Why evaluating the sound of a single speaker is essential

[kharan]

If a speaker sounds better off-axis than on, then I would think there is a flaw in that speaker.

Really good speakers hardly sound different on vs slightly off axis anyways.

What about on-wall speakers designed to be mounted flush and facing straight into the room with no toe-in?

Or in general there are plenty to speakers designed to minimize toe-in because toe-in doesn't look as good as straight in most living rooms.

 

[MayI]

I think there is evidence that a significant number of speakers are superior/most preferred off axis (X degrees) rather than on-axis.

Ok, present you evidence of those numbers vs total number of speakers in same market. Hard facts thanks.
If corner cases have a problem with mono testing, the answer is they do their own and present the evidence.

I think if a speaker is superior/most preferred off-axis, then it can only be considered a less than ideal version of itself when used as a centre channel for example (on-axis at the main listening position).

So poor design for MCH, not any fault of mono testing. ideal MCH uses the exact same center and/or sound near identical.

I'm not against single mono speaker evaluation in a non-anechoic environment, but it does not seem to be the perfect ideal standard that many seem to believe.

Classic strawman

 

[Floyd Toole]

Classic strawman

Yes, mostly because of a confusion of purpose. The double-blind, equal loudness multiple-loudspeaker evaluations were designed to maximize the detection of resonances, not to determine if the overall spectral balance flattered specific recordings - recordings do not have consistent spectral balance. Resonances are more easily heard in mono - discussed in Chapters 4 and 5. The elimination of resonances, results in smooth, flattish direct sound, and if directivity is also smoothly changing, high sound quality ratings. If such a spectral balance is not found to be enjoyable in a particular situation, it is then a challenge to decide what is responsible. Often a bass issue (30% of our overall sound quality rating) which is a small room acoustics problem that is often inadequately corrected. Excessive bass is easily confused with insufficient HF, and vice versa. As I have said, only trustworthy anechoic data will describe what the speaker is doing, and in-room measurements are needed to evaluate what the room is contributing. Spinoramas enable the variables to be sorted out and addressed.

 

[krabapple]

I agree, but stereo is "the hobby".

It's part of it. But pure 2.0 hasn't been "my hobby" for decades now.

But really I had and have no hypothesis, but rather I was/am questioning testing procedures/methodology.

You may not know it, but 'questioning' the often-explained Harman mono speaker evaluation strategy have been a perennial here on ASR.

Your post tells me it's spring again!

 

[Buckchester]

What about on-wall speakers designed to be mounted flush and facing straight into the room with no toe-in?

Or in general there are plenty to speakers designed to minimize toe-in because toe-in doesn't look as good as straight in most living rooms.

Fair points. But I feel these examples or more exceptions.

The poster that I was responding to is insinuating that those speakers that are “designed” to be listened to off axis should be tested that way. I feel like this is such an unimportant tangent. Consider this: if two speakers are compared, it is the one with the better spin that will usually win regardless of this axis stuff. If the two speakers have similarly good spins, one was designed to be listened to off axis and the other on axis, do you really think if you test them both that way, listening to the one “designed” for off axis in that manner is going to beat the one designed for on axis and listening to it as such? I seriously doubt it.

 

[Duke]

Fair points. But I feel these examples or more exceptions.

The poster that I was responding to is insinuating that those speakers that are “designed” to be listened to off axis should be tested that way. I feel like this is such an unimportant tangent. Consider this: if two speakers are compared, it is the one with the better spin that will usually win regardless of this axis stuff. If the two speakers have similarly good spins, one was designed to be listened to off axis and the other on axis, do you really think if you test them both that way, listening to the one “designed” for off axis in that manner is going to beat the one designed for on axis and listening to it as such? I seriously doubt it.

Do you think there could be any valid reason for a designer to optimize for off-axis listening?

 

[Buckchester]

Do you think there could be any valid reason for a designer to optimize for off-axis listening?

Sure.

 

[gnarly]

Fair points. But I feel these examples or more exceptions.

The poster that I was responding to is insinuating that those speakers that are “designed” to be listened to off axis should be tested that way. I feel like this is such an unimportant tangent. Consider this: if two speakers are compared, it is the one with the better spin that will usually win regardless of this axis stuff. If the two speakers have similarly good spins, one was designed to be listened to off axis and the other on axis, do you really think if you test them both that way, listening to the one “designed” for off axis in that manner is going to beat the one designed for on axis and listening to it as such? I seriously doubt it.

If a speaker is designed to be listened to off-axis, some particular X deg horizontal, Y deg vertical, its best spin will normally come from using that designed off-axis as the reference axis for the spins, and not 0 deg H, 0 deg V.

If the speaker were measured/spun around 0H,0V, it usually will not have spins nearly as nice as when spun around the design axis.
At least none of my designs do, and the logic only makes sense, imo.

I think it's part of competent speaker design, measuring and spinning around the design axis.

 

[Salt]

Do you think there could be any valid reason for a designer to optimize for off-axis listening?

The baffle wide's diffraction can result into linearity issues on axis, that measure linearilizead 15 or 30 degrees off axis.
Some speaker designer, like Joachim Gerhard, recommend to toe in speakers to the position of your feet ...

 

[sigbergaudio]

Here is 0 vs 20 degrees on our SBS speaker system, which is a coaxial configuration that is designed with a reference axis that is not on-axis. I suspect the main perceived difference will be one of tonality rather than "better or worse".

Presumably the tonality will still be more neutral on the reference axis, so I generally agree that is what should be tested. But the difference typically isn't huge. In a casual listening situation say in a couch, it essentially sounds the same wherever you sit.

 

[Salt]

Here is 0 vs 20 degrees on our SBS speaker system, which is a coaxial configuration that is designed with a reference axis that is not on-axis. I suspect the main perceived difference will be one of tonality rather than "better or worse".

Presumably the tonality will still be more neutral on the reference axis, so I generally agree that is what should be tested. But the difference typically isn't huge. In a casual listening situation say in a couch, it essentially sounds the same wherever you sit.

View attachment 525708

Levelling, 10 degrees would be optimum But besides, it is very fine, on axis and with toe in, no doubt.

 

[MayI]

Here is 0 vs 20 degrees on our SBS speaker system, which is a coaxial configuration that is designed with a reference axis that is not on-axis. I suspect the main perceived difference will be one of tonality rather than "better or worse".

So perfectly testable in mono. Looks good.

 

[Satanica]

Ok, present you evidence of those numbers vs total number of speakers in same market. Hard facts thanks.
If corner cases have a problem with mono testing, the answer is they do their own and present the evidence.

So poor design for MCH, not any fault of mono testing. ideal MCH uses the exact same center and/or sound near identical.

If you look at Erin's stereo speaker reviews, he regularly toes speakers out because his measurements indicate to him they tonally will be more neutral off axis then on, that's a fact. Can you produce hard facts that counter my view of the current on/off axis product landscape?

Have you ever noticed that in wall speakers with identical Left, Center, Right usually all fire straight into a room? Therefore, at the main listening position one is hearing the Center on axis and the Left and Right off axis.

Let me be clear, I'm not against single on axis testing of speakers. But I still believe that I've presented a case to consider the limitation of such test. Dr Toole has already admitted/mentioned in this thread that toeing a speaker out in room could be a way to "optimize" them. Therefore, in those instances, on axis would be considered non-optimized.

 

[Satanica]

It's part of it. But pure 2.0 hasn't been "my hobby" for decades now.


You may not know it, but 'questioning' the often-explained Harman mono speaker evaluation strategy have been a perennial here on ASR.

Your post tells me it's spring again!

Thanks for the belittlement, but if you're going to insult me, you should know that it's Autumn in the southern hemisphere

 

[jeffaegrim]

I subscribe to pretty much all ruling dogmas on this forum, but I am convinced that there are edge cases of off-axis listening, in which a worse measuring speaker can be preferred to the better measuring speaker when both pairs are deployed/compared in stereo. This configuration found a mention in this thread already but I didn't see this topic expanded upon - the constant directivity horns in the JBL DD55000, 4660, S2600 and S3100 systems are able to create the illusion of a stereophonic center image even when sitting completely off center. The effect provided by these horns - a phantom center outside the MLP - can not be evaluated when listening to a single speaker, and the advantages (greatly increased range over which stereo is perceived as such) are unequivocally preferred in my listening environment. Instead of the sound sharply veering left or right depending on sitting position, the phantom center remains mostly stable. This is achieved by way of varying directivity depending on the listening angle - the directivity of these systems is low right on axis and increases the further one moves off axis. I can get quite a few speaker to sound better at the MLP in stereo. I can't get them to sound better in all other positions - simply because there is no stereo there, since all the sound is perceived as coming from one speaker. The effect really isn't ambiguous at all.

Of course, I am unable to quantify the improvement gained from increased range of the stereo effect, which means it is difficult to juxtapose it with the improvement gained from having more neutral, lower DI loudspeakers (the former also not being related to the "sound" of the speaker at all...). Still, in the spirit of discussion, I wanted to mention these designs again, because I believe that they have merit and because they might constitute a rare case in which factors besides our generally accepted requirements for excellent loudspeakers (can) play a role in how we perceive sound.

Some polar plots from the DD50000 to help visualize what's going on:

 

[Buckchester]

If you look at Erin's stereo speaker reviews, he regularly toes speakers out because his measurements indicate to him they tonally will be more neutral off axis then on, that's a fact. Can you produce hard facts that counter my view of the current on/off axis product landscape?

Have you ever noticed that in wall speakers with identical Left, Center, Right usually all fire straight into a room? Therefore, at the main listening position one is hearing the Center on axis and the Left and Right off axis.

Let me be clear, I'm not against single on axis testing of speakers. But I still believe that I've presented a case to consider the limitation of such test. Dr Toole has already admitted/mentioned in this thread that toeing a speaker out in room could be a way to "optimize" them. Therefore, in those instances, on axis would be considered non-optimized.

Did Dr. Toole not also say that his tests took into account when a speaker was optimized and recommended to be listened to off axis? I thought he did.

 

[Duke]

I subscribe to pretty much all ruling dogmas on this forum, but I am convinced that there are edge cases of off-axis listening, in which a worse measuring speaker can be preferred to the better measuring speaker when both pairs are deployed/compared in stereo. This configuration found a mention in this thread already but I didn't see this topic expanded upon - the constant directivity horns in the JBL DD55000, 4660, S2600 and S3100 systems provide a stereophonic center image even when sitting completely off center. The effect provided by these horns - a phantom center outside the MLP - can not be evaluated when listening to a single speaker, and the advantages (greatly increased range over which stereo is perceived as such) are unequivocally preferred in my listening environment. Instead of the sound sharply veering left or right depending on sitting position, the phantom center remains stable. This is achieved by way of varying directivity depending on the listening angle - the directivity of these systems is low right on axis and increases the further one moves off axis. I can get quite a few speaker to sound better at the MLP in stereo. I can't get them to sound better off axis - simply because there is no stereo off axis, since all the sound is perceived as coming from one speaker. The effect really isn't ambiguous at all.

Of course, I am unable to quantify the improvement gained from increased range of the stereo effect, which means it is difficult to juxtapose it with the improvement gained from having more neutral, lower DI loudspeakers (the former also not being related to the "sound" of the speaker at all...). Still, in the spirit of discussion, I wanted to mention these designs again, because I believe that they have merit and because they might constitute a rare case in which factors besides our generally accepted requirements for excellent loudspeakers (can) play a role in how we perceive sound.

Some polar plots from the DD50000 to help visualize what's going on:

View attachment 526063

Excellent illustration of why and how a speaker might be optimized for off-axis listening; the "why" being a huge increase in sweet-spot-width, and the "how" being what I would call "time-intensity trading", in this case built into the loudspeaker design itself.

Unfortunately the "ruling dogmas on this forum" (to use your words) would indeed label this a "worse measuring speaker", and unfortunately many here would probably reject it without taking the time to understand why the measurements actually indicate good performance for the intended use case. So that would be just one more uphill battle to be fought (and probably lost) by a designer who optimizes for an unorthodox use case.

 

[Satanica]

Did Dr. Toole not also say that his tests took into account when a speaker was optimized and recommended to be listened to off axis? I thought he did.

I don't know man, you're telling the story. But if you're referring to the following, then I think you should pay attention to the bit in bold. I've made the point before, the overall best listening axis for a particular user in a particular room can't be assumed to be a manufacturers spec which they seemingly most likely have not produced anyway. The objectively best measured axis, can't be assumed to be a manufacturers spec, that can only be determined from spinorama.

"In my many years of evaluating loudspeakers I have always respected the manufacturer's "reference axis" for both measurements and listening - mono or stereo. To do otherwise would be irresponsible. Over the years the vast majority of loudspeakers performed best on-axis, so in the absence of a stated reference axis, that was used. That said, most manufacturers don't specify a reference axis, or reveal any useful measurements, so either they don't know or don't care."

 

[Satanica]

Here is 0 vs 20 degrees on our SBS speaker system, which is a coaxial configuration that is designed with a reference axis that is not on-axis. I suspect the main perceived difference will be one of tonality rather than "better or worse".

Presumably the tonality will still be more neutral on the reference axis, so I generally agree that is what should be tested. But the difference typically isn't huge. In a casual listening situation say in a couch, it essentially sounds the same wherever you sit.

View attachment 525708

I'm quite perplexed by your statement above that I've bolded. I thought we would all be in agreeance that differences in tonality can be and will likely be percieved as "better or worse". Can't it be quite simply assumed that at least some listeners will overall prefer either the 0 or 20 axis tonality above? I'm confused that we have got to the point where this is being questioned.

 

[a4eaudio]

..I thought we would all be in agreeance...

LOL, welcome to the Internet.