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Speaker Testing: why mono is better

amirm

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#1
This topic of "why Amir tests speakers in mono" keeps coming up. I must have explained that a hundred times in text. Most of you probably know why. But I thought I do a video that covers the research and explains it all. Here it is:


References:
https://www.aes.org/e-lib/online/browse.cfm?elib=11740
Subjective Measurements of Loudspeakers: A Comparison of Stereo and Mono Listening

https://www.aes.org/e-lib/browse.cfm?elib=14622
Comparison of Loudspeaker-Room Equalization Preference for Multichannel, Stereo, and Mono Reproductions: Are Listeners More Discriminating in Mono?

https://www.aes.org/e-lib/browse.cfm?elib=8338
A New Laboratory for Evaluating Multichannel Audio Components and Systems
 

Thomas_A

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#2
Thanks Amir,

that mono speakers are more sensitive for evaluations are quite clear, but did you bring up the issues with the flaws of stereo (comb filtering)? Which means that a mono speaker sounds different from a mono source played by a stereo setup, regardless of the speaker is perfect or not.
 

MarsianC#

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#4
Conspiracy:
Mono is used only to save the poor postal worker's back. And Amir's too ;)

I have tried listening/comparing in mono. It is no fun business (as it should be!). My main problem is positioning the speakers, especially with short listening distances around 2 m. When I used my living room without proper acoustic the bass is to boomy and clouds my impression with 50 shades of boomy bass (LOL :D).
 
OP
amirm

amirm

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Thread Starter #5
When doing listening tests speakers in mono. Is the audio playing in stereo(listening to either L or R) or is it downmixed to mono?
I have tried it both ways and makes no difference as long as you are consistent.
 

restorer-john

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#6
So my question is, if mono speaker testing is the goto de-rigueur, why does Harman persist with the crazy ass speaker lateral-forwards-backwards shuffler when they could do it much more easily, faster, quieter and more precisely with a single (mono) version of the Toole rotator used back in the day?

Mount four speakers all facing out and spin it into position. Could be done in a second vs 4 seconds
 
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#7
"Mono is better" is what I do not believe 100 per cent, or I say I believe 99 per cent.
Yes, you will be able to tell a bad loudspeaker and a good loudspeaker more easily and consistently, hence it's pretty much useful in most case.
But if there are several very good loudspeakers, I think it could be affected by the lack of another source.

In stereo listening, if you move, or you are not on the exact sweet-spot, you will get both the influence of off-axis response and timing, which missed in the mono test.
Yes, it will be affected by the source, toe-in, size of the triangle, room, listener, and so on, in short, it will be way much more fiddly and time-consuming.

Likewise, in the subjective preference rating, off-axis roll-off is virtually neglected as long as the total response was an "even" roll-off, moreover, it does not evaluate off-axis response itself.
(As long as I know. Is that correct understanding?)
I think the rating is way too easy to the evaluation of the characteristics of the listener's movement and the size of the listenable area so that probably not good enough at rating reasonably well-engineered loudspeakers.

Currently, I am designing a loudspeaker for the very first time and I do not have confidence about my off-axis roll-off profile, neither the negligibility of it.
And I want more mild characteristics of the image shift to the listening point and listener's movement, so it could matter.
I don't have any resource to do such an intensive testing so what all I can do is just make everything good and well, crossing my fingers. :)
 
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KSTR

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#8
Some really important things in listening evaluations can definitely not be judged with a single speaker. But listening evaluation is not performed by Amir, other than some very basic stuff, that is. Measurement are always mono. Plus the shipping and setup issues.
All that combines into why we see only mono listening here.
None of the known to me speaker designers (including my humble self) would ever rely on mono listening only.
 

whazzup

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#9
Some really important things in listening evaluations can definitely not be judged with a single speaker. But listening evaluation is not performed by Amir, other than some very basic stuff, that is. Measurement are always mono. Plus the shipping and setup issues.
All that combines into why we see only mono listening here.
None of the known to me speaker designers (including my humble self) would ever rely on mono listening only.
In your experience, have you found / rectified any issue that only surfaced after a stereo test (and wasn't apparent in mono listening)? Or is it more of a preference thing (to test in stereo vs mono)? Curious to hear what someone goes through when designing speakers.
 

Arnandsway

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#10
Some really important things in listening evaluations can definitely not be judged with a single speaker. But listening evaluation is not performed by Amir, other than some very basic stuff, that is. Measurement are always mono. Plus the shipping and setup issues.
All that combines into why we see only mono listening here.
None of the known to me speaker designers (including my humble self) would ever rely on mono listening only.
Could you elaborate on those "really important things"? I am assuming directivity/soundstage related things. But I wonder what is so important if tonality is the main gripe.
 

rxp

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#11
Excellent explainer as always! Would love a Room EQ video too :)

What this has told me is that is it really worth worrying about how good a speaker is if you have it in a multi channel setup? If the differences are so small and you won't notice, is it worth fretting about?
 

KSTR

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#12
Could you elaborate on those "really important things"? I am assuming directivity/soundstage related things. But I wonder what is so important if tonality is the main gripe.
Tonality issues are benign in practice. We quickly adapt to frequency magnitude response irregularities if not to blatant. But you never adapt to flawed imaging, phase issues, distortion, etc.
And yes, soundstage. For example position/size/compactness of phantom images (incl mono center) vs frequency. You'll never catch a speaker design that has issues there without stereo listening in a properly designed room. Measurement of unit-to-unit variations don't catch that.
Part of the imaging properties are related to the excess phase (of a typical multiway). While on can assess speed/timbre issues from excess phase in mono, the effect on imaging is missed.
Etc, etc.
 

daftcombo

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#15
I have tried it both ways and makes no difference as long as you are consistent.
Do you know if the "mono" option in Windows 10 Ergonomy settings works well? It's the only option I have to listen to Youtube without headphones at the office on a speaker, and to me (subjectively) it seems to blurry the bass.
I don't feel the same with the "downmix to mono" plug-in in Foobar2000 for instance.
 
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#18
I have tried it both ways and makes no difference as long as you are consistent.
It seems to me if you're using music you're familiar with on a stereo system, downmixing would be preferable because potentially you're a) losing information you're used to hearing and b) the apparent balance of the mix would be off?
 
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#19
This makes sense. They also sell four tires for each car whereas one would be sufficient.
I like stereo therefore I also wish I had a steering wheel for each wheel.
 

NTK

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#20
So my question is, if mono speaker testing is the goto de-rigueur, why does Harman persist with the crazy ass speaker lateral-forwards-backwards shuffler when they could do it much more easily, faster, quieter and more precisely with a single (mono) version of the Toole rotator used back in the day?

Mount four speakers all facing out and spin it into position. Could be done in a second vs 4 seconds
Could it be because their "Multichannel Listening Lab" was designed to be flexible enough to test stereo speakers too?
https://www.harman.com/documents/HarmanWhitePaperMLLListeningLab_0.pdf

harman.PNG


harman2.PNG


I wonder in the 20+ years since Harman has this lab, have they done a comparison between mono and stereo test? It seems perfect for it. Hmmm....
 
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