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post #1231 of 1494 Old 08-28-2017, 01:50 PM
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Originally Posted by Jesse44 View Post
I've been surprised by the number of albums available in multichannel from independent classical labels like Channel Classics, BIS, and Pentatone. Many are excellent.

Of course I wish there were more!
Yes, I have heard some and you are right, they are good. The most impressive demo I have heard was in Auro3D, where one was truly in the venue (concert hall & cathedral), even getting up and walking around the home theater. Impressive. But almost all classical: "5% of 5%" market share, sadly.

I enjoy classics - including season tickets to the LAPhil - but there is so much interesting stuff that could be done in pop and jazz, and I am definitely not talking about "middle of the band" perspectives. I can hear hints of it in some upmixed modern stereo studio recordings - I can almost see the creators yearning for a larger palette.
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post #1232 of 1494 Old 08-28-2017, 02:36 PM - Thread Starter
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The other day there was some discussion about whether or not Harman was moving away from the "Spinorama" measurement. They are not. However, they are coming up with a newer method in regard to in-wall speakers, like the SCL2, 3 and 4.
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post #1233 of 1494 Old 08-28-2017, 02:39 PM
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post #1234 of 1494 Old 08-28-2017, 03:26 PM
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Since you can't really move the wall...I suspect it involves an arc'd track ;-)
Yes it is a 2 pi, hemi-anechoic chamber measurement - an enlarged version of the facility used for transducer measurements.

The old original version for in walls involved a section of wall that was rotated - true story.
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post #1235 of 1494 Old 08-28-2017, 03:28 PM
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Originally Posted by John Schuermann View Post
The other day there was some discussion about whether or not Harman was moving away from the "Spinorama" measurement. They are not. However, they are coming up with a newer method in regard to in-wall speakers, like the SCL2, 3 and 4.
So that response Genesplitter received about the 5 series was...misinformation?

Life is Lambertian
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post #1236 of 1494 Old 08-28-2017, 03:37 PM - Thread Starter
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Originally Posted by 12B4A View Post
So that response Genesplitter received about the 5 series was...misinformation?
I'm not sure. I'll see what I can find out specific to Studio Series.
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post #1237 of 1494 Old 08-28-2017, 06:41 PM
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Originally Posted by Floyd Toole View Post
SFM, as explained in the AES paper and my books, involves making transfer-function (amplitude and phase) measurements from each possible subwoofer location to each of the seats chosen for preferred treatment - or all seats, if you wish. This can be done with a single subwoofer moved around the room. That data gets stored in a laptop. The next step is to select some number, preferably four, of the measured locations and let the optimization algorithm do the tedious task of finding the best combination of delay, level and one band of parametric equalization in each of the subwoofer feeds. The goal is to minimize seat-to-seat variations so that any global EQ that may be needed benefits all of the listeners. The result of the optimization can be seen, so it is possible to repeat the exercise with different combinations of sub locations to find the best choice, but it will be hard to beat the four corners. Once the best combination is decided on, SFM can be run again with the subs that are intended to be used - they need not be identical.

The simple way is just to decide on four locations, put the subs in place and run SFM. It will do the best it can, which may or may not be the best possible solution.

This differs from "garden variety" EQ in that it is transfer function, not steady-state response, that is used for the optimization. Obviously, with patience, this can be done by trial and error, or perhaps someone else has developed an optimization routine. So long as it does not violate the Harman patent, that too can work.

I don't yet know how well the SDP75 implementation will work. There are several examples of the original system in my books. The gains in bass uniformity, absence of room resonances and efficiency are impressive.
Steady state response of a system can include magnitude and phase.

So ... still not following what phase consideration does in addition to magnitude, ultimately.

I get that phase affects superposition magnitude result, sure.

(May not be worth further delving either my inability to parse these notions or explainers' inability to tease them out adequately.)
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post #1238 of 1494 Old 08-28-2017, 06:53 PM
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any owners/engineers of these m2's/salon2 care to give comparison vocabulary on why they picked these vs others and why the competition wasnt desired? I know I didnt chose some speakers purely for aesthetics and others cause I wanted a flat top...no angles or odd shapes...I guess everyone can say cause they sounded the best, but that doesnt really explain the details...now if these speakers were top sellers and everyone bought them I guess argument would be easier...not only are they the best measured but in sales also...but I dont think they are the best in sales, thus asking what made the buyes/owners buy?

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post #1239 of 1494 Old 08-28-2017, 07:33 PM
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Originally Posted by davidrmoran View Post
Steady state response of a system can include magnitude and phase.

So ... still not following what phase consideration does in addition to magnitude, ultimately.

I get that phase affects superposition magnitude result, sure.

(May not be worth further delving either my inability to parse these notions or explainers' inability to tease them out adequately.)
Have you read the Welti and Devantier article about SFM?

Noah Katz's original question was about what makes SFM different from conventional EQ. It might have been better to explain that SFM reduces seat-to-seat response variation and that conventional EQ does not and cannot. In order to do this, SFM must make calculations based on measurements that take the phase response of each individual sub into account, while conventional EQ does not. In this regard, individual sub phase response measurement is part of the means to the end (of reducing seat-to-seat variation) and not the end itself. Maybe that's where some of the confusion arises.

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post #1240 of 1494 Old 08-28-2017, 07:49 PM
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Originally Posted by andyc56 View Post
Have you read the Welti and Devantier article about SFM?

Noah Katz's original question was about what makes SFM different from conventional EQ. It might have been better to explain that SFM reduces seat-to-seat response variation and that conventional EQ does not and cannot. In order to do this, SFM must make calculations based on measurements that take the phase response of each individual sub into account, while conventional EQ does not. In this regard, individual sub phase response measurement is part of the means to the end (of reducing seat-to-seat variation) and not the end itself. Maybe that's where some of the confusion arises.
How is it that "conventional EQ does not and cannot"? What is the difference in measurable and audible outcome b/w SFM and spatially averaged (spatially to smooth seat-seat variation) conventional EQ? What does taking "phase response of each individual sub into account" do that proper level measurements, and level EQ based thereon, do not do?

I assume the purported answer may have to do with some acousticians call frequency time dispersion; I guess we know this as 'delay' (??). The FT book does not touch on this much, I believe, doing a search now. The Welti-DeVantier paper states 'Setting the range for the delay correction factor is far less intuitive. In the end it was decided to limit the amount of delay so as to minimize questions about the time domain performance of SFM', but then goes on to say 'It should be noted that delay is a very effective modifier for room 1' and 'These data suggest that subwoofer gain and delay are equally powerful modifiers in the general sense'. But I do not see that it describes how or what the audible consequence ultimately is other than level change. Hence my genuine LF curiosity: what other than level, achievable by prudent level EQ?

And (OT) to revisit how many frequency cycles are needed to be able to make, or fail to make, spectral / timbral judgments, I urge the curious to read / reread chapters 6-11 of the FT book, where his mastery of the learning and his ability to synthesize are most striking. Just one example: 'Haas described this [experiment result] as an “echo suppression effect.” Some people have taken this to mean that the delayed sound is masked, but it isn’t. Within the precedence effect fusion interval, there is no masking—all of the reflected (delayed) sounds are audible, making their contributions to timbre and loudness, but the early reflections simply are not heard as spatially separate events. They are perceived
as coming from the direction of the first sound; this, and only this, is the essence of the “fusion.” The widely held belief that there is a “Haas fusion zone,” approximately the first 20 ms after the direct sound, within which everything gets innocently combined, is simply untrue.' This is followed by a wonderful summary quote from the great Arthur Benade, listing the 40ms bundle as 'singly perceived composite entity represents the accumulated information about the acoustical features shared by the set of signals (tone color, articulation, etc.). It is heard as though all the later arrivals were piled upon the first one without any delay—that is, the perceived time of arrival of the entire set is the physical instant at
which the earliest member arrived', which may be why some think we sense other than localization with a few cycles. FT continues in his own words that Benade 'emphasize[s] that there is an accumulation of information from the various members of the sequence. It is quite incorrect to assume that the precedence effect is some sort of masking phenomenon which, by blocking out the later arrivals of the signal, prevents the auditory system from being confused. Quite to the contrary, those arrivals that come in within a reasonable time after the first one actively contribute to our knowledge of the source.' Anyway, it is quite the scholarly and intellectual performance.

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post #1241 of 1494 Old 08-28-2017, 08:05 PM
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like a famous engineer once told me...when it comes to stereo music reproduction...everything matters. way above my paygrade...so im out...feel like Im talking with my dad.

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post #1242 of 1494 Old 08-28-2017, 08:22 PM
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Originally Posted by davidrmoran View Post
How is it that "conventional EQ does not and cannot"? What is the difference in measurable and audible outcome b/w SFM and spatially averaged (spatially to smooth seat-seat variation) conventional EQ?
Just to clarify, I'm referring only to the modal region in the following discussion, as SFM is a technique that targets only the modal region. It's only for subs.

A spatially averaged response calculation by definition removes seat-to-seat response variation by averaging. The purpose of SFM is to reduce the seat-to-seat variation itself, as quantified by a metric called MSV (mean spatial variance). It's all in the Welti and Devantier article that I linked in my previous post.

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What does taking "phase response of each individual sub into account" do that proper level measurements, and level EQ based thereon, do not do?
SFM attempts to control not the final response at the main listening position or some spatially averaged computation of multiple listening positions, but the interaction of the subs with one another at many listening positions by having different EQ for each. The metric for determining its success or failure is the MSV.
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post #1243 of 1494 Old 08-28-2017, 08:34 PM
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any owners/engineers of these m2's/salon2 care to give comparison vocabulary on why they picked these vs others and why the competition wasnt desired? I know I didnt chose some speakers purely for aesthetics and others cause I wanted a flat top...no angles or odd shapes...I guess everyone can say cause they sounded the best, but that doesnt really explain the details...now if these speakers were top sellers and everyone bought them I guess argument would be easier...not only are they the best measured but in sales also...but I dont think they are the best in sales, thus asking what made the buyes/owners buy?
As an engineer I appreciate good engineering and Harman has that in spades. Lots of research and some of the most well-known and most-respected names in the business contributing. And of course they have great measurements.

As a musician I appreciate speakers that offer natural sound, and that means realistic (not necessarily "real" but that should go, too), and an image that is stable and precise. It bugs me when the sound and position changes as a singer or instrument runs up and down the scale and some really well-respected speakers exhibited little discontinuities in their sound with solo instruments or voices. I also want a speaker that can handle dynamics, as in not falling apart when the orchestra swells, and presents a solid image that does not move around as the sound gets louder or softer.

As an audiophile I want the sound to be engaging, meaning smooth and not shrill or boomy, with a sense of "space" that "fills out" the room. Accurate and clean, natch, without the sound field collapsing when it gets soft or loud.

A number of speakers have one or more of these attributes, and some probably have all, but for me Harman/Revel got the most right and least wrong for the price. I was looking in the $10k to $20k or so price range and fully expected to end up with a new pair of Magnepans or an ESL. I did not do a lot of comparison listening for various reasons, but I have not regretted at all my choice of Salon2's instead of another planar. I know what they (planar speakers) sound like, and the Salon2s certainly match or beat the conventional systems to which I had listened in that price range (and a couple well above).

FWIWFM - Don
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post #1244 of 1494 Old 08-28-2017, 08:40 PM
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Originally Posted by davidrmoran View Post
How is it that "conventional EQ does not and cannot"? What is the difference in measurable and audible outcome b/w SFM and spatially averaged (spatially to smooth seat-seat variation) conventional EQ? What does taking "phase response of each individual sub into account" do that proper level measurements, and level EQ based thereon, do not do?

Assuming "conventional EQ" means applying the same EQ to all subs, it will smooth response at the mic location may just as well make it worse somewhere else.

Because in some sense phase is equivalent to distance, SFM is effectively moving the subs relative to each other* to achieve lower spatial variation.

Adding control of relative level expands the variables in play to the same end.

* Not completely like moving them, since in the same position the subs will excite the same modes.
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post #1245 of 1494 Old 08-28-2017, 09:09 PM
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thanks don, that made alot of sense to me. my favorite speakers from a kid were planar speakers and always said I would own a pair....just never got the right space for em...

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post #1246 of 1494 Old 08-28-2017, 09:59 PM
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Originally Posted by noah katz View Post
Assuming "conventional EQ" means applying the same EQ to all subs, it will smooth response at the mic location may just as well make it worse somewhere else.

Because in some sense phase is equivalent to distance, SFM is effectively moving the subs relative to each other* to achieve lower spatial variation.

Adding control of relative level expands the variables in play to the same end.

* Not completely like moving them, since in the same position the subs will excite the same modes.
>> smooth response at the mic location

why I said spatially averaged several times --- meaning several mike locations, using temporal averaging.

>> the interaction of the subs with one another at many listening positions by having different EQ for each. The metric for determining its success or failure is the MSV.

and so the net net outcome is different how? Or, to put it another way, can SFM somehow be replicated by other (simpler, cheaper) means with good-enough level measurements?
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post #1247 of 1494 Old 08-28-2017, 10:07 PM
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Originally Posted by davidrmoran View Post
Or, to put it another way, can SFM somehow be replicated by other (simpler, cheaper) means with good-enough level measurements?

Sure, you could do SFM manually with a multichannel EQ like MiniDSP.

It would be cheaper, but not simpler; trying out the endless permutations of phase (by different delay settings), parametric EQ, and levels would be a nightmare.
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post #1248 of 1494 Old 08-28-2017, 10:10 PM
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if you have a small enough theater or big enough subwoofers, you may not need so much eq

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post #1249 of 1494 Old 08-28-2017, 10:17 PM
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Dr. Toole,

Unrelated, but a discussion in another thread brought a long-unanswered burning question to mind.

Do you know why it is that no auto-EQ system (that I'm aware of) closes the loop and allows an "after" measurement of response?
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post #1250 of 1494 Old 08-28-2017, 10:20 PM
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Originally Posted by noah katz View Post
Sure, you could do SFM manually with a multichannel EQ like MiniDSP.

It would be cheaper, but not simpler; trying out the endless permutations of phase (by different delay settings), parametric EQ, and levels would be a nightmare.
sigh, why I said level measurements --- magnitude, amplitude only

Last edited by davidrmoran; 08-28-2017 at 10:22 PM. Reason: elaboration
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post #1251 of 1494 Old 08-29-2017, 02:16 AM
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I was trying to keep this succinct to avoid overwhelming the thread with tech info no one else cares about, but it seems I failed. Apologies to everyone in advance. If anyone wants me to elaborate on these points or continue the conversation, feel free to point me to another thread in which this discussion is more appropriate.

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your statement was in the context of the specular region. you continue to ignore that the specular region of a bounded space is not a static definition - it is dependent upon room/boundary dimensions. a large (flat/planar) boundary that is large with respect to a "low frequency" still adheres to the principle.

your comment regarding a 6"x6" panel is another strawman with no relevancy. and it was already noted (and renoted) in the original response that a diffuser must be large with respect to wavelength "to be seen" (thus to limit diffraction around). you seem to be mixing (or confusing) the context of the conversation to steer away from the original responses.

perhaps you could be more specific and actually illustrate how "these models dont work" - in detail - under the strict context of the conversation that has been provided.

yes, diffraction is a fundamental concept of wave behavior but not in the context of the original statement being made. could you actually explain how diffraction is in play with respect to the original reply that you made: "Diffraction is the term people use to describe physics that defies the over-simplistic specular model".

what do you actually mean by this use of the word? and why do you continue to purposely ignore the strict context of which a statement is made under?
Suppose one sketches a control room design and performs geometric calculations to determine the various reflection points for a listener confined to a narrow region of space in the room. A naive designer might conclude that a 6"x6" panel (make it 12"x12" if you like, to give the listener some freedom to move his or her head) of sufficient depth at each reflection "point" is sufficient to eliminate that reflection. This is reasonable for high frequencies but for low frequencies, a larger area must be treated to eliminate the reflection. An acoustician might say "you should make the panel bigger to account for diffraction".

I purposely avoided examples involving diffusion because they are more complicated to reason about. For example, the minimum width requirement relates to how the diffuser itself works, which while based on the principles of diffraction and superposition (how/why phase grating diffusers are able to scatter sound in space as well as time) are not quite the same. In fact, if the reflection is eliminated first with sufficient absorption, then diffusion can be synthesized actively using an omni microphone, point source loudspeaker, and signal processing. Such a diffuser will have ideal spatial diffusion properties and potentially ideal temporal diffusion properties while functioning to as low a frequency as is desired while taking up near zero space (except for the absorption).

Hey wait, that sounds kind of like multi-channel ambiance reinforcement.

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...

again, missing the context of the original statement that is with respect to the specular region where boundary size is large with respect to wavelength.
Specular behavior is very much a scale-related phenomenon, which you do seem to grasp, albeit incompletely. The size of the boundary relative to wavelength is not the only consideration. The distances of source and receiver are also important, which is where the terms "near-field" and "far-field" come about. In the classic single slit experiment, the far-field approximation is used to simplify the math by assuming sufficient distance exists between the slit and screen for particular mathematical terms to be disregarded.

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my original statement was that shallow diffusers are tantamount to thin porous absorbers - as each are only effective to the HF band and thus allow the lower-mid band to persist - thus impeding the listening position with a colored/EQ'd/LPF reflection. this is exasberated further by the fact that a typical loudspeaker will have less HF energy dispersed off-axis (eg, to sidewall) than lower/mid band energy.

what is your citation that a shallow diffuser "degrades the soundfield" more-so than a thin porous absorber - both of which are non-broadband treatments that color the specular reflection?
Please re-read my response. What I stated was the opposite of what you wrote in bold. A shallower diffuser degrades the sound-field less than a thin porous absorber because it does not remove nearly as much high frequency energy relative to low frequency energy from the room. Its tendency to absorb is only marginal.

And just to remind you: in one of my previous posts, I did in fact agree with you that in the context of treating early reflection "points", a diffuser that is active over only part of the bandwidth will alter the spectral content of that reflection.

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the absorption characteristics of phase gratings are fairly well understood and thoroughly explored by the work of trevor cox and peter d'antonio (RPG Inc) - and they are not inherently benign.
I am well aware of that. That's why I used the word "marginal". The effective absorption is still nowhere near as high as a fiber glass panel in most instances. If anything I believe Cox and D'antonio's research was done to try to debunk those who were claiming that diffusers absorb too much. Also it is noted in that reference that absorption is much greater in true Schroeder diffusers, in which the wells are isolated all the way to front end of the diffuser, than in pseudo-diffusers in which the wells are not isolated. The diffusers used in the Blackbird studio example you discussed below were of the pseudo-diffuser variety, which also means they weren't true primitive root diffusers (PRDs) in a theoretical sense.

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sorry but you cannot simply hand-wave away an obvious fact. the first-order returns modified solely by the use of wooden diffusers attenuates the signal by -30dB. the losses from edge diffraction not "marginal". the room is not "anechoic" (it has a wooden floor and humans also deal with the integration of the diffused returns over 0.3s) - but it highly damped. it's an absolute valid example detailing how diffusers induce losses. simply saying something is not "a valid example" does not override real world measurements.
No, I am not hand waving this away at all. You are misinterpreting data from the Energy-Time Curve (ETC) plot, which I am presenting here for discussion and which, by the way, you should have called out for context when you posted your "-30 dB" claim:



What you are citing as evidence of lossiness in diffusers is the -30 dB gap between the initial sound arrival and the first several milliseconds of reflected sound arrivals. Nothing could be further from the truth.

First of all, the gap itself is largely meaningless without additional information. Do you know what happens if the mic is moved to half the distance from the speaker and the measurement repeated? The gap increases by approximately 6 dB. That's not surprising because the direct-to-reflected sound ratio is also increasing. One reason "near-field" monitoring is so popular is that it helps to increase that ratio. But we aren't talking about that here. We're talking about diffuser lossiness.

Second of all, the Y-axis of the ETC isn't really energy, it's more like energy density. To obtain an energy quantity, one must compute the area under the curve over a finite span of time. That can't be done using the data as it is depicted here because of how it is displayed. The resolution is lower than the sampling rate of the measurement, and where multiple samples share the same column in the picture, the plotter is probably showing only the maximum of those samples. It's far easier to compute these kinds of quantities from the raw data using a computer.

Ignoring the technical complications of the visualization and the changes in direct-to-reflected sound ratio with measurement ratio, the fact that the Y-axis of the ETC shows a -30 dB gap needs to be interpreted in terms of area. One effect of the diffusers is to spread reflected energy out in time. In units of "energy density", -30 dB is 0.1%. So that means that 1000 samples at -30 dB have the same energy as a single sample at 0 dB. Note that at a sample rate of 48000 Hz, 1000 samples is about 21 ms. But given the caveats I mention above, you can't really read much into my numbers here. I just discuss this to illustrate that a lot of energy can still be present in the measurement even if the max ETC "level" remains under -30 dB.

And because of the differences in direct-to-reflected ratio depending on mic distance, there's absolutely no way to tell how much loss is occurring upon the initial interaction of the sound with the diffusers. Perhaps the one and only bit of quantitative information that *can* be gleaned from this ETC is the decay rate of the diffuse sound-field, which reveals a log-linear loss of about -20 dB in 0.1 seconds or an RT60 of 0.3 seconds. Those are actual losses within the room as opposed to effects of temporal smearing and differences in direct-to-reflected sound ratio. While the diffusers may be making some contribution to the losses, I'd bet that the majority of those losses are occurring because of the large absorption panels shown in this room picture:



Oddly enough, I recall reading that the panels were specifically sized as part of the design to achieve the target RT60. Perhaps someone who knows the designer could ask if the absorbers were specified a priori using, e.g. the Sabine equation, and if so, how close the room performed to the spec. That's be one way to answer the question of just how lossy those diffusers are. But honestly, I don't care that much. I'm just trying to debunk your argument here.

You said yourself that Cox and D'antonio have already done the work on the subject of lossy diffusion. They do, in fact, offer guidelines for how to keep absorption to a minimum. Subjectively speaking, I find diffusers to increase the apparent liveness of the room despite very slight reductions in mid and high frequency decay time. I also don't have a problem with lingering reflections being low-passed because that's encountered naturally. Many if not acoustic sources have increasing directivity with frequency just like speakers. So used in moderation, I feel diffusers are a big win, even if they only work over a limited bandwidth.

On the subject of the ETC, here's something else you probably aren't aware of. Like the impulse response, the primitive signal used to generate the ETC is the Dirac Delta or Impulse, and the spectral density of the Impulse is flat, like white noise, as opposed to pink noise which has a 1/f spectral density. In other words if the bandwidth of the impulse is 20 kHz, then half of the energy is contained in the last octave. A whopping 95% of the energy of the ETC is contained in the frequencies above 1 kHz. This means that using ETC for most acoustic analysis is actually a very bad idea. It's unfortunate that a lot of people are probably treating their rooms to make the ETC meet a target and leaving serious low frequency problems unaddressed because of have such little weight in the ETC. I dare say much of the recommendations around ETC are a kind of Cargo Cult Science.

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ok - your original statement was that: "Diffusers, when they are properly designed, only marginally absorb sound, so unlike absorbers, they are not permanently removing energy from the room within their active bandwidth. The made analogy is flawed." so you erroneously make the claim that diffusers do not "permanently remove energy from the room" and then instead of providing citation or evidence against a room that clearly details this, you attempt to distract and go off on a tangent about the room's response. whether or not people prefer working in the room or prefer absorption at sidewalls vs diffusion is entirely independent of the real-world behavior and absorptive losses the broadband diffusers impart - entirely contradicting your statement. just another distraction away from the original claim.
Insert the words "more than a marginal amount of" between "removing" and "energy" above. Satisfied now? If not, then you must still misunderstand what I wrote above about the ETC and what it actually means.

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again, you continue to propagate the very well known and understood fundamentals of reflection phase gratings as some sort of "gotcha". thankfully empirical measurements also indicate an inherent lossy component (1/4wave resonance, viscous losses, edge diffraction, etc) - negating your original statement that diffusers do not permanently remove energy from the room.

if you have data to contrast in comparision to cox & d'antonio's work to support your statement, then please provide it.



the devices were presented as examples of ways of extending the bandwidth of a diffuser in response to the statement: "Can you point me to what those look like, broadband diffusers properly scattering sound down to an octave-plus below middle C? "

their proper use and deployment (eg, real estate constraints) is entirely independent of the fact that they exist and can be used to extend their bandwidth to create "broadband diffusers properly scattering sound down to X". phase gratings scale with wavelength - this is entirely independent of whether it is useful in a small residential size room. that's an entirely different conversation.
Please stop putting words in my mouth. In my original statement, many posts ago, I used the word "marginal" to indicate that some slight absorption does occur. Far too many words have been wasted over a failure to comprehend what I wrote in the first place. And I don't even understand this because you explicitly quoted my use of the word *marginal* later on in your response. If you continue to insist that absorption in competently manufactured diffusers is anything more than marginal, then we will just have to agree to disagree or we can take our argument about what ETC and impulse response data actually means to another thread.

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post #1252 of 1494 Old 08-29-2017, 02:36 AM
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If I'm understanding the above correctly, I believe the assertion is that if I take my old Story and Clark upright piano, and put it in a wide variety of venues, I would always be able to tell that what I am hearing is my old Story and Clark piano. I would most likely not mistake it for a Steinway Grand or any other piano (even one much closer in character to my Story and Grand), no matter what the environment - even a tile bathroom.

Yes! Except I was also suggesting that in the tile bathroom (assuming very small like in my 1950s era house) or closet, it might be harder to tell them apart because of the perceived excess of low frequencies in the sound. Likewise if sitting too far away in the gym. There's a point at which the acoustics become "bad", to the point where it's difficult to discern what's going on. At that point, usually non-acoustiphiles begin to take note.
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Even the "good ones" typically have diffusion coefficients that struggle to break 0.5 and quite a bit of variation vs. frequency.
If the array is large enough and one uses modulation, it can get higher as shown below with RPG Modffusor. Obviously Modffusor doesn't operate above 4-5Khz but that's possible with fractals. A custom deeper unit would diffuse lower as we know but either way; treatment of early arriving specular reflections with absorption or redirecting yields higher accuracy if that's the goal.



This discussion is probably better suited in another thread.
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As an engineer I appreciate good engineering and Harman has that in spades. Lots of research and some of the most well-known and most-respected names in the business contributing. And of course they have great measurements.

As a musician I appreciate speakers that offer natural sound, and that means realistic (not necessarily "real" but that should go, too), and an image that is stable and precise. It bugs me when the sound and position changes as a singer or instrument runs up and down the scale and some really well-respected speakers exhibited little discontinuities in their sound with solo instruments or voices. I also want a speaker that can handle dynamics, as in not falling apart when the orchestra swells, and presents a solid image that does not move around as the sound gets louder or softer.

As an audiophile I want the sound to be engaging, meaning smooth and not shrill or boomy, with a sense of "space" that "fills out" the room. Accurate and clean, natch, without the sound field collapsing when it gets soft or loud.

A number of speakers have one or more of these attributes, and some probably have all, but for me Harman/Revel got the most right and least wrong for the price. I was looking in the $10k to $20k or so price range and fully expected to end up with a new pair of Magnepans or an ESL. I did not do a lot of comparison listening for various reasons, but I have not regretted at all my choice of Salon2's instead of another planar. I know what they (planar speakers) sound like, and the Salon2s certainly match or beat the conventional systems to which I had listened in that price range (and a couple well above).

FWIWFM - Don

I appreciate you speaking common English for the few of us peons left here. And sorry to read that you left the panel plantation. I'm still here, unlikely to ever leave, but I have always had other systems, many with conventional cone and dome type speakers.

I understand about 10 - 20 % of what many have written here in the last few pages of texts. However, what this did do is get me to go down to the listening room to give another shot at fixing my bass, which I've never been happy with since I've moved in this house 2 1/2 years ago. It was fine in the last house so I know it wasn't the equipment. So finally last night at about 1:00am I moved the one sub and leave the other one where it is and success instead of suckcess. I moved the sub on the left to almost the front left corner of the room and then experimented with the right sub and found so far that it sounded better where it is. I'm not symmetrical. I'll fix this or screw it up as I get time. REALLY strange thing is that soundstage is more expansive especially when it comes to depth. I didn't think that would be possible. WTH would a sub or two have to do with that? I understand response being smoother down there, but effect on the total soundstage?

Anyway, still trying to figure out what to do with the sub on the right that's by my equipment rack. And thanks (to everyone) for the encouragement to keep after it.






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post #1255 of 1494 Old 08-29-2017, 10:01 AM
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sigh, why I said level measurements --- magnitude, amplitude only
In that case, the answer is no, you can't (replicate SFM by other (simpler, cheaper) means ).
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In that case, the answer is no, you can't (replicate SFM by other (simpler, cheaper) means ).
I won't use the word "replicate" here, as to do so would be a violation of Harman's patents. However, if the question is, "Is there freely available software that can take the results of measurements of each sub's response at each listening position, and compute individual EQ, delay and gain parameters for minimizing seat-to-seat amplitude response variation?", then yes, MSO does that.
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"then yes, MSO does that"

Then is this true?

"Some two-channel and even multi-channel systems operate the subs in stereo mode. For such systems, MSO is not an appropriate tool for optimization and its use will likely cause unpredictable results"

Looks like my method by brail is the only one available for use with stereo subs and zero bass management.
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post #1258 of 1494 Old 08-29-2017, 11:19 AM
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Then is this true?

"Some two-channel and even multi-channel systems operate the subs in stereo mode. For such systems, MSO is not an appropriate tool for optimization and its use will likely cause unpredictable results"
Yes, that's true. Neither SFM nor MSO works with stereo subs. The usage of stereo subs is discussed in Welti and Devantier's article about SFM, in an AES article by Welti about stereo subs, and in Dr. Toole's book.
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post #1259 of 1494 Old 08-29-2017, 11:23 AM
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I wasn't aware of MSO, thanks!!


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...then yes, MSO does that.
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post #1260 of 1494 Old 08-29-2017, 11:58 AM
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Yes, that's true. Neither SFM nor MSO works with stereo subs. The usage of stereo subs is discussed in Welti and Devantier's article about SFM, in an AES article by Welti about stereo subs, and in Dr. Toole's book.

I presume its the same as this one below. The one you linked above has a pay wall.

"Have you read the Welti and Devantier article about SFM?"

I read the above last night and now can't remember a thing about it. That's not good!
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