Modern Measurement Tools Are Tricking Audiophiles Into Trusting Bad Data, Warns Veteran Speaker Designer

[René - Acculution.com]

Thanks for your difficult-to-understand but intuitive explanation. I believe that some designers, if not geniuses, certainly possess above-average knowledge. The fact remains that even the "non-genius" who is passionate about his work, such as Andrew Jones, having studied science, is able to delve deeper into the topics you've discussed in this post, something inevitably inaccessible to the "do-it-yourselfer." In this specific case, we're not talking about an assembler, but rather a designer who, having a need, participates in the creation of transducers. I'll end by thanking you again, but I don't admire the subject; it's my ears that thank that concentric circle.

I am not sure that AJ can delve deeper into this than a DIY'er, if the standard for "do-it-yourselfer" would be the likes of @NKT or @KSTR and other on this forum, who have shown very good understanding of complex mathematics, whereas I have never seen anything theoretical from AJ. Not saying that he hasn't published/couldn't publish, but I just haven't seen anything pointing towards a deep understanding of the mathematical foundation, and I also haven't looked. I am listening to the video right now, so let us see if there is any theory mentioned.

Going from "good loudspeaker" to "good theoretical knowledge" is typical the wrong way to go, simply because you can build loudspeakers with very specific knowledge only, but you would then likely struggle if you were to work across many different products and/or write technical articles and journal papers, where a much deeper (and broader) knowledge is needed.

 

[Gary_G]

FROM GOOGLE

Andrew Jones's CV

Education and expertise

• Education: Degree in Physics with Acoustics from Surrey University and postgraduate research at Essex University focusing on computer-aided crossover network design and optimization.
• Technical Skills: Expertise in acoustics, computer-aided design, crossover network optimization, and the development of advanced driver technologies like concentric drivers and active woofers.
• Design Philosophy: Applies a scientific, research-based methodology to both high-end and affordable speaker designs, focusing on achieving the best possible sound quality within given constraints.

 

[Juhazi]

Interview of AJ, his background https://www.soundstageultra.com/ind...treme-andrew-jones-of-technical-audio-devices

Genelec 8361A nearfield - port on backside, woofer slots on edges of front baffle

 

[Sokel]

I am not sure that AJ can delve deeper into this than a DIY'er, if the standard for "do-it-yourselfer" would be the likes of @NKT or @KSTR and other on this forum, who have shown very good understanding of complex mathematics, whereas I have never seen anything theoretical from AJ. Not saying that he hasn't published/couldn't publish, but I just haven't seen anything pointing towards a deep understanding of the mathematical foundation, and I also haven't looked. I am listening to the video right now, so let us see if there is any theory mentioned.

Going from "good loudspeaker" to "good theoretical knowledge" is typical the wrong way to go, simply because you can build loudspeakers with very specific knowledge only, but you would then likely struggle if you were to work across many different products and/or write technical articles and journal papers, where a much deeper (and broader) knowledge is needed.

Give the comment I read some posts ago, that loudspeakers are easier to do using the established knoledge but drivers is a whole other area, doesn't the measured results of its own coaxial drivers (not speakers) show a deeper-than-average understanding?

 

[René - Acculution.com]

Give the comment I read some posts ago, that loudspeakers are easier to do using the established knoledge but drivers is a whole other area, doesn't the measured results of its own coaxial drivers (not speakers) show a deeper-than-average understanding?

You might still get there via a trial-and-error. Perhaps AJ is superbly skilled in advanced vibroacoustics and signal processing. I just haven't seen anything point towards that, the way I have with some people Samsung and KEF and a few other loudspeaker companies. We cannot deduce from someone making a nice loudspeaker that they have a deep theoretical foundation, unless the involved technology points directly towards it (obvious usage of shape or topology optimization, white papers along the line of Purifi and KEF, or similar). I don't see that with the coax here, that is all that I am saying.

 

[Sokel]

You might still get there via a trial-and-error. Perhaps AJ is superbly skilled in advanced vibroacoustics and signal processing. I just haven't seen anything point towards that, the way I have with some people Samsung and KEF and a few other loudspeaker companies. We cannot deduce from someone making a nice loudspeaker that they have a deep theoretical foundation, unless the involved technology points directly towards it (obvious usage of shape or topology optimization, white papers along the line of Purifi and KEF, or similar). I don't see that with the coax here, that is all that I am saying.

There's an explanation of the difficulties they had to construct it somewhere at a video and how the industry overcame that (I'm talking about the Mofi's coaxials)
He was also at Kef for a decade I think (at TAD too), there some legendary (for the time) speakers of that era came out of him (don't ask which, I was never interested at Kef, it's just the word all of these years)

 

[Toni Mas]

We cannot deduce from someone making a nice loudspeaker that they have a deep theoretical foundation...

Sure, but they are paid for being successfull making nice loudspeakers ... Theoretical foundation is a different job, though will help doers to improve their performance...

 

[ssashton]

You might still get there via a trial-and-error. Perhaps AJ is superbly skilled in advanced vibroacoustics and signal processing. I just haven't seen anything point towards that, the way I have with some people Samsung and KEF and a few other loudspeaker companies. We cannot deduce from someone making a nice loudspeaker that they have a deep theoretical foundation, unless the involved technology points directly towards it (obvious usage of shape or topology optimization, white papers along the line of Purifi and KEF, or similar). I don't see that with the coax here, that is all that I am saying.

I think your points are fair and should in no way be seen as a negative comment towards AJ.

In my experience designing speakers, it’s best to be a jack of all trades — acoustics, electronics, woodworking, even knowing about paint types all come into play. Knowing enough to get the job done is a skill in itself, like learning how to use measurement gear properly to get clean results. But understanding how a sweep is deconvolved via an FFT process into an impulse response doesn’t really get you any further in practice. Edit: I mean, as a speaker designer. Obviously signal processing and foundational knowledge is key for other work.

 

[Sokel]

You might still get there via a trial-and-error. Perhaps AJ is superbly skilled in advanced vibroacoustics and signal processing. I just haven't seen anything point towards that, the way I have with some people Samsung and KEF and a few other loudspeaker companies. We cannot deduce from someone making a nice loudspeaker that they have a deep theoretical foundation, unless the involved technology points directly towards it (obvious usage of shape or topology optimization, white papers along the line of Purifi and KEF, or similar). I don't see that with the coax here, that is all that I am saying.

Found it, at about 27:30 he's talking about this new (?) magnet structure he adopted for Mofi's (and older TAD;s perhaps, that's unclear)

 

[Suono]

Going from "good loudspeaker" to "good theoretical knowledge" is typical the wrong way to go, simply because you can build loudspeakers with very specific knowledge only, but you would then likely struggle if you were to work across many different products and/or write technical articles and journal papers, where a much deeper (and broader) knowledge is needed.

Using mathematics to study tensor fields. Maybe this is your subject. When a designer writes this, he's similar to an assembler, or we can define him as different from other designers. To my ears, it's 2/3, no more. Thanks again for your willingness to converse with an audiophile enthusiast.

 

[René - Acculution.com]

There's an explanation of the difficulties they had to construct it somewhere at a video and how the industry overcame that (I'm talking about the Mofi's coaxials)
He was also at Kef for a decade I think (at TAD too), there some legendary (for the time) speakers of that era came out of him (don't ask which, I was never interested at Kef, it's just the word all of these years)

Sure there are probably many technical difficulties involved. I am talking here about having an expectation about AJ or others having a deep understanding of the Klippel NFS or other topics, solely based on them making loudspeakers.

 

[Curvature]

Yes, but that is actually what diffuse means.

I do not see why being strong and specular would make a lateral early reflection a treat. In a concert hall it is not a treat to sit close to a reflecting side wall in my experience.
And why do you think that the "reflection" will have an "inconsistent" spectrum? These QRD diffusers can be calculated and the reflection will be diffused over a wide area. So, if sufficient care is taken, the diffuse lateral sound can certainly be "consistent". From the pictures I would estimate that the room is about 3.5m high and ≥6m wide, so the listener has about 2.5-3m distance to either ceiling or walls.
So the diffusors may "have their own polar patterns" but this is true for a wall, furniture or anything else too, but here it probably is taken into account and the distance is large enough to have the QRDs do their work.
There might be other ways to build a decent listening room but without details or better measurements I do not see how to judge the effort. At least these people seem to know what they are doing.

Think about this: we know that an off-axis response consistent with the on-axis sounds good on a speaker. Plenty of research on that topic. Moreover, just in terms of speaker design, it is very hard to make the on and off-axis responses smooth and resonance-free, particularly at crossover points, and then keep that pattern control down to low frequencies. After all that effort, why install a kind of treatment which converts that clean off-axis FR into multiple closely-arriving, relatively high SPL waves with uneven and different FR?

This kind of response would be unacceptable from a speaker. Why is it ok for early reflections?

A flat wall on the other hand will be spectrally consistent. My specific point was about the use of these on every major wall, particularly the sidewalls. Diffusers in small rooms are used to preserve energy and control late reflections. They are meant to make the late reflection field more perceptually distinct from the direct sound and early reflections. One of the main measurements used to evaluate their effectiveness is the consistency of decay tails.

Furthermore, are you aware that if you use the same QRD across a wall you actually increase lobing dramatically, increasing the require distance? In their room you can see that Magico flip the QRDs and use spacers to mitigate the effect somewhat. Just like diffusers need a clear mathematical period for well depth and width, so do diffuser arrays.

 

[René - Acculution.com]

Using mathematics to study tensor fields. Maybe this is your subject. When a designer writes this, he's similar to an assembler, or we can define him as different from other designers. To my ears, it's 2/3, no more. Thanks again for your willingness to converse with an audiophile enthusiast.

No idea what you are trying to convey here.

 

[René - Acculution.com]

I think your points are fair and should in no way be seen as a negative comment towards AJ.

In my experience designing speakers, it’s best to be a jack of all trades — acoustics, electronics, woodworking, even knowing about paint types all come into play. Knowing enough to get the job done is a skill in itself, like learning how to use measurement gear properly to get clean results. But understanding how a sweep is deconvolved via an FFT process into an impulse response doesn’t really get you any further in practice. Edit: I mean, as a speaker designer. Obviously signal processing and foundational knowledge is key for other work.

Exactly. I am not saying that I could build a good loudspeaker, but I doubt that the common loudspeaker designer would want to work with me for a week.

 

[Curvature]

Exactly. I am not saying that I could build a good loudspeaker, but I doubt that the common loudspeaker designer would want to work with me for a week.

Your main output, if I understand your previous work, is optimizing loudspeaker drivers specifically, no? Just a few steps outside of speaker design specifically.

 

[Curvature]

Another question which imho remains quite obscure is that of loudspeakers colorations, and seems to be totally overlooked while other aspects like frequency response, directivity control or harmonic distortion measurements are considered enough to evaluate the quality of a loudspeaker. You can have and compare graphically smooth enough spiroramas, but audible diferences still exists between speakers, so that what you see on those graphs is only a part of what you hear,and maybe too much attention is paid to some ugly details on a curve that is not really tragical at all, and other aspects remains masked between curves...

Probably the fact that most sales of audio gear are now realized on line have made necessary the use of a visual way of evaluating equipments, while the physical opportunity to make an audition has become less available to customers.

It's a little bit of both. Audition has become harder, but audition is also inconsistent because listeners are inconsistent. Measured data not only lets you analyze speaker performance, it also helps you listen by revealing potential flaws.

 

[Curvature]

My personal opinion is there is way too much attention given to on-axis response. It is the only thing you can easily reverse in a speaker with the simple use of DSP.

It's a strange opinion since the links between direct sound and perception are well-grounded.

Is the unwillingness to doubt ´existing research´ the only reason to dismiss the theory? Or have you made an A/B comparison yourself? I mean, which research of the last 15 years (since competitive constant directivity speakers are available as potential A/B test rivals) has underlined the theory that colorated reverb is preferable over linear reverb tonality?

I had the chance to have a blind A/B comparison by being provided with otherwise identical speaker prototypes, allowing a comparison of solely different tweeter directivity while the on-axis response stayed the same. The experiment was repeated several times by recording engineers and students. It was pretty interesting and made me seriously doubt the positive outcome of waveguides, which I had previously preferred.

On the other hand, I am not doubting the findings by Toole regarding preference. I don't think there is a major flaw in the research, but that the way the experiments had been conducted at Harman lab back in the days, were leading to a result which does not translate properly to the world of living room listening, people's preference with their own favorite music and the way they set up their speakers. Interestingly, AJ in the stereophone interview refers to Toole´s preference experiments:

If you provide any evidence outside of noting your personal experience and anecdotes I would take you more seriously.

 

[blueone]

Do any of these guys own anything other than t-shirts? If you want to be taken seriously, dress the part.

Years ago when I used to travel to Israel regularly to meet with a couple of the engineering teams in my group, one of the engineers asked me why I wore a dress shirt every day. I always wore polo shirts, usually corporate swag, so I was confused.

"Why do you think I wear dress shirts? This is just a polo shirt."

"It has a collar."

 

[René - Acculution.com]

Your main output, if I understand your previous work, is optimizing loudspeaker drivers specifically, no? Just a few steps outside of speaker design specifically.

Lots of different work with virtual prototyping, microacoustics, signal processing, offshore projects, mathematically driven optimization, composite materials, non-linear effects, audioXpress articles, journal papers, training of teams etc. More focus on mathematical methods and physics than looking singularly on loudspeakers, where (in my experience) a lot of misconceptions creep in among some loudspeaker engineers, but a lot of my clients work with loudspeakers, headphone drivers (dynamic, electrostatic), microphones (smart speaker, video conference), and other types of transducers.

 

[Heinrich]

I am not sure that AJ can delve deeper into this than a DIY'er, if the standard for "do-it-yourselfer" would be the likes of @NKT or @KSTR and other on this forum, who have shown very good understanding of complex mathematics, ...

Where is it? O/k, i didn't do Laplace transformation by hand recently, and never proved the math/ peculiarities of the Hankel functions. The concept is otherwise very clear, as always w/ maths. Don't hide it behind a curtain of strange looking signs. To argue that an successful engineer wouldn't understand the Klippel is somehow strange. And not only is AJ an experienced engineer, he is a physicist by education (post #182).
He doesn't tell in the whole article that measurements are a bad tool. He tells that measurement results in the hand of uneducated audiophiles can be misleading. I agree, fully. He says, that measurements can go wrong, agreement here. As the physicist he is, he raises the focus on measurement as science in expecting the unexpected--no button-push-publish. Same here, admittedly.
So what's the point? He questions the layman's interpretation of measurements as possibly wrong. He doesn't mean you.