Some more very helpful comments of him
In think if you go back and review my - extensive - contributions to this thread you will realize that "neutral" is not "only in anechoic chamber". What has been found over several decades of conscientious investigation and publication is:
(a) in double blind tests in normally reflective rooms (different ones over the years) listeners give the highest ratings to loudspeakers that measure essentially flat and smooth on axis, and at least smooth off axis in an anechoic chamber or functional equivalent. What they are recognizing and responding favorably to is the absence of resonances - i.e. neutrality.
(b) Room curves do not correlate as well with listener preferences, except at bass frequencies, below the about 300 400 Hz transition frequency. Adjusting loudspeakers having different flaws to match full-bandwidth room curves of highly rated loudspeakers cannot yield the same high quality sound. This is especially true if narrow-band equalization is used above the transition frequency. This fact is not to be found in the advertising literature of "room EQ" products. Guess why?
(c) Although different rooms add their own "signature" sounds, when evaluated in different rooms listeners unerringly zero in on the most neutral - resonance-free - loudspeakers. It is merely that loudspeakers in different rooms are identifiable, just as in live sound we hear the same voices and musical instruments, but in different rooms. Humans have a significant ability to separate the two - except at bass frequencies in small rooms, where the room is the dominant factor and intervention is necessary to restore broadband neutrality - Chapter 8 in the 3rd edition.
Audio professionals, in my experience, are generally not aware of these facts. However, they substantially determine what we get to listen to.
From
https://www.avsforum...57.html#post58521736
As for "voicing", what I wrote early in Chapter 3 says it all:
LOUDSPEAKER “VOICING”.
Music composition and arrangement involves voicing to combine various instruments, notes and chords to achieve specific timbres. Musical instruments are voiced to produce timbres that distinguish the makers. Pianos and organs are voiced in the process of tuning, to achieve a tonal quality that appeals to the tuner or that is more appropriate to the musical repertoire. This is all very well, but what has it to do with loudspeakers that are expected to accurately reproduce those tones and timbres?
It shouldn’t be necessary if the circle of confusion did not exist, and all monitor and reproducing loudspeakers were “neutral” in their timbres. However that is not the case, and so the final stage in loudspeaker development often involves a “voicing” session in which the tonal balance is manipulated to achieve what is hoped to be a satisfactory compromise for a selection of recordings expected to be played by the target audience. There are the “everybody loves (too much) bass” voices, the time-tested boom and tizz “happy-face” voices, the “slightly depressed upper-midrange voices” (compensating for overly bright close-miked recordings, and strident string tone in some classical recordings), the daringly honest “tell it as it is” neutral voices, and so on. It is a guessing game, and some people are better at it than others. It is these spectral/timbral tendencies that, consciously or unconsciously, become the signature sounds of certain brands. Until the circle of confusion is eliminated, the guessing game will continue, to the everlasting gratitude of product reviewers, and to the frustration of critical listeners. It is important for consumers to realize that it is not a crime to use tone controls. Instead, it is an intelligent and practical way to compensate for inevitable variations in recordings, i.e. to “revoice” the reproduction if and when necessary. At the present time no loudspeaker can sound perfectly balanced for all recordings.
From
https://www.avsforum...57.html#post58522906
To Resonate or not to Resonate, That is the Question?
Apologies to Shakespeare . . .
This discussion has drifted into an area of literal interpretations of classical definitions with some semantics thrown in. If there is a shallow hump in a frequency response, in literal terms it is a very low-Q resonance, implying a mechanical, electrical or acoustical system with a "favored" frequency range. In a physical system as complex as a loudspeaker it may sometimes be difficult to decide what is happening. Crossovers are equalizers, by any other name, that interact with transducers having inherently non-flat tendencies - the result is a combination of both electrical and mechanical elements. Equalizers can be resonators just as surely as acoustical cavities, enclosure panels and cone breakup. So a frequency response feature may be partly mechanical and partly electrical , but the end result can be that of a resonance having Q. Achieving a desirable flat on-axis sound using passive or active networks can result in non-flat off-axis behavior because transducers have frequency-dependent directivity. In a room the result is that even with flat direct sound, the early reflected and later reflected sounds may exhibit emphasis over a range of frequencies that could forgivably be interpreted as a low-Q resonance.
As discussed many times in this thread, transducers are inherently minimum-phase devices, so electrical EQ can modify the performance of mechanical resonances - a huge advantage for active loudspeakers or those for which accurate anechoic data are available.
In the crossover between a 6- to 8-inch woofer and a 1-inch tweeter, a directivity mismatch at crossover is unavoidable. Above crossover, the tweeter has much wider dispersion than the woofer, so there is an energy rise over a wide frequency range. Is this a resonance? Technically not, in the dictionary definition sense. However, there is a broad hump in radiated energy, so perceptually it may appear to be so. Figure 4.13 shows such an example where even crude room curves were adequate to recognize the energy excess in an above-crossover energy excess and attenuate it. Because wide bandwidth (low-Q) phenomena are detected at very small deviations there was a clear improvement in perceived sound quality even though medium and higher-Q "real" resonances were essentially unchanged. Addressing all of the "resonances" was not surprisingly the best.
So, don't get hung up on semantics. Deviations from a linear frequency response are all describable as "resonances" if one chooses to. Broadband trends are very low-Q, narrower trends, medium Q, and so on. Even a bass tone control is an opportunity to manipulate a "resonance" - in this case the hump that develops above the low cutoff frequency which, depending on the system design will have a Q.
Narrow dips are usually the result of destructive acoustical interference and are usually audibly innocuous because they change with direction/position. Broader dips can be interpreted as anti-resonances if one chooses to, whether there is an associated frequency selective absorption process or not. Mostly not.
From
https://www.avsforum...61.html#post58530612
As I said, because loudspeaker transducers are minimum-phase devices one can use electrical parametric EQ to attenuate the mechanical resonances in transducers - using anechoic data of course. So, if you add a hump to an otherwise neutral/resonance free speaker you have added a resonance. This is why it is crucial to pay attention to what "room equalizers" are doing. If they "see" a ripple in a measured curve caused by acoustical interference of direct and reflected sound, and try to flatten it, they may be adding a resonance and degrading a good loudspeaker.
From
https://www.avsforum...61.html#post58530898
Yes spatial averaging smooths curves; they look better - that is one reason why it is favored. However, because these curves are typically steady-state curves little of value is learned about the speaker, and nothing is specific to the prime listening location. Spectral smoothing is another "feature" that smooths curves. Tradeoffs are not always advantages.
Spatial averages reduce the ability to be analytical about room modes/standing waves.
So, it comes down to "how much do you know about the loudspeaker - in anechoic data?" If none, the usual case, such room curve data cannot be trusted. If one knows a lot, e.g. a spinorma, one can predict the room curve with reasonable precision. The room curve, by itself, is not reliably associated with sound quality.
From
https://www.avsforum...61.html#post58534080
, וכד'
