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Why evaluating the sound of a single speaker is essential

As may have been mentioned, early side wall reflections will be delayed quite a bit with mono vs stereo. Meaning the acoustic and psychoacoustic result will be different than stereo unless side wall reflections are well treated.

I personally use mono most of the time when I AB test speakers or drivers in speaker under development. But that's mainly because I can switch faster which is important in an AB test due to the audible memory.
First let me say this has been one heck of a great thread. :>)
Um.. not so great I guess.. so a #2 :facepalm: Last several posts the use of single speakers for the majority of speaker tests. :facepalm:
Now not just this mono part! Thing is.. right along side of it being totally logical.. Shure took one long damned time to sink in.
Yikes. The last several posts and yours Sir ..that tags on perfectly :>)

Primarily I came to wonder if the speaker(s) under test would- or might remain in typical ‘left or right room locations.. vs dead center for example?

Borrowing some from Vladimir Filevski here which seems to fit in..
Simple - with listening to single loudspeaker in a room, taking (subjectively) reflections into account.
[and]
If the measurements are similar, than both speaker models are equal in localization stability. For evaluating if the image is more distant or near (or flat), you have to listen/evaluate/review single loudspeaker. You can't calculate that, you have to listen to a single loudspeaker (not stereo pair!).

The early side wall reflections will be delayed quite a bit with mono vs stereo I sort of don't know how, maybe it's a 'where to go with. Thank you so much, Mr. Bjorn.. Everyone :)
 
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It is not only about wide or narrow dispersion, but also the actual angles count at which an SPL comparable to the on-axis response is retained, as well as the directivity over frequency.

Of particular importance is the frequency band 2-4K and the neighboring bands. It is not only the band signaling more or less frontal angle of attack of the direct sound when being boosted slightly in level (see HRTF and Blauert´s directional band theory), it is also the band underrepresented in perception of the diffuse soundfield.

You have chosen two extreme examples of loudspeakers concerning these frequency bands: The Focals seemingly have a very broad-dispersing tweeter and a convex baffle hence very low d.i. in this freq band and lots of SPL at angles causing direct reflections the most. The KEF on the other hand show a step up in directivity index somewhere in this region due to the tweeter placement and huge midrange cone acting as a waveguide. So you compare one speaker with significantly overrepresented 2-4K band in the indirect sound field (Focal) and one with significantly underrepresented (KEF).

I personally perceive both as flawed and would prefer a more neutral one. The overall level of reverberation added in the listening room and d.i. is a separate question.



The original Marvin Gaye recording?
Well... I find both speakers pretty neutral, just mostly with two very different dispersion patterns - as you also point out. And I believe that they are both neutral, yet different enough to give a clear idea of how important the actual power response is, and how no type of EQ can ever change this - only a different speaker can. Which I why I specified that I only changed distortion in the frequency response that was linear in form - also meaning - represented at all angles in the horizontal plane.

What is a more neutral speaker to you - which brand/model? And how did you evaluate the sound - measurement/subjective/objective?

Yes - the original one. To me, music is good if I like it - no matter who, where, what or when.
 
... early side wall reflections will be delayed quite a bit with mono vs stereo ...
Is there a common understanding what the spinorama, and the score is made for? We're speculating reflections, but very basic questions are not yet answered (post #120).

Is 'the score' a consumer guide? I think, decidedly, not. The spinorama could serve as such, but only in the very rare case that the reader understands its quite tight limitations.

In short, proof is made that the previous methods of speaker assessment were just insufficiant. No proof is made (yet), that contemporary assessment methods are final.

Biggest problem: what is my very own personal preference, that, once fulfilled, will relief me from looking out for any other. Why do we discuss what other people might like, the basis of 'the score' - other peoples' preference?!

So, better discuss if a KEF is equivalent a Genelec is equivalent a Neumann, and if not, by what: subjectively. (Unwatch)
 
The sound we hear is coming from the loudspeakers, shaped with the room acoustics.

So despite from cases which are close to anechoic conditions, like some 1980s style overdamped studio control rooms, the room acoustics will play an important part significantly affecting the reproduction quality, will they not? In my understand that would have the consequence that people who design or set up loudspeakers would necessarily have to have a certain degree of understanding how their products interact with the room and what to do to make them achieve the goals in terms of sound quality.

At least a certain degree of recognition that things are not sounding alright, I would expect from a big company designing and selling loudspeakers. If they are confronted with issues which are not solvable by their loudspeaker or installation specialists, they could have hired an acoustician from the start of the project. That is the way I am used to when it comes to planning such projects, and a flagship store showroom seemingly is of a certain importance.
 
If stereo equalizes the preferences for, in parts vastly, different speakers, why bother with optimising for mono. The use case is stereo, so what for?

Actually, monaural listening does make sense when it comes to discrimination tests, particularly in the stage of loudspeaker development or choice of design/parts. If you think of subtle differences caused by distortion, narrow-banded FR imperfections, edge diffraction or alike, it is pretty useful to have the most sensitive testing method. These issues might not be audible in stereo or surround under usual conditions, but you never know who will be listening to which material on the speakers in which room. A certain headroom for attenuating or eliminating potential flaws is never a bad thing.
 
I am happy to do it - the name of the book is "Sound reproduction: The Acoustis and Psyhoacustics of Loudspeakers and rooms".
Got it? Sound reproduction! The rooms and rooms acoustics do not reproduce sound. The loudspeakers do. The sound we hear is coming from the loudspeakers, shaped with the room acoustics.
Field of science research of how we hear loudspeakers through the room acoustic (i.e. Psychoacoustics) is not the same as the field of designing room acoustics. You really don't know they are different fields of science (and business)?! :facepalm: You really don't know the loudspeakers are the Harman's business - not designing and building room acoustics?! :facepalm: I am sure Floyd Toole have more important things to do in his life than designing acoustic of that particular showroom.

I bolded only the beginning of the title - Sound Reproduction, pointing to the main theme.

That's not really true. But we digress...
 
As may have been mentioned, early side wall reflections will be delayed quite a bit with mono vs stereo. Meaning the acoustic and psychoacoustic result will be different than stereo unless side wall reflections are well treated.
The early side wall reflections will be delayed quite a bit with mono vs stereo I sort of don't know how, maybe it's a 'where to go with.
That s not true. If you connect to the amplifier only the left speaker (or right) than you have mono loudspeaker and all wall reflection will be the same.
 
Pair matching down to +/-0.2dB is not needed for proper imaging and soundstage, in case anyone are worried about there being anything wrong with their speakers despite not meeting this criteria. :)
 
Dunno if it is so, but do you, in American English, take the word 'science' for engineering and vice versa?
In this contest maybe "engineering" is more appropriate than "science", especially considering that particular showroom acoustics design was pure engineering. But in many Harman's products real science is involved in their design/engineering.

On topic, I've got a few questions.
The mono, how is it made? Is it just one channel, or the two of stereo combined? Any problems with special artifacts from either method?
I am using only one channel. Can't see why both cbannel combined in mono would have any artifacts.

A mono speaker is going to energize the room with a lots of standing waves (aka resonances), and no second speaker would help out. How is the crucial bass quality maintained?
Standing waves are the same.

As far as I understood, people are more consistently able to detect the presence of resonances in comparison when listening to a mono speaker. What does detection mean in this context, and how does that translate to a preference score?
Less resonances = better sound quality.

If stereo equalizes the preferences for, in parts vastly, different speakers, why bother with optimising for mono. The use case is stereo, so what for?
Simple - if you optimize the mono loudspeaker to have good sound quality, it will be good in stereo also.

By what criteria are speakers equivalent under the test methods used?
In science there's a certain paradigm that if one finds an experimental contradiction to a theory, the latter has to be adapted, or gets dumped alltogether. I understand that speaker assessment isn't strict science in this philosophical sense for better reasons. But for the fun of it, what does a hypothesis look like, that could be falsified with an experiment? I think I read it once, namely "People in general are more discriminative, and over the board more consitent, in assessing speakers for quality when listening mono, while the verdict is based on subjective preference." Can that be confirmed, is this the underlying hypothesis?
Yes, that is the underlaying hypothesis.
 
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Pair matching down to +/-0.2dB is not needed for proper imaging and soundstage, in case anyone are worried about there being anything wrong with their speakers despite not meeting this criteria. :)
Of course that tight matching is not necessary for proper imaging, but for excellent imaging it may be advantageous. In audio science it is accepted fact that good pair matching is necessary. Anyway, tests show that even some cheap loudspeakers (from reputable brands) have excellent pair matching.
 
The data I recall was from Genelec 83xxA models and KEF Reference 1.
I don't see any significant difference?

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H-m-m-m. Let us first get the horse in front of the cart. The definitive comment on loudspeaker performance is how it sounds - that is a subjective judgement. Ideally, one would want the loudspeaker to be a "transparent", neutral reproducer, so we get to hear what the artists created for us. If we don't like what we hear, then we can play with tone controls, equalization, to see if it can be improved. That is the basis of the audio industry.

The problem with subjective judgments is that humans are influenced by much more than the sound. Appearance, price, brand, other opinions and reviews all exercise bias in forming our opinions - the evidence is abundant. The worst subjective evaluations are those conducted in the fully sighted,"take it home and listen to it" method used by most reviewers and virtually all a casual listeners. There are no references, and adaptation sets it. Some call it "breaking in", but it is humans adapting, not electronic or mechanical devices changing. This practice has been the basis of audio opinions from day one, and it has led to the notion that we all must find the loudspeaker we like, because we all "hear differently".

Proof that this is rubbish was revealed to me in 1966 when I conducted my first blind, loudness equalized, four-loudspeaker comparison test at the National Research Council of Canada. The loudspeakers of that era were very distinctively "colored", not at all neutral, but most of the listeners in the group agreed on what was good sounding, even those who criticized the loudspeakers they selected and lived with at home. When they heard something "better" they preferred it. Where were the personal preferences? The second important observation was that the loudspeakers most preferred had the best looking - i.e. flattest and smoothest - anechoic frequency responses. These logically should be the most neutral. All electronics, even then, had ruler flat frequency responses. Why would loudspeakers be different?

There began a research career that extended over 5 decades, many papers, three books, an industry loudspeaker measurement standard, and many fundamentally neutral loudspeakers in the marketplace. For those willing to read, the scientific proofs are there, and have been for many years. An hour and 14 minutes will give a good summary of some of the key science:

Now we can recognize a neutral loudspeaker by inspecting the right set of anechoic measurements. This does not ensure satisfaction because recordings vary - they are created in recording control and mastering rooms by people listening through unknown loudspeakers in unknown rooms. It is wrong to assume that recordings are flawless, and all audible faults are attributable to the playback apparatus. Stereo soundstage and imaging are primarily determined in the recording control room, and there are no standards. Playback apparatus and rooms matter, but at a secondary level.

Except: A fact that cannot be ignored is that bass accounts for about 30% of one's overall evaluation of sound quality, and bass sound quality is dominated by the listening room - and they are all different. Arguably this is the weakest link in sound reproduction, but it is often ignored. There are excellent multiple subwoofer solutions to room resonance problems, but most people think that a bigger sub is the solution - or bigger tower speakers. Wrong.
Many thanks for this. It feels that some of the things I have read elsewhere (but mostly on ASR) are coming into focus, even if there is still far to travel.
 
Some lively discussion here but is drifting off topic and am getting complaints.

Off topic content deleted, thread is open again.
 
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It is quite interesting to see the different perspectives on how people view the topic of loudspeaker reproduction. I believe engineering to be the interface between business and science. I also see that might be needed in this discussion as well. Floyd's book does cover all of this in more detail. Some of the confusion concerning 'the center channel' and 'mono vs stereo' goes back to understanding why these issues occur in our evaluations subjectively. The majority of recordings are made in stereo. These recordings include mixing effects that take advantage of our binaural hearing in order to achieve many of the psychoacoustic effects we perceive in stereo. It is pleasant to most people. The more independent channels, the more envelopment we experience. Hence why many omni-directional designs create this effect due to the fact much of the reflected energy is nearly as strong as the direct energy to the listener (lessens the precedence effect). But many studies have shown that humans ability to discern timbre and linear frequency response anomalies is reduced when listening in a more diffuse field (more reflections over time from the initial sound). Ideally in order to listen in mono for subjective evaluation, it would be more suitable to have recordings made in mono. But these are rarely available and not in the quantity that stereo recordings are made. In Floyds book he discusses the 'Circle of confusion" as well as the lack of standards in specific areas of the recording industry and how this can create incongruent results in audio reproduction. I believe in some of the earlier discussions concerning mono vs stereo evaluations, that humans binaural hearing, stereo recordings, room acoustic effects and how a loudspeaker works gets a bit conflated regarding our judgement of fidelity in a loudspeaker. As stated before a great loudspeaker in mono will not get worse with more channels of the same loudspeaker. A lousy loudspeaker will never get better with multichannel system of that same loudspeaker. But in multi-channel it will have a better ambience and be more pleasurable. But the great loudspeaker in mono will always give better performance once scaled up to multi-channel. A center channel can add a better sense of space in a three channel recording vs stereo. I think Belle Labs found this almost a hundred years ago. I don't think I said anything new that hasn't already been said in this discussion. But I hope people can understand that stuff like imaging is primarily done in the recording studio not from the loudspeakers any more than the amplifier creates a stereo image. Not forgetting that how well a loudspeaker reproduces that recording and all of the stereo effects are all in the engineering of that loudspeaker.
 
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Ideally in order to listen in mono for subjective evaluation, it would be more suitable to have recordings made in mono. But these are rarely available and not in the quantity that stereo recordings are made.

Fully agree. And yes, the number of designated monaural recordings containing timbre of natural instruments plus natural reverb is rather low (there is the lot from the 1950s, though). On the other hand, there are lots of spoken word recordings being mixed for mono with none of a minimum of reverb. These are regularly used for monaural listening tests I am aware of, and this method is very useful for any type of discrimination test. For example when trying to figure out if resonance or distortion effects are audible.

As stated before a great loudspeaker in mono will not get worse with more channels of the same loudspeaker.

It will not get worse in the sense of exhibiting unacceptable new flaws. But nevertheless we have no possibility to predict how exactly it will perform in stereo regarding imaging, localization, depth-of-field, perception of reverb, transparency, detail resolution and some other aspects.

But I hope people can understand that stuff like imaging is primarily done in the recording studio not from the loudspeakers any more than the amplifier creates a stereo image.

A certain imaging is surely created by the recording engineer, but how this will translate to the listening room and perceived by the listener, is highly dependent on the loudspeakers and how they interact with the listening room. So to really understand how they perform, a stereo listening test is mandatory IMHO.
 
Fully agree. And yes, the number of designated monaural recordings containing timbre of natural instruments plus natural reverb is rather low (there is the lot from the 1950s, though). On the other hand, there are lots of spoken word recordings being mixed for mono with none of a minimum of reverb. These are regularly used for monaural listening tests I am aware of, and this method is very useful for any type of discrimination test. For example when trying to figure out if resonance or distortion effects are audible.



It will not get worse in the sense of exhibiting unacceptable new flaws. But nevertheless we have no possibility to predict how exactly it will perform in stereo regarding imaging, localization, depth-of-field, perception of reverb, transparency, detail resolution and some other aspects.



A certain imaging is surely created by the recording engineer, but how this will translate to the listening room and perceived by the listener, is highly dependent on the loudspeakers and how they interact with the listening room. So to really understand how they perform, a stereo listening test is mandatory IMHO.
Well as far as imaging is concerned, perhaps you should do some reading on how the physics of acoustics functions in relation to human perception. Imaging is a psychoacoustic effect. But if believing that loudspeakers have some special attributes that defy the physics of acoustics, all I have to say is that there was a time when most humans believed that the earth was a flat plane. Human perception is limited as to what we perceive verses how our universe actually functions. It appears that the sun descends into the ocean on the west coast of the North America in the late evening hours. . But there is strong evidence that it does not.
 
But if believing that loudspeakers have some special attributes that defy the physics of acoustics, all I have to say is that there was a time when most humans believed that the earth was a flat plane.

Where have I written that loudspeakers are defying the laws of acoustics in order to achieve phantom imaging?

You know, it is pretty cheap to call others ´flat-earthers´. It is seemingly more difficult to understand how a loudspeaker interacts with the room and how the resulting soundfield comprised of direct sound, reverb contained in the direct sound plus indirect reflections, is creating a phantom image with two-channel stereo recordings. I do not see a single solid evidence why phantom localization, ambience and depth-of-field of stereo recordings could be judged easily in mono with a downmixed or channel-mapped recording.
 
I just discovered Techno a few months ago......I'm 58. I can't get enough of it. Why....? Because some of it has crazy complex tones & all levels of bass & real 100 ish slam . Reason I bring this up is it might not be the music your comfortable with that is a test of what ya got going on.
I'm just a tad younger than you and I also found electronic music about a decade ago now and have been enamored ever since. I still listen to other genres, but not nearly as much as electronic music.

There is absolutely great artistry and musicality in the better examples. I would throw out a few suggestions for you. Pitch Black, Bluetech and Phutureprimitive are quick suggestions.
 
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