Which speakers are the Classical Music Pros using?

[GXAlan]

Yes, I have an opinion. May I quote you? "Lots of marketing hyperbole:"

I had to make my own measurements and find someone with the expertise to go into the software and modify what it had automatically done to restore the inherent timbral neutrality of the excellent speakers.

That’s helpful insight to share. More and more we hear about software fixing hardware issues. EQ to address irregularities in frequency response and now “sound field” processing and speaker “remapping” to address sound stage issues.

It seems like pretty much, there is no reward without effort.

 

[BDE]

[...] I happen to have a Synthesis SDP-75/Trinnov processor. I will tell you that the "magic" microphone did not prevent it from degrading the sound from my excellent loudspeakers during its "calibration" routine. I had to make my own measurements and find someone with the expertise to go into the software and modify what it had automatically done to restore the inherent timbral neutrality of the excellent speakers. Yup, marketing.

Do you have some interest to open a topic on how you made the measurements and room correction, maybe even with publishing some measurements?
e.g.
# What kind of measurements were used? Single point, multi point (what location and how averaged/ weighted) or MMM
# What did you correct? house curve? Full bandwidth vs. limited bandwidth (up to which frequency, Schroeder?)
# and so on

So at the end some kind of recepie on how you came to the best result!

 

[Duke]

Here is my theory: classical (as produced by an ensemble of quartet or larger), heard live from mid-hall or closer, sounds LARGE. Ditto anything produced by banks of PA speakers. Solo vocal, heard unamplified from pretty close, sounds SMALL. That is, well localized. You can tell if the singer moves a foot to the left or right. Compared to that localization, even a solo violin sounds larger and harder to localize. (My daughter played violin in a youth orchestra, so I've heard a LOT of solo violin from her practcing.)

Mark, thank you very much for taking the time to reply.

I totally agree with you about the audible size of sound sources, and imo that sense of scale includes the venue size as well.

IMO, wide directivity speakers add room reflections that mimic that missing hall sound. For a well localized source (solo vocal, plucked guitar string, ...), the reflections do not mimic anything missing on the recording, and so narrow directivity speakers sound more realistic.

Wide-pattern speakers DO result in more reflected energy which in turn increases the sense of spaciousness, which plays a major role in the enjoyment of large-scale music. And wide-pattern speakers also have stronger early sidewall reflections which can widen the soundstage, also generally desirable for large-scale music, but that comes at the expense of precise image localization, and precise imaging is desirable for small-scale music. So under these conditions I generally agree that wide-pattern speakers are better suited for large-scale music, and narrow-pattern speakers are better suited for small-scale music... "these conditions" being, where the acoustic signature of the room plays a significant role in listener perceptions.

There is an alternative paradigm which is arguably genre-agnostic, and it goes something like this: "The spatial information on the recording, rather than the acoustic signature of the playback room, should be perceptually dominant." So if the spatial information on the recording says "you're in a concert hall", or "you're in a magical floaty space", THAT is the perception you want. Or if the spatial information on the recording says "you're in a small jazz club", then THAT is the perception you want. In neither case would you want the acoustic signature of the playback room to be dominant, constantly reminding that "you're actually in a re-purposed spare bedroom."

You might think of it this way: In home audio, there are two competing sets of venue cues: The desirable venue cues on the recording, and the undesirable "small room signature" cues inherent to the playback room. In general the early reflections are the ones which most strongly convey "small room signature" while the later ones are the most effective carriers of the venue cues (in particular the reverberation tails) on the recording. So if we can "tilt" the balance of the in-room reflections in favor of the later-arriving ones, assuming they are spectrally correct, we can facilitate the venue spatial cues on the recording dominating over the "small-room signature" of the playback room.

Imo such a system could be effectively genre-agnostic, and even if it fell short of that, the playback room would still have a relatively benign acoustic signature.

 

[sarumbear]

The first process in most upmixers is to separate the sum and difference signals, sending the difference/poorly-correlated sounds to the surround channels after an added delay.

If David Hafler RIP had a delay…

 

[MarkS]

There is an alternative paradigm which is arguably genre-agnostic, and it goes something like this: "The spatial information on the recording, rather than the acoustic signature of the playback room, should be perceptually dominant." So if the spatial information on the recording says "you're in a concert hall", or "you're in a magical floaty space", THAT is the perception you want. Or if the spatial information on the recording says "you're in a small jazz club", then THAT is the perception you want. In neither case would you want the acoustic signature of the playback room to be dominant, constantly reminding that "you're actually in a re-purposed spare bedroom."

Of course this is right, assuming the spatial info is actually all on the recording. But even in the very best classical 2-channel recordings (eg Telarc), I think it may be only partially there. Capturing the hall sound is an art. Telarc does it as well as anyone, but even they put the mikes quite close to the orchestra (much closer than the average audience member). And if we go back to pre-70s analog recordings (which comprise many great performances), they were often produced with literally dozens of spot mikes on specific instruments, and then mixed down later. Sadly, a lot of it sounds really bad.

And then, I assume we're talking 2-channel here, which is huge bottleneck. With a proper multi-channel recording, it seems to me that of course the best system is multi-channel with narrow directivity speakers, to cut out the listening room as much as possible.

But, in a modestly sized room, and with 2 channels only, using wide directivity to generate "fake" hall sound sounds, to me, quite convincing. For me, it also works all the way down to solo violin recordings. I had some bipolar Deftechs for a long time (chosen because I liked how they sounded better than anything else in the price range that I was able to audition), and I was quite happy with them.

As for solo voice, that's not anything I ever listen to. And I don't care about pinpoint imaging because I never hear it in live music. When I hear an audio system do it, it sounds artificial to me, kind of like the audio analog of Toy Story style 3D animation.

 

[Duke]

But, in a modestly sized room, and with 2 channels only, using wide directivity to generate "fake" hall sound sounds, to me, quite convincing. For me, it also works all the way down to solo violin recordings. I had some bipolar Deftechs for a long time (chosen because I liked how they sounded better than anything else in the price range that I was able to audition), and I was quite happy with them.

In practice I don't think there is necessarily much difference between what you have found to work well, and what I have found to work well. The difference may be as little as speaker positioning, and perhaps not even that:

You mentioned Def Tech bipolar speakers, and imo the bipolar format is one of the BEST there is, for two main reasons:

First, it puts a LOT of spectrally-correct energy out into the reflective field, and if nothing else that promotes rich, natural-sounding timbre, as long as the room isn't overdamped. My guess is that natural timbre is what initially drew you to the Def Techs.

Second, fully HALF of their "off-axis" energy is deliberately sent away from the listening area, such that those reflections take a considerably longer-than-normal path before reaching the listening area. This can have spatial quality benefits.

Ime bipolars (and dipoles) can give excellent spatial quality (within the limits of two channel) if you are able to pull them far enough out from the wall, and/or toe them in aggressively enough, that their rear-firing energy arrives a good 10 milliseconds or so later than the first-arrival sound. This corresponds to a path length difference of 11 feet, and that exact number is not critical. In other words, pull your Def Techs about five feet out from the "front" wall and really good things start to happen: The venue spatial cues on the recording start to dominate over the "small room signature" of the playback room, and in my experience you don't need a superb recording for this to happen. You start to "feel" a different (and more true-to-the-performance) acoustic space from one recording to the next, instead of approximately the same acoustic space for pretty much all recordings.

Let me explain what I think is going on: At the risk of oversimplifying, the ear senses the size of an acoustic space from three things: The first reflections; the reverberant tails; and the temporal "center of gravity" of the reflections. And recall that we have two competing sets of these room size cues: The venue cues on the recording, and the playback room's cues. So let's look at how our Def Tech speakers positioned well out into the room deliver the playback room's cues, and then how they deliver the recording's venue cues.

The playback room's first reflections are disrupted by the way we have positioned the Def Techs. We have some of the early reflections arriving when the ear would expect them to based on the actual room size, but then other first reflections are arriving much later, as if the room was bigger than it really is. Also, the center of gravity of the reflections is pushed back in time, and is now inconsistent with the actual size of the room. So the ear is not getting a strong and consistent set of cues about the size of the playback room.

The venue cues are being delivered to the ears by the in-room reflections, which act as "carriers". And in particular the reverberant tails of those venue cues are being effectively delivered because we have a LOT of late-arriving reflections coming from all around and they are spectrally correct, or close enough. This is still a poverty of cues compared with the real thing, but it can be sufficient IF the "small room signature" cues have been disrupted enough.

So the ear is being presented with two competing sets of spatial cues: The disrupted "small room" cues of the playback room, and the venue size cues in the recording's reverberant tails. The ear may well select the venue cues as being the more plausible, in which case the system has crossed the threshold into a "you are there" presentation. But EVEN IF the system never crosses that threshold, the net result is STILL a really, really good "they are here" presentation. So you win either way.

In my opinion.

 

[tuga]

In practice I don't think there is necessarily much difference between what you have found to work well, and what I have found to work well. The difference may be as little as speaker positioning, and perhaps not even that:

You mentioned Def Tech bipolar speakers, and imo the bipolar format is one of the BEST there is, for two main reasons:

First, it puts a LOT of spectrally-correct energy out into the reflective field, and if nothing else that promotes rich, natural-sounding timbre, as long as the room isn't overdamped. My guess is that natural timbre is what initially drew you to the Def Techs.

Second, fully HALF of their "off-axis" energy is deliberately sent away from the listening area, such that those reflections take a considerably longer-than-normal path before reaching the listening area. This can have spatial quality benefits.

Ime bipolars (and dipoles) can give excellent spatial quality (within the limits of two channel) if you are able to pull them far enough out from the wall, and/or toe them in aggressively enough, that their rear-firing energy arrives a good 10 milliseconds or so later than the first-arrival sound. This corresponds to a path length difference of 11 feet, and that exact number is not critical. In other words, pull your Def Techs about five feet out from the "front" wall and really good things start to happen: The venue spatial cues on the recording start to dominate over the "small room signature" of the playback room, and in my experience you don't need a superb recording for this to happen. You start to "feel" a different (and more true-to-the-performance) acoustic space from one recording to the next, instead of approximately the same acoustic space for pretty much all recordings.

Let me explain what I think is going on: At the risk of oversimplifying, the ear senses the size of an acoustic space from three things: The first reflections; the reverberant tails; and the temporal "center of gravity" of the reflections. And recall that we have two competing sets of these room size cues: The venue cues on the recording, and the playback room's cues. So let's look at how our Def Tech speakers positioned well out into the room deliver the playback room's cues, and then how they deliver the recording's venue cues.

The playback room's first reflections are disrupted by the way we have positioned the Def Techs. We have some of the early reflections arriving when the ear would expect them to based on the actual room size, but then other first reflections are arriving much later, as if the room was bigger than it really is. Also, the center of gravity of the reflections is pushed back in time, and is now inconsistent with the actual size of the room. So the ear is not getting a strong and consistent set of cues about the size of the playback room.

The venue cues are being delivered to the ears by the in-room reflections, which act as "carriers". And in particular the reverberant tails of those venue cues are being effectively delivered because we have a LOT of late-arriving reflections coming from all around and they are spectrally correct, or close enough. This is still a poverty of cues compared with the real thing, but it can be sufficient IF the "small room signature" cues have been disrupted enough.

So the ear is being presented with two competing sets of spatial cues: The disrupted "small room" cues of the playback room, and the venue size cues in the recording's reverberant tails. The ear may well select the venue cues as being the more plausible, in which case the system has crossed the threshold into a "you are there" presentation. But EVEN IF the system never crosses that threshold, the net result is STILL a really, really good "they are here" presentation. So you win either way.

In my opinion.

Do you think that there's an advantage in the bipole being omni from the lower midrange (or upper-bass) down vs. the dipole bass of say a Quad ESL-29xx?
Both are able to use the front-wall reflections but the latter avoids what we both consider to be side-wall "interference" (most noticeable with complex orchestral or choral material).

 

[tuga]

What my research, and that done at Harman, was focused on was sound quality. If a loudspeaker is colored or distorted who cares what the spatial presentation is like? All loudspeakers of all possible directional configurations were evaluated for sound quality, and the prime requirement - neutrality/absence of resonances - was equally obvious in measurements made on all directivity options. How this fits into differing listener expectations for "soundstage and imaging" is a second level of judgment, where the consistency of directivity - whatever it is - is likely the key factor. So to the extent that there is "standardization" it is really only an attempt to ensure timbral accuracy of the reproduced sound, so that if a listener hears something he/she does not like - don't blame the loudspeaker. The recordings are also "weak links". Unfortunately, in a stereo reproduction it is difficult to alter "spatial" factors in loudspeakers that are affordable - active array designs are elegant solutions for the price of a decent car. So, "gasp", upmixing remains a viable option for most recorded material. That requires an upmixer that does not corrupt the soundstage or timbre, and that is a whole different discussion.

What exactly was the methodology used for assessing sound quality (which I presume to be tonal balance and absence of distortions)?
Was this single-speaker/mono testing only or also stereo, and were the speakers positioned in a way which respected the requirements of their topology? In other words, were the listeners sitting on the correct axis for that particular speaker and was the speaker located in the room for best balance as per per design/manufacturer requirements?

You seem to be assuming that "neutrality/absence of resonances" is the prime concern for most audiophiles. Can you claim with certainty that it isn't "soundstage and imaging" or even some other nebulous perceptual characteristic that is hard to pin down (let's call it "engagement")?
Some types of distortion produce perceptual effects which are pleasing to the ear, such as the BBC dip ("distant" perspective), floor-bounce cancellation ("fast/tight" bass), an exaggerated top octave ("air") or even the limited low end extension of small standmounts. How the speakers interact with the room in the midranges and treble is a matter of preference and some people seem willing to trade "envelopment" for a flat frequency response or "sharper" imaging. (even though I don't have scientifically gathered statistical evidence to back me up, I am nonetheless relying on over a decade of observing audiophile behaviour in several forums where I have or currently participate in the US, UK, France, Spain and Portugal)

 

[sarumbear]

if we go back to pre-70s analog recordings (which comprise many great performances), they were often produced with literally dozens of spot mikes on specific instruments, and then mixed down later. Sadly, a lot of it sounds really bad.

I think you are mistaken with the era. There were neither "dozens of" inputs on audio mixers nor a live recording company owned dozens of microphones during 60s (pre-70).

 

[Floyd Toole]

What exactly was the methodology used for assessing sound quality (which I presume to be tonal balance and absence of distortions)?
Was this single-speaker/mono testing only or also stereo, and were the speakers positioned in a way which respected the requirements of their topology? In other words, were the listeners sitting on the correct axis for that particular speaker and was the speaker located in the room for best balance as per per design/manufacturer requirements?

You seem to be assuming that "neutrality/absence of resonances" is the prime concern for most audiophiles. Can you claim with certainty that it isn't "soundstage and imaging" or even some other nebulous perceptual characteristic that is hard to pin down (let's call it "engagement")?
Some types of distortion produce perceptual effects which are pleasing to the ear, such as the BBC dip ("distant" perspective), floor-bounce cancellation ("fast/tight" bass), an exaggerated top octave ("air") or even the limited low end extension of small standmounts. How the speakers interact with the room in the midranges and treble is a matter of preference and some people seem willing to trade "envelopment" for a flat frequency response or "sharper" imaging. (even though I don't have scientifically gathered statistical evidence to back me up, I am nonetheless relying on over a decade of observing audiophile behaviour in several forums where I have or currently participate in the US, UK, France, Spain and Portugal)

Tuga asked several important questions, all of which have been answered in great detail in my JAES papers starting 39 years ago, and my two “Sound Reproduction” books, the 3rd edition in 2017. I won’t attempt fully verified/referenced answers, but I will add a few comments.

“What exactly was the methodology used for assessing sound quality (which I presume to be tonal balance and absence of distortions)?”

The motivation for me to get involved in scientific research into sound reproduction was a blind listening test conducted in 1966 on a few loudspeakers that measured (and consequently sounded) very different from each other. All were highly regarded “HiFi” products and my question was simply “how can loudspeakers that are so very different all be considered examples of the state-of-the-art?” The result of that rudimentary exercise was that there was a clear consensus among the listeners, some of whom owned the loudspeakers under test, as to which ones were most preferred. But there was a second factor at play, because I had done on- and off-axis anechoic measurements on the loudspeakers (see Figure 18.1 in the 3rd edition of my book). The products that were highest rated exhibited the most appealing frequency response curves if one places value in flatness and smoothness. Reliable (blind or double-blind, equal loudness) subjective and (anechoic on- and off-axis) objective data evidently were useful information. Both sets of data were, and largely remain, absent from casual, and even “professional” assessments of loudspeakers. Decent measurements are becoming more common, but definitive subjective evaluations remain largely elusive. A lot of "hand waving" substitutes. The listening methodology was described in my JAES paper: Toole, F. E. (1982). “Listening tests – turning opinion into fact”, J. Audio Eng. Soc., 30, pp. 431-445. It has, of course, evolved since then, but the fundamental tenets are intact.
Olive, S.E., Castro, B and Toole, F.E. (1998). “A New Laboratory for Evaluating Multichannel Audio Components and Systems”, 105th Convention, Audio Eng. Soc., Preprint 4842.

“Was this single-speaker/mono testing only or also stereo, and were the speakers positioned in a way which respected the requirements of their topology? In other words, were the listeners sitting on the correct axis for that particular speaker and was the speaker located in the room for best balance as per per design/manufacturer requirements?”

Both stereo and mono tests were done, but in terms of evaluating sound quality mono tests were by far the most reproducible and consistent across populations of listeners. Loudspeakers that rated highly in mono tests always rated highly in stereo tests, even when there was an attempt to separate the tonal and spatial aspects of what was heard. See Section 7.4.2 for a detailed discussion of a serious stereo vs. mono comparison test (published in JAES in 1985-86). As for listening configurations, the world still awaits such guidance from most manufacturers. Trial and error seems to be the near universal advice to new owners.

“You seem to be assuming that "neutrality/absence of resonances" is the prime concern for most audiophiles”.

I don’t think I ever attempted to assume anything on behalf of “most audiophiles”, a population of limitless variability. All that has been presented are the results of tests conducted on, by now, hundreds of loudspeakers by hundreds of listeners. The first published subjective/objective evaluations showed clearly that listeners responded most favorably to loudspeakers that exhibited the least evidence of resonances. Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31. Toole, F. E. (1986). “Loudspeaker measurements and their relationship to listener preferences”, J. Audio Eng. Soc., 34, pt.1, pp. 227-235, pt. 2, pp. 323-348.

“Can you claim with certainty that it isn't "soundstage and imaging" or even some other nebulous perceptual characteristic that is hard to pin down (let's call it "engagement")?”

Pages 174-186 in the 3rd edition discuss the importance of spatial dimensions of perception, showing evidence that they are comparable with sound quality. My personal attitude is that if something doesn’t sound timbrally correct I don’t much care about space – especially now that relatively neutral reproduced sound quality can be achieved. Failure to radiate relatively neutral sound is evidence of engineering incompetence or of caring less. As for nebulous factors, the fact that two channel stereo with its inherent timbral and spatial flaws is found to be a satisfactory end goal by so many is one to be sure.

“Some types of distortion produce perceptual effects which are pleasing to the ear, such as the BBC dip ("distant" perspective), floor-bounce cancellation ("fast/tight" bass), an exaggerated top octave ("air") or even the limited low end extension of small standmounts.“

These are factors that include the program material, human hearing, the specific loudspeakers and rooms, none of which are consistent – in addition to personal preferences. When the issue can be addressed by tone controls or easily-accessed equalization, one can argue that there is virtue in starting with broadband neutral loudspeakers, or adding the missing bass to small neutral bookshelf loudspeakers. Why would one deliberately not reproduce the bass drum or organ pedals? Oh yes, “tight” bass. Each to his/her own. BTW low bass performance accounts for approximately 30% of one’s overall assessment of sound quality (Section 5.7 in the 3rd edition).

“How the speakers interact with the room in the midranges and treble is a matter of preference and some people seem willing to trade "envelopment" for a flat frequency response or "sharper" imaging. (even though I don't have scientifically gathered statistical evidence to back me up, I am nonetheless relying on over a decade of observing audiophile behaviour in several forums where I have or currently participate in the US, UK, France, Spain and Portugal)”

We each work from our own sources of information. I put my trust in data that are reproducible from time to time, place to place, over a statistically interesting proportion of the population. Accurate measurements qualify, as do controlled double-blind listening tests. I have been fortunate over my career to have had access to both for 26 years at the National Research Council of Canada, and 16 years at Harman International.

 

[Floyd Toole]

Do you have some interest to open a topic on how you made the measurements and room correction, maybe even with publishing some measurements?
e.g.
# What kind of measurements were used? Single point, multi point (what location and how averaged/ weighted) or MMM
# What did you correct? house curve? Full bandwidth vs. limited bandwidth (up to which frequency, Schroeder?)
# and so on

So at the end some kind of recepie on how you came to the best result!

In other forums on this site I have commented extensively on the value and meaning of room measurements and "correction". I published a paper, which you can freely access that explains some of it: Toole, F. E. (2015). “The Measurement and Calibration of Sound Reproducing Systems”, J. Audio Eng. Soc., vol. 63, pp.512-541. This is an open-access paper available to non-members at www.aes.org http://www.aes.org/e-lib/browse.cfm?elib=17839. "House curve" is a term used in pro audio in days when steady-state measurements were all that could be done and it was assumed that each venue had an "ideal" curve. It was wrong but the term still lingers. The direct sound is what matters most as a starting point in venues of any size. Once the sound has been launched into a reflective space - any normal room - it is not possible to interrogate the detailed performance of a loudspeaker from measurements at the listening location. Comprehensive anechoic data are essential to understanding what a "room curve" is showing. This is usually absent, so there develop endless discussions of "optimum" room curves.
In brief, I used REW, a free downloadable measurement program, and a single calibrated mic located at 2 m on axis to evaluate and correct the direct sound - which the "automatic calibration" had seriously altered. This is an essential factor to get right. This was confirmed at the listening location with a small spatial average to assess the bass performance and to finess the EQ of the four subwoofer "Sound Field Management" scheme I used (described in Section 8.2.8 in the 3rd edition).

 

[MarkS]

I think you are mistaken with the era. There were neither "dozens of" inputs on audio mixers nor a live recording company owned dozens of microphones during 60s (pre-70).

Well dozens may be an exaggeration, but:

“by about ’64 they finally settled on the standard tree that has mics about two feet apart, left to right, and another about one-and-a-half feet out in front, plus outriggers.

“Later on many spot microphones, echo returns and a lot of other techniques were used to create the Decca sound.”

The Decca Sound: Secrets Of The Engineers

In 1984, Mike Gray helped assemble a discography of Decca’s classical releases, giving him access to their engineers and recording logs, and a valuable insight into how their records were made. He reveals the truth about the famous Decca tree and the creation of the label’s unique sound.

polymathperspective.com

 

[sarumbear]

Well dozens may be an exaggeration, but:

“by about ’64 they finally settled on the standard tree that has mics about two feet apart, left to right, and another about one-and-a-half feet out in front, plus outriggers.

“Later on many spot microphones, echo returns and a lot of other techniques were used to create the Decca sound.”

The Decca Sound: Secrets Of The Engineers

In 1984, Mike Gray helped assemble a discography of Decca’s classical releases, giving him access to their engineers and recording logs, and a valuable insight into how their records were made. He reveals the truth about the famous Decca tree and the creation of the label’s unique sound.

polymathperspective.com

Very interesting article. However, as you read it you realise that at most there were six microphones. Even accepting exaggeration that is considerably less and changes the information.

There was a big jump in recording technology and available equipment at the start of the 70s. It was a very fast change. We went from 50s type equipment to pre-digital type in a couple of years. By 1971 multi-track recorders and large mixing desks became the norm.

 

[Duke]

Do you think that there's an advantage in the bipole being omni from the lower midrange (or upper-bass) down vs. the dipole bass of say a Quad ESL-29xx?
Both are able to use the front-wall reflections but the latter avoids what we both consider to be side-wall "interference" (most noticeable with complex orchestral or choral material).

This will be a generalization: Imo dipole and cardioid radiation patterns are superior to bipole and monopole radiation patterns in the bass and lower mid region, but ime good conventional box speakers (be they monopole or bipole) have better impact in the bass through lower mid regions. So it's a juggling of tradeoffs.

Personally I'm less concerned about radiation pattern control south of about 700 Hz or so (this figure comes from Geddes). Also the kinds of woofers that work well in conventional boxes have more powerful motors than those which tend to work well in dipoles and cardioids, and I like the things a powerful motor does especially if we're running the woofer well up into the midrange region.

 

[MarkS]

Very interesting article. However, as you read it you realise that at most there were six microphones. Even accepting exaggeration that is considerably less and changes the information.

No. "Many spot microphones" in addition to the six principle ones.

 

[tuga]

Tuga asked several important questions, all of which have been answered in great detail in my JAES papers starting 39 years ago, and my two “Sound Reproduction” books, the 3rd edition in 2017. I won’t attempt fully verified/referenced answers, but I will add a few comments.

Thank you for your replies.

“What exactly was the methodology used for assessing sound quality (which I presume to be tonal balance and absence of distortions)?”

The motivation for me to get involved in scientific research into sound reproduction was a blind listening test conducted in 1966 on a few loudspeakers that measured (and consequently sounded) very different from each other. All were highly regarded “HiFi” products and my question was simply “how can loudspeakers that are so very different all be considered examples of the state-of-the-art?” The result of that rudimentary exercise was that there was a clear consensus among the listeners, some of whom owned the loudspeakers under test, as to which ones were most preferred. But there was a second factor at play, because I had done on- and off-axis anechoic measurements on the loudspeakers (see Figure 18.1 in the 3rd edition of my book). The products that were highest rated exhibited the most appealing frequency response curves if one places value in flatness and smoothness. Reliable (blind or double-blind, equal loudness) subjective and (anechoic on- and off-axis) objective data evidently were useful information. Both sets of data were, and largely remain, absent from casual, and even “professional” assessments of loudspeakers. Decent measurements are becoming more common, but definitive subjective evaluations remain largely elusive. A lot of "hand waving" substitutes. The listening methodology was described in my JAES paper: Toole, F. E. (1982). “Listening tests – turning opinion into fact”, J. Audio Eng. Soc., 30, pp. 431-445. It has, of course, evolved since then, but the fundamental tenets are intact.
Olive, S.E., Castro, B and Toole, F.E. (1998). “A New Laboratory for Evaluating Multichannel Audio Components and Systems”, 105th Convention, Audio Eng. Soc., Preprint 4842.

I understand the need for blind testing as a means to remove bias.
I have found that familiarity provides the highest level of discrimination in a listening assessment, and that is achieved over long term listening with familiar music and in a familiar system/room, and in that way assessing only a single variable/change to the system/sound.
Is this something that you considered when developping the methodology for your tests and testing facilities?

Was this single-speaker/mono testing only or also stereo, and were the speakers positioned in a way which respected the requirements of their topology? In other words, were the listeners sitting on the correct axis for that particular speaker and was the speaker located in the room for best balance as per per design/manufacturer requirements?”

Both stereo and mono tests were done, but in terms of evaluating sound quality mono tests were by far the most reproducible and consistent across populations of listeners. Loudspeakers that rated highly in mono tests always rated highly in stereo tests, even when there was an attempt to separate the tonal and spatial aspects of what was heard. See Section 7.4.2 for a detailed discussion of a serious stereo vs. mono comparison test (published in JAES in 1985-86). As for listening configurations, the world still awaits such guidance from most manufacturers. Trial and error seems to be the near universal advice to new owners.

I have stressed the importance of familiarity but another extremely important factor in my view is the adequate set up of speakers in the room for best bass frequency response (and your research indicates that "low bass performance accounts for approximately 30% of one’s overall assessment of sound quality") and room "activation" (how differences in directivity interact with the room for "spatiality" effects, such as dipoles and omnis), and axial positioning or toe-in (e.g. Dali speakers are designe for flat response 30° off-axis).

Would you confirm that neither aspect was/is addressed in the shuffler rooms?
If that was not the case then some speakers were listened in sub-optimal conditions and thus unfairly handicaped.
Although I understand that providing optimal conditions for testing would have been impractical.

In regard to the mono vs stereo performance, your research shows that "spatial quality" ratings when listening in stereo improve for narrowing directivity monopoles (Kef) and for dipoles (Quad).
This seems to indicate that wider directivity is less important in stereo pairs, which is how speakers have been used for 50 years, and thus my interpretation of the data would have led me to dismiss mono as a means to assess "spatial quality".

Also, I would expect that anomalies in both the axial response and also the quality and amount of bass would still have influenced the listener preference when assessing "spatial quality" (as you've mentioned, "if something doesn’t sound timbrally correct I don’t much care about space"). Were these aspects corrected through optimal positioning and/or high-passing and the use of EQ?
I understand that again the question of practicality arises. It would be difficult to find even a pair of prototypes of the same speaker one with wide- and the other with narrowing-directivity, but that in my view would have prevented the introduction of other variables which undermine the effectiveness of the tests. Once we introduce more than one variable we no longer know for certain what the listeners are reacting to (is it the different bass response, a dip in the presence region, or how the speakers interact with the boundaries is generating a more pleasing level of "envelopment" and "spaciousness"?).

For the reasons highlighted I feel reluctant to agree with your interpretation of both the adequacy of mono testing for "spatial quality" assessment and, consequently, of the results which resulted from that testing.

“Some types of distortion produce perceptual effects which are pleasing to the ear, such as the BBC dip ("distant" perspective), floor-bounce cancellation ("fast/tight" bass), an exaggerated top octave ("air") or even the limited low end extension of small standmounts.“

These are factors that include the program material, human hearing, the specific loudspeakers and rooms, none of which are consistent – in addition to personal preferences. When the issue can be addressed by tone controls or easily-accessed equalization, one can argue that there is virtue in starting with broadband neutral loudspeakers, or adding the missing bass to small neutral bookshelf loudspeakers. Why would one deliberately not reproduce the bass drum or organ pedals? Oh yes, “tight” bass. Each to his/her own. BTW low bass performance accounts for approximately 30% of one’s overall assessment of sound quality (Section 5.7 in the 3rd edition).

Harman's "target curve" research also seems to indicate that untrained listeners prefer a lot more bass and more treble (sloping upwards with frequency). This is also my impression from observing people's reports on different speakers and show systems.
Isn't this indicative that people have different preferences when it comes to tonal balance?

I think most would agree that the ultimate goal of a playback system is to provide listening enjoyment to the end user. And because we have different tastes in music and in "presentation", and different rooms, perhaps creating a standard on-size-fits-all kind of speaker is a disservice to the community.

“You seem to be assuming that "neutrality/absence of resonances" is the prime concern for most audiophiles”.

I don’t think I ever attempted to assume anything on behalf of “most audiophiles”, a population of limitless variability. All that has been presented are the results of tests conducted on, by now, hundreds of loudspeakers by hundreds of listeners. The first published subjective/objective evaluations showed clearly that listeners responded most favorably to loudspeakers that exhibited the least evidence of resonances. Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31. Toole, F. E. (1986). “Loudspeaker measurements and their relationship to listener preferences”, J. Audio Eng. Soc., 34, pt.1, pp. 227-235, pt. 2, pp. 323-348.

“How the speakers interact with the room in the midranges and treble is a matter of preference and some people seem willing to trade "envelopment" for a flat frequency response or "sharper" imaging. (even though I don't have scientifically gathered statistical evidence to back me up, I am nonetheless relying on over a decade of observing audiophile behaviour in several forums where I have or currently participate in the US, UK, France, Spain and Portugal)”

We each work from our own sources of information. I put my trust in data that are reproducible from time to time, place to place, over a statistically interesting proportion of the population. Accurate measurements qualify, as do controlled double-blind listening tests. I have been fortunate over my career to have had access to both for 26 years at the National Research Council of Canada, and 16 years at Harman International.

There's no doubt that the research you conducted was pioneering and produced a significant amount of valuable data. But as mentioned earlier I have some reservations in regard to both some of the metodology used in the tests as well as the interpretation of some of the data, but I am just a curious and inexperienced amateur with a lot of questions.

(I wish I could have expressed myself more clearly and eloquently but my means of expression is the drawing not the word, and English is not my first language)

 

[Phorize]

I don't know about the BBC but they are managed by bean counters rather than engineers or program makers these days.
The Harbeth M40 is a large speaker able to handle big power and capable of high spl.

When that many beans are involved, it pays to have influential bean counters rather than creative types and engineers. Who wants to be the next Betamax

 

[tuga]

I don't know about the BBC but they are managed by bean counters rather than engineers or program makers these days.
The Harbeth M40 is a large speaker able to handle big power and capable of high spl.

It appears to distort quite a bit at high levels:

 

[Phorize]

Not speakers, but a bit of trivia that has stuck with me for a long time now is that Wu-Tang Clan (or did) use Chord amplifiers in their studios: https://www.stereophile.com/integratedamps/701chord/index.html

In think that makes sense given the wider associations with showy, expensive paraphernalia-Glaciers of Ice and all that:

 

[killdozzer]

Much to my amazement, I've noticed a lot of musicians don't care. They just ask for a regular one, no fuss. They often tell me any which one will do, just as long as its regular and does the job. They seem to listen to some other aspects. I've seen pro classical musicians with anything from small Yamaha bookshelves to whatever is available at the shopping mall. Also, very often I see they get some of the equipment through whatever club/society/foundation funds the orchestra and in that case it's the ones locally manufactured. In Vienna, I've seen a lot of musicians having Vienna Acoustics. In Italy, it's Sonus Faber (smaller and cheaper ones)