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Spatial audio speakers

Juszat

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Is there any measurment based on CEA 2034 standard of Spatial auidio speakers ( open baffle speakers from Utah designed by Clayton Shaw) ?
 

sfdoddsy

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They sound quite different to my own open baffles which measure pretty flat on axis at least. Quite a bit livelier, which generally means a tipped up response similar to that in the link.
 

abhijitnath

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Interesting- I don't think I've found them bright specifically (although they do sound lean, which may be the same thing)?
 

TheInquiring

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To my surprise, I found no measurement results published neither on Spatial Audio website nor on their forum at AudioCircle. Frankly, I cannot believe Clayton does not measure his designs "playing it by ear" instead so to speak...
 

FrantzM

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To my surprise, I found no measurement results published neither on Spatial Audio website nor on their forum at AudioCircle. Frankly, I cannot believe Clayton does not measure his designs "playing it by ear" instead so to speak...
Wellllllllllllllll , that says all that one needs to know about those speakers ...
 

Duke

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Frankly, I cannot believe Clayton does not measure his designs "playing it by ear" instead so to speak...

Are those your words or Clayton's?

Wellllllllllllllll , that says all that one needs to know about those speakers ...

You might want to wait until TheInquiring responds to my question before jumping to conclusions.
 
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TheInquiring

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Sorry for the delay, dear experts.
Are those your words or Clayton's?
The words are mine. I am certainly not a Guru in the field, but I imagine any competent designer (and Clayton certainly is) does measure his designs thoroughly. What is intriguing me is the fact I was unable to find the measurement results published... I quite liked the X5 model: 8 Ohms nominal, 97 dB sensitivity (easy to drive with my small PASS amp), goes down to 25 Hz (!). Outstanding! BUT why, oh why, can't we see the actual measurements?!
 

Duke

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The words are mine.

Thanks for clarifying.

I have reason to believe that Clayton Shaw is not "playing it by ear, so to speak."

I've had conversations with Clayton wherein we discussed measurements. We have measured some of the same drivers and compression driver/horn combinations.

BUT why, oh why, can't we see the actual measurements?!

Have you asked Clayton?
 
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TheInquiring

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Thank you Duke!

I'll likely never buy a speaker for which I can't find CEA-2034 (or something comparable), and I'm much more likely to purchase from those who provide the measurement results themselves. High chance, in my mind, that companies who don't publish the data themselves do so because they know it would paint them in a poor light.

Just my take…
 

richard12511

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Thank you Duke!

I'll likely never buy a speaker for which I can't find CEA-2034 (or something comparable), and I'm much more likely to purchase from those who provide the measurement results themselves. High chance, in my mind, that companies who don't publish the data themselves do so because they know it would paint them in a poor light.

Just my take…

or my take? ;)
 

peanuts

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no way a passive dipole like that will measure good. they need eq, all of them. also he uses dome tweeters with 15"? woofers, *facepalm*. polars will be awful
 

ctrl

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The M3 and M5 Sapphire at least have a very unusual concept.

A (modified?) 1.25'' tweeter from Peerless taking over at 575Hz with a second order high pass. Even with 32mm voice coil, that's brave.
This is definitely a very interesting tweeter from Peerless.

It says on the product page "Crossoverless Dome Midrange/treble Driver", but then in a review it says that capacitors are used to protect the tweeter, which is of course a crossover :D

There are probably no measurements because the frequency range above 1-2kHz radiation may not be very uniform. Below that it should be pretty good but, as @peanuts already said, will require EQ.
 

andreasmaaan

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The M3 and M5 Sapphire at least have a very unusual concept.

A (modified?) 1.25'' tweeter from Peerless taking over at 575Hz with a second order high pass. Even with 32mm voice coil, that's brave.
This is definitely a very interesting tweeter from Peerless.

It says on the product page "Crossoverless Dome Midrange/treble Driver", but then in a review it says that capacitors are used to protect the tweeter, which is of course a crossover :D

There are probably no measurements because the frequency range above 1-2kHz radiation may not be very uniform. Below that it should be pretty good but, as @peanuts already said, will require EQ.

Wow, that's a really wild design!
 

Duke

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no way a passive dipole like that will measure good.

Imo it would be a mistake to evaluate a dipole (or any other polydirectional loudspeaker) by the same target curve as what Harman has developed for evaulating monopoles. Quoting Floyd Toole on the subject:

"Remember, the Harman curve relates to conventional forward-firing loudspeaker designs. Legitimate reasons for differences are different loudspeaker directivities - omni, dipoles, etc. - or rooms that are elaborately acoustically treated, or both."

they need eq, all of them.

Not necessarily. A designer who knows what he's doing might use custom woofers whose parameters result in a low-end response which complements the inherent dipole rolloff.

In my opinion Clayton Shaw knows what he's doing.
 
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ctrl

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Since there are no measurements of the M3 or M5, we simply simulate the radiation pattern of the tweeter without crossover and analyze the result - wow, how exciting :rolleyes:

I lack the exact dimensions (membrane height, suspension,...) of the tweeter, there may be deviations in the range above 6-8kHz. Also, I have had the software reliably calculate the simulation only up to 9kHz.

Here is the sketch of the simulation:
1607937911235.png
The virtual measurement microphone is located at the height of the tweeter axis at a distance of 2m.

All diagrams show only the tweeter response - keep that in mind!
But due to the fact that the crossover frequency to the tweeter is 570Hz, the directivity of the tweeter represents almost the entire speaker.
UPDATE: The simulation software assumes an ideally behaving tweeter. Deviations in the frequency response that the real tweeter has are not included.

Horizontal Frequency responses of the tweeter deg0-90
1607937931014.png
The speaker should probably be listened to directly on axis, because then you benefit from a frequency response drop in the range of 2.5-3.2kHz, which should provide a pleasant sound.


Horizontal normalized frequency responses of the tweeter deg0-90
1607937946425.png
As expected, the speaker shows a very good dispersion behavior below 1 kHz. The reason for this is the flat baffle, I use this effect myself in all my projects.
Since the crossover at 570Hz is done with a second order filter, the transition to the open-baffle woofer should not cause an abrupt change in directivity.

Things get a bit wilder in the frequency range 1-4kHz - also as expected. The directivity is uneven in this frequency range. Therefore, the manufacturer is probably not interested in publishing measurements.


Horizontal normalized spectrogram of the tweeter deg0-180
1607938055115.png
A lot of "sound energy" is emitted horizontally from the upper midrange to the middle high frequency range.

Vertical normalized spectrogram of the tweeter deg0-180 (the lower half of the diagram shows the directivity upwards over the tweeter axis.)
1607938157484.png
Due to the low crossover frequency of the tweeter, the vertical dispersion of the speaker is exceptionally good.


Early reflections (expected in room response) for a linear on-axis frequency response
1607942186891.png
The conditions for very good behavior in the listening room are given.

Please do not be put off by the hump in the 2-3 kHz range, as we saw above with the simulated frequency responses, there is a dip on axis in this range.
This means that this hump should not be so pronounced in the real loudspeaker (as long as the axial frequency response will not be linearized).

A really very interesting concept that also works out quite well.
The speaker's power handling should be within limits due to the very low crossed tweeter.
It is difficult to predict how the radiation problems in the frequency range 1-4kHz will play out in reality.

But maybe @amirm will get a M3 or M5 to measure.
 
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Duke

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Very illuminating simulation, @ctrl. I had wanted to make a similar analysis just with words, but decided not to because I couldn't back it up with graphs. Thank you very much for taking the time.

Below the crossover frequency the pattern will be the familiar dipole figure-8, with a directivity index fairly similar to what the tweeter is doing north of the crossover frequency, though the radiation pattern shapes will obviously be very different.

In my opinion the different pattern shapes above and below the 575-Hz crossover region won't be a problem. Each is wide enough to provide exceptionally uniform coverage across a 60 degree arc, which should cover the listening area and then some, given proper set-up (which includes some toe-in). There will be significant spectral variation in the individual reflections, but the average spectral balance of the reflections will be unusually smooth. The ear tends to perceive the average spectral balance of reflections over a time interval, rather than the spectral balance of individual reflections. That time interval is in the 10-15 milliseconds ballpark as I recall.

As a result the perceived spectral balance of the reverberant sound (and yes I know the use of this term is problematic in the context of small rooms) will probably track the spectral balance of the direct sound fairly closely over most of the spectrum.

So despite how counter-intuitive it seems to combine a 15" woofer with a (rather large) dome tweeter, the Spatial Audio M3 is imo an example of how to do it right.
 
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