Shootout between JBL M2 and Revel Salon 2

[Cosmik]

Each Kii uses four high excursion drivers , Devialet do much the same with their 'Phantoms'
Keith

If they can go loud enough then I think it is the perfect arrangement. Obviously, bigger high excursion drivers could go even louder to satisfy the bassheads. Personally, I love bass, but I don't require anywhere near the SPLs that some people do!

 

[Purité Audio]

In my 5x7 metre room they are more than loud enough without the limiting feature activating, Kii claim RMS 105dB and 110dB for peaks.
What might be interesting would be an additional ' bass module' for the Kiis which would extend their controllled directivity further into the lower frequencies.
Keith

 

[Sal1950]

Actually, I know a fair bit about the distortion reduction via motion feedback. But, that is not what I was talking about. Rather, it is the maximum SPL. This is where I, Sal too I think, are questioning what the Kii is capable of. As I said, I suspect it cannot move enough air, motional feedback included. I am sure it does great, especially for a stand mounted speaker of its size. I just think it could benefit from one or more good subwoofers, just like most speakers do.

Yes exactly, the Three is a nice little speaker that I'm sure can deliver good low bass into a small to medium home listening room.
They're in no way the first to be able to do this, eq and motional feedback isn't new, and there's no new miracle law of physics breaking tech going on,
So for Christ's sake Keith, let's be real. They like every thing else they have limits. To hear you carry on you'd think my local IMAX could replace their entire LFE array with a pair of Three's and their 4 little 6.5" mini-woofers.
Ain't gonna happen.
Can we move on now?

 

[Purité Audio]

I realise it's difficult tocotowihthe fact that it isn't today necessary to have large cabinets and large woofers to produce low bass, have a look at the Devialet Phantoms they are physically smaller than the Kii's.
I have measured the Kii's in room against all the other speakers I have here, and only the Dutch&Dutch 8C can match them for extension and output.
Keith

 

[Thomas savage]

I realise it's difficult tocotowihthe fact that it isn't today necessary to have large cabinets and large woofers to produce low bass, have a look at the Devialet Phantoms they are physically smaller than the Kii's.
I have measured the Kii's in room against all the other speakers I have here, and only the Dutch&Dutch 8C can match them for extension and output.
Keith

Keith,

This is a thread about JBL M2's and revel salon 2, please stop jumping in with your Kii three propaganda. Your persistence in doing this is irritating members.

 

[Purité Audio]

Of course your lordship.
Keith

 

[watchnerd]

What might be interesting would be an additional ' bass module' for the Kiis which would extend their controllled directivity further into the lower frequencies.

You can't control directivity when the wavelength is bigger than the room. 20 Hz = 17m.

That's really the whole point of Schroeder...below the room's f(s) you're dealing with resonances and nodes rather than reflection / diffraction.

 

[Thomas savage]

Of course your lordship.
Keith

I do understand how desperate life can be for peasants and common folk but I'm afraid there is a limit to the grace I afford you.

 

[FrantzM]

Yes exactly, the Three is a nice little speaker that I'm sure can deliver good low bass into a small to medium home listening room.
They're in no way the first to be able to do this, eq and motional feedback isn't new, and there's no new miracle law of physics breaking tech going on,
So for Christ's sake Keith, let's be real. They like every thing else they have limits. To hear you carry on you'd think my local IMAX could replace their entire LFE array with a pair of Three's and their 4 little 6.5" mini-woofers.
Ain't gonna happen.
Can we move on now?

Love that reply!

I find the Kii interesting having read the accolades especially those of Kal Rubinson. THe laws of Physics remain though. There is no substitutes for displacement when it comes to low bass and SPL. 110 dB at 20 Hz will tax the Kii small drivers.... no "ifs" , "buts" or "perhaps". Lot of clean power (cheap these days ) in a pair or better, a trio of 18" long excursion subwoofer drivers will get there with you electronics-like distortion ...

 

[Purité Audio]

You can't control directivity when the wavelength is bigger than the room. 20 Hz = 17m.

That's really the whole point of Schroeder...below the room's f(s) you're dealing with resonances and nodes rather than reflection / diffraction.

The Kii's use their extra drivers to cancel off-axis response, you can use an out of phase sub to actively destroy modes.
Keith

 

[watchnerd]

The Kii's use their extra drivers to cancel off-axis response, you can use an out of phase sub to actively destroy modes.
Keith

Managing bass nodes isn't directivity control. It's in the realm of room EQ.

It uses a different term because it's a different phenomenon.

 

[Purité Audio]

If you cancel the response to the rear and sides you are controlling directivity, that's what the Kii's and Beolabs do.
Keith

 

[watchnerd]

If you cancel the response to the rear and sides you are controlling directivity, that's what the Kii's and Beolabs do.
Keith

Keith, you don't get to redefine acoustic terms of art just to suit your own purposes.

Directivity refers to managing reflection and diffraction patterns above the Schroeder frequency.

Room EQ or room correction are the terms used for what you're describing. Dirac, Sonarworks, etc, don't claim to address directivity.

 

[Purité Audio]

I am just explaining to you how Kii and B&O create their 'controlled directivity'.
They use a sophisiticated crossover design and multiple drivers to cancel off-axis response, so the sound effectively comes out of the front.
Keith

 

[Jakob1863]

Keith, you don't get to redefine acoustic terms of art just to suit your own purposes.

Directivity refers to managing reflection and diffraction patterns above the Schroeder frequency.

Room EQ or room correction are the terms used for what you're describing. Dirac, Sonarworks, etc, don't claim to address directivity.

Seems to be a misunderstanding; directivity is a property of the signal source (i.e. loudspeaker) while the Schroeder frequency describes a property of the room/hall.

See for example the loudspeakers and technical we are "discussing" in this thread:

http://www.audiosciencereview.com/f...ardiodic-directivity-in-the-bass-region.1859/

 

[watchnerd]

Seems to be a misunderstanding; directivity is a property of the signal source (i.e. loudspeaker) while the Schroeder frequency describes a property of the room/hall.

See for example the loudspeakers and technical we are "discussing" in this thread:

http://www.audiosciencereview.com/f...ardiodic-directivity-in-the-bass-region.1859/

Sure, but at omni-directional bass frequencies, there is no directivity to control -- it's omni.

 

[Thomas savage]

It's important we stick to the proper terminology here, it's a pita at times and can be unpleasant to be told your talking nonsense but that's just the way it's got to be.

 

[Jakob1863]

Sure, but at omni-directional bass frequencies, there is no directivity to control -- it's omni.

But that´s one of the main points of these speakers that they aren´t "omni" anymore in the bass region. If you follow the links to the thread and within that to the manufacturer´s page you´ll notice that, as they´ve published quite comprehensive data. Of course it depends a bit on the model, but level "behind" the speaker is down around 6 dB - 10 dB in the bass region below 120 Hz compared to the level "on axis" .

 

[watchnerd]

But that´s one of the main points of these speakers that they aren´t "omni" anymore in the bass region. If you follow the links to the thread and within that to the manufacturer´s page you´ll notice that, as they´ve published quite comprehensive data. Of course it depends a bit on the model, but level "behind" the speaker is down around 6 dB - 10 dB in the bass region below 120 Hz compared to the level "on axis" .

Two points:

1. Yes, manufacturers are doing sophisticated things to reduce bass nodes in localized areas and to mitigate boundary effects (not just in the bass). However, calling this "directivity control" conflates the activity with "controlled directivity speakers", which is primarily concerned with a very different phenomenon, namely that of addressing above-the-bass reflections off walls, objects, etc.

If for no other reason to avoid confusion, a different term should be used.

2. Applying phasing effects to reduce the bass by 6 dB - 10 dB behind the speaker will reduce the boundary effect, but the wavelengths involved are > 2.9 meters / 9.4 feet, making them above the beaming frequency of any normal driver and thus tending towards omni (as gated by baffle width). And, again, the primary acoustic problem with sub-Schroeder frequencies isn't directivity, but room nodes, so calling it 'directivity' is just confusing and isn't speaking to the main problem.

 

[Blumlein 88]

I have thought what the Kii and B&O do is similar to how microphones works. You could have two woofers facing opposite directions and the phase reversed. One cancels the other. You could feed one a reduced signal, maybe 6 db lower and get partial cancellation that would result in something like a supercardiod pattern even in the bass even if the drivers are not large relative to the wavelength. It would be a rather inefficient method, but I see no reason it would not work. We also know with a large enough baffle you can get directional bass like anything else. I would imagine some more sophisticated software could use both channels to have time delay such that two speakers could have a somewhat directional mono bass at least in principle without breaking any laws of physics.

So after writing the above looked for someone doing that. Came up with right away.
http://www.fohonline.com/ci/31-tech-feature/15387-cardioid-subwoofer-setups.html

Here is a page about DIY efforts at cardioid bass response.

http://kimmosaunisto.net/CardSub/CARDSUB.html