What uncontroversial audible differences cannot be measured?

[esldude]

1 hour ago, Paul R said:

 

Hi Bill, Dennis - yep, pretty much OK. Just doing those 18hour work days for a while.   I am reading all you guys though, and still enjoying the conversations as much as ever. Just not much time to reply. 

I hope they don't last too long.  18 hr days will make you age in a hurry. 

 

Take care of yourself Paul. 

[fas42]

4 hours ago, esldude said:

As I suggested, and will do one last time.

 

Why don't you start a thread about your topic specifically?

 

I had the thought of kicking off the blog mechanism available here - but I had done similar several times before and got close to zero interest shown, or mainly detractors contributing ... so, I am not motivated unless I feel there will be positive feedback ...

[STC]

58 minutes ago, fas42 said:

 

I had the thought of kicking off the blog mechanism available here - but I had done similar several times before and got close to zero interest shown, or mainly detractors contributing ... so, I am not motivated unless I feel there will be positive feedback ...

 

I don't blame them for that. After 23 pages , I am still trying to figure it out how a man with his parrot consider a Youtube video capturing the sound with poor microphone several meters away from the sweet spot can suggest that the sound that one should have. It is so simple. No measurements than it must fluke or  imagination. 

[fas42]

26 minutes ago, STC said:

 

I don't blame them for that. After 23 pages , I am still trying to figure it out how a man with his parrot consider a Youtube video capturing the sound with poor microphone several meters away from the sweet spot can suggest that the sound that one should have. It is so simple. No measurements than it must fluke or  imagination. 

 

It's a historical fragment ... I couldn't take the capture any closer because the recorder would overload - I would suggest that people turn their rigs up to high levels, and then record quite some distance away - and post their recordings.

 

It's not trivial to record a system in full cry, cleanly - the microphone has to be able to handle the SPLs, without gain control cutting in - that earlier violin and piano playback post was of the current combo running at a very mild volume setting, yet the waveform went very close to the ADC's peak level. If you want to hear a highly compressed recording of what a system is generating, well ...

[fas42]

... and again, a duplicate

[STC]

1 hour ago, fas42 said:

It's not trivial to record a system in full cry, cleanly - the microphone has to be able to handle the SPLs, without gain control cutting in -......

 

All microphones are somewhat limited with the ability to capture full dynamic range of live performance or even my system playing at realistic level of 85dB where the peak can go above 100dB. Without cutting the gain there is no way, I could capture the sound without clippings. 

 

If you are insisting recording the sound away from the source than there are several paparmeter that going to alter the evaluation. 

 

1) how far from the system. 

 

2) how reveberant is the spot where you are recording? I can record the sound of my system from one door where I will be standing on highly reverberant room ( outside my music room) or from the window standing on a ladder where there will be no other reflection reaching my microphone. 

 

3) the exact location where you place the microphone. If your door is located in the back centre than that sound will be different from one door at the side of the room. 

 

In no(2) above, I am sure you do have software that can measure the direct sound and secondary sound reaching the microphone where you can tell how live or dead the room is. Are you using some kind of software? Yes or No will do. 

 

Btw, have you done any live performance demonstrating your ability? Any video proof of that? Just asking. 

[Don Hills]

13 hours ago, Jud said:

 

I could presumably have used the analog audio input on my MBP, though I don't know its quality.  And I wouldn't have had much idea what I was looking at in Audacity (that being the only software I would have known to use for the purpose).  But I didn't think of that, just listened instead.

...

 

You didn't need any test equipment at all, just your ears.

Start with two identical channels. Feed them identical signals. Invert the output of one and electrically mix it with the other. Trim the levels until maximum cancellation is achieved (audibly). Change the components in one channel and see if the cancellation is less exact, and more importantly, if the difference signal is audible at normal listening levels.

(Nowadays of course, you could record the 2 channels and invert and level match in Audacity.)

[jabbr]

8 hours ago, esldude said:

I hope they don't last too long.  18 hr days will make you age in a hurry. 

 

 

Hey a man has to pay for his AC power cables

 

[francisleung]

Sorry, I am quite late in giving this thread my personal views. Dispersion as I described below is one of the phenomena that I think is unmeasurable. 

I copy and paste the posts that I sent to a local forum on dispersion:

 

""As you will soon be attending a concert, I suggest you focus on a particular sound aspect that enables you to compare it with what you hear at home—handclaps of the audience. Several occasions of that will take place in the concert. At the time you may close your eyes and try to compare their characteristics with what you previously heard at home in advance preparation. You may also try to remember the characteristics as heard there and use them later to compare again with the renditions by your audio system at home. 
Reproducing audience claps true to live is a difficult and demanding task for most TWO CHANNEL audio systems, except the very few that have top notch dispersion capability. It is a quality that I think is unmeasurable by instruments hence speaker designers and manufacturers do not address it or try to achieve it. 
Set out below in 4 posts are 5 tracks that may be used for evaluating dispersion property of an audio system.  
It is most probable that you won’t be sitting in the centre of the first one or two rows. From where you sit you will hear claps of  audience IN FRONT of you as well as those sitting afar on your two sides. You focus on the headcount, crispiness of the claps, amplitude, location etc. 

First of the 5 tracks:
Mahler Symphony 8 (of a thousand), 4th movement ripped from DVD, Bernstein conducting Wiener Philharmoniker
There are 1.7 minutes of audience clapping before the end of the track of the last movement. A true fidelity audio system should render several rows of audience clapping being located between listener and the speaker plane, in a curtain of sound extending from side wall to side wall of the listening room and up to the ceiling on both. If an audio system has the clapping located at the back of the speakers near the rear wall, that is a dispersion error. Some may argue such backwards location is merely a mixing issue, not a dispersion error but if one examines the Golden Hall as shown in the photo here, there are no seats at the rear of the stage, hence no audience and no clapping should come from there. Handclaps being heard, apart from those located between the listener and the speaker plane, should also come from wall to wall in the listening room and up the ceiling with these coming from the audience sitting on the balconies of the Golden Hall as shown in the photo. The closer to these phenomena (front, two sides and up the ceiling), the better is the dispersion capability of the audio system. 

The second one is Matilda, the last track from the album Belafonte at Carnegie Hall. This album is ubiquitous and when there is a chance I use the LP to compare with CD and CAS. 
As with the Mahler 8 track, for assessing dispersion, merely focus on audience clapping and cheering prior to the end of track, some 
1.3 minutes of them. The scale and amplitude of clapping and cheering as recorded in the track are smaller in size than those in the Mahler 8 track but the phenomena of the audience in front of speakers, wall to wall and up the ceiling are similar. The photo here shows the Hall having no seats at the rear of the stage. The album was recorded prior to renovation of the Hall and the old photo showed no seats at the time either.  
There are other features as with the Mahler track to be noted during evaluation but suffice it to focus on dispersion capability for the time being.

The third one for evaluating dispersion capability is from 2L-090C, Tchaikovsky Souvenir de Florence. One may merely buy the 4th movement from the web, 2L.no. As shown here in the stage layout of the recording session, the players sat in a circle and the microphones were placed in the centre of the circle. Morten Lindberg himself did the recording, mixing and mastering. The soundstage imaging even from a TWO CHANNEL audio system is that the listener should be able to spot the microphones being placed in the centre of the plane of his two speakers. In this way sound from the 20 string players comes from a circle around this centre. A two channel audio system with truthful dispersion capability should project sound from some players sitting IN FRONT the speakers with their backs facing the listener. If the players are all pushed into two rows near the rear wall behind the speakers, there is dispersion problem of the system.
I listened to this work once at the Chamber Music Festival. There were only about half the number of players in comparison with 20 in this recording. They all sat in an arc in the conventional way, all facing the audience, that is, without the circular sound in this recording with the back of some players facing the audience. 

Earlier I mentioned putting in a fourth post to cite more tracks for evaluating dispersion. And here it is, two drum set recordings that would reveal performance of an audio system in this regard.
*One of the two is the Sheffield Drum Record, a direct to disc LP that I played often in yesteryears; an album with sound good enough for me to keep a spare as replacement for the work horse when it is worn out. At the recording session, a dummy analogue tape was used for back up and that was later digitised. This is the source of the track that I have been using in my CAS for comparison with the LP version in recent years. Many audiophiles prefer side 1, the track played by drummer Jim Keltner. This has 4 more percussion instruments, for example, a sleigh bell but I prefer side 2, the track by Ron Tutt, drummer of Elvis Presley. The reason is because I find the high frequencies (produced by the cymbals) more balanced with the low ones (by kick drum). I also have the M &K Hot Stix direct to disc album that commands a much higher price in eBay than the Sheffield but I still stick with the Ron track for regular listening. 
The sleeve notes of the LP set out what and how to listen in those two tracks but here I would confine to dispersion features on the Ron track. By the way, I went to a Cantonese Opera concert a couple of days ago with the orchestra in the pit. The sound of the cymbals and drum in real live put to shame the drum set sound coming from the Goldmund US$ 1 million system that I admire.
This Sheffield track was recorded with 2 modified AKG microphones hung two feet above the drum set. A third one was placed to record the snare drum and a fourth, the kick drum. The sound from these two additional microphones blended and mixed well with the two main ones and did not spoil the image of the drum set being heard as a whole. Now on dispersion. Image of the drum set should span DIAGONALLY no more than 7 to 8 ft, with ALL its comprising items being positioned within the soundstage between the inner frames of the two speakers. I have heard expensive systems rendering hits on the cymbal top near one speaker box but disappointingly those on the ride (body of cymbal) some 15 feet diagonally away. 
Proper dispersion in reproducing this track should have hits on the two frontal cymbals (one ride and one crash) coming from left and right just off centre, whilst those from high hat and snare closely behind them. The additional crash cymbal on the drummer’s right (listener’s left) is somehow positioned a bit too far away at the back but it should keep ringing after being hit (not dampened by drummer). 
All in all the listener should be able to follow what instruments of the set are being played throughout the track and discern whether each is being correctly positioned. The album did not provide a session photo and only mentioned the toms were Ludwig and the cymbal, Zildjian. The photo here of a Ludwig set is only indicative of the one being used in the recording session.
*Putting the audio system to a harder dispersion test is an experimental recording of a drum set by Mario of PlayClassics. He recorded 3 tracks (and also flamenco pieces) to test how they would sound in the venue and recording setup he calibrated for classical works. By the way his mainstream recordings of piano, soprano and tenor have become my references. Mario uses two microphones to record all his albums, set up in ORTF manner. The venue has a stage where players perform, not with them sitting on ground level.
Number 3 of the tracks from Mario is what I use. The drum set is Gretsch but I forgot the model number that he mentioned. Why I said it is a harder test because the drummer faced the backstage, meaning the microphones recorded the drum solo from his back. So the audio system will have to reproduce the instruments at reverse positions in comparison with the Ron Tutt track. In this case, counting/viewing from the back of the listening room, are firstly the ride and crash cymbals, then the hanging toms, the high hat and snare, with the kick drum nearest to the microphones (the listener); all should be in 3D and within a soundstage confined to the inner boundaries of the two speakers if the listening room is 15 ft or more in width. The high hat sounds quite real in this recording and also its mechanical taps may be discerned. The photo here shows various instruments comprised in a drum set when viewed from the back of the drummer. 
The conclusion is that if an audio system, at whatever price, is unable to reproduce the drum set correctly under both conventional and reverse microphone placements, it has dispersion deficiency. ""

[esldude]

4 hours ago, fas42 said:

 

It's a historical fragment ... I couldn't take the capture any closer because the recorder would overload - I would suggest that people turn their rigs up to high levels, and then record quite some distance away - and post their recordings.

 

It's not trivial to record a system in full cry, cleanly - the microphone has to be able to handle the SPLs, without gain control cutting in - that earlier violin and piano playback post was of the current combo running at a very mild volume setting, yet the waveform went very close to the ADC's peak level. If you want to hear a highly compressed recording of what a system is generating, well ...

 

https://www.parts-express.com/minidsp-umik-1-omni-directional-usb-measurement-calibrated-microphone--230-332

 

For $85 you could get this USB measuring microphone.  This and a computer with USB port or iPad would let you do recordings. 1% THD at 133 db SPL.  As well as working with measuring software like REW, it will show up as a source to record using any number of free sound recording programs or apps.  It has a very nice response and will record cleanly even up close to the speaker.

 

https://www.parts-express.com/dayton-audio-imm-6-calibrated-measurement-microphone-for-tablets-iphone-ipad-and-android--390-810

 

This you can get for $16.25 with 18hz-20khz response.  Works with iPhones, iPads, most Android phones and tablets (some Android phones act weirdly and chop off response at 8 khz).  Also with the proper adapter works with most computer or laptop sound card input jacks.  1% THD at 127 db SPL. 

 

So either one of these lets you record in a way that means something instead of noisy, compressed, seriously flawed recordings of systems and telling us how it should sound to us. 

[francisleung]

One more track, Jay Leonhart on double bass whilst singing:

The audio system should have the double bass positioned in front of him (his voice). Most systems have the double bass emanating from the back wall behind the speakers. If  this track is reproduced that way, with the double bass behind his voice it means dispersion problem. I have downloaded and ripped this track and have the double bass positioned at the speaker plane with Jay's voice just behind.

[STC]

47 minutes ago, francisleung said:

""As you will soon be attending a concert, I suggest you focus on a particular sound aspect that enables you to compare it with what you hear at home—handclaps of the audience. Several occasions of that will take place in the concert. At the time you may close your eyes and try to compare their characteristics with what you previously heard at home in advance preparation. You may also try to remember the characteristics as heard there and use them later to compare again with the renditions by your audio system at home. 
Reproducing audience claps true to live is a difficult and demanding task for most TWO CHANNEL audio systems, except the very few that have top notch dispersion capability. It is a quality that I think is unmeasurable by instruments hence speaker designers and manufacturers do not address it or try to achieve it. 
Set out below in 4 posts are 5 tracks that may be used for evaluating dispersion property of an audio system.  
It is most probable that you won’t be sitting in the centre of the first one or two rows. From where you sit you will hear claps of  audience IN FRONT of you as well as those sitting afar on your two sides. You focus on the headcount, crispiness of the claps, amplitude, location etc. 

 

With stereo, it is not exactly possible to move the hand claps around us front the front stage presentation of the loudspeakers placed in the front. Although, I used Matilda often to demonstrate the huge soundstage with stereo, it will never be possible to retrieve all the hidden 3D information with stereo alone. To extract the ambiance you have to add the hall ambiance by producing the convoluted sound using other channels.  

 

It it is difficult, to explain what is true 3D but even with your stereo system if you retrieve the ambiance with convoluted speakers around the rear half you would be part of the audience. 

 

Our brain is so good in filling the missing information when it comes to localization especially after someone read your descriptive account of what to listen for in the tracks you mentioned. Suggestive power can distort what you really hear. 

[esldude]

20 minutes ago, francisleung said:

One more track, Jay Leonhart on double bass whilst singing:

The audio system should have the double bass positioned in front of him (his voice). Most systems have the double bass emanating from the back of the wall behind the speakers. If  this track is reproduced that way, it means dispersion problem. I have downloaded and ripped this track and have the double bass just positioned in front of the speaker plane. 

How does this work with one microphone exactly? 

 

You seem to be hearing what pictures and videos you see. 

 

In this case shouldn't the bass come not between his voice and you, but rather beside and slightly closer than his voice?

 

Nice clean recording of him and the double bass, but in my room it sounds like he and the instrument come from the same spot right in the middle.  Just like good monophonic sound should.  His mike appears to be a KSM 32.  I have one and they are very nice mics.  It could be a KSM44. 

[francisleung]

1 hour ago, STC said:

 

With stereo, it is not exactly possible to move the hand claps around us front the front stage presentation of the loudspeakers placed in the front. Although, I used Matilda often to demonstrate the huge soundstage with stereo, it will never be possible to retrieve all the hidden 3D information with stereo alone. To extract the ambiance you have to add the hall ambiance by producing the convoluted sound using other channels.  

 

It it is difficult, to explain what is true 3D but even with your stereo system if you retrieve the ambiance with convoluted speakers around the rear half you would be part of the audience. 

 

Our brain is so good in filling the missing information when it comes to localization especially after someone read your descriptive account of what to listen for in the tracks you mentioned. Suggestive power can distort what you really hear. 

I take your point about the possibility of the brain filling in or making up the illusion of images located at the plane or in front of the speakers. In my view and experience I think dipole speakers from mid bass to tweeter are better in reproducing such images I mentioned than box/cabinet speakers. If you like to experiment further, you may get hold of the tracks other than Matilda and find out whether you obtain the phenomena or not. The 2L track costs only a small amount. 
By the way live concerts have only one ambience, all the way from the stage to the back of the hall, or the same ambience in the whole lounge. If we listen carefully to audio systems we may discern in many, there is one ambience behind the speakers to the back wall and ANOTHER from the speaker plane to the listener. That represents the dispersion issue I mentioned and the listener would NOT be able to hear/locate the frontal images I described.

[STC]

3 minutes ago, francisleung said:

By the way live concerts have only one ambience, all the way from the stage to the back of the hall, or the same ambience in the whole lounge.

 

A concert hall got thousands of reflected sound creating the 3D ambiance.  I myself using 32 impulse response of a concert hall. You can buy 360 degrees impulse response. 

[francisleung]

1 hour ago, esldude said:

How does this work with one microphone exactly? 

 

You seem to be hearing what pictures and videos you see. 

 

In this case shouldn't the bass come not between his voice and you, but rather beside and slightly closer than his voice?

 

Nice clean recording of him and the double bass, but in my room it sounds like he and the instrument come from the same spot right in the middle.  Just like good monophonic sound should.  His mike appears to be a KSM 32.  I have one and they are very nice mics.  It could be a KSM44. 

Well, I do not have the technical perceptive as you.

I ripped the track and it becomes two channel (stereo) in wav. To be honest I do not know whether the original in YouTube is mono or stereo. If you download and rip, it may sound different to direct playing from YouTube.

I have the double bass positioned in centre at the plane of the speakers and Jay's voice slightly to the left (from listener's view) behind it. 

[francisleung]

5 minutes ago, STC said:

 

A concert hall got thousands of reflected sound creating the 3D ambiance.  I myself using 32 impulse response of a concert hall. You can buy 360 degrees impulse response. 

I attend concerts at centre seat in first or second row, getting more direct sound than reflective sound. Am attending one this evening.

I use only two channels and do not slip in any sound processing. The phenomena/images I described represent reproduction in stereo system. 

[STC]

7 minutes ago, francisleung said:

To be honest I do not know whether the original in YouTube is mono or stereo

 It is easy. Just look at files in audacity. Anyway, I think it stereo from the little part I listened. 

[esldude]

I think this video with Jay Leonhart can be very, very educational.

 

I downloaded it with two different places providing the audio.  Dumped it in Audacity.  The average level if I invert one channel and mix them is -92 db.  There are some very low frequency bumps and thumps that spike up to -72 db.  Maybe an artefact of dithering each channel separately during the down conversion.  Each thump, each one, lasts .05 seconds at very low level.  Amplified it is obviously a down-conversion artefact.  There is no imaging here.

 

I suppose all of us let our eyes fool us.  I saw one microphone.  Where is the stereo supposed to come from?  One fellow off camera yells from elsewhere at one point.  Sounds like the rear of a cardioid mike.  Some saw the position of the instruments and heard imaging.  I saw one microphone and heard mono.  It is mono. 

 

So much for behind the speaker soundfields to the rear wall, soundfields that should not be heard in front of the speakers.  So much for audible effects of this curious dispersion on imaging.

[STC]

30 minutes ago, francisleung said:

I attend concerts at centre seat in first or second row, getting more direct sound than reflective sound. Am attending one this evening.

I use only two channels and do not slip in any sound processing. The phenomena/images I described represent reproduction in stereo system. 

 

I  received this email yesterday  from someone who spent half of his life recreating concert hall sound in listening room. We were discussing about something else about my system and  reproducing the ambiance correctly in recordings. Reproducing the relevant part here. 

 

". .......  ( redacted )........

...........

In halls there is a concept called the critical radius.  This is the point in front of an orchestra where the level of reverb is the same as the level of the direct sound.  This point is normally in the first row or even just behind the conductor.  By the time you are a few rows back the sound is 90% reverb.  But since reverb is late and has directional cues all over the place, the human brain just hears the direct sound for localization purposes and uses the reverb to assess space and reality.  You will see that you can get the surround speaker levels quite high before you have a problem with the front stage.  If you sit in the balcony you essentially just hear reverb with a mono front stage but you can still tell that the stage is in front of you even with your eyes closed.  Now if you put all this reverb into two speakers in front of you with the direct sound, you get the sewer effect.  So that is why hall ambience needs to come from all these side and rear directions but not much from the front.

 

Different halls have different levels and they have different levels depending on how many people are in the audience, etc. so it is all very subjective.  I have one remote control that allows me to adjust all the speakers together so it is easy to have visitors also have the hall they want.

 

Audiophiles that become Ambiophiles will spend the rest of their listening lives tweaking concert halls.  I feel sorry for them.  This is worse than deciding what cable sounds best.

 

Ralph "

 

 

[STC]

25 minutes ago, esldude said:

I think this video with Jay Leonhart can be very, very educational.

 

I downloaded it with two different places providing the audio.  Dumped it in Audacity.  The average level if I invert one channel and mix them is -92 db.  There are some very low frequency bumps and thumps that spike up to -72 db.  Maybe an artefact of dithering each channel separately during the down conversion.  Each thump, each one, lasts .05 seconds at very low level.  Amplified it is obviously a down-conversion artefact.  There is no imaging here.

 

I suppose all of us let our eyes fool us.  I saw one microphone.  Where is the stereo supposed to come from?  One fellow off camera yells from elsewhere at one point.  Sounds like the rear of a cardioid mike.  Some saw the position of the instruments and heard imaging.  I saw one microphone and heard mono.  It is mono. 

 

So much for behind the speaker soundfields to the rear wall, soundfields that should not be heard in front of the speakers.  So much for audible effects of this curious dispersion on imaging.

 

Ok. It is mono. Thanks. 

[semente]

3 hours ago, francisleung said:

Sorry, I am quite late in giving this thread my personal views. Dispersion as I described below is one of the phenomena that I think is unmeasurable. 

I copy and paste the posts that I sent to a local forum on dispersion:

 

""As you will soon be attending a concert, I suggest you focus on a particular sound aspect that enables you to compare it with what you hear at home—handclaps of the audience. Several occasions of that will take place in the concert. At the time you may close your eyes and try to compare their characteristics with what you previously heard at home in advance preparation. You may also try to remember the characteristics as heard there and use them later to compare again with the renditions by your audio system at home. 
Reproducing audience claps true to live is a difficult and demanding task for most TWO CHANNEL audio systems, except the very few that have top notch dispersion capability. It is a quality that I think is unmeasurable by instruments hence speaker designers and manufacturers do not address it or try to achieve it. 
Set out below in 4 posts are 5 tracks that may be used for evaluating dispersion property of an audio system.  
It is most probable that you won’t be sitting in the centre of the first one or two rows. From where you sit you will hear claps of  audience IN FRONT of you as well as those sitting afar on your two sides. You focus on the headcount, crispiness of the claps, amplitude, location etc. 

First of the 5 tracks:
Mahler Symphony 8 (of a thousand), 4th movement ripped from DVD, Bernstein conducting Wiener Philharmoniker
There are 1.7 minutes of audience clapping before the end of the track of the last movement. A true fidelity audio system should render several rows of audience clapping being located between listener and the speaker plane, in a curtain of sound extending from side wall to side wall of the listening room and up to the ceiling on both. If an audio system has the clapping located at the back of the speakers near the rear wall, that is a dispersion error. Some may argue such backwards location is merely a mixing issue, not a dispersion error but if one examines the Golden Hall as shown in the photo here, there are no seats at the rear of the stage, hence no audience and no clapping should come from there. Handclaps being heard, apart from those located between the listener and the speaker plane, should also come from wall to wall in the listening room and up the ceiling with these coming from the audience sitting on the balconies of the Golden Hall as shown in the photo. The closer to these phenomena (front, two sides and up the ceiling), the better is the dispersion capability of the audio system.

Are you talking about 2 channel or 5.X?

One think that I have read in many serious sources is that in properly recorded 2 -channel stereo the image does not extend outside the speakers.

 

Besides far as I know, a relaxation in the "presence" region (2-5KHz) will result in an impression of sources being more distant - this has nothing to do with dispersion.

[esldude]

Just for the record, I re-used a youtube ripper that gave me the audio in .wav format.  Using that and inverting channels resulted in a signal level of -infinity.  Zero.  Nothing there.  Definitely completely mono. 

 

Does anyone believe your brain combined with your ears and eyes can play tricks on you now?

[semente]

1 hour ago, STC said:

Audiophiles that become Ambiophiles will spend the rest of their listening lives tweaking concert halls.  I feel sorry for them.  This is worse than deciding what cable sounds best.

 

I can't help but smile at this...

 

Music is about sound not space, and yet for many audiophiles and audio critics space seems to be THE most important aspect of reproducing music.

I find this very, very strange.

[francisleung]

I won’t say I am immune to illusion entailed from sight.
There are other tracks that I do not have the stage photo or set up diagram of the recording session but am still able to discern positioning and imaging as in the more conspicuous tracks that I quoted.
Two more examples:
High Life from Jazz at the Pawnshop 1. 
The vibraphone is located at the plane of the speaker and in front of it when it is on solo (louder being closer to the listener). On the other hand, the tambourine as played by the drummer is located at the rear wall behind the speakers. I have heard expensive systems with substandard dispersion having the tambourine in front near the speakers. 
House of the Rising Sun from Opus 3 Test CD 4.1
The female singer as with any other band should be at the plane of the speakers upfront. I have heard systems staging her at the back behind the instruments. To me that is dispersion problem.

+++++++++++++++++++++++++
Actually what I am trying to say in my first post to this thread relates to the title, that is, in my view dispersion is a phenomenon or feature that is not measurable. 
Of course what I described in the examples as heard by me should first be established that they are there. If they aren’t, measurable or not does not come in at all.  The way forward as I see it is for me to stage local sessions sometime in future and see if others hear them in manner as I described.