Speaker Testing: why mono is better

[Mnyb]

Why the hang up on stereo aka 2.0 audio .

Lets play with the thought that it would be impossible to judge speakers without a stereo test .
Following that logic.

What about 2.1 and 5.1 or 5.2 or 7.1 etc audio shall we then also demand that amir gets 7 speakers and set up in his HT room ?
Otherwise one would have no idea how a speaker would perform as a HT speaker ?

The same speaker could be used in mono or a multispeaker setup in a restaurant or club .

Some bars where i live have genelecs as PA not that any critical listening is going on but anyway .

One can almost view a speaker as a kind of acoustical projector that can have many uses

 

[pozz]

By these differences, I mean only those that could possibly be hidden in stereo. Are there any hints to the question of their nature?

The comb filtering stands out as one of those hidden artefacts, especially for strongly correlated passages in the phantom center. Something about the way we use the spectrum of the first arriving wavefront to set the timber of the image overrides the notches. Playing a piece of music in mono through one speaker and in mono through two doesn't sound tonally different, all other qualities aside. Which is really shocking considering what's happened acoustically. Same goes for using treatment: the net effect, if the absorption is really broadband (not just highs) and balanced throughout the room, is a sense of accuracy or precision, not tonal difference, even though many notches have been removed.

 

[pozz]

One can almost view a speaker as a kind of acoustical projector that can have many uses

+1

 

[q3cpma]

I think the weight of showing that stereo testing is better would need some sort of study rather than just objections with no data. If people are objecting that stereo testing is needed, are there studies from AES to corroborate this?

Fortunately, logic can save you some significant time and effort. In this case: how can mono be strictly better than stereo when (or if) the goal is to evaluate speaker stereo performance? It simply can't.

 

[tuga]

Fortunately, logic can save you some significant time and effort. In this case: how can mono be strictly better than stereo when (or if) the goal is to evaluate speaker stereo performance? It simply can't.

To evaluate stereo performance (and preference) one has to listen to a pair of speakers.

 

[amirm]

For example, what would be the result with two "perfect" speakers (flat on axis, CD down to a similar frequency, low nonlinear distortion) with only horizontal directivity width varying?

If you have side walls, the one with wider directivity will enlarge the apparent size of the speaker which most people tend to prefer. Tons of research has been done in this regard (side reflections versus not). In mono testing as I explained, you can observe this effect in the speaker presenting a large spatial image than a point source.

 

[amirm]

Fortunately, logic can save you some significant time and effort. In this case: how can mono be strictly better than stereo when (or if) the goal is to evaluate speaker stereo performance? It simply can't.

That has been the goal from start. Research shows that mono testing is more accurate than stereo testing. The overall ranking remains the same in either mode. You seem to be arguing for less accurate instrumentation to arrive at the same goal.

 

[amirm]

To evaluate stereo performance (and preference) one has to listen to a pair of speakers.

Only if the stereo effect is the subject of evaluation, not speaker quality. When listening to music, you have no control of the #1 factor that creates that stereo effect: the content. Everything else is by far secondary as far as speakers in stereo.

Take a crappy 5.1 system and pan the sound to be behind you. You think that is a function of the quality of the speakers or the said content that did the panning?

There is a great magic show where magicians come and see if they can outsmart Penn and Teller. Average person just watches the magic trick and is impressed. Penn and specially Teller, look for how the magic is done. They don't get distracted by the showmanship to look where the magician wants you to look. They look at the other hand. What is going on elsewhere. Such is the issue with stereo. You get to experience a magic trick, forgetting the task at hand of evaluating the speaker itself.

Ultimately this whole thing depends on whether you put your intuition above people who have tested the validity of such and published authoritative work. You have to give up your gut feeling to get enlightenment here.

 

[AudioJester]

So if you have crappy poor measuring speakers - buy more, go multichannel, and will sound as good as a well measuring stereo speaker pair? Or at least will be harder to differentiate.

Is an AVR the best way to setup multichannel for music?

 

[amirm]

So if you have crappy poor measuring speakers - buy more, go multichannel, and will sound as good as a well measuring stereo speaker pair? Or at least will be harder to differentiate.

Only if you have said content that is more captivating than failings of the speakers. And you have enough of it to enjoy.

A speaker that blows its brains out when you turn it up, will be horrible in mono or 10 channels. A speaker that is overly bright, will be bad in both situations just as well.

Mono testing helps when situations get more difficult. If you have a few dB boost or dip here and there. Can you pick that up or will the other channel stomp on that difference?

Also, for multichannel you have center speaker that is mono so you best have well engineered speaker there.

 

[tuga]

Only if the stereo effect is the subject of evaluation, not speaker quality.

That is what I meant: one listens to a single speaker to evaluate speaker performance but we need a stereo pair to evaluate stereo performance and also preference.

 

[amirm]

That is what I meant: one listens to a single speaker to evaluate speaker performance but we need a stereo pair to evaluate stereo performance and also preference.

That research was the heart of what I presented in video. Even spatial/stereo effects were better assessed in mono than stereo. From Dr. Toole's book (same research I showed):

Now, if you are working on creating content for stereo effects, then yes, stereo speakers are mandatory. But not for assessing speakers.

 

[KSTR]

this kind of solutions never made sense to me. they don't work for music (are intended for movie center extraction). the center channel should be used as panning, the same way it works in 2 channel stereo. I tried something like this here (without realy having much knowhow on how realizing something like this): https://www.audiosciencereview.com/...e-aka-phantom-center.13923/page-2#post-439738
also I asked about a musical solution here, and got some answer which are a little over m head: https://www.avsforum.com/threads/upmixing-stereo-music-into-true-3-channel-stereo-not-3-0.3164657/

You might want to read Michael A. Gerzon's original paper. Don't feel put off by lots of math, the main text gives enough info even if you don't follow the math in all details.
And rest assured this does work for music and it is exactly NOT aimed at center "extraction" a la Dolby Surround upmixers.
Only some very special things like Q-Sound encoded effects are rendered less clear than with two speakers. Also, there is a slight timbre shift for the center signal but nothing to really worry about.

 

[Vasr]

Sure did. You question the research with no research whatsoever on your side as to why you have a valid point. To the extent you are sticking to such argument, then you put your belief and gut feelings above research.

This is as close to bible-thumping as I have seen here with no attempt to understand what the disagreement is. If a piece of research is used incorrectly in the inferences made, then the rebuttal to that is not more research (this is not a difficult concept to understand). Until one is able to differentiate between the validity of a piece of research and the validity of an application of that research, no coherent debate can be had.

For the nth time, the argument is not with the "research" you are using as the bible. It is with the application and inferences that is being drawn from the application of that research. This is a logic issue not a counter by more research issue.

No one is disagreeing that stereo makes it difficult to measure the innate quality of a speaker as your research shows. What is being pointed out is that such a measurement is not necessarily indicative or relevant as a measure of the sound quality of a stereo reproduction (except in the extreme cases of a speaker being broken in its innate measures). Because what small differences occur in mono measurements may be masked (just like some distortion may be masked even if they exist) and so irrelevant to a judgment of the sound quality. In addition, there are other qualities of stereo reproduction that are factors in the evaluation of a pair of speakers to use.

To summarize the nature of the debate:

A: From my tests of people in my lab (which is based on solid research work X) , I conclude that men fart more than women in public.
V: Wait, the behavior of people in your lab is not indicative of the behavior of people in public.
A: But a public setting masks the sound of people farting because of all kinds of extraneous noises appear and people confuse the farting sounds with other sounds and think people don't fart.
V: That is true. But, not measuring in that context cannot be used to say anything about the behavior in that public context. Purely as a matter of logic.
A: But you are just arguing, you have no research that counters X and just giving your opinions and saying that is logic. From that perspective, any disagreement with research is logical.
V:

I am just going to leave it that.

 

[tuga]

That research was the heart of what I presented in video. Even spatial/stereo effects were better assessed in mono than stereo. From Dr. Toole's book (same research I showed):

View attachment 120147

Now, if you are working on creating content for stereo effects, then yes, stereo speakers are mandatory. But not for assessing speakers.

Yes the differences in "spatial quality" were much greater in mono. This was due to differences in directivity. The Quad, but also the Kef have an overall smoother on- and off-axis response (i.o.w. better balance) than the Rega and yet the latter was preferred. I am convinced that this was due to the wider-directivity of the Rega, which seems to be preferred by most people and I would expect by most if not all Harman-trained listeners.
I disagree with Toole's interpretation of the data.

 

[Pennyless Audiophile]

Mono testing helps when situations get more difficult. If you have a few dB boost or dip here and there. Can you pick that up or will the other channel stomp on that difference?
.

If, in general, these defects tend to be masked in stereo listening, isn't it a good thing from the point of view of the consumer? Since I will always listen stereo, I am not really concerned if in mono it turns out that the quality is not the best. If it sounds ok for my taste in stereo, then it is fine for me, I suppose.
If anything, it broadens the range of speakers that can be bought with decent perceived outcome from the point of view of the listener.

 

[beagleman]

I dont understand why some reject this , a speaker has a job and testing in stereo not only brings a variable to the process that makes results less reliable and complex to compile it also dose all this with no benefits whatsoever as far as I can see.

Its totally bonkers .

I am not saying it applies to ME at all, but I can easily get why some are bothered by it. It measures in a way that is not completely similar to how "we" listen, and introduces variables into the equation, of an opposite sort.

Mind you, I do not have issue with it, but can easily see why some might.

 

[Rick Sykora]

Your information in the video on what makes a center blend well correlates with my experience with center speakers. My ominidirectional OMD-5 blends better with other main speakers than most center channel speakers I have owned. This was even when the center channel was identical or designed to be timbre-matched to the stereo pair.

IMO, nuggets like this (that have more practical application) have greater value than more esoteric arguments like mono vs stereo for speaker reviews. While I agree with most of the premise as a speaker builder, it seems impractical for the layman to apply. Lacking a clear path to a more gratifying result, the target market for most of the content seems limited to reviewers and review consumers. Would be surprised if it changes decades of engrained behavior by the established industry.

Thanks in any case!

 

[Vasr]

A good write-up on the difficulty of evaluating spatial quality (and rigorously defining what it means) including Toole's work:

https://www.ece.uvic.ca/~peterd/30604/rumseyattributes.pdf

 

[amirm]

If, in general, these defects tend to be masked in stereo listening, isn't it a good thing from the point of view of the consumer? Since I will always listen stereo, I am not really concerned if in mono it turns out that the quality is not the best. If it sounds ok for my taste in stereo, then it is fine for me, I suppose.
If anything, it broadens the range of speakers that can be bought with decent perceived outcome from the point of view of the listener.

First answer is philosophical: if for the same money you could get a better speaker, would you not want to?

Second, you all are relying on my assessment of a speaker. Don't you want my assessment to be more accurate?

Third, we have speakers like center channel in home theater that are always used in mono.

Forth, there is no guarantee of masking always working. I have second generation master tapes of 1960s and 1970s music with hard pans. There, speakers play a lot of mono content.

Last but not least, the defects in speakers don't completely disappear in stereo. They become harder for an evaluator to identify them in testing.