Audio Science in the Service of Art

MylesBAstor

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Apr 20, 2010
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Of those companies you mention, how many have access to and use anechoic chambers to measure and test their designs?

I will check with as many as I can and find out.

But considering what each of the designers have achieved in the sound of their respective speakers, what does that say for anechoic testing (and they've gotten just as many raves in SP and good marks from JA)? I'd say it's nice but not absolutely a requisite for a successful design.

Oh and one could throw Avalon in there too.
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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I will check with as many as I can and find out.

But considering what each of the designers have achieved in the sound of their respective speakers, what does that say for anechoic testing (and they've gotten just as many raves in SP and good marks from JA)? I'd say it's nice but not absolutely a requisite for a successful design.

Oh and one could throw Avalon in there too.

Unfortunately, I have not had the opportunity to listen and measure all of the brands you mention. I have tested several of them.

One manufacturer I have not tested but it stands out as being very accurate is the Magico V2 based on its measurements at NRC. I just found out recently that the anechoic chamber at NRC was not calibrated below 100 Hz when it was rebuilt. As a result, you cannot trust what you see below 100 Hz in the measurements. At the time, reviewer Doug Schneider of SoundStage said "it’s a true audiophile-grade performer with an overall sound quality that makes it the best passive loudspeaker I’ve ever reviewed " I actually believe him based on its performance. If you compare their measurements to those of some of the other brands SoundStage tested, they are night and day.

(note: Since this review was written, Doug has tested the Revel Salon 2 and believes it is even better concluding: " for now, at least, the Ultima Salon2 is the best passive loudspeaker I’ve ever reviewed".

Magico's website indicates they design their own transducers and have access to FEA tools for modeling and measuring transducers. That is a competitive advantage that not all high-end brands have.To design a speaker that measures that well is not an accident, but rather indicates some appreciation and application of good scientific and engineering practices.
 
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tonmeister2008

WBF Technical Expert
Jun 20, 2010
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Unfortunately, I have not had the opportunity to listen and measure all of the brands you mention. I have tested several of them.

One manufacturer I have not tested but it stands out as being very accurate is the Magico V2 based on its measurements at NRC. At the time SoundStage said it's the best loudspeaker they've ever heard or tested. I actually believe them based on its performance. If you compare their measurements to those of some of the other brands SoundStage tested, they are night and day.

Magico's website indicates they design their own transducers and have access to FEA tools for modeling and measuring transducers. That is a competitive advantage that not all high-end brands have.To design a speaker that measures that well is not an accident, but rather indicates some appreciation and application of good scientific and engineering practices.

I just found an interview with the owner of Magico Alon Wolf here:.To me his philosophy sounds llke "science in the service of art" I quote:

"If our design efforts measure well," says Wolf, "we will probably have a pretty darn good-sounding loudspeaker. If we don't like what we hear, it's usually small things that need changing, and we know where to adjust. As long as the subjective changes fall within the objective scientific parameters that we are willing to accept, that's fine. Plus or minus 2dB across the entire spectrum is a lot. I mean a lot. I can make the speaker sound lush or lean, or bright or dull, within these parameters. But I don't build speakers just to sound good for me. I don't sign off before the science part is safe and sound.

"Our goal is to give you a technically unassailable speaker that performs well in any reasonable environment. If a speaker has a hump at 80Hz just because it sounds better to its designer in a particular environment, then the hump remains no matter what. If the speaker lacks a full midrange, or its bass alignment is off, there's nothing a consumer can do to change it. If you have a 10dB suckout at a poorly executed crossover point, the missing energy is never coming back. Magico would rather give you a solid design that has everything there rather than one with missing or added parts that consumers cannot retrieve or subtract. The goal of a Magico design is to move out of the way. That's the bottom line: to move out of the way."
 

Jeff Fritz

[Industry Expert]
Jun 7, 2010
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At the time SoundStage said it's the best loudspeaker they've ever heard or tested. I actually believe them based on its performance. If you compare their measurements to those of some of the other brands SoundStage tested, they are night and day./QUOTE]

Actually, one person, Doug Schneider, stated it was the best passive speaker he's had in his room. Nowhere did he state that it was the best speaker "SoundStage!" had tested. How could he? We have 35 writers and have been publishing for 15 years -- that's a lot of speakers that were never compared! And in no way, shape, or form did he make any comparisons of the measurements of the V2 versus other measurements of other speakers. And to top it off, Doug actually liked the Revel Salon2 better and stated so in his very next loudspeaker review the following month. This is not to disparage the V2, only to set the facts right.
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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At the time SoundStage said it's the best loudspeaker they've ever heard or tested. I actually believe them based on its performance. If you compare their measurements to those of some of the other brands SoundStage tested, they are night and day./QUOTE]

Actually, one person, Doug Schneider, stated it was the best passive speaker he's had in his room. Nowhere did he state that it was the best speaker "SoundStage!" had tested. How could he? We have 35 writers and have been publishing for 15 years -- that's a lot of speakers that were never compared! And in no way, shape, or form did he make any comparisons of the measurements of the V2 versus other measurements of other speakers. And to top it off, Doug actually liked the Revel Salon2 better and stated so in his very next loudspeaker review the following month. This is not to disparage the V2, only to set the facts right.

Thanks for the clarification. If you have 35 writers independently reviewing loudspeakers I can see that makes it difficult to recommend a Best-In-Class loudspeaker/amplifier,etc like Stereophile does every year. How do they manage do that?
 

Jeff Fritz

[Industry Expert]
Jun 7, 2010
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Thanks for the clarification. If you have 35 writers independently reviewing loudspeakers I can see that makes it difficult to recommend a Best-In-Class loudspeaker/amplifier,etc like Stereophile does every year. How do they manage do that?

I can't comment specifically on what Stereophile does. I assume by "Best in Class" you're referencing their Product of the Year Awards. We do those too. This past year we awarded a number of speakers:

Thiel CS2.4SE
Magico V2
Revel Salon2
MartinLogan Summit X
Dynaudio X12
Rockport Ankaa
Crystal Cable Arabesque
Aperion HT System

These awards are from multiple publications in multiple categories. The V2 is a fine speaker and deserved the award it received. I was only taking exception to your statement that we somehow implied that the V2 was "the best loudspeaker they've ever heard or tested."
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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At the time SoundStage said it's the best loudspeaker they've ever heard or tested. I actually believe them based on its performance. If you compare their measurements to those of some of the other brands SoundStage tested, they are night and day./QUOTE]

Actually, one person, Doug Schneider, stated it was the best passive speaker he's had in his room. Nowhere did he state that it was the best speaker "SoundStage!" had tested. How could he? We have 35 writers and have been publishing for 15 years -- that's a lot of speakers that were never compared! And in no way, shape, or form did he make any comparisons of the measurements of the V2 versus other measurements of other speakers. And to top it off, Doug actually liked the Revel Salon2 better and stated so in his very next loudspeaker review the following month. This is not to disparage the V2, only to set the facts right.

I've modified my original post so it now accurately reflects the facts that you've brought to my attention. Sorry for any problem this caused. I'm pleased to hear that Doug considered the Revel Salon2 to be even better than the Magico V2 (or any other passive speaker he reviewed up to that point in time). That's quite a compliment, and implies we must be doing something right :)
 
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Jeff Fritz

[Industry Expert]
Jun 7, 2010
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I've modified my original post so it now accurately reflects the facts that you've brought to my attention. Sorry for any problem this caused.

Thanks Sean. And now back to the discussion. Here is an excerpt from something I wrote recently:

"A speaker’s frequency-response (FR) plot can tell you a lot about its sound. The most obvious example is how FR defines tonal balance. If there’s a rise in the midband (100-1000Hz), then voices will typically sound more forward in the soundstage and have greater presence. If the very high frequencies (above 10kHz) are rolled off, the sound will lack air and the overall presentation will be somewhat dull. If there’s a hump in the midbass (60-100Hz) but little in the way of true low bass (below 40Hz), the sound will be weighty and hard-hitting, but will lack the foundation that the deepest bass provides. The examples are endless. The key is to understand how what you see in the graph correlates with what you hear at your seat. The sound you hear will always be a combination of your loudspeakers’ output and the room’s contribution to and shaping of that output. How these combine at the listening position is what you hear.

"But as anyone knows who’s had any experience with in-room measurements, while a speaker’s FR plot can tell you a lot about what you’re hearing, it can’t tell you the whole story. There is a long list of other sound characteristics that, in my experience, have no correlation with in-room frequency response: resolution, transparency, soundstaging, imaging, etc. Although a set of anechoic measurements can get to the bottom of some technical elements, such as distortion, I’m not aware of any that can tell you exactly how a soundstage will develop in your room."

I never can wrap my head around why someone is either all measurements or all subjective listening. Most experienced audiophiles know that both combine to tell the larger, more complete story that defines the product.
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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Thanks Sean. And now back to the discussion. Here is an excerpt from something I wrote recently:

"A speaker’s frequency-response (FR) plot can tell you a lot about its sound. The most obvious example is how FR defines tonal balance. If there’s a rise in the midband (100-1000Hz), then voices will typically sound more forward in the soundstage and have greater presence. If the very high frequencies (above 10kHz) are rolled off, the sound will lack air and the overall presentation will be somewhat dull. If there’s a hump in the midbass (60-100Hz) but little in the way of true low bass (below 40Hz), the sound will be weighty and hard-hitting, but will lack the foundation that the deepest bass provides. The examples are endless. The key is to understand how what you see in the graph correlates with what you hear at your seat. The sound you hear will always be a combination of your loudspeakers’ output and the room’s contribution to and shaping of that output. How these combine at the listening position is what you hear.

"But as anyone knows who’s had any experience with in-room measurements, while a speaker’s FR plot can tell you a lot about what you’re hearing, it can’t tell you the whole story. There is a long list of other sound characteristics that, in my experience, have no correlation with in-room frequency response: resolution, transparency, soundstaging, imaging, etc. Although a set of anechoic measurements can get to the bottom of some technical elements, such as distortion, I’m not aware of any that can tell you exactly how a soundstage will develop in your room."

I never can wrap my head around why someone is either all measurements or all subjective listening. Most experienced audiophiles know that both combine to tell the larger, more complete story that defines the product.

I agree with your first paragraph.

The 2nd paragraph needs more explanation. As I have shown in my paper about predicting loudspeaker preference, in-room measurements above 300-400 Hz lack important information about the frequency response of the speaker that are evident in anechoic measurements but absent in in-room measurements: you cannot easily separate the direct, early and late reflected sounds in an in-room measurement, hence they don't predict sound quality as well as anechoic measurements.

The directivity of the loudspeaker based on its anechoic measurements will tell you a lot about some perceived spatial properties as shown in the work of Klippel and others: Spaciousness, envelopment, apparent source width are all enhanced by wider dispersion loudspeakers. As long as your room acoustics/setup promote strong lateral reflections, then you will benefit from these loudspeaker characteristics. Highly directional speakers (dipoles, narrow horns, horizontal line arrays) will sound less spacious and give you higher ratios of direct/reflected sound - all things being equal. On the other hand directional speakers give your more pin-point imaging, which some people like.

When you move from stereo to surround sound, the directivity of the speakers may matter less since the cues in the surround channels may dominate your impressions of spaciousness and envelopment. Spatial qualities in stereo reproduction are highly dictated by the microphones techniques used in the recording. Spaced omni's produce much more uncorrelated signals at the ears than coincident microphone techniques, and hence will sound more spacious. Listen to the Telarc recordings: most of them are made using spaced omnis (which BTW typically have more bass than a directional microphone).

Don't discount how important the frequency response of the loudspeaker influences spatial attributes: our perception of distance has a spectral element to it. Further sound sources are less bright than closer ones, due to room and air absorption at HF).

Finally, there are binaural measurement techniques for measuring and predicting the location of a sound source, the sense of envelopment and apparent source width. If you look up the work of Professor Jens Blauert, and Dr. Wolfgang Hess (a former PhD student of Blauert) who works at Harman, you can see how this works. This method could be applied to loudspeaker measurements in the future with some more research.

Nonlinear distortion is the biggest research problem to solve. I am working on it right now, so hopefully there will be something to report in the future. For now, nonlinear distortion is a very small factor in the performance of well designed loudspeakers - at least until you start pushing them beyond their excursion limits. Masking helps out a lot here.
 
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Jeff Fritz

[Industry Expert]
Jun 7, 2010
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I agree with your first paragraph.

The 2nd paragraph needs more explanation. As I have shown in my paper about predicting loudspeaker preference, in-room measurements above 300-400 Hz lack important information about the frequency response of the speaker that are evident in anechoic measurements but absent in in-room measurements:

Here is the entire article, for complete context: http://ultraaudio.com/opinion/20100501.htm

I agree with what you've said. I was speaking specifically of in-room measurements. If you look at the two graphs in the article, it is clear that the room is swamping the FR. What you're seeing is primarily room, and the two graphs look very similar -- the room modes are quite obvious. The anechoic graphs would shed more light on the two designs and you'd have a deeper understanding of the individual speakers. For instance, diffraction or driver break-up modes can be gleaned from the anechoic FR. Those two issues would be masked by the room acoustics in the in-room graphs. In room two designs that look almost identical on an FR plot can sound very, very different.

Also, it should be clear that in the example I am using two extremely flat, neutral speakers. Both of these speakers are on the order of +/- 1.5dB anechoic.
 
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tonmeister2008

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Jun 20, 2010
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What is masking?

Auditory masking is the perceptual phenomena where the audibility of one sound is reduced (sometimes it becomes inaudible) by the presence of another sound. It is the explanation for why perceptual coders like Mp3 or AAC work: the coders have a perceptual model that calculates the amount of perceptual masking that occurs in the music and throws away information that is masked and we can't hear.

The amount of masking that occurs depends on the relationship between the frequency, relative and absolute level, and relative timing of the two sounds.

The more widely spaced in frequency the two sounds, the less masking occurs. There is more masking when the masked sound is higher in frequency than the masker (known as "upward" masking) than when it's below the masker in frequency. This is in part due to the asymmetrical shape of the auditory filters in our hearing mechanism used for frequency analysis. The upward slopes of the filters are wider and less steep than the bottom slopes. When two sounds are close enough in frequency that they fall within the same auditory filter more masking occurs.

As the absolute and relative level increases between the two sounds, the more masking occurs. As the absolute level increases, the shapes of the auditory filters widen, and so more sounds fall within the filter of the masking sound. Our auditory filters also widen with age, which explains why our frequency selectivity gets worse, and we have difficulty resolving speech in a noisy bar. We also can detect less distortion at higher SPL due to increased masking, and the fact that the ear itself produces more distortion at higher SPLs.

Temporal masking occurs when two sounds are separated in time arrival. Forward masking occurs when the masked sound follows the masker. Backward masking occurs when the masked sound precedes the masking sound. Forward masking generally produces more masking than backward masking.

Masking explains a lot about how the ear works and how we perceive sound. It is a lot more complicated than how I've explained it but those are the highlights.
 
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tonmeister2008

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Jun 20, 2010
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Here is the entire article, for complete context: http://ultraaudio.com/opinion/20100501.htm

I agree with what you've said. I was speaking specifically of in-room measurements. If you look at the two graphs in the article, it is clear that the room is swamping the FR. What you're seeing is primarily room, and the two graphs look very similar -- the room modes are quite obvious. The anechoic graphs would shed more light on the two designs and you'd have a deeper understanding of the individual speakers. For instance, diffraction or driver break-up modes can be gleaned from the anechoic FR. Those two issues would be masked by the room acoustics in the in-room graphs. In room two designs that look almost identical on an FR plot can sound very, very different.

Also, it should be clear that in the example I am using two extremely flat, neutral speakers. Both of these speakers are on the order of +/- 1.5dB anechoic.

Yep. In-room measurements don't give you enough information about the direct, early and late reflected sounds above 200-300 Hz as you confirmed. Comparing those 1/6-octave smoother in-room curves, I would have guessed the Rockport Arrakis sounds better in the bass and mid/treble -- but the full set of anechoic data would confirm this.

A single FR curve is not enough.
 

sasully

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Jun 29, 2010
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Sean,

Correct me if I misremember, but didn't you say recently that the NRC anaechoic test chambers are no longer properly calibrated for accurate bass frequency measurements? If so, wouldn't that render Soundstage's measurements less reliable as indicators of audio quality?
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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Sean,

Correct me if I misremember, but didn't you say recently that the NRC anaechoic test chambers are no longer properly calibrated for accurate bass frequency measurements? If so, wouldn't that render Soundstage's measurements less reliable as indicators of audio quality?

SoundStage contacted me and told me that NRC has in fact applied a low frequency correction below 100 Hz, so my information is apparently incorrect.

How well the NRC correction works depends on the extent to which the loudspeaker's woofers and ports are located within space of the chamber where the correction is valid. For large loudspeakers like Revel Salon 2, the woofers and rear ports fall outside that space, and the NRC chamber will not accurately reflect its true LF response of the loudspeaker. We recently had to supply SoundStage accurate LF data on the Salon 2 when it was reviewed and tested in the NRC chamber. But for more typical sized speakers where the woofers/ports are physically located within the correction zone, you would expect a more accurate characterization of the response below 100 Hz
 

Jeff Fritz

[Industry Expert]
Jun 7, 2010
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923
SoundStage contacted me and told me that NRC has in fact applied a low frequency correction below 100 Hz, so my information is apparently incorrect.

Doug Schneider just wrote a piece on our use of the NRC: http://soundstagenetwork.com/index....t-the-nrc&catid=42:regular-features&Itemid=40

I think it is fair to say that the NRC's speaker measurements were the springboard for much of the excellent speaker research available today. And although I'm sure many of you know this already, we pay the NRC for our measurements. The actual measurements are done by the engineers at NRC -- we don't simply use the facilities and do the measurements ourselves. :eek:

Lastly, there are a few interesting bits in Doug's article on a couple of speakers we've measured, along with some preliminary info on a set of measurements that will accompany a forthcoming review. It's a brand many here will be interested to read about.
 

tonmeister2008

WBF Technical Expert
Jun 20, 2010
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Doug Schneider just wrote a piece on our use of the NRC: http://soundstagenetwork.com/index....t-the-nrc&catid=42:regular-features&Itemid=40

I think it is fair to say that the NRC's speaker measurements were the springboard for much of the excellent speaker research available today. And although I'm sure many of you know this already, we pay the NRC for our measurements. The actual measurements are done by the engineers at NRC -- we don't simply use the facilities and do the measurements ourselves. :eek:

Lastly, there are a few interesting bits in Doug's article on a couple of speakers we've measured, along with some preliminary info on a set of measurements that will accompany a forthcoming review. It's a brand many here will be interested to read about.

Nice article. I agree that the NRC measurements puts SoundStage far ahead of any other review magazine in terms of trustworthy meaningful loudspeaker measurements. Looking forward to hearing what unusual performance you found in a manufacturer's speakers. Often manufacturer don't clearly understand the LF behavior of their speakers because of poor S/N in their measurements or insufficient frequency resolution at LF. This happens a lot with time-gated measurements where the reflection-free time window is too short. There is no substitute for a quiet anechoic space.

If you want to measure more loudspeakers with NRC accuracy or better without paying the high NRC costs, please send the speakers to me. I'd be happy to measure them for you for free :) You can even say they were measured by (ex) NRC scientists.
 

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