adds to or corrects them.

Why doesn't a piano sound like a piano?

I believe that the main reason is the difference in the direct and reflected sound patterns in the living room compared to the concert hall. In a concert hall, a considerable proportion of the overall sound to reach the ears is ambient, reflected and delayed.

Most rooms don't sound like concert halls. This leads to many speaker manufacturers, myself included, suggesting that the speakers be placed away from the walls by a distance of 1 metre or more. It seems that when the reflected sound is delayed by this amount (with the corresponding reduction in amplitude owing to the longer path) the brain somehow filters it out and hears the speakers more directly. My own speakers go further and the line arrays significantly reduce the early reflections from the floor and ceiling in the critical mid-band.

However, this still doesn't duplicate the actual sound of the concert hall. Since when did the audience applause come totally from in front of the listener in a concert hall?

The various omni-directional moving coil approaches, whether they be Bose 901 type systems or 'reflective dish' type systems are far too room influenced to ever be considered accurate (although they may give a pleasant enough sound).

The modern vogue for surround sound/home theatre systems attempts to address this and follows the lead of great pioneers such as Hafler who used a simple system to decode the out of phase ("ambient") signal and play it through a rear speaker in order to give the impression of the concert hall ambience.

The modern Dolby decoding systems claim to solve this problem, although in reality, the systems and recordings are attempting more to achieve cinema-type special effects - like a large dinosaur breathing heavily behind your right shoulder or helicopters flying loudly overhead. There's not much music with dinosaurs and helicopters.

Of course at the bass frequencies, there are other problems due to the resonant nodes of the room leading to peaks and troughs in the frequency response. I believe that, at these frequencies, correction could be applied to get around the problem (such as the TACT systems). Still, there's a danger that the correction system somehow robs the sound of life.

I also have a feeling that there's another inherent property of moving coil loudspeakers which ensures that the piano doesn't really sound like a piano and this is, I believe, to do with the dispersion patterns. With a moving coil driver the dispersion becomes progressively narrower as the frequency increases. A piano doesn't act in this way. Speaker systems that incorporate a number of drivers with a crossover unit may have wider dispersion at high frequencies, owing to the dispersion properties of the tweeters but they're even worse at the crossover frequencies where there are dramatic changes in dispersion between one driver and the next.

Finally, systems such as the NXT panels discussed gives totally different radiation and dispersion patterns. The evidence seems to be that, used alone, they're even more disconcerting and 'wrong sounding' than moving coil systems.

This is probably one of those posts which 'I'll regret the next day' but, for what it's worth ...
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Old 8th June 2004, 08:31 PM   #36
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Interesting thread... I will offer my 2 amateur cents (on credit due to oil prices and upcoming Canadian elections).

I've heard some cheapo NXT panels at the computer store. Not horrible but certainly not worse that just about any other computer speaker system, like the Monsoon or the Creative. I didn't get a chance to try them out with my portable CDP, so I cannot tell what they are like with a reasonably good source. I don't own any so I cannot give a long-term opinion.

I was also at a live concert last night (KD Lang and Vancouver Symphony) so my memory of a concert grand has been renewed quite recently. First, let me say that the hall had more reflections than a disco ball. Also, it seems they used sound reinforcement on everything, even the orchestra when they were playing selections before the main event. Worse, they gave KD Lang a horrible mic or preamp - noise floor so bad that it was more like a ceiling. She is good, but not enough to overcome the acoustics. No wonder I like small venues.

That said, many passages with the piano... and it was definitely more "real" when just the orchestra was on. I would say they didn't use as much mic'ing for that. Even so, it didn't sound like a piano would up close (FYI, I have some musical training - now mostly lost).

With this recent sonic signature in mind, I still think that the closest thing to a real piano I have heard from speakers is on a mid-sized Genelec. The ESL 63 did not do as well. These are both from test-drives in the store... I can't afford such baubles. In any case, I believe this is because drivers provide the "punch" necessary to recreate the attack of the hammer.

If Dr. Katz says that combo of NXT and driver makes for closer sound, then my guess (and this is a guess!) is that the panel helps create the diffraction pattern caused by the large sound box of the instrument. Recall that a piano has a huge area of wood and when opened and propped, creates a huge flap that bounces the sound towards the audience. (If you ever get a chance, listen to a piano from both sides of the lid - it is slightly different). Maybe Dr. Katz hears the panel creating properly diffuse decay sounds.

:)ensen.
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Old 8th June 2004, 10:16 PM   #37
sreten is offline sreten  United Kingdom
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The point about the "layered sound" concept is its patentable.

This implies a unique and individual implementation of something,

it in no way implies the theory is correct or the "implementation"
technology is the best way of implementing the theory.

I can easily see promise in adding NXT panels to a speaker,
(which by the way struggle above 5kHz and below 500Hz
by definition, so this is the range of interest in layered sound)
to improve spatiality of a mundane speaker.

It may well be the case this works well with a solo piano recording

but what is the effect on on the precision of image of say a large
orchestra, and why not throw in some choirs as well.

I'm sorry if I seem pessimistic, but IMO a technology that
improves bad acoustics (only application so far) is far from
being shown to being the next step up the ladder.

7V I'm not suggesting you shouldn't pursue the matter,
far from it, but personally I can't take the jargon and
marketing approach seriously, I want hard facts.

However for small domestic speakers they change from omni
to hemispherical at around 500Hz, so a NXT panel placed edge
on with the listening axis being a dipole will have no effect
on the axial response (so it doesn't need to be - 6dB) and
will fill out the off axis response considerably.

Of course "layered sound" can't consider whether a electrostatic
or magnetic planar panel might do this more accurately, or even
an open baffle driver, because by definition it uses NXT panels.

Remember NXT started out as noise cancelling techonology,
measured in dB reduction, fine resolution was not an issue,
but it showed the principle could be used as a transducer.

sreten.
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Old 9th June 2004, 12:44 AM   #38
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Emmmm am not sure if I should say this?
As I donít like to be so disagreeable but I think the reason a grand piano does not sound the same from your speakers or any speakers is not just the poor old speakers fault, I have worked with many microphones over many years and every single microphone has a specific pick up pattern and there is no microphone in the word that sounds like a human ear! trust me I have look for many and found none!
that is to say evolution has given our ears a certain pick up range that is very narrow in the frequency range of sound but is most commonly heard by us humans, our brains have limited power and most of that power is used to process light from our stereo eyes, Yes music does sound better with our eyes closed or in the dark, a grand piano has a very complex sound wave and a single or even stereo microphone with a heavy, yes heavy diaphragm compared to our ears will never pick up the precious changes in air pressure that our ears can, there are some microphones that are more accurate and lets just say better than our ears! but thatís not what we hear! The quality of a recording and the Engineering making the recording make a massive difference in the quality we get on a recording, our ears hear a stereo omni directionally sound and some mics do also, but our ears can also do the cardio pattern, well what am saying is we cant plug our ears into a machine and test what we hear on a graph, we can only know what we hear and that is that, If we could use our ears as microphones then am sure you would get that sound back from the speakers but we can not until cybernetic systems become available! So I think we should cut the old boy coil and cones some slack and realise the what we hear is the very last link in a chain of processes and it has inherent flaws and limitations built into it. We can not reproduce everything that is crucial to accurate reproduce the sound we record, from the air temperature, humidity, barometric air pressure even the light energy and there are just to many variable factors need to create that sound again! Itís not our fault that we canít make ultra realistic speakers, ok it is! But thatís not the point, the microphone needs to do better, and itís almost a 200 year old design by some Welsh chap I think, David Edward Hughes, ďthanks GoogleĒ so lets blame the real culprit! Itís not my fault Governor I only work here.
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Old 9th June 2004, 12:55 AM   #39
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Quote:
Originally posted by sreten
... It may well be the case this works well with a solo piano recording

but what is the effect on on the precision of image of say a large
orchestra, and why not throw in some choirs as well. ...

... 7V I'm not suggesting you shouldn't pursue the matter,
far from it, but personally I can't take the jargon and
marketing approach seriously, I want hard facts.
I'm happy to try to oblige but I don't really know how. If you tell me the nature of the hard facts that would determine whether or not the system works well with a solo piano and/or works well with a large orchestra and choirs, I will do my best to provide them.

Quote:
However for small domestic speakers they change from omni to hemispherical at around 500Hz, so a NXT panel placed edge on with the listening axis being a dipole will have no effect on the axial response (so it doesn't need to be - 6dB) and
will fill out the off axis response considerably.
Hmmm, I'm not sure I agree here, although you may well be right. Yes, the NXTs will fill out the off-axis response but wouldn't it also change the sound for a listener precisely on-axis as well? For example, won't the listener gain a different impression of the sounds coming from behind him or from the sides?

I appreciate that these effects may be secondary but that may be the nature of what we're looking for?
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Old 9th June 2004, 01:15 AM   #40
7V is offline 7V  United Kingdom
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Quote:
Originally posted by Paradise_Ice
... So I think we should cut the old boy coil and cones some slack and realise the what we hear is the very last link in a chain of processes and it has inherent flaws and limitations built into it.

... So I think we should cut the old boy coil and cones some slack and realise the what we hear is the very last link in a chain of processes and it has inherent flaws and limitations built into it.
Everything you say is spot on and, if I might say so, well said.

Still, it's the responsibility of speaker designers (amateur and professional) to push the boundaries out as far as we can. It's a thankless and some would say ultimately pointless task - this search for truth and beauty - but someone's got to do it.

Quote:
... But thatís not the point, the microphone needs to do better, and itís almost a 200 year old design by some Welsh chap I think, David Edward Hughes, ďthanks GoogleĒ so lets blame the real culprit! Itís not my fault Governor I only work here.
If we can improve the speakers maybe they'll improve the microphones.

Now, I've got this idea for a new microphone, using a combo with reverse flat panel technology ...
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