What's the problem with modern proper loudspeaker cabinets decoupling?

You are totally wrong about needing 100 KHz bandwidth to measure ITD. That was also the mistake Kunchur made, which I assume is where you got your misinformation. This is from my Audio Expert book, based on information I got from James "JJ" Johnston who you might have heard of.

Temporal Resulution

Another researcher, Milind Kunchur, thought he found a different way to prove that high sample rates are needed based on our hearing's temporal resolution. He claimed that human ears can detect left-right arrival time differences as small as 5-10 microseconds, which is true, but he wrongly concluded that reproducing such small timing offsets requires a sample rate higher than 44.1 KHz. What Dr. Kunchur didn't consider is that bit depth also affects timing resolution, and 44.1 KHz at 16 bits is in fact more than adequate to resolve timing to much finer than anyone can hear. The formula is simple, based on the highest frequency accommodated and the number of bits in use:

1 / (2 * Pi * Fmax * 2^Bits)

So for CD quality audio with an upper limit of 20 KHz at 16 bits, the resolution is:

1 / (2 * Pi * 20,000 * 65,536) = 0.12 nanoseconds

Even if music is so soft that it occupies only 8 bits (-48 dBFS), the timing resolution is still 31 nanoseconds, or 0.031 microseconds, which is 300 times better than anyone can hear.
 
You are totally wrong about needing 100 KHz bandwidth to measure ITD.
No, I am right if someone tried to measure it the way you did.

ITD has little or nothing to do with the approximately 20kHz limit on human perception of frequency. We are talking about phase differences at certain frequencies and between stereo channels. Look up the ITD literature. I'm not making this stuff up. 10us corresponds to a frequency of 100kHz, but its not pitch that humans are detecting. Its phase coherence between stereo channels.

EDIT: To clarify, I meant you were trying to measure with only one channel and one mic. To measure a time resolution of 10us with one channel would take a bandwidth of 100kHz to capture one full cycle. Not that it would be a suitable way to measure ITD, but at least it would get closer to the needed time scale if one were looking for comb filtering anywhere near ITD limits.
 
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EDIT: To clarify, I meant you were trying to measure with only one channel and one mic. To measure a time resolution of 10us with one channel would take a bandwidth of 100kHz to capture one full cycle.
To believe that ITD delays of 5-10 microsecond are responsible for reports of increased bass fullness and tightness is quite a leap. Use your common sense sir! I handed it to you several times. Here it is again:

The main reason people believe they hear a change with isolation is because the speakers are then in a different location.

Another reason is the frailty of human hearing perception, no matter what people are certain they heard.

Perhaps I need to offer another graph. The graph below shows the low frequency response in a room about 16 by 11-1/2 by 8 feet high at two locations four inches apart. Even over such a small physical span the response changes substantially at many frequencies. The reason the response changes so much even at low frequencies is because many reflections, each having different time and phase delays, combine in different amounts at every point in the room. In small rooms the reflections are strong because the reflecting boundaries are all nearby, so that further increases the contribution from each reflection. Also, nulls tend to occupy a relatively narrow physical space, which is why the nulls on either side of the 92 Hz marker have very different depths. Indeed, the null at 71 Hz in one location becomes a peak at the other.
 

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To believe that ITD delays of 5-10 microsecond are responsible for reports of increased bass fullness and tightness is quite a leap.
I don't disagree, which is why when I gave my example in an earlier post I said I would skip the bass tightness issue at that point in time. Instead I took up the easier question of imaging and localization perception.

Why bass seems to tighten up would take some more work to try to better understand. For now it remains speculative. However, I believe that it does seem to have a tightening perceptual effect because the effect is easy to hear under the correct conditions with stereo near field monitors, and if using Recoil Stabilizers.

Given that a possible improvement in imaging/localization is easy to understand, that then tends to make it less likely that mass hallucination among listeners accounts for all reports of beneficial effects of isolators. Thus, I don't think we can just jump to some conclusion that only mass hallucination can account for the reported bass tightening. Maybe we just have to say we don't have a final conclusion on bass tightening at this time.
 
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We're getting closer. I think you just need another piece of the puzzle. Though first, I'm sure you agree that "mass hallucination" is common among audiophiles who hear differences with wires and even AC power fuses, yes? So please let's discount that. With 80 percent of the world's population believing in god, mass hallucination has quite a long history. (I hope that doesn't offend anyone too much.)

As for imaging, it is never stable unless absorption is present at the side-wall reflection points. I'm pretty sure I made that point already. Just like the large LF response changes over 4 inches, it's even worse at mid and high frequencies, as you can see in the image below from the same two sweeps but expanded out to 20 KHz. Most audiophiles have no acoustic treatment, and so don't even know what good imaging sounds like. You move your head an inch or two, or raise the speakers a few inches, and the imaging really does change. But not because of any isolation devices.
 

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I'm sure you agree that "mass hallucination" is common among audiophiles who hear differences with wires and even AC power fuses, yes?
Not always, as it turns out. There are a couple of AES papers on cables affecting sound, one of them peer reviewed. Electrostriction was believed to be the main culprit in that case. In another case with headphone cables, magnetostriction was implicated. In the case of fuses, I seem to recall some information that their resistance can be modulated with current and in some cases an audible effect can be produced. In all of the above cases it was not claimed that there were always audible effects, only that there were plausible explanations is some limited cases.

However, we can certainly agree that people can easily imagine sound effects that are not real. Possibly less so in specially trained listeners, at least according to some published information. But, yes, overall it tends to be a common problem with audiophiles.
 
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Perhaps in some limited cases. But c'mon man, I'm sure you know that the vast majority of "wire" claims are BS. Equally so for claims that wire direction is a factor. I hesitate to post this because it's half an hour long, and I hate when others tell me to watch or read something that long. But this proves with hard science - a null test - that wire claims are mostly nonsense:

 
I'm going to skip the cable thing for now, but I will say there is some interesting discussion about cables in other threads, including for terminating them in their RF characteristic impedance. Some of that work has been done by very serious measurement folks.

Regarding wall treatment at first reflection points, I believe there was some earlier discussion on that by the speaker oriented guys.

For myself, I mostly use Sound Lab large area ESL panels which have a modified figure-8 pattern. They are toed in so that nulls more or less point to where first reflections would occur with many box speakers. No treatment needed on the walls there. Some other spots in the room do need it though.
 
...the vast majority of "wire" claims are BS.
I have been skeptical in the past of claims that cables could sound different, but more recently have heard some systems where cables do have some influence on the sound of a system. Could be I am just running into some of the situations described in the AES papers. I suppose if I really wanted to know more about the vast number of cases I would have to go out in the field, visit some audiophile installations where cables are claimed to influence sound and do a little investigating. Maybe you have already done that?

Regarding null testing, there are lots of variations on ways to do it, with there likely being thousands of wrong ways and a few right ways, much like the anecdotal reporting of #227. I will say this, I have investigated quite a few cases involving very advanced medical devices where operators of the equipment have reported intermittent problems that could affect life-safety of patients. In many of those cases engineers involved in the design of the equipment were adamant that the equipment could not possibly do what the operators claimed. The engineers often claimed that the operators were imagining things that weren't real. In every case of that type that I can recall, it always turned out in the end that the equipment operators were correct. Once that was proven, the design engineers involved got busy doing a serious investigation which ended up finding and fixing the problem (except in one case where the equipment was taken off the market). It pretty much always was the case that the mental model inside the engineers' heads of what they had designed was a simplified model of how they intended the design to work so as to guarantee patient safety. Only when confronted with enough evidence did they stop to think more deeply about what could be going on. Thus, I have learned to be very careful and very serious about field investigations.
 
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Is it worth a third go at trying to drum up interest in applying the scientific method to get a handle on the thread topic or is it perhaps wiser to wait for a healthier thread where the OP is still around and there aren't quite so many diverting posts to wade through?
 
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All I can and will add here are three points…..the argument against table or console speakers holds water….there’s likely not enough mass to keep the surface and structure from resonating. That’s a fairly easy problem to mitigate to the point of inaudibility.

Constrained layer damping construction of speaker enclosure walls works…..and works well…….a .5 inch core wrapped in a damped layer and then laminated with a suitably thick solid layer. This also allows for flush mounted driver frames to never directly touch the outer layer.

True ribbon tweeter users…….isolation from the mid and bass drivers delivers audible improvement…….keep those bar magnets from vibrations outside of the pass band of the foil ribbon and there’s an improvement in clarity and dynamics with complex music signal. It’s subtle but it’s there so for those on the path of perfection…..a better application than silly audiphool interconnects.
 
Is it worth a third go at trying to drum up interest in applying the scientific method to get a handle on the thread topic...
You have kind of proposed maybe a high school level, or at least an introductory form of the scientific method without getting into more advanced ideas/details such as, disproving the alternate hypothesis, the application of statistics, etc. OTOH, in university studies such as engineering, the curriculum is typically designed to eventually make the student into some kind of expert who is also trained in doing independent scientific research by the time the PhD level is achieved.

Also it turns out audio is a very complex and vast field where there is sometimes contentious polarization in the views of practitioners. Simplistic efforts to teach and apply introductory level approaches to the scientific method are likely to run into trouble in such an environment.

Probably better if part of the standard undergraduate curriculum in engineering and science included a course in the philosophy of science. A good book on the subject is: https://www.amazon.com/Philosophy-S...cphy=9032419&hvtargid=pla-2281435178058&psc=1

Some other info: https://www.uwo.ca/philosophy/pdf/graddocs/Sci Reading List - 20111.pdf

Also good: https://www.amazon.com/Structure-Scientific-Revolutions-50th-Anniversary/dp/0226458121/ref=sr_1_1?crid=2EZ3ZKBBWV2L5&dib=eyJ2IjoiMSJ9.wwc08CAlYyQMM0PPdG9o4_6w_oaErwpbMkQQ-_dWFI-Z3mJM_sXIH7iejzwiLKJWiL3GxjT1_aT_43mKJKWMgIw2WKKbX1ljO_OB_6B7FjZlcdjg57i_6pNv8kytKc9tgoh5xutCOZAWpi71qvKzl8AIgbJU5LBndeLZoaAJ1ku-tLIca5ifdWqLsckd5g97tccBFjCAkvnNAP6-mqkX_-2AA3VFmrAvez6uzYO1wlc.96q_5amqMshmmKeKyrii1LlHFBfq4MxKuA7zQ3vkadI&dib_tag=se&keywords=the+structure+of+scientific+revolutions&qid=1750763534&s=books&sprefix=scientific+revolu,stripbooks,168&sr=1-1
 
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...the argument against table or console speakers holds water….there’s likely not enough mass to keep the surface and structure from resonating. That’s a fairly easy problem to mitigate to the point of inaudibility.
True in some cases. Back when Recoil Stabilizers were introduced there was a problem mix engineers sometimes had to deal with when working in someone else's studio. Its important to know how a mix needs to sound in order to translate to many different consumer systems. When faced with unfamiliar monitors in a studio, it wasn't too uncommon to place ubiquitous NS-10 monitors on the top of the meter bridge of the console. It was a lousy place to put them but sometimes it was the only place available to put the speakers while still being able to access the mix console controls. In that case good isolators could be blessing.

Now, I don't know what's happened since then, nor what Bob Katz may have claimed, but likely there could still be some situations where it isn't practical to mount speakers on metal stands bolted to a concrete floor.

EDIT: Presumably some of what is going on now involves someone sitting at a computer desk "mixing in the box," which is to say mixing a record using a computer. Could be monitor speakers are being placed on either side of a video monitor. Again, its a vibrating desktop situation. Also, a lot of studios today are considered "project studios," which may be a spare room in the house of the producer. Maybe the producer lives in a house with raised wood floors (which can vibrate, squeak when walked on, and or possibly vibrate at spots on the floor of an adjacent room from loud music playing in the mix room).
 
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From working with producers for nearly forty years, perhaps risking a 'no true Scotsman' fallacy, producers passionate about their work never relied solely on the sonic presentation of one studio. They listened to their product at home or in the car, with different speakers in different studios to confirm their aesthetic choices were truly universal. The commonly raised 'circle of confusion' objection is wildly simplistic IMO, especially in the case of live musicians where the producer can hear the source in room direct. Producers can and do consider and compensate for the acoustic signatures of their studio systems.
BTW, I posted a link to a free download Bob Katz AES paper investigating speaker isolation up-thread.
 
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You have kind of proposed maybe a high school level, or at least an introductory form of the scientific method without getting into more advanced ideas/details such as, disproving the alternate hypothesis, the application of statistics, etc. OTOH, in university studies such as engineering, the curriculum is typically designed to eventually make the student into some kind of expert who is also trained in doing independent scientific research by the time the PhD level is achieved.

Also it turns out audio is a very complex and vast field where there is sometimes contentious polarization in the views of practitioners. Simplistic efforts to teach and apply introductory level approaches to the scientific method are likely to run into trouble in such an environment.

I suggested applying the scientific method which we were taught at school but without response. Then I posted a summary of the scientific method to see if that might move things along but it didn't. A third go would likely involve explaining why hypotheses are central (i.e. the science) and measurements somewhat secondary. This is largely missing from the preceding discussion and is why it is unlikely to come to a satisfactory conclusion (i.e. all sides agreeing on the same thing). The scientific method on the other hand is designed to iterate towards a hypothesis (or set of) that successfully predicts the outcome of all relevant experiments.

In this case where the subject is something well established the application of the scientific method is more of a systematic way to guide the looking up and pulling together the relevant science/engineering. There's no need to perform actual experiments though they can serve as a check which is often wise. It will require working with scientific/engineering quantities though like force, velocity, impedance, area, etc... which many hobbyists don't want to do. Fair enough, it's is a hobby and one then keeps the freedom to choose which of the conflicting statements we see in this thread and in other audiophile material seems the most plausible and/or attractive.