Why don't all speaker manufacturers design for flat on-axis and smooth off-axis?

[Bjorn]

You're avoiding the time behaviour of the room and just looking at the frequency response. That's like overlooking quality to large degree and is exactly correcting what's not minimum phase.

 

[Krunok]

You're avoiding the time behaviour of the room and just looking at the frequency response. That's like overlooking quality to large degree and is exactly correcting what's not minimum phase.

Is that so? Here is step response for my left and right speaker..

 

[Bjorn]

Which shows nothing of the time behaviour of the room. We're talking about room correction, not speaker correction.

 

[Krunok]

Which shows nothing of the time behaviour of the room. We're talking about room correction, not speaker correction.

Here..

How about you post yours?

 

[Krunok]

REW's "Var Smoothing" roughly corresponds to this:

"Variable smoothing applies 1/48 octave below 100 Hz, 1/3 octave above 10 kHz and varies between 1/48 and 1/3 octave from 100 Hz to 10 kHz, reaching 1/6 octave at 1 kHz. Variable smoothing is recommended for responses that are to be equalised"

View attachment 29642

Yes, that is what is says, but in practice when I was doing my manual correction 1/12 worked for me up to 300Hz and 1/6 from there up.

What is also important is spatial aspect of the measurements meaning that your measurements should cover some area at LP rather than single point. Here is an example how it looks with my left speaker:

This was taken from the point at LP where app my left ear is. Red line is a sine sweep and green line is RTA pink noise. As you can see they are practically identical.

This is RTA where I moved mike in a horizontal circle with a diameter of 20cm (so around the area where my head would be):

This is RTA where I moved mike in a horizontal circle with diameter of 1m (so around the area where my sofa is):

This is a single point sweep taken app 5cm behind the first sweep (shown on first pic). As you can see it differs from first sweep quite a bit.

This is sofa spatial sweep vs left ear sweep, for comparison:

The point being here is the spatial aspect of the measurements that Dr. Toole is repeatedly stating in his numerous papers.

 

[Bjorn]

Here..

View attachment 29679

How about you post yours?

Which still shows nothing about the time domain of the room.

Post mine? What has that to do with correcting non minimum phase behavior.

 

[maty]

Yesterday, Stereophile made a comparison between Magnepan LRS and KEF LS50.

Herb Reichert, the subjective listening

* https://www.stereophile.com/content/magnepan-lrs-loudspeaker-page-2


John Atkinson, the objective measurements

* https://www.stereophile.com/content/magnepan-lrs-loudspeaker-measurements


But two different technologies and a very different frequency and spectral response! And Magnepan: 50 Hz at -3dB and LS50 79 Hz at -3dB. Column versus bookshelf speakers (without subwoofer).

Fig.6 Magnepan LRS, cumulative spectral-decay plot on mid-panel tweeter axis at 50" (0.15ms risetime).


https://www.stereophile.com/content/kef-ls50-anniversary-model-loudspeaker-measurements

Fig.9 KEF LS50, cumulative spectral-decay plot on HF axis at 50" (0.15ms risetime).

 

[Krunok]

Which still shows nothing about the time domain of the room.

This is in-room phase measurement showing actual phase, minimum phase and excess phase of my left speaker. What other measurement you had in mind?

Post mine? What has that to do with correcting non minimum phase behavior.

It would demonstrate your point better than constantly making statements without proof. It would also demonstrate your credibility about this topic.

 

[Wombat]

Yesterday, Stereophile made a comparison between Magnepan LRS and KEF LS50.

Herb Reichert, the subjective listening

* https://www.stereophile.com/content/magnepan-lrs-loudspeaker-page-2


John Atkinson, the objective measurements

* https://www.stereophile.com/content/magnepan-lrs-loudspeaker-measurements


But two different technologies and a very different frequency and spectral response! And Magnepan: 50 Hz at -3dB and LS50 79 Hz at -3dB. Column versus bookshelf speakers (without subwoofer).

Fig.6 Magnepan LRS, cumulative spectral-decay plot on mid-panel tweeter axis at 50" (0.15ms risetime).


https://www.stereophile.com/content/kef-ls50-anniversary-model-loudspeaker-measurements

Fig.9 KEF LS50, cumulative spectral-decay plot on HF axis at 50" (0.15ms risetime).

Do you have a point, here? We all know loudspeakers can be different.

 

[maty]

What is better, a strawberry or a watermelon? It is an improper comparison of a magazine that pretends to be serious.

 

[Bjorn]

This is in-room phase measurement showing actual phase, minimum phase and excess phase of my left speaker. What other measurement you had in mind?



It would demonstrate your point better than constantly making statements without proof. It would also demonstrate your credibility about this topic.

You have clearly shown that you don't understand what minimum phase behaviour of the room means. Nothing wrong with that, but you need to learn the fundamentals if you're going to involve yourself in the discussion about it. Just showing you a graph isn't going to give you this understanding, but something you need to learn by reading yourself.

 

[March Audio]

Which would imply a lot of the room modes cannot be fixed either, since a great deal of them are not minimum phase behavior. A general statement that room modes can be corrected by room correction is simply wrong.

"a great deal" which means some can be. Lets just take it as read that none of us here are daft enough to generalise and understand there are limitations. My experience is that is has always been better to EQ a large room mode generated peak than not, assuming other methods such as acoustic treatments or multiple subs are not an option.

 

[March Audio]

You have clearly shown that you don't understand what minimum phase behaviour of the room means. Nothing wrong with that, but you need to learn the fundamentals if you're going to involve yourself in the discussion about it. Just showing you a graph isn't going to give you this understanding, but something you need to learn by reading yourself.

Regardless, his point is valid. dealing with that 12dB peak by EQ is still appropriate.

 

[Juhazi]

About mono Vs. Stereo testing. I just can't understand how a single mono speaker in a testing room can have any spatial quality! It should be sharp. I am glad to see that now Harman has multichannel listening rooms. Stereo and multi-ch imaging is crucial for hifi.

 

[MZKM]

About mono Vs. Stereo testing. I just can't understand how a single mono speaker in a testing room can have any spatial quality! It should be sharp. I am glad to see that now Harman has multichannel listening rooms. Stereo and multi-ch imaging is crucial for hifi.

You can’t hear spacial placement (imaging) in mono, correct. However, if a speaker has a well controlled off-axis (correlates to good imaging) then the reflections will be close in tonal response to the on-axis, which is more preferable to speakers with suckouts or peaks off-axis.

 

[Krunok]

You have clearly shown that you don't understand what minimum phase behaviour of the room means. Nothing wrong with that, but you need to learn the fundamentals if you're going to involve yourself in the discussion about it. Just showing you a graph isn't going to give you this understanding, but something you need to learn by reading yourself.

Wait.. I must be missing something. You haven't provided a single argument that support your statement. You also haven't provided any links to research paper supporting it. You definitely don't seem to grasp the concept of excess phase in relation to measurement of in-room phase response and yet you speak like that. My kids stopped behaving/speaking like that when they were 15, which is normal as adult person shouldn't behave like that, at least not a reasonable one. This speaks much of you..

 

[Krunok]

My experience is that is has always been better to EQ a large room mode generated peak than not, assuming other methods such as acoustic treatments or multiple subs are not an option.

And that is exactly what Audiolense and other premium EQ software also do.

 

[MRC01]

...
Very important slide - don't make EQ based on a single sweep made at one point, what you need to make good equalisation are spatial measurements and aim for resonances:
...
In my limited experience pretty much all peaks can be fixed, dips not that much.

Good advice. I do the same thing: measure the same sweep from several locations and EQ only what they have in common. Also you can't fix big dips through EQ, they require room treatment. Not because I read the book but because I learned the hard way through trial & error.

PS: and the most important: fix whatever you can by room arrangement, setup, treatment first. EQ is the last step to fix whatever remains. By doing room setup & treatment first, you're addressing the root cause of the problem, getting a better response and your EQ will be milder and more transparent.

 

[svart-hvitt]

I have not idolized any one individual. I have praised the research that goes miles and miles beyond anything that the rest of the industry has done combined. Credit is of course given where it is due. But no one has made any appeal to authority here. In every argument research data is provided to stand as proof, not someone's opinion.

In reverse, you keep displaying this irrational allergy to this work in post after post. That is not data. Put forward contrary research and we can examine that. Without it, constantly objective is of no value and actually does damage to people who want to get through these topics and have to sort through these emotional posts.

@amirm , you keep saying I am irrational.

Definition of «irrational»:

«Definition of irrational
(Entry 1 of 2)
: not rational: such as
a(1) : not endowed with reason or understanding
(2) : lacking usual or normal mental clarity or coherence
b : not governed by or according to reason irrational fears
c Greek & Latin prosody
(1) of a syllable : having a quantity other than that required by the meter
(2) of a foot : containing such a syllable
d(1) : being an irrational number an irrational root of an equation
(2) : having a numerical value that is an irrational number a length that is irrational».

You display here a form of suppression technique, accusing others of having mental and emotional problems.

In my post, I flagged the same concern as @oivavoi did previously:

«The most important thing, I think, is actually to get other research groups to replicate the experiments, and see if they come to the same results (...) What troubles me slightly with lifting up the Harman research to the status of an undisputed audio gospel is that this is basically one research group...»
Source: https://www.audiosciencereview.com/...s-and-smooth-off-axis.8090/page-4#post-199430

Then, @MattHooper wrote:

«Well...how tightly do the data from the blind testing conform to, or predict, actual consumer long-term satisfaction with a speaker?

As far as I'm aware, at this point, it doesn't. It only predicts what people will prefer on the specific blind-test conditions. The first thing we'd want to worry about is the "Pepsi-Challenge" effect, where as everyone knows (at least in lore) Coke re-designed their product to be sweeter like Pepsi, because Pepsi kept winning blind challenges. New Coke being sweeter then fared well in blind tests against Pepsi. But New Coke failed in the marketplace, for various reasons (it's not a straight-line effect story), one of which is plausibly that many who had always preferred coke to pepsi drank quite a bit of coke, and they found the "less obviously sweet" original formula faired better when drinking such quantities. The test tended to favor a flavor profile that stood out when taken in small amounts like that blind test. (This resonates with me, as I can enjoy a little bit of a very sweet drink, but it wears on me fast if I have much of it, hence I actually choose to drink mostly less sweet-tasting drinks)».
Source: https://www.audiosciencereview.com/...s-and-smooth-off-axis.8090/page-9#post-200118

I also raised the question of cui bono, as did @oivavoi in his post, on the fact that funding may influence science.

I don’t get it why you label people who raise valid questions «irrational». The questions raised (reproduceability, testing bias and cui bono) are flags that are often raised in other research areas. Why not raise them in a discussion of audio research and science?

 

[svart-hvitt]

This is a myth created by people who go by sound bytes rather than reading the full texts. THe statement against room EQ is in regards to attempting to fix directivity problems with a speaker. This is something that cannot be done since any electric manipulation impacts both direct and indirect sound. No such position is taken at all against usefulness of EQ.

Everyone at Harman including Dr. Toole are completely in favor of EQ for fixing room modes. This is so without exception.

@amirm , please don’t reduce this discussion to frequencies below transition area only, where everyone is in agreement on benefits of room EQ.

In his «enticing marketing story» paper, @Floyd Toole wrote:

«For decades it has been widely accepted that a steady-state amplitude response measured with an omnidirectional microphone at the listening location in a room is an important indicator of how an audio system will sound. Such measurements have come to be known as generic “room curves,” or more specific “house curves.” That belief has a long history in professional audio, and now it has penetrated consumer audio with stand-alone products and receivers in- corporating automated measurement and equalization capa- bilities. The implication is that by making in-situ measurements and manipulating the input signal so that the room curve matches a predetermined target shape, imperfections in (unspecified) loudspeakers and (unspecified) rooms are measured and repaired. It is an enticing marketing story».
Source: https://www.audiosciencereview.com/...-theory-without-measurement.7127/#post-162524

I read this as a critique of software packages like Audiolense and Acourate, not an endorsement of said and related solutions. Maybe @UliBru can correct me if he read Toole as an endorsement?

Olive et al. published a paper on room correction a decade ago:

http://www.aes.org/e-lib/browse.cfm?elib=15154

That paper opens up the door for potential benefits of room correction. As far as I understand, the paper does not write off the potential benefits of room EQ as a low frequency issue only. So there is a potential inconsistency here between @Floyd Toole and Olive et al. because Toole writes off target curves while Olive et al. found benefits when applying target curves.

Olive et al. wanted at that time (2009) to investigate further:

«The authors are currently investigating these research questions and hope to present the fruits of this labor in upcoming papers».

AFAIK, these results were never published. The Olive et al. paper from 2009 is AFAIK the only AES paper on room correction software.

@Floyd Toole uses strong words in his «enticing marketing story» paper. But I cannot see that his strong opinion is supported by evidence. Where is the evidence for writing off room EQ above transition area? I must admit I am a but surprised that a science journal published such strong statements without solid evidence. Without evidence, Toole’s paper is more of an opinion piece, not science.

So I stand by my observation that Olive et al. found possible evidence for beneficial room EQ above transition area, while Toole ridicules such corrections. For some reason Olive et al. didn’t publish their later research on room EQ, as promised in their 2009 article.