Speaker Testing: why mono is better

[Thomas savage]

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

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 .

 

[Daverz]

I think channel matching is an important metric for speaker quality, since we do tend to buy them in pairs. I'm not sure how best to test channel matching or what would be an adequate test short of doing the Klippel scan twice, but it does require obtaining a matched pair.

 

[KSTR]

Every serious audiophile knows that trinaural is best.

Now we're talking!
Trinaural / Gerzon's Trifield is IMHO indeed the best projection mechanism for two-channel stereo.
It's beyond me why it gets close to no coverage and discussion. After a Trinaural session a two-speaker setup just sounds broken and extremely sensitive to any minor parameter shift.

 

[abdo123]

Now we're talking!
Trinaural / Gerzon's Trifield is IMHO indeed the best projection mechanism for two-channel stereo.
It's beyond me why it gets close to no coverage and discussion. After a Trinaural session a two-speaker setup just sounds broken and extremely sensitive to any minor parameter shift.

maybe because it's a difficult setup to have outside of bulky AVRs? And when you do get an AVR, 5.1 is much more attractive then?

 

[Mnyb]

Now we're talking!
Trinaural / Gerzon's Trifield is IMHO indeed the best projection mechanism for two-channel stereo.
It's beyond me why it gets close to no coverage and discussion. After a Trinaural session a two-speaker setup just sounds broken and extremely sensitive to any minor parameter shift.

OT can one have Trifield outside of a Meridian System , I use it all the time .

 

[Ismapics]

Hello Fellow Members. Here is the unknowledgeable question for today. Is the All Ch Stereo setting (sometimes called the party setting) on my AVR, Mono or an interpretation of Mono by the AVR processor?

 

[KSTR]

[OT]

maybe because it's a difficult setup to have outside of bulky AVRs? And when you do get an AVR, 5.1 is much more attractive then?

It is actually very simple to implement, You do not need three source channels for that. Just set L and R according to the simple formulas L' = L - R/2 and R' = R - L/2. The center channel is simply the average and can be obtained passively at the power amp input.
Maybe I should open a thread for this....
[/OT]

 

[abdo123]

[OT]
It is actually very simple to implement, You do not need three source channels for that. Just set L and R according to the simple formulas L' = L - R/2 and R' = R - L/2. The center channel is simply the average and can be obtained passively at the power amp input.
Maybe I should open a thread for this....
[/OT]

please do! would love to hear about it

 

[617]

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.

What do you mean by this? How does excess phase affect anything, much less speed, timbre and imaging?

 

[KSTR]

@617 , assume the bass is coming one day later than the midrange and the mids are behind one hour after the treble, then it is clear I hope

 

[Billy Budapest]

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 .

Because in real life, people don’t listen to one speaker. The interaction between two speakers—in essence, their ability to convey the space of the recording, commonly called imaging—is something important to most consumers and cannot be evaluated using one speaker. In essence, people don’t listen that way, and the subjective component to any review should be at least a little bit useful. By listening to only one speaker, your subjective review is completely useless to the consumer.

It’s not only “bonkers,” as you said, it’s just silly.

 

[617]

@617 , assume the bass is coming one day later than the midrange and the mids are behind one hour after the treble, then it is clear I hope

@617 , assume the bass is coming one day later than the midrange and the mids are behind one hour after the treble, then it is clear I hope

Excess phase normally refers to the excess phase wrap caused by the distance between microphone and source. As for your other example, it is hard to imagine a frequency response which corresponds to a fortnight delay in frequencies across the audible spectrum.

 

[Midwest Blade]

Oh boy, mono testing, can already feel youtube heating up on this subject. "Captain, should we raise the shields".

 

[Chrise36]

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 .

That also applies to headphones why is headphone testing done in stereo then?

 

[KSTR]

Excess phase normally refers to the excess phase wrap caused by the distance between microphone and source. As for your other example, it is hard to imagine a frequency response which corresponds to a fortnight delay in frequencies across the audible spectrum.

I see, a misunderstanding here. Excess phase is not the time-of-flight delay. While delay is a constant phase slope vs. frequency (in linear scale!) and can thus be undone straight away, the excess phase of system is not constant slope. The classic example for excess phase is an allpass function (amplitude is 1 but phase is varying, and not a constant slope).

 

[aarons915]

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.

How would 2 speakers make imaging, phase issues, distortion, etc any different than a single speaker? If anything wouldn't comparing the speaker in mono make any of these issues easier to discern than in stereo where they may be masked?

Is there some sort of interaction between identical speakers that only exists when listening to 2 of them? And why is 2 the magic number? I personally listen to my front 3 speakers for music and many people listen in 5.1/7.1/atmos, using this logic we will only spot these differences when listening this way.

 

[wemist01]

Klemperer: "Stereo is an invention of the fakers!"

 

[sergeauckland]

I think channel matching is an important metric for speaker quality, since we do tend to buy them in pairs. I'm not sure how best to test channel matching or what would be an adequate test short of doing the Klippel scan twice, but it does require obtaining a matched pair.

Exactly.

Stereo positioning depends on the loudspeakers being closely matched. discounting room effects, which no loudspeaker manufacturer can control, what defines how accurate and stable phantom image production depends totally on the two loudspeakers being closely matched for frequency response.

With poorly matched loudspeakers, a solo instrument or speaker will drift about left to right depending on the frequenc(ies) being reproduced and not form a solid image. Close matching, and the image will be stable, and won't drift about. The accuracy of timbre will be dependent on the frequency response of the pair, but the pair matching is what determines stereo phantom imaging. Manufacturers in the past used to quote pair-matching accuracy as part of the specification, but I don't see that as common any more.

One might remember that one aspect of BBC licenses for loudspeaker manufacturers was that the BBC could buy a quantity of loudspeakers, put them into stores, then users could take any two, didn't need to be concerned about serial numbers or date of production, and use them as a stereo pair with the pair matching being good enough.

Kippel is excellent at showing the performance of one loudspeaker, and could be used to provide a graph of pair matching, but it would require the on-axis frequency response to be run for each loudspeaker of the pair.

S.

 

[rofo]

I have been doing one speaker listening tests for decades. I learned early on there is no way to properly evaluate a loudspeaker with more than one playing. I discovered this on my own before I ever read anything to back up my methods. In the day one of my reference speakers was the Frazier CAT 40 coax speaker inexpensive, good quality sound, good dispersion. I ran a pro audio company for several years as well as being the AV dude at a university.
If you look up (google) the word stereo, the definition is more about equipment and recording methods. I remember looking it up in the dictionary in the 70's and it was defined as "depth perception".

PS F. Toole designed the voice recording studio at the same university back in the 60's when peg board was a common wall surface.

 

[3ll3d00d]

I see, a misunderstanding here. Excess phase is not the time-of-flight delay. While delay is a constant phase slope vs. frequency (in linear scale!) and can thus be undone straight away, the excess phase of system is not constant slope. The classic example for excess phase is an allpass function (amplitude is 1 but phase is varying, and not a constant slope).

The excess phase of a multiway speaker usually refers to the excess above and above a minimum phase response, typically caused by the filters used to implement the crossover. Assuming a pair of speakers built to a reasonable tolerance, what is the impact on imaging (beyond off axis response)?