Time Domain measurements?

[dc655321]

It's kind of weird that even though the periodicity is that of a 15 Hz sine wave, there is no spectral energy at that frequency.

It's not too weird - the remaining spectral components must have been derived from a 15Hz fundamental, hence the 15Hz envelope.
It is the envelope that our hearing is sensitive to...

 

[Don Hills]

Now think about tracing the physical movement over time of a speaker cone reproducing a square wave...

 

[dc655321]

Now think about tracing the physical movement over time of a speaker cone reproducing a square wave...

Would that not be proportional to the twice integrated SPL as a function of time?

 

[Joachim Gerhard]

@Joachim Gerhard I can´t seem to find an answer to your thoughts onto the following in this thread
How much emphasis do you put on the time coherence of your speakers and why would you drop the absolute phase coherence in a passive x-over?
I guess everything is a compromise and you can´t get everything, so I assume every product is the best compromise possible to do
Looking at step responses from Stereophile on both Virgo and Virgo III they look really very close (and nice) but not fully phase coherent
(I was really close to purchasing the Virgo III, probably a bad choice not to get them)

Would you current passive portrait extended edition look something similar, maybe without the delay between tweeter and mid?

Virgo step response from Stereophile
View attachment 73273

Virgo III step response from Stereophile
View attachment 73274

That is a classic result of my 3 way speakers in the 90th. The crossover from mid to tweet is a L/R 4th order and the cross between mid and bass is a phase inverted Butterworth 3rd order. i did this for a linear amplitude response and good radiation pattern. With most music this is fine and they image very well as you have experienced yourself. Today I can do better. The Portrait has better step response. When I find he time I will post measurements of a speaker i recently made and then you can see the difference. Anyway, if you use the Virgo 2 or 3 with Accurate it is easy to improve the step response to a respectable result.

 

[Joachim Gerhard]

I'm not raving about them ... I auditioned them and either it's something wrong with me, something wrong with speakers or it was a horrible demo....

I thought they were lifeless, sounded artificial, no magic ..... that was the Kii three BXT (with woofer modules) fed from an Auralic G2.1 streamer.
24 woofers and the bass was lagging, unprecise and inadequate...

I really wonder why anyone would want to buy these speakers

When you have a mighty Tool like This you can do a lot wrong. Maybe the speakers where not well placed or the room had standing waves and too long reverberation. I bet it was a poor demo. Many dealers have no clue how to adjust a Maschine like that. I would have trouble to fully understand it.

 

[KaiserSoze]

Because the former is the correct term to use - a transfer function can be expressed as a function of amplitude/magnitude and phase.

My comment was inferred from your misuse of terminology, and more directly by this:

All physical systems are bandwidth-limited - perfect square wave reproduction would require (impossibly) infinite bandwidth.
Not sure it's more complicated than that...

You extracted a piece of what I had written, deliberately deleting the part that would render apparent the fact that you were falsely interpreting the quote you used!!!!! If I live to be a hundred and ten years old, I will not understand what makes people try to pull stunts like this on web forums.

Here is the full sentence that I had written:

"Yes, but dare I ask how this helps to answer the question of why it isn't reasonable to expect audio components to reproduce square waves?"

Here is the snippet you so cleverly extracted:

"why it isn't reasonable to expect audio components to reproduce square waves?"

The snippet is obviously not a syntactically correct question, which fact is inescapable and renders apparent the fact that what you did is not on the up and up.

In the post where the sentence that I actually wrote appears, I was asking another person how the observation he had made helped to answer the central question (i.e., the question of why it isn't reasonable to expect audio components to reproduce square waves). I would not expect even a college freshman's level of reading comprehension to fail to understand the difference. Did you understand the difference, or do you just not care about intellectual honesty?

The full extent of the egregiousness of what you did can only be fully appreciated in light of the fact that the question that you attempted to make it seem that I was asking is the very question that I had in fact answered in an eloquent manner a few pages earlier!!!! I wrote this:

Yes, we do not need for our speaker to produce squares, ... It think it is useful to identify three reasons...

Reason #1: A square wave transitions instantaneously between two different levels, which is to say, it contains a vertical slope. The steepest slope in a waveform determines the highest frequency component needed to represent the waveform in an equivalent Fourier series of pure sinusoids. ... Since frequencies higher than a threshold (generally taken to be 20 kHz) are not audible, there is no need for an amplifier or especially a speaker to reproduce the vertical slopes seen in a square wave. ... In fact the upper frequency limit of the device may be inferred from the steepness of the slope in the output. ...

Reason #2: If the fundamental frequency of the square wave is below the lowest frequency the audio device is capable of reproducing ... the fundamental frequency of the square wave will be missing. ... If we accept that we cannot hear below a certain threshold, generally accepted to be 20 Hz, then there is no need for an audio device to preserve the fundamental frequency of a square wave if the fundamental frequency of the square wave is below this threshold.

Reason #3: If the numerous and various frequency components needed to produce a square wave (subject to the two preceding considerations) are not phase-coherent, then the output will not look anything like a square wave. It will have the required frequency components, but if the different frequency components vary appreciably in phase they will also vary appreciably in time. ...

It has been brought to my attention that some of the elaboration I gave with Reason #2 was wrong, even in my subsequent attempt to correct it. But that has no relevance here and now. What I was fundamentally saying, about the need for the frequency of the square wave to not be below the natural lower cutoff frequency of audio equipment, was absolutely correct and on the mark. In fact, I have no qualms with saying that this post of mine is patently the best summary answer to the central question that anyone here has offered, by a very long country mile!!

And yet, in spite of this, you deliberately extracted a snippet out of a sentence where I asked another person how the points he had made helped to answer the central question about the use of square waves. You did this so that you could make it seem that I had asked the very question to which I had in previously given an eloquent answer, so that you could parrot the answer!!!!!!!!!!!!!! ARRRRGGGHHH!!!! Please help me to understand why I shouldn't regard what you did as an exhibition of intellectual dishonesty.

It goes without saying that if you reply to this, you will attempt to make it seem that this was an innocent misunderstanding. No, it wasn't. I would never, ever, ever do something like what you did.

 

[dc655321]

You extracted a piece of what I had written, deliberately deleting the part that would render apparent the fact that you were falsely interpreting the quote you used!!!!! If I live to be a hundred and ten years old, I will not understand what makes people try to pull stunts like this on web forums.

Here is the full sentence that I had written:

"Yes, but dare I ask how this helps to answer the question of why it isn't reasonable to expect audio components to reproduce square waves?"

Here is the snippet you so cleverly extracted:

"why it isn't reasonable to expect audio components to reproduce square waves?"

The snippet is obviously not a syntactically correct question, which fact is inescapable and renders apparent the fact that what you did is not on the up and up.

In the post where the sentence that I actually wrote appears, I was asking another person how the observation he had made helped to answer the central question (i.e., the question of why it isn't reasonable to expect audio components to reproduce square waves). I would not expect even a college freshman's level of reading comprehension to fail to understand the difference. Did you understand the difference, or do you just not care about intellectual honesty?

The full extent of the egregiousness of what you did can only be fully appreciated in light of the fact that the question that you attempted to make it seem that I was asking is the very question that I had in fact answered in an eloquent manner a few pages earlier!!!! I wrote this:



It has been brought to my attention that some of the elaboration I gave with Reason #2 was wrong, even in my subsequent attempt to correct it. But that has no relevance here and now. What I was fundamentally saying, about the need for the frequency of the square wave to not be below the natural lower cutoff frequency of audio equipment, was absolutely correct and on the mark. In fact, I have no qualms with saying that this post of mine is patently the best summary answer to the central question that anyone here has offered, by a very long country mile!!

And yet, in spite of this, you deliberately extracted a snippet out of a sentence where I asked another person how the points he had made helped to answer the central question about the use of square waves. You did this so that you could make it seem that I had asked the very question to which I had in previously given an eloquent answer, so that you could parrot the answer!!!!!!!!!!!!!! ARRRRGGGHHH!!!! Please help me to understand why I shouldn't regard what you did as an exhibition of intellectual dishonesty.

It goes without saying that if you reply to this, you will attempt to make it seem that this was an innocent misunderstanding. No, it wasn't. I would never, ever, ever do something like what you did.

Would you like a tissue?

 

[Absolute]

I'm not raving about them ... I auditioned them and either it's something wrong with me, something wrong with speakers or it was a horrible demo....

I thought they were lifeless, sounded artificial, no magic ..... that was the Kii three BXT (with woofer modules) fed from an Auralic G2.1 streamer.
24 woofers and the bass was lagging, unprecise and inadequate...

I really wonder why anyone would want to buy these speakers

*Please let me know if this post is too demanding with several pictures, I'll fix it if it's bothersome.*

To be fair, it's not possible for the bass to be lagging, unprecise and inadequate if the frequency response and time domain response is that good. Assumptions must go towards the room/placement in such case.

My thoughts are that Kii is not really suitable for very loud spl with or without BXT. They run into audible distortion quite quickly in the upper bass/lower mids, perhaps due to undamped cabinet, lack of headroom in the driver or maybe just interference from the cardioide pattern;

I did experiment a bit with this distortion issue while I had the Kiis by trying subs crossed over at 200 hz and found that the audible strain at high spl diminished quite a bit, something easily audible if you try to switch on and off BXT during loud passages;

All in all I found that the Kiis are excellent speakers in a home-environment where you don't play at deafening volume levels, but they are too bright as standard with a few desibels too much in the top-end to my liking. Easily fixed by the on-board EQ, but usually the dealers don't fiddle with that - or even worse, actually increase the top end to create "more air", like Duet Audio did at some demos.
Constant directivity designs with a narrower directivity than normal speakers may perhaps be perceived as a little less airy per default?

I'd like to see a spinorama of Kii because I suspect there's some resonance around 3-4 khz that can be heard as ringing based on the smoothed measurement in the first picture in this post, but I didn't know enough about measurements at the time when I had them to find out for myself.
Regardless, they sound absolutely incredible once the top end is dialed down a bit in my opinion. Here's an in-room comparison of default Kii before room EQ vs my preferred tonal balance adjusted with Kii Control also before room EQ;

Comparing the Kii BXT with my preferred settings directly with Kef Blade, I preferred the Blade due to a more relaxing mid/high response, but the bass wasn't comparable at all. BXT just blew it completely out of the water below 250 hz, which was expected of course.
The subjective feeling in that department was that the Blade had a softer bass with far less snappy punch, and of course lacked the oomph in the deepest frequencies. Measured spl in the listening position was around 95 dB average with my phone app, far louder than I feel comfortable with. But very fun!

 

[haraldo]

*Please let me know if this post is too demanding with several pictures, I'll fix it if it's bothersome.*

To be fair, it's not possible for the bass to be lagging, unprecise and inadequate if the frequency response and time domain response is that good. Assumptions must go towards the room/placement in such case.

My thoughts are that Kii is not really suitable for very loud spl with or without BXT. They run into audible distortion quite quickly in the upper bass/lower mids, perhaps due to undamped cabinet, lack of headroom in the driver or maybe just interference from the cardioide pattern;

View attachment 73390



I did experiment a bit with this distortion issue while I had the Kiis by trying subs crossed over at 200 hz and found that the audible strain at high spl diminished quite a bit, something easily audible if you try to switch on and off BXT during loud passages;



View attachment 73391

View attachment 73392
View attachment 73393


All in all I found that the Kiis are excellent speakers in a home-environment where you don't play at deafening volume levels, but they are too bright as standard with a few desibels too much in the top-end to my liking. Easily fixed by the on-board EQ, but usually the dealers don't fiddle with that - or even worse, actually increase the top end to create "more air", like Duet Audio did at some demos.
Constant directivity designs with a narrower directivity than normal speakers may perhaps be perceived as a little less airy per default?

I'd like to see a spinorama of Kii because I suspect there's some resonance around 3-4 khz that can be heard as ringing based on the smoothed measurement in the first picture in this post, but I didn't know enough about measurements at the time when I had them to find out for myself.
Regardless, they sound absolutely incredible once the top end is dialed down a bit in my opinion. Here's an in-room comparison of default Kii before room EQ vs my preferred tonal balance adjusted with Kii Control also before room EQ;

View attachment 73407
View attachment 73408



Comparing the Kii BXT with my preferred settings directly with Kef Blade, I preferred the Blade due to a more relaxing mid/high response, but the bass wasn't comparable at all. BXT just blew it completely out of the water below 250 hz, which was expected of course.
The subjective feeling in that department was that the Blade had a softer bass with far less snappy punch, and of course lacked the oomph in the deepest frequencies. Measured spl in the listening position was around 95 dB average with my phone app, far louder than I feel comfortable with. But very fun!


View attachment 73409

Do we live in same city? This is Duet Audio showroom in Bergen!

I believe I been victim of a sub-par demo

I may not consider a speaker bad after a single demo (This was a demo in Oslo), with the case of the Kii three, I also tend to believe that there must have been something wrong with settings, for the demo I referred to above, speakers were set up in a way there would certainly be minimal room gain at play. Also, as I see now, even for an expert there can be information overload in getting dsp settings for these speakers correct.

I'm certainly going to pay them a listen again, now with all the incredibly hard work being done by Martin & co at the showroom in Bergen. These are really nice guys, working very hard and being very customer oriented.

I would like to check again another time. The acoustics of that room is way different and better from beforehand; If you haven't checked lately I would recommend to

 

[haraldo]

That is a classic result of my 3 way speakers in the 90th. The crossover from mid to tweet is a L/R 4th order and the cross between mid and bass is a phase inverted Butterworth 3rd order. i did this for a linear amplitude response and good radiation pattern. With most music this is fine and they image very well as you have experienced yourself. Today I can do better. The Portrait has better step response. When I find he time I will post measurements of a speaker i recently made and then you can see the difference. Anyway, if you use the Virgo 2 or 3 with Accurate it is easy to improve the step response to a respectable result.

It´s not only the imaging, it's the resolution, the sense of being there, the snap, the realism of the instruments, the voices, the wish to permanently just play one more song. I am not sure if I ever heard Leftfield, Leftism ever the way it was reproduced by Virgo III, all the aspects mentioned above combined together in a way there is no way to stop smiling...
but still there was something with that magic of the Duntech's that kept me from replacing speakers, the Virgo III were way better in many ways, but then there was that magic...

I assume that your speakers now follow the same principles just infused and bettered by even many more years of experience and way better drivers and technology at hand. But with speakers I always seem to face that issue, there is no-one speaker that do everything I want...

For those of you who never listened to any @Joachim Gerhard designed speakers, your loss, I am thinking of the possibility of fixing that mistake of not having a pair at home

 

[Absolute]

Do we live in same city? This is Duet Audio showroom in Bergen!

I believe I been victim of a sub-par demo

I may not consider a speaker bad after a single demo, with the case of the Kii three, I also tend to believe that there must have been something wrong with settings, for the demo I referred to above, speakers were set up in a way there would certainly be minimal room gain at play. Also, as I see now, even for an expert there can be information overload in getting dsp settings for these speakers correct.

I'm certainly going to pay them a listen again, now with all the incredibly hard work being done by Martin & co at the showroom in Bergen. These are really nice guys, working very hard and being very customer oriented.

I would like to check again another time. The acoustics of that room is way different and better from beforehand; If you haven't checked lately I would recommend to

That we do
Maybe it was a bad demo, maybe you expected something otherwordly, maybe it was a bad match between your taste and the way Kii delivers music. It is interesting to investigate such things, at least for me.
My experience with demos is that they only work well if you are left alone to relax with the remote and music selection at your own control and with enough time. I've been fortunate enough to spend quite a lot of time alone with different set-ups in that room with nothing but me, myself and I without other customers disturbing - and I've been allowed to fiddle with settings, comparing A-B, play at all volume levels etc.

I find that, in general, audio demos are often played too loud for my taste - resulting in listening fatigue and difficulties with enjoying music because I'm over-analyzing the sound itself, trying to make sense of why it sounds so different at 100 dB than 65 dB
By adjusting placement, toe-in, spl level, distance from the speaker etc I find that I can usually find a way to enjoy most set-ups I listen to. The only exception being too aggressive top end, I literally despise shrill sound.

This particular audio store allows me to do all that and also lets me A-B test stuff like a Solution amplifier ($ 45 000) vs Rega amplifier ($ 700) etc, so I feel like they are very customer focused and generally curious and enthusiastic about sound themselves.
I've learned a lot from this store over the years thanks to Martin and am genuinely thankful for the value that store has added to my hobby.
It's been awhile though, so I guess I'll have to bring along something nice and visit Martin again

 

[Joachim Gerhard]

It´s not only the imaging, it's the resolution, the sense of being there, the snap, the realism of the instruments, the voices, the wish to permanently just play one more song. I am not sure if I ever heard Leftfield, Leftism ever the way it was reproduced by Virgo III, all the aspects mentioned above combined together in a way there is no way to stop smiling...
but still there was something with that magic of the Duntech's that kept me from replacing speakers, the Virgo III were way better in many ways, but then there was that magic...

I assume that your speakers now follow the same principles just infused and bettered by even many more years of experience and way better drivers and technology at hand. But with speakers I always seem to face that issue, there is no-one speaker that do everything I want...

For those of you who never listened to any @Joachim Gerhard designed speakers, your loss, I am thinking of the possibility of fixing that mistake of not having a pair at home

I think part of the magic in the Virgo 2 and Virgo 3 was the way I placed the drivers. The front is very narrow so there is not much cabinet resonance there and the radiation pattern is wide. The push- push woofers on the side do force cancelation. This gives an improvement in cabinet resonance of up to 20dB. This speakers are simply very quiet because the cabinet contributes very little. This is in stark contrast to classic English speakers in the BBC tradition like the Spendor BC1 for example. A speaker like that may sound muddy and foggy, how ever beautiful the tone is.

 

[Absolute]

I think part of the magic in the Virgo 2 and Virgo 3 was the way I placed the drivers. The front is very narrow so there is not much cabinet resonance there and the radiation pattern is wide. The push- push woofers on the side do force cancelation. This gives an improvement in cabinet resonance of up to 20dB. This speakers are simply very quiet because the cabinet contributes very little. This is in stark contrast to classic English speakers in the BBC tradition like the Spendor BC1 for example. A speaker like that may sound muddy and foggy, how ever beautiful the tone is.

I'm sorry if this has been asked before, but how do you measure the cabinets contribution specifically? I know Stereophile use an accelerometer taped on the side, but according to Floyd Toole that's absolutely useless.

 

[tuga]

I think part of the magic in the Virgo 2 and Virgo 3 was the way I placed the drivers. The front is very narrow so there is not much cabinet resonance there and the radiation pattern is wide. The push- push woofers on the side do force cancelation. This gives an improvement in cabinet resonance of up to 20dB. This speakers are simply very quiet because the cabinet contributes very little. This is in stark contrast to classic English speakers in the BBC tradition like the Spendor BC1 for example. A speaker like that may sound muddy and foggy, how ever beautiful the tone is.

The BBC RD goal was to build cheap, light and sturdy speakers. The Virgo weighs twice as much as an LS3/6 or a BC1, and is at least 25 years younger.
Resonant cabinets as a goal is just current-day marketing or maybe just a misunderstanding, they actually measured the speakers with different panel construction and damping materials and decided for the best case scenario which was controlled/attenuated resonance.
Other research seems to indicate that lower frequency resonances are less audible than higher frequency ones.

 

[Absolute]

Do you know of a better scientific way?
Is there any better way than using accelerometer, just wonder and I am very interested in this topic

You could use laser, which is what I'm guessing most manufacturers use. But I can imagine some resorting to simulation only while others might create a sound-proof(ish) box around the front of the speaker while listening/measuring behind if there's much leakage, or maybe someone who swears to the good ole knuckle-test.

Floyd Toole said all cabinet resonances will show up in the spinorama if audible. If the spins are clean all around, there's no audible resonances from the cabinet.

 

[Joachim Gerhard]

An acceleromer helps to identify spots on the cabinet that may need stiffening. You can also do a laser scan like Wilson and Fink do. Fink has a Polytec laser. Mr. Fink told me that it happens many times that when you stiffen one region, resonances show up in another region so it is kind of an art and it will not tell you how it sounds.
I myself experienced that extremely stiff cabinets may not sound as good as one could hope for. In the Good old times we Even build speakers from stone or concrete or damped the cabinet walls with lead. My explanation is that the internal sound finds its way then though he driver cones. Of cause you can use sandwich cones that are maybe opaque but they are quite heavy and that reduces sensitivity. One problem is that the noise inside the cabinet is very high. Linkwitz RIP told me ones that he put a microphone into a closed cabinet and found enormous pressure inside. I do not remember the value but it was staggering. I myself use 2 methods. Place two speakers front to front and reverse the phase of one speaker. Then you can measure quite well on the cabinet walls with a microphone. You can also place a small speaker inside a bigger speaker. Then you can even measure what comes out through the cones. And finally there is Distortion Isolation in the time domain. I had the idea and Bill Waslo programmed it. That way you can separate all distortion and noise from the music and you can listen over headphones to the residue.

 

[tuga]

Floyd Toole said all cabinet resonances will show up in the spinorama if audible. If the spins are clean all around, there's no audible resonances from the cabinet.

Did he really say that or are you misinterpreting?
How can you determine if a low-level low-Q resoance at say 200Hz is a cabinet resonance from a Spinorama?

 

[haraldo]

That we do
Maybe it was a bad demo, maybe you expected something otherwordly, maybe it was a bad match between your taste and the way Kii delivers music. It is interesting to investigate such things, at least for me.
My experience with demos is that they only work well if you are left alone to relax with the remote and music selection at your own control and with enough time. I've been fortunate enough to spend quite a lot of time alone with different set-ups in that room with nothing but me, myself and I without other customers disturbing - and I've been allowed to fiddle with settings, comparing A-B, play at all volume levels etc.

I find that, in general, audio demos are often played too loud for my taste - resulting in listening fatigue and difficulties with enjoying music because I'm over-analyzing the sound itself, trying to make sense of why it sounds so different at 100 dB than 65 dB
By adjusting placement, toe-in, spl level, distance from the speaker etc I find that I can usually find a way to enjoy most set-ups I listen to. The only exception being too aggressive top end, I literally despise shrill sound.

This particular audio store allows me to do all that and also lets me A-B test stuff like a Solution amplifier ($ 45 000) vs Rega amplifier ($ 700) etc, so I feel like they are very customer focused and generally curious and enthusiastic about sound themselves.
I've learned a lot from this store over the years thanks to Martin and am genuinely thankful for the value that store has added to my hobby.
It's been awhile though, so I guess I'll have to bring along something nice and visit Martin again

I love it when I go into a hi-end store and they show me to their absolute hi-end room and just say .... knock yourself out
Like playing "Batman begins" from start to end ... I am spending as much time as I can listening to all sorts of different gear, this is fun and you learn a lot along the way.... At the end of the day, when you do this enough I think you get a pretty good sense of what is good for you and not. In the end it's only you that can say and decide.

My ears is the final judge, not an audio precision analyzer.... anyways our ears work very different from a microphone

 

[haraldo]

An acceleromer helps to identify spots on the cabinet that may need stiffening. You can also do a laser scan like Wilson and Fink do. Fink has a Polytec laser. Mr. Fink told me that it happens many times that when you stiffen one region, resonances show up in another region so it is kind of an art and it will not tell you how it sounds.
I myself experienced that extremely stiff cabinets may not sound as good as one could hope for. In the Good old times we Even build speakers from stone or concrete or damped the cabinet walls with lead. My explanation is that the internal sound finds its way then though he driver cones. Of cause you can use sandwich cones that are maybe opaque but they are quite heavy and that reduces sensitivity. One problem is that the noise inside the cabinet is very high. Linkwitz RIP told me ones that he put a microphone into a closed cabinet and found enormous pressure inside. I do not remember the value but it was staggering. I myself use 2 methods. Place two speakers front to front and reverse the phase of one speaker. Then you can measure quite well on the cabinet walls with a microphone. You can also place a small speaker inside a bigger speaker. Then you can even measure what comes out through the cones. And finally there is Distortion Isolation in the time domain. I had the idea and Bill Waslo programmed it. That way you can separate all distortion and noise from the music and you can listen over headphones to the residue.

I recently talked to Peter Lyngdorf on this exact topic and he also referred to the incredible SPL levels inside a cabinet and he suggested that there is no good way of damping that enough so that it does not ricochet back through drivers. (I think there was talks on 120+ dB)
That's one of his reasonings for going dipole in the Steinway Lyngdorf speakers

 

[Absolute]

Thank you, Mr. Gerhard! Interesting stuff, indeed. I follow the reasoning that too stiff a cabinet may very well backfire in the sense that you get the bad stuff back through the cone itself. Logically it would be preferable if as much energy as possible is translated to heat or inaudible vibrations in the cabinet.
I think I remember that the reason KEF went with that plastic stuff in their Blades was that the material is both strong enough and flexible enough to absorb/convert much more energy into vibrations/heat than other materials. Don't place any bets on my memory, though.
May not be surprising that both Kii Three and Devialet Phantom is built with the same type of stuff, when I think about it.

Distortion Isolation sounds awfully interesting, and complicated!

Here's an idea; make acoustic cancellation speakers inside the cabinet to reduce the violent SPLs, kinda like the noise-cancelling headphones. If someone patents that because of me, I deserve an ice cream.