Why don't all speaker manufacturers design for flat on-axis and smooth off-axis?

[Krunok]

I am the first person usually to point out that speakers are «boring» in the sense that I think good speakers have more similarities than obvious differences. But it doesn’t mean I think 8331, 8341, 8351, S360 and Kii Three sound exactly the same even if their specifications and measurements are similar. Even if this forum wants me to shut up, fall into the fold and repeat the gospel that correct speakers all sound the same, I will not. Should I be sorry for perceiving differences between 8331, 8341, 8351, S360 and Kii Three (i.e. speakers that I have heard in the same room)?

On every DAC review topic you will find a few folks claiming the same thing as you are - modern DACs don't sound the same. Did you compare those speakers in a proper blind test?

P.S. Nobody wants you to shut up, but you should have learned by now that you are expected to provide valid arguments for your statements. Only if you can't do that, well, in that case you better..

 

[Krunok]

Toole & Olive's research does not predict all speakers with "correct" responses sound the same.

IMO in some way it does. As manufacturers will continue to build better and better speakers their spinorama charts would start to look alike, distortion componenets would become lower and lower and they will all be able to deliver mighty bass at decent SPLs. That actually means that their acoutstic signature will converge and they will all start to sound pretty much the same, as it happend with DACs and amps. Experiment that @mitchco made with his JBLs and Kef LS50+subs confirms this.

 

[Cosmik]

Some of the measurements and data tells something about the sound, but they do not completely visualize how the speaker will sound when I put it in my room.

Throughout this discussion I think there are multiple ideas intertwined:

1. There is a rational (a.k.a. 'philosophical' [spit emoji]) argument that says that humans have evolved to focus on what a source sounds like, even in a room. They use two ears, head movement, frequency response, phase and timing of transients to hear through the room and to register the room sound separately from the speaker. Most audiophiles don't believe this; it is not possible to devise an experiment to demonstrate it directly and objectively so it cannot be real; it is mere philosophy [spit emoji].
2. The opposing argument says that speaker and room are a system with a composite frequency response at the listener's ears which can be modified to some desired result by changing the EQ of the speaker. This is the basis of target curves and room correction. It assumes no ability for a human to hear through the room. It is easy to measure with a laptop and mic. Coincidentally, this view has arisen over recent years at the same time as laptops and cheap measurement mics have become available.
3. If a truly neutral speaker existed then if (1) was true it would sound the same in any room OR for (2) it would still need its EQ playing with.
4. Real world speakers have non-neutral dispersion and the on-axis sound is different to the off-axis sound. This fact is accepted by most audiophiles - and has been known for many decades (I have a reference in the 1950s somewhere). However, for the (2)-believing person, it is almost an abstract issue, and even if they are aware of research concerning preferences for certain dispersion patterns it makes no difference to their room correction efforts: 'Spin-o-rama' results have no input to their target curves.
5. Non-neutral dispersion (and this includes the smooth variant) results in non-neutral sound; a mishmash of direct and indirect sound with different EQ characteristics. And this is imposed on the composite recording i.e. all the sources identically, so is different from the listener's acceptance of a single source's arbitrary dispersion characteristics. It broadcasts its presence.
6. It might be suggested that the result of (5) could be improved subjectively by modifying the speaker's EQ. If so, in the philosophical realm it would be apparent that this was a compromise not a correction, room-dependent and could not be done independently of the speaker's dispersion characteristics. Thus the (1) person would accept that EQ tweaking was necessary, but (2) people would assume this to be confirmation that (2) was correct. If it wasn't correct, however, (2) would produce random sonic results and a belief that speakers are still mysterious and unpredictable in the 21st century.
7. Many audiophiles accept research that says that smooth dispersion patterns are preferred over lumpy ones (even if they don't act directly on it). But they don't seem to worry about the overall depth of variation of dispersion. Roughly, a wider baffle would result in less need to tweak the EQ in (6) and consequently less of a compromise, but this is not known to most audiophiles.
8. Drivers beam as frequency increases - simple, objective physics. A large, beaming driver crossing over to a small driver produces an abrupt change in directivity. Adding an extra midrange driver in between them maintains wider dispersion and smoother directivity overall, plus other benefits related to power handling etc. However, traditional crossover filters have sonic side effects resulting in many speaker designers stretching the frequency ranges over which drivers have to work - even for supposedly up-market speakers.
9. A neutral or non-neutral speaker with flat on-axis FR will give a non-flat FR in a real room if the measurement includes the room sound. An average speaker and average room will yield an average FR. A solely empirical view of this based on real speakers in real rooms results in the belief that listeners prefer an average FR and hence the notion of the target curve. This is then even extended to headphones. In the philosophical realm this can be anticipated and debunked but only in a way that is incompatible with the empiricist world view.
10. Belief that frequency response is everything results in odd appendages to speakers such as bass reflex that provide the right frequency response results at the expense of timing performance. It also excuses any kind of crossover as long as it results in the right FR at the measurement mic. FR 'correction' using simple EQ methods also alters phase and timing - another variable in the mix.

Putting all that together we have a vague, woolly, nebulous field of activity. I think the results reflect this: few people seem more satisfied with their audio systems than they did in the 1970s. Ironically, the engineering limitations that forced speakers of the 1970s to be the way they were may have resulted in several desirable characteristics that modern speakers struggle to replicate (the by-products of large, sealed boxes, large woofers, wide baffles, three-way drivers). And the 1970s designers used expensive anechoic chambers, eschewing the much cheaper and easier (and naive?) option of in-room FR measurements.

'Philosophers' would design speakers differently from modern, empirical-only, laptop & mic technicians.

 

[edechamps]

There is a rational (a.k.a. 'philosophical' [spit emoji]) argument that says that humans have evolved to focus on what a source sounds like, even in a room. They use two ears, head movement, frequency response, phase and timing of transients to hear through the room and to register the room sound separately from the speaker.

@Floyd Toole would agree with this, based on his book, but only above the transition frequency. At low frequencies, the room dominates over the speaker because of our inability to distinguish between direct sound and reflections at these frequencies, combined with the huge impact of modal resonances.

Most audiophiles don't believe this; it is not possible to devise an experiment to demonstrate it directly and objectively so it cannot be real; it is mere philosophy [spit emoji].

Such experiments have, in fact, been done. The conclusion is that a human listener is quite capable from separating the room from the speaker. See also section 7.6.2 of Toole's book (Third Edition) in which this study and others are discussed.

The opposing argument says that speaker and room are a system with a composite frequency response at the listener's ears which can be modified to some desired result by changing the EQ of the speaker. This is the basis of target curves and room correction. It assumes no ability for a human to hear through the room. It is easy to measure with a laptop and mic. Coincidentally, this view has arisen over recent years at the same time as laptops and cheap measurement mics have become available.

Again, this is not true above the transition frequency.

If a truly neutral speaker existed then if (1) was true it would sound the same in any room OR for (2) it would still need its EQ playing with.

You missed a third option: (3) it would not necessarily sound the same in all rooms, but it would still be preferred to any other speaker in most rooms.

Many audiophiles accept research that says that smooth dispersion patterns are preferred over lumpy ones (even if they don't act directly on it). But they don't seem to worry about the overall depth of variation of dispersion. Roughly, a wider baffle would result in less need to tweak the EQ in (6) and consequently less of a compromise, but this is not known to most audiophiles.

Again, the research does not quite support the idea that speakers that are less directional sound the same as speakers that are more directional. However, I think one could make the case that, as long as their on- and off-axis responses are flat and consistent, these speakers will be given similar preference ratings.

Drivers beam as frequency increases - simple, objective physics. A large, beaming driver crossing over to a small driver produces an abrupt change in directivity. Adding an extra midrange driver in between them maintains wider dispersion and smoother directivity overall, plus other benefits related to power handling etc. However, traditional crossover filters have sonic side effects resulting in many speaker designers stretching the frequency ranges over which drivers have to work - even for supposedly up-market speakers.

Good speakers (JBL LSR30x, M2, Revel, Genelec, Neumann etc.) use techniques to mitigate this problem (in particular, waveguides), and judging from their off-axis measurements, these techniques seem to be effective. (Note: as far as I know, loudspeaker waveguides did not exist back in the 1970s. Horns did exist, but they're not quite the same thing.)

A neutral or non-neutral speaker with flat on-axis FR will give a non-flat FR in a real room if the measurement includes the room sound. An average speaker and average room will yield an average FR. A solely empirical view of this based on real speakers in real rooms results in the belief that listeners prefer an average FR and hence the notion of the target curve. This is then even extended to headphones. In the philosophical realm this can be anticipated and debunked but only in a way that is incompatible with the empiricist world view.

I'm not quite sure what you mean by "In the philosophical realm this can be anticipated and debunked". I believe you are describing Toole's famous "circle of confusion". The key here is that recordings are produced using monitoring systems that are comprised of speakers such as Genelecs, which have a flat on-axis response, positioned optimally in a well-treated room. Therefore, these recordings are calibrated to sound their best using neutral speakers in good rooms. Therefore, if you want the best possible sound, you need to replicate this setup - a neutral speaker in a good room. And indeed this is precisely what listeners prefer, according to the research results. This makes a lot of sense, IMHO.

Belief that frequency response is everything results in odd appendages to speakers such as bass reflex that provide the right frequency response results at the expense of timing performance.

"Timing performance"? Where is this coming from? Can you cite studies that show that this "timing performance", as you say, is relevant in subjective loudspeaker evaluation?

It also excuses any kind of crossover as long as it results in the right FR at the measurement mic.

If by "measurement mics" you mean the on- and off-axis responses of the speaker as measured in anechoic conditions, then sure. If you mean the response measured "in-situ" at the listening position, then no, absolutely not. Two ears and a brain can distinguish between the speaker's response and the room contribution; a measurement microphone can't (or at least, not easily).

1970s designers used expensive anechoic chambers, eschewing the much cheaper and easier (and naive?) option of in-room FR measurements.

Today's serious loudspeaker manufacturers, such as Harman, Genelec, or Neumann, use anechoic chambers to design their speakers. Not in-room measurements.

 

[sergeauckland]

Putting all that together we have a vague, woolly, nebulous field of activity. I think the results reflect this: few people seem more satisfied with their audio systems than they did in the 1970s. Ironically, the engineering limitations that forced speakers of the 1970s to be the way they were may have resulted in several desirable characteristics that modern speakers struggle to replicate (the by-products of large, sealed boxes, large woofers, wide baffles, three-way drivers). And the 1970s designers used expensive anechoic chambers, eschewing the much cheaper and easier (and naive?) option of in-room FR measurements.

One benefit of today's measurement possibilities is that of doing pseudo anechoic measurements without needing an anechoic chamber or outdoor test range. With a decent sized room, accurate measurements down to 150-200Hz are possible, and with near field measurements, LF measurements up to 150-200Hz are possible depending on the size of the woofer, albeit with some approximation, but near enough.

That just wasn't available to designers of the 1970s who either had to spend heavily on anechoic facilities or do it substantially by ear/calculation with limited access to measurements.

Today, there's absolutely no reason other than commercial/ego, to design a loudspeaker that isn't flat on-axis, and with decent off-axis performance.

S

 

[Cosmik]

"Timing performance"? Where is this coming from? Can you cite studies that show that this "timing performance", as you say, is relevant in subjective loudspeaker evaluation?

If you define a speaker as a transducer that should reproduce the time domain signal as well as the correct frequency response to continuous sine waves, then a delayed, resonant energy storage and release device driven from the main cone is a problem. It's one of the elements that adds into the mix of dimensions of the system. Empirically, maybe some people will like it when combined with other deviations from neutral, and indeed those deviations from neutral ('voicing') may be deliberately included by the designer in response to the sonic effects of the resonating appendage.

But the philosopher-designer will aim to minimise the number of deviations from neutral to start with.

Quoting Linkwitz on this point:

Vented bass speakers are resonant structures and store energy which is released over time. For accuracy, bass must be reproduced from sealed or open baffle speakers that are non-resonant.

 

[edechamps]

Sure, but I don't see the point in discussing it unless you can cite studies that show that the phenomenon that you're describing is actually audible and is a significant factor when evaluating a loudspeaker in a blind test.

 

[Cosmik]

Sure, but I don't see the point in discussing it unless you can cite studies that show that the phenomenon that you're describing is actually audible and is a significant factor when evaluating a loudspeaker in a blind test.

You must have missed the earlier stuff on rationalism and empiricism

The opposite of rationalism is empiricism

I think we need to make a case in audio for 'philosophy' as a short cut through dimensionality. As I point out above, even if you put together a blind test, you can't be sure that all else is equal when you append and remove your resonator from the speaker. The philosopher-designer realises that, and simply sticks to the path of neutrality in order to avoid getting completely lost.

 

[DDF]

Linkwitz did no favors to discourse with that statement. It uses opaque terms that add confusion, not illumination

Sealed and open baffle speakers are also resonant structures, second order. Vented merely adds 2 orders. The ear is insensitive to the additional group delay with rational alignments.

Vented can introduce far worse impairments:
- absence of box stuffing required to make an efficient port leads to a reduction in back wave absorption which can and does leak through the port in the upper bass to mid range, and or is transmitted through the cone. Numerous measurements at Sterophile can be used to confirm this, for the vent

 

[edechamps]

As I point out above, even if you put together a blind test, you can't be sure that all else is equal when you append and remove your resonator from the speaker.

I would not underestimate the ability of researchers to come up with clever experiment designs that isolate particular variables. You've already made that mistake before, by assuming that we can't design an experiment that controls for the loudspeaker and the room it's in (that's false).

Furthermore, you seem to be operating on the principle that some deviation from neutrality is audible until proven otherwise. I work under the opposite principle, which is that such deviations are inaudible until proven otherwise. I guess we could argue endlessly as to which approach is best, but I can tell you which one my bank account prefers

 

[Kvalsvoll]

On a Norwegian hifi forum I have been accused of citing «guru Toole». On this forum, I am accused of being hostile North American research. So the truth is probably somewhere in between. Middle way is often better than a binary position.

But to be clear: I think @Floyd Toole ‘s book is the single most valuable source to understanding audio reproduction.

However, are there some issues that cannot be readily answered by that book, say for example why Salón won a shooutout versus M2? What should I look for in this research to determine what is the best speaker; a Salón or an M2? Or do we still need listening tests to determine this?

Greetings from sunny Florida

I think most of the problem with getting through with your message - which I partly agree upon, I think - is that you do not have an engineering/technical/scientific background and mindset, and that is revealed in this statement; the idea that science is something that can be agreed upon and solved as a political compromise.

In science there is one correct answer, and then all the other answers are simply wrong. And the decision on what is correct and what is wrong is based in scientifical technical evidence, and the decision process in itself is based on logic. So there is no middle way.

This way, we occasionally find answers that do not fit into our perception of how the world is supposed to be, but we accept the answers as truth because there is a backtrack of evidence and a logical decision behind.

I know no norwegian forum where you can have a meaningful discussion about Toole's work or anything similar.

 

[Cosmik]

I would not underestimate the ability of researchers to come up with clever experiment designs that isolate particular variables. You've already made that mistake before, by assuming that we can't design an experiment that controls for the loudspeaker and the room it's in (that's false).

Furthermore, you seem to be operating on the principle that some deviation from neutrality is audible until proven otherwise. I work under the opposite principle, which is that such deviations are inaudible until proven otherwise. I guess we could argue endlessly as to which approach is best, but I can tell you which one my bank account prefers

I don't know that an audio system that shifts pitch down by 2% wouldn't be preferred by me and other people. And whether that would be permanent. Or a novelty that would wear off after 2 days. Or 2 weeks. Or 6 weeks. Am I going to do it to see what happens? No. On philosophical grounds. It's a deviation from neutral, and I don't feel inclined to test for it, even though some people say it's great.

Ditto an audio system that expands the dynamic range of sounds it identifies as percussion. Or an audio system that deliberately adds harmonic distortion - even if it does it 'properly' rather than using a bent transfer function.

I'm just not interested in deliberate deviations from neutral even if science tells me that the subset of people that were selected for an experiment, listening to the subset of possible equipment playing the subset of possible music in the subset of possible rooms with the speakers positioned in the subset of possible positions at the subset of possible volume levels, found it inaudible or even preferable - usually.

 

[edechamps]

I don't know that an audio system that shifts pitch down by 2% wouldn't be preferred by me and other people. Ditto an audio system that expands the dynamic range of sounds it identifies as percussion. Or an audio system that deliberately adds harmonic distortion - even if it does it 'properly' rather than using a bent transfer function.

It's unlikely a majority of people would have a preference for the alterations you're describing, because if they did, then music/soundtrack producers would pick on this and apply this alteration directly in the production chain. Indeed, why would record producers pass on making alterations that would benefit the majority of listeners? And in fact, it's precisely for that reason that harmonic distortion is sometimes deliberately introduced in the production chain (think electric guitar amps). For these reasons, I find it unlikely that, in general, an audio system can deviate from neutral in ways that most people would prefer, and I find myself unswayed by your line of reasoning.

 

[Cosmik]

It's unlikely a majority of people would have a preference for the alterations you're describing, because if they did, then music/soundtrack producers would pick on this and apply this alteration directly in the production chain. Indeed, why would record producers pass on making alterations that would benefit the majority of listeners?

Nevertheless, it exists.

Today at RMAF, Schiit Audio previewed The Gadget, the first of a new class of "Music Signal Processors," intended to enhance the experience of recorded music. The Gadget dynamically re-tunes music to C=256Hz without altering tempo, and allows the user to change the re-tuning frequency and A/B the result. The result, many listeners report, is greater satisfaction with their recorded music.

"The Gadget has been described as a 'digital joint,' an 'aaaahhh box,' and a 'music immersion processor,'" said Mike Moffat, Schiit's Co-Founder and head of digital development. "Many listeners want to listen longer, and enjoy listening more, with The Gadget."

https://www.schiit.com/news/news/schiit-previews-the-gadget

 

[edechamps]

Nevertheless, it exists.

https://www.schiit.com/news/news/schiit-previews-the-gadget

We're discussing serious, scientific double-blind studies here, not wild marketing claims.

 

[Cosmik]

We're discussing serious, scientific double-blind studies here, not wild marketing claims.

Every deviation from neutrality starts as a marketing claim or an engineering short cut. Until it is tested, no one knows whether it really is a good thing in terms of preference or audibility. So are you going to be doing some experiments on pitch shifting? I am serious: that sort of thing is the bread and butter of the empiricism-driven approach, and the true science-based designer should surely pursue it even if only to dismiss it.

Someone, somewhere has to start off with the thing that you're going to be testing. For example, a hole in the speaker box designed to make the box 'honk' or 'boom' in a desirable manner.

To dismiss it out of hand is 'philosophical' . I choose that path.

 

[MattHooper]

IMO in some way it does. As manufacturers will continue to build better and better speakers their spinorama charts would start to look alike, distortion componenets would become lower and lower and they will all be able to deliver mighty bass at decent SPLs. That actually means that their acoutstic signature will converge and they will all start to sound pretty much the same, as it happend with DACs and amps. Experiment that @mitchco made with his JBLs and Kef LS50+subs confirms this.

I am likely alone on this forum in viewing the above scenario as more dystopian and utopian ;-)

I certainly don't mean that such research, as HK et al are doing, shouldn't be done or that it shouldn't be used to advance speaker design. Quite the opposite! I want as much good science thrown at speaker design as possible, so there are ever more powerful tools and theories for the loudspeaker designers to advance the field.

So I want speakers that converge, as you describe above, to exist as a choice for myself, and anyone else.

BUT...I ALSO happen to very much enjoy the variety that is out there in speaker design and sound. I've heard the HK speakers. But I also like different sounding speakers quite a bit and would be quite sad to see those choices removed by speakers being commodified to a single sound/design. It would be like everyone being issued the exact same car. There goes the joy of car enthusiasts who actually enjoy different types of cars for different reasons. I like variety of choice.

Now, of course the total commodification of speakers this way is highly unlikely. But philosophically speaking, I've seen objectivists who seem to have that goal as a good thing "I want a speaker that is neutral and tests with the best possible scores in blind tests...then I'm done and don't have to think about speakers anymore." That would be great for those people with that type of mindset. But....some of us aren't constituted that way, and we have scratches that need to be itched. Again, I've heard the Revel speakers, but I sure would be bummed if I could never listen to another pair of Quads again because that's a damned compelling listening experience too.

 

[Kvalsvoll]

Throughout this discussion I think there are multiple ideas intertwined:

1. There is a rational (a.k.a. 'philosophical' [spit emoji]) argument that says that humans have evolved to focus on what a source sounds like, even in a room. They use two ears, head movement, frequency response, phase and timing of transients to hear through the room and to register the room sound separately from the speaker. Most audiophiles don't believe this; it is not possible to devise an experiment to demonstrate it directly and objectively so it cannot be real; it is mere philosophy [spit emoji].
2. The opposing argument says that speaker and room are a system with a composite frequency response at the listener's ears which can be modified to some desired result by changing the EQ of the speaker. This is the basis of target curves and room correction. It assumes no ability for a human to hear through the room. It is easy to measure with a laptop and mic. Coincidentally, this view has arisen over recent years at the same time as laptops and cheap measurement mics have become available.
3. If a truly neutral speaker existed then if (1) was true it would sound the same in any room OR for (2) it would still need its EQ playing with.
4. Real world speakers have non-neutral dispersion and the on-axis sound is different to the off-axis sound. This fact is accepted by most audiophiles - and has been known for many decades (I have a reference in the 1950s somewhere). However, for the (2)-believing person, it is almost an abstract issue, and even if they are aware of research concerning preferences for certain dispersion patterns it makes no difference to their room correction efforts: 'Spin-o-rama' results have no input to their target curves.
5. Non-neutral dispersion (and this includes the smooth variant) results in non-neutral sound; a mishmash of direct and indirect sound with different EQ characteristics. And this is imposed on the composite recording i.e. all the sources identically, so is different from the listener's acceptance of a single source's arbitrary dispersion characteristics. It broadcasts its presence.
6. It might be suggested that the result of (5) could be improved subjectively by modifying the speaker's EQ. If so, in the philosophical realm it would be apparent that this was a compromise not a correction, room-dependent and could not be done independently of the speaker's dispersion characteristics. Thus the (1) person would accept that EQ tweaking was necessary, but (2) people would assume this to be confirmation that (2) was correct. If it wasn't correct, however, (2) would produce random sonic results and a belief that speakers are still mysterious and unpredictable in the 21st century.
7. Many audiophiles accept research that says that smooth dispersion patterns are preferred over lumpy ones (even if they don't act directly on it). But they don't seem to worry about the overall depth of variation of dispersion. Roughly, a wider baffle would result in less need to tweak the EQ in (6) and consequently less of a compromise, but this is not known to most audiophiles.
8. Drivers beam as frequency increases - simple, objective physics. A large, beaming driver crossing over to a small driver produces an abrupt change in directivity. Adding an extra midrange driver in between them maintains wider dispersion and smoother directivity overall, plus other benefits related to power handling etc. However, traditional crossover filters have sonic side effects resulting in many speaker designers stretching the frequency ranges over which drivers have to work - even for supposedly up-market speakers.
9. A neutral or non-neutral speaker with flat on-axis FR will give a non-flat FR in a real room if the measurement includes the room sound. An average speaker and average room will yield an average FR. A solely empirical view of this based on real speakers in real rooms results in the belief that listeners prefer an average FR and hence the notion of the target curve. This is then even extended to headphones. In the philosophical realm this can be anticipated and debunked but only in a way that is incompatible with the empiricist world view.
10. Belief that frequency response is everything results in odd appendages to speakers such as bass reflex that provide the right frequency response results at the expense of timing performance. It also excuses any kind of crossover as long as it results in the right FR at the measurement mic. FR 'correction' using simple EQ methods also alters phase and timing - another variable in the mix.

Putting all that together we have a vague, woolly, nebulous field of activity. I think the results reflect this: few people seem more satisfied with their audio systems than they did in the 1970s. Ironically, the engineering limitations that forced speakers of the 1970s to be the way they were may have resulted in several desirable characteristics that modern speakers struggle to replicate (the by-products of large, sealed boxes, large woofers, wide baffles, three-way drivers). And the 1970s designers used expensive anechoic chambers, eschewing the much cheaper and easier (and naive?) option of in-room FR measurements.

'Philosophers' would design speakers differently from modern, empirical-only, laptop & mic technicians.

To clarify a bit further, what actually can be predicted.

The same speaker, in different rooms - different size, very different acoustic properties.

In-room frequency response can to a large degree be predicted, and surely - the speaker measures quite similar in all rooms. So similar, that any huge differences in sound must be caused by other aspects being different. The measured in-room freq r is also quite close to the anechoic response. This is a result from the speakers radiation pattern/freq response - it is smooth, and it is also a little more directive at lower frequencies compared to a ordinary small box.

But the sound is very different. Not in tonality - tonal balance is perceived as not very different. But the soundstage, realism and placement of instruments, how sound objects and instruement appear, overall clarity, is very different. In one room, the speakers sound just like ordinary speakers, with what is perceived as natural tonal balance. In another room, the singer and the instruments appear like they are there, in the room, it is real, and does not sound like 2 small speakers.

Those differences can be seen in the time domain. They are mostly caused by different levels of early reflected sound.

Frequency response thus can be predicted, but how the overall 3-dimensional presentation appears in a room is not so easy to see from measurements.

 

[Kvalsvoll]

IMO in some way it does. As manufacturers will continue to build better and better speakers their spinorama charts would start to look alike, distortion componenets would become lower and lower and they will all be able to deliver mighty bass at decent SPLs. That actually means that their acoutstic signature will converge and they will all start to sound pretty much the same, as it happend with DACs and amps. Experiment that @mitchco made with his JBLs and Kef LS50+subs confirms this.

Speakers are funamentally differnet from dacs and amps. A speaker would have need to have same radiation pattern to sound the same, and when you turn up the volume, capacity matters.

The experiment you refer to actually is a good example for how different those speakers sound - even when the frequency reponse and level is somewhat matched.

 

[Floyd Toole]

Linkwitz did no favors to discourse with that statement. It uses opaque terms that add confusion, not illumination

Sealed and open baffle speakers are also resonant structures, second order. Vented merely adds 2 orders. The ear is insensitive to the additional group delay with rational alignments.

Vented can introduce far worse impairments:
- absence of box stuffing required to make an efficient port leads to a reduction in back wave absorption which can and does leak through the port in the upper bass to mid range, and or is transmitted through the cone. Numerous measurements at Sterophile can be used to confirm this, for the vent

To which needs to be added three points:
1. Woofers, closed box or vented, behave as minimum-phase systems, meaning that the time domain performance is predictable from the amplitude response. Therefore, equalization can alter both amplitude and time behavior.
2. It is now widely accepted that in-room measurements and EQ are beneficial at low frequencies, and that reasonably high frequency resolution is necessary to address room modes. Doing this alters the perception of annoying room modes and in doing so alters the inherent behavior of the woofer(s).
3. There is convincing evidence that humans are remarkably tolerant of time-domain misbehavior at all frequencies, including even the medium/high-Q room resonances. Woofer tuning variations, by comparison, are very low Q, meaning that while differences may be heard, it is improbable that it is "ringing".