JBL 705i/708i (7 Series Master Reference Monitors) & 725G/728G (subwoofers): Jan 2015 - Page 72 - AVS Forum | Home Theater Discussions And Reviews
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post #2131 of 3084 Old 03-20-2018, 09:29 PM
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Originally Posted by 12B4A View Post
I've seen this term used several times over the years but I don't think I've ever seen a measurement demonstrating "low level resolution" differences between loudspeakers. It kinda goes up to the line where I'd judge it to be magical thinking. I just wonder if it's misnomer used to describe perceptual differences in previously unheard ambiance cues that are caused to happen under the right speaker radiation and room reflection conditions.
I don't think it's frequency response or directivity related.

There are many speakers with high resolution and poor directivity (B&W as an example). There are many speakers with excellent directivity and poor low level resolution (many PA monitors).

IMO it's related to how accurately and linearly the the speaker transducers track changes to the input voltage.

I do not think we know for sure which measurements are required to characterize a speakers dynamic performance, and hence get us from high 80% in the correlations that we have now between better spins and subjective preference. I think more primary research is required.

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post #2132 of 3084 Old 03-21-2018, 03:10 AM
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Originally Posted by Nyal Mellor View Post
I don't think it's frequency response or directivity related.

There are many speakers with high resolution and poor directivity (B&W as an example). There are many speakers with excellent directivity and poor low level resolution (many PA monitors).

IMO it's related to how accurately and linearly the the speaker transducers track changes to the input voltage.

I do not think we know for sure which measurements are required to characterize a speakers dynamic performance, and hence get us from high 80% in the correlations that we have now between better spins and subjective preference. I think more primary research is required.
I'm just going to literally quote Floyd Toole on this one:

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This audiophile thing called "resolution" is very misleading. There is no - none, nada - metric for "resolution" as an isolated perceptual dimension. However, there is 40+ years worth of evidence indicating that as distracting resonances are removed, as non-linear distortions are reduced, and as directivity is rendered more uniformly, that listener ratings go up. So, I suggest that high resolution is what is left after the flaws in loudspeakers are eliminated. It is not a property that is "added".

The spinorama presentation was developed especially to show a big portion of the qualities that are identifiable (anyone correct me if I'm wrong).
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post #2133 of 3084 Old 03-21-2018, 05:00 AM
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One aspect that probably affects dynamics is transient response and attack time. While linearity will tell us if the output matches the input how fast it does that is another measurement. In creating sounds we have 4 basic parts of the sound. The first is called the attack or how fast it goes from 0-100 let's say. the second how long its sustained, the third how it is released and finally how long it takes to decay. The attack plays an important role in our perception of sound. For instance let's use an example of a gunshot which has a very fast attack. Imagine if we slowed that down, it would give us a different sound.

While this might be an extreme example even everyday instruments have this initial attack of sound like plucking a guitar string or that initial strike of a piano key. There is a difference between when one plucks a string with their finger versus using a pick. A speaker's ability to reproduce this initial attack has a lot to do with it often being called "dynamic" or having better "resolution". This is one measurement passive speakers do not do as well. Usually because of the crossovers inductors and capacitors it significantly slows that initial attack. When powering a driver directly an amplifier it is usually at least 10x faster. Of course audiophiles might say a speaker is "sharp" or has an "edge" and they prefer the passive one because it is "smoother". But, that's the difference between reference and preference
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post #2134 of 3084 Old 03-21-2018, 07:35 AM
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Originally Posted by TimVG View Post
I'm just going to literally quote Floyd Toole on this one:









The spinorama presentation was developed especially to show a big portion of the qualities that are identifiable (anyone correct me if I'm wrong).


Agreed the spins give a lot of info, as I KEEP on mentioning, but they do not tell you everything. Take resonances for example, a lowish level resonance may not show up easily on a spin. Shows up much better on a spectral decay measurement.


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post #2135 of 3084 Old 03-21-2018, 07:44 AM
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Originally Posted by Nyal Mellor View Post
Agreed the spins give a lot of info, as I KEEP on mentioning, but they do not tell you everything. Take resonances for example, a lowish level resonance may not show up easily on a spin. Shows up much better on a spectral decay measurement.


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Didn't the BBC also do a ton of research on the audibility of resonances? I believe the conclusion was that as resonances are masked by primary sounds they become inaudible (oversimplified statement, but true). They did a lot of research into their thin walled cabinets.

Resonances do show up in spinoramas - in fact if I'm correct it's easy to spot them as they remain consistent throughout the different parts of the spinorama (listening window, first reflections, sound power)

What the spinorama doesn't give you is distortion numbers. I'm not sure if a lot more matters - from the blind tests I've participated in .. not really would be my guess. Now, in sighted tests, and when the owners of certain speakers come into play .. Then a lot more starts to matter all of a sudden. Anechoic measurements such as the spinorama have honestly not yet lied to me coupled to a little bit of common sense. I've been lied to a lot worse by salesmen in fact
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post #2136 of 3084 Old 03-21-2018, 07:49 AM
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I agree that spins do not show everything. For designing rooms with acoustical treatments I would much rather see the off axis graphs, a polar plot or a directivity index than a spin graph. Spins are great to get an idea of a speakers capabilities and I think they should be the standard for speaker comparisons instead of the specs we get now like 65hz-20khz +/-3db and 89db sensitivity.
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post #2137 of 3084 Old 03-21-2018, 07:59 AM
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Originally Posted by Ellebob View Post
I agree that spins do not show everything. For designing rooms with acoustical treatments I would much rather see the off axis graphs, a polar plot or a directivity index than a spin graph. Spins are great to get an idea of a speakers capabilities and I think they should be the standard for speaker comparisons instead of the specs we get now like 65hz-20khz +/-3db and 89db sensitivity.
Apart from the polar, the remaining data can be found in a spinorama.

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post #2138 of 3084 Old 03-21-2018, 08:25 AM
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Not really. The spin is not detailed enough to decide what type of acoustic treatment to use especially if deciding between various combo type treatments. It is not great at showing where off axis problems occur and what exactly is happening at those locations. Similar to when Toole talks about looking at waterfall graphs and you have to choose between frequeny and time resolution but it can't do both well at the same time. But you can get a general idea of a speaker's performance by looking at a waterfall graph but for more detailed work you need more detailed graphs. Do not misunderstand me. It is a great comparison tool, its just sometimes more information is needed and other measurements provide that better.

Looking at the spinorama does not give me as much off axis info as something like this. Of course the other measurments the spinorama doesn't show at all.

https://soundstage.com/index.php?opt...nts&Itemid=153
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post #2139 of 3084 Old 03-21-2018, 08:43 AM
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Got ya - thanks for clarifying.
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post #2140 of 3084 Old 03-21-2018, 10:45 PM
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Quote:
Originally Posted by TimVG View Post
Didn't the BBC also do a ton of research on the audibility of resonances? I believe the conclusion was that as resonances are masked by primary sounds they become inaudible (oversimplified statement, but true). They did a lot of research into their thin walled cabinets.



Resonances do show up in spinoramas - in fact if I'm correct it's easy to spot them as they remain consistent throughout the different parts of the spinorama (listening window, first reflections, sound power)



What the spinorama doesn't give you is distortion numbers. I'm not sure if a lot more matters - from the blind tests I've participated in .. not really would be my guess. Now, in sighted tests, and when the owners of certain speakers come into play .. Then a lot more starts to matter all of a sudden. Anechoic measurements such as the spinorama have honestly not yet lied to me coupled to a little bit of common sense. I've been lied to a lot worse by salesmen in fact

The BBC derived thin wall cabinet was related to audibility of resonance - the reasoning was high Q, quickly decaying resonances would be less audible than low Q, slow decaying. Its kind of fallen out of fashion, whether that is because the research was flawed or marketing departments didn’t like it, who knows.

Resonances may not show up on spins if they are low level and masked by directivity changes, a spectral decay shows the data way better.

I believe masking has been over stated - maybe you can’t hear a resonance over pink noise, but with a more sparse music signal I’m confident you can. For example, sweep a sine wave and find a buzz or rattle in your room. Pretty audible huh? Now play pink noise. Can’t hear it can you?




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post #2141 of 3084 Old 03-21-2018, 11:30 PM
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Originally Posted by Nyal Mellor View Post
First, an issue is that a 6.5" driver is not actually 6.5" in terms of the width of the radiating element. The ATC SCM20 driver is 4.9"
Just like pretty much every other "six and half."

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Second, the assumption in the math is that driver behaves as a piston. Pistonic drivers (e.g. metal, ceramic, etc) will have worse off axis than a non-pistonic driver at the top of their pass band. It is possible to engineer a driver such that the outer part of the cone "decouples" at higher frequencies, such that the radiating area is less, and hence off axis is better. The SCM20 driver has multiple components that provide such a function
And it doesn't work very well in my listening experience. The use of the soft dome dustcap is a marketing gimmick, just like the old ScanSpeak midranges that used their 38mm twiddler dome as a dustcap.

Beyond that, what's the difference between "decoupling" and "smearing?" Either way you're talking about basically uncontrolled motion...

(Yes, I am aware JBL makes similar claims for the M2 woofer.)

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But, there is much, much more to how a speaker sounds than just speaker directivity. Once we are in the "neutral" ballpark,
You can't have "neutral" if the total sound output includes a midrange mushroom cloud.

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Of course it's possible to design a well-behaved loudspeaker without a waveguide.
Let me go on record as saying I don't believe it's possible to design a well-behaved 6.5-7" 2-way speaker with a 1" dome tweeter without a waveguide. They all suffer from upper midrange problems as a result of the directivity shift. Even Joseph Audio, with their super-steep elliptical crossover, haven't managed it.

I've heard the ATC. There's no secret sauce there.

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I don't think it's frequency response or directivity related.

There are many speakers with high resolution and poor directivity (B&W as an example).
What makes B&W speakers "high resolution," besides the marketing? Current ones, not the old Dickey models that were great speakers for their day and probably still quite good.

They do make high performance drivers, but let them down with slapdash crossovers and appalling ugly cabinets. The current ones look like excessively-finished sewer pipes! At least the previous generation had coherent styling, even if they didn't sound very good.

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There are many speakers with excellent directivity and poor low level resolution (many PA monitors).
Many PA monitors sound bad because their crossovers are unrefined and their drive units (especially cheap compression drivers) have loads of in-band resonances. Also, the horn geometries may be non-ideal.

Some PA monitors actually sound quite good, though. I've been impressed with some QSC models in the past. IMO they're too big and ugly to use at home.

I suspect high efficiency speakers actually track the input signal better than a standard "hifi" speaker at low levels.

I wonder how a suitably EQ'ed Monoprice or Behringer type (i.e. bottom-rung) PA speaker would fare in a blind test against the latest-"greatest" B&W, even if the test was limited to trained listeners comparing on "resolution."

In other news, it looks like Mr. Sprinkle has left the proverbial building. I wonder how deep Harman's bench is.

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post #2142 of 3084 Old 03-22-2018, 03:30 AM
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..a spectral decay shows the data way better..

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Don't shoot the messenger. But Toole says while it may show the data - that doesn't necessarily mean the data is very relevant for real world performance. Now, his book book is full of scientific research performed over many years, and he cites many many credible studies and sources. Don't be offended that I hold that opinion in higher regard than an opinion on the internet.


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..a spectral decay shows the data way better..

I believe masking has been over stated - maybe you can’t hear a resonance over pink noise, but with a more sparse music signal I’m confident you can. For example, sweep a sine wave and find a buzz or rattle in your room. Pretty audible huh? Now play pink noise. Can’t hear it can you?

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I think we're in disagreement over the term masking. To me it's when the primary signal masks secondary sources in the forms distortion, resonances, .. rattles.. Even in a sine sweep or when going over test tones. When the secondary source is sufficiently masked to the human ear, it's no longer an issue in real world applications. Can you measure it? Yes. But it's no longer relevant at that point. Spinoramas are an indicator, and a good tool for comparing loudspeakers. Does it contain all the data? No. But apart from distortion/compression numbers, it does hold the data required to determine performance.
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post #2143 of 3084 Old 03-22-2018, 03:33 AM
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Let me go on record as saying I don't believe it's possible to design a well-behaved 6.5-7" 2-way speaker with a 1" dome tweeter without a waveguide. They all suffer from upper midrange problems as a result of the directivity shift. Even Joseph Audio, with their super-steep elliptical crossover, haven't managed it.

I've heard the ATC. There's no secret sauce there.
I was not referring to any particular midwoofer size. In possible in general, and to a certain degree. Although I agree across the board: well implemented waveguides are simply the better solution.
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post #2144 of 3084 Old 03-22-2018, 07:08 AM
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In other news, it looks like Mr. Sprinkle has left the proverbial building. I wonder how deep Harman's bench is.
They do have all the people back who had left JBL for Samsung. The talent will be there but corporate faction/grudge mismanagement would likely result in new products being meh. I'd imagine the prototypes will be awesome but the bad production decisions will undermine solid original designs. Quality Harmsung products...

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post #2145 of 3084 Old 03-24-2018, 08:01 PM
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Anyone using Audyssey with their 7 series speakers? How do you find it? When I had some 708Ps on loan a while back, I tried Audyssey but immediately heard that something was not right and switched it off. It may have been a speaker placement issue as I placed the 708s on my old speaker stands which were too short for the 708s (in particular, being too low, the right 708 was close to a cabinet).

Another thing, Audyssey claimed both 708s were out of phase. Has anyone else experienced that?
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post #2146 of 3084 Old 03-25-2018, 05:06 AM
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Anyone using Audyssey with their 7 series speakers? How do you find it? When I had some 708Ps on loan a while back, I tried Audyssey but immediately heard that something was not right and switched it off. It may have been a speaker placement issue as I placed the 708s on my old speaker stands which were too short for the 708s (in particular, being too low, the right 708 was close to a cabinet).

Another thing, Audyssey claimed both 708s were out of phase. Has anyone else experienced that?
Since the 7-series measure so well anechoically, correcting them above a couple of 100hz would be pointless, and could explain your experience. However, a good loudspeaker deserves good placement and a good room to get the most out of them. That being said, they are surprisingly forgiving of rooms and placement as long as it's not a complete disaster.
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post #2147 of 3084 Old 03-25-2018, 07:19 AM
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Are you using Audy or Audy32? I had that absolute phase issue running A32. I also had it with Magnepans even after switching polarity but not so with LSR305s so *shrug*. It's quite possible the analog pre/amp portions in the 7's invert absolute phase and it wasn't inverted from the DSP to correct.

I dunno Tim, room nodes can reach well above 100hz and a big factor in SQ perception is in the 50-250Hz bass range. At least Audyssey finally caught on to your sentiment and implemented a way for people to limit the range of correction on newer models with an app.

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post #2148 of 3084 Old 03-25-2018, 07:45 AM
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Are you using Audy or Audy32? I had that absolute phase issue running A32. I also had it with Magnepans even after switching polarity but not so with LSR305s so *shrug*. It's quite possible the analog pre/amp portions in the 7's invert absolute phase and it wasn't inverted from the DSP to correct.

I dunno Tim, room nodes can reach well above 100hz and a big factor in SQ perception is in the 50-250Hz bass range. At least Audyssey finally caught on to your sentiment and implemented a way for people to limit the range of correction on newer models with an app.
I did say up to a couple of 100hz I've used anywhere from 200hz to 500hz depending on the speaker and its placement. Above that we'll still hear the effects of the room, but the direct sound of the loudspeaker becomes the dominant factor in the overall perceived sound, and correction is often more detrimental than helpful.
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post #2149 of 3084 Old 03-25-2018, 02:33 PM
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Since the 7-series measure so well anechoically, correcting them above a couple of 100hz would be pointless, and could explain your experience. However, a good loudspeaker deserves good placement and a good room to get the most out of them. That being said, they are surprisingly forgiving of rooms and placement as long as it's not a complete disaster.
My experience was that they sounded great without EQ, even with less than optimal placement. I thought I would try Audyssey just out of curiosity. Ideally I would have EQed the speakers as well (and not just my sub) but limited correction to the recommended 300-500 Hz but my older version of Audyssey doesn't have that capability. Anyway, I was just wondering if others had tried it and achieved good results. (I know some have had bad experiences with it.)

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Are you using Audy or Audy32? I had that absolute phase issue running A32. I also had it with Magnepans even after switching polarity but not so with LSR305s so *shrug*. It's quite possible the analog pre/amp portions in the 7's invert absolute phase and it wasn't inverted from the DSP to correct.
XT32. The phase error seems strange. Can't say that anything sounded a miss. The 708s and my sub sounded great together.
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post #2150 of 3084 Old 03-25-2018, 07:25 PM
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My experience was that they sounded great without EQ, even with less than optimal placement. I thought I would try Audyssey just out of curiosity. Ideally I would have EQed the speakers as well (and not just my sub) but limited correction to the recommended 300-500 Hz but my older version of Audyssey doesn't have that capability. Anyway, I was just wondering if others had tried it and achieved good results. (I know some have had bad experiences with it.)


XT32. The phase error seems strange. Can't say that anything sounded a miss. The 708s and my sub sounded great together.
Have some questions for you.

I remember you got to test/loan/try out the 708Ps. How would you rate their SPL capabilities? Can they get "impressively" loud in a small room and/or relatively short listening distances (7-8 ft)? Do you believe they could be used as LCR speakers in a small room?
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post #2151 of 3084 Old 03-25-2018, 08:05 PM
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^^^
I think you will be completely satisfied with their SPL capabilities Seriously. You have a (very) small room. I can't see how they wouldn't get loud enough for you. Though I recall you asking others the same question and getting a similar response . I suspect you will only truly be convinced once you hear them for yourself. If you can't audition them in the UAE, take a trip to somewhere nearby that does have them. The cost of the flight and your time would be a great investment and give you peace of mind.

Just a PSA: I love loud but now my hearing is damaged from going to rock concerts when I was younger. Thankfully it's not too bad but anyway it doesn't take much to damage your hearing. I think we have all experienced sitting at home and watching a film or listening to music and being unable to properly hear the person seated next to us. Well that's a indication that you're listening too loud.
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post #2152 of 3084 Old 03-26-2018, 02:18 PM
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I originally was using a Marantz SR7010 with Audyssey XT32 with my LSR708s (at that point I was using them as LCR). I never did like what Audyssey did with them, even when I broke out my old Audyssey Pro calibration kit. It always seemed to "smear" the top and middle frequencies, and I never really liked how it blended them with my subs. (By smearing I felt I was losing the pinpoint imaging the 708s had with Audyssey off).

Caveat - this was in the days before you could limit correction to below 500 hz (or the target of your choice). That should solve the "smearing" problem but not sure if they've made improvements with sub / satellite blending.

I know I'm a broken record on this, but outside of what I've experienced with a full Synthesis calibration, Anthem's ARC has it all over Audyssey, especially in tying in subs and satellites.

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post #2153 of 3084 Old 03-26-2018, 03:50 PM
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A few comments

John S. suggested that I should look in on this discussion, so I have just skimmed the last few contributions. Part of what I see is natural confusion created when the data necessary for comparing products is not available. Then the discussion devolves into whose "voice" is louder (power compression included :-) A few things jumped out:

That 80% correlation between measurements and subjective data is not perfect. Yup. However, as I point out in my books, and have stated in these forums, that number is for 70 loudspeakers of all prices and sizes - inexpensive bookshelf units to monster high-end floor standers. As Olive showed, about 30% of our subjective ratings is attributable to bass performance. That means that a good speaker with bass beats an equally good speaker with less bass. So, in a very uneven playing field, it is indeed remarkable that a correlation coefficient of 0.8 was achieved. When the LF bandwidth factor was substantially removed by comparing only bookshelf speakers, in a separate well-controlled DB test, the correlation was 0.997. So, how much information is in a spinorama? A lot! In real circumstances, the performance at low frequencies includes the room, so no anechoic measurement will be totally predictive of results.

Resonances exist in transducers, and because transducers are minimum-phase devices the evidence is in both the frequency response and in impulse/waterfall responses. However, the correlation with audibility is that which is seen in the frequency response. It is mentioned in my books, but there is much more detail in the original paper: Toole, F. E. and Olive, S.E. (1988). “The modification of timbre by resonances: perception and measurement”, J. Audio Eng. Soc., 36, pp. 122-142. The conclusion there was that we simply do not seem to hear the ringing. This has also been shown in recent work by others to be true at bass frequencies (this is in my new book). Waterfalls are pretty, but not very informative - especially when, as is common, the measurement parameters are incorrectly set. If an audible resonance exists, the evidence is that it will be visible in a high resolution spinorama.

Of course, spinoramas do not display evidence of power compression or non-linear distortion. And, equally of course, those factors are also measured in the design process. They too could be displayed in a comprehensive spec, but unfortunately the correlations between measured quantities and audibility are poor. The power compression data shown in soundstage.com data were measured in my old NRCC lab, and I created the process. It was recognized as a gross oversimplification back then (mid 1980s) but it was a start. It is done using a swept pure tone at sound levels which, if extended to full bandwidth, would be deafening. I would do it differently now.

Measures of non-linear distortion, as discussed in my book, are almost useless for predicting audible effects. They are useful for design engineers, but the only certain metric is that zero is the goal. Anything above zero may or may not be audible. We await new measures that incorporate perceptual factors - masking being the dominant one.

It is unfortunate that everyone does not, or cannot, provide reliable anechoic data on their loudspeakers. I recently saw an example of a student doing research who requested such data from a highly respected British monitor manufacturer. He got an on-axis and 45 deg off axis curve measured at 1 meter! The mic was in he near field (too close) and 45 deg is not sufficient to be able to estimate what happens in the reflected sound field in a room. The final insult was that the curves were obviously smoothed. So-o-o-o. One has to wonder what they measure when they design their products. KEF, for one, has admitted to using spinorama, and has published one. It is known that others are doing it stealthily. So there is progress.

The BBC did some good pioneering work many years ago. I visited them, and knew a few of the people involved. Their goals were highly influenced by the nature of their listening environments: mostly small, very dead control rooms. The on-axis response was the dominant factor, so off axis behavior mattered less. Sadly, this "guidance" was picked up by some loudspeaker manufacturers who were addressing a market in which listeners were in normally reflective rooms. The evidence can still be seen - and heard.
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post #2154 of 3084 Old 03-26-2018, 11:40 PM
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Originally Posted by John Schuermann View Post
I originally was using a Marantz SR7010 with Audyssey XT32 with my LSR708s (at that point I was using them as LCR). I never did like what Audyssey did with them, even when I broke out my old Audyssey Pro calibration kit. It always seemed to "smear" the top and middle frequencies, and I never really liked how it blended them with my subs. (By smearing I felt I was losing the pinpoint imaging the 708s had with Audyssey off).

Caveat - this was in the days before you could limit correction to below 500 hz (or the target of your choice). That should solve the "smearing" problem but not sure if they've made improvements with sub / satellite blending.

I know I'm a broken record on this, but outside of what I've experienced with a full Synthesis calibration, Anthem's ARC has it all over Audyssey, especially in tying in subs and satellites.
So far there hasn't been a positive response to my post so I suspect I will have to end up getting a new AVR.

Regarding sub / sat blending, I think I must be pretty lucky. Starting with a sub position that minimized dips pre-EQ and then using a small bubble around the main listening position in which to place the mic while running Audyssey, Audyssey does a really good job for me. One strange thing though: if I change the delay in the sub channel, it is very hard to see much if any change in the REW measurements . Perhaps it is a feature of smaller rooms? Not really sure.
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post #2155 of 3084 Old 03-26-2018, 11:51 PM
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Originally Posted by Floyd Toole View Post
That 80% correlation between measurements and subjective data is not perfect. Yup. However, as I point out in my books, and have stated in these forums, that number is for 70 loudspeakers of all prices and sizes - inexpensive bookshelf units to monster high-end floor standers. As Olive showed, about 30% of our subjective ratings is attributable to bass performance. That means that a good speaker with bass beats an equally good speaker with less bass. So, in a very uneven playing field, it is indeed remarkable that a correlation coefficient of 0.8 was achieved. When the LF bandwidth factor was substantially removed by comparing only bookshelf speakers, in a separate well-controlled DB test, the correlation was 0.997. So, how much information is in a spinorama? A lot! In real circumstances, the performance at low frequencies includes the room, so no anechoic measurement will be totally predictive of results.
Factoring out bass, that is really an extraordinary correlation.

If I may, one question that that I've always had about the M2 and measurements: during the M2's development, apparently earlier prototypes were not as good as the final model. For example, one of the ones that Frank Filipetti heard was not quite right to his ears (while he loves the final product). Presumably the early prototypes had good spins. So I'm wondering why at least to some ears they didn't sound quite right while still measuring very well?
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post #2156 of 3084 Old 03-27-2018, 10:07 AM
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Originally Posted by Zzzzz... View Post
Factoring out bass, that is really an extraordinary correlation.

If I may, one question that that I've always had about the M2 and measurements: during the M2's development, apparently earlier prototypes were not as good as the final model. For example, one of the ones that Frank Filipetti heard was not quite right to his ears (while he loves the final product). Presumably the early prototypes had good spins. So I'm wondering why at least to some ears they didn't sound quite right while still measuring very well?
Zzzzz... said: "Presumably the early prototypes had good spins. So I'm wondering why at least to some ears they didn't sound quite right while still measuring very well?"

Measurements are constants, stable and unchanging with time. Opinions are . . . different. I am not aware of this event, but it is quite possible that minor performance changes were involved . . . or not. I don't know what the man had been listening to and had adapted to. In my time on the job, I have seen experienced listeners, including audio professionals and reviewers, change their opinions dramatically based on "something" having nothing to do with the product, which was unchanged. In some cases, reviews especially, the change is attributed to "break in", or the like.

I almost hate to mention it, but it was professional recording engineers, engaged in double-blind listening tests evaluating studio monitors, who revealed the importance of hearing loss to me. It is discussed in a paper: Toole, F. E. (1985). “Subjective measurements of loudspeaker sound quality and listener preferences”, J. Audio Eng. Soc., 33. pp. 2-31. It is also explained in both of my books. Hearing loss is an occupational hazard in pro audio and it takes very little to cause easily observed and measured inconsistencies in subjective judgments. It is not uncommon for double-blind subjective ratings of the same loudspeaker to change dramatically over a few hours. It is not difficult to understand that if one is not able to hear low level timbral cues and distortions, opinions may be different from those of normal-hearing listeners, and may vary with time and program material. Critical listening is a task for young healthy ears :-( "Greybeards" should enjoy their music, but keep their opinions to themselves. I do - my hearing performance is shown in my books, and I am sitting here listening to my tinnitus which was partly sound and partly drug (OTC NSAID) induced.

Some people find it a problem that so much information is embedded in "simple" frequency responses. They persist in beliefs that something important is being ignored, usually related to non-linear distortion or waveform-related aspects, like phase shift, rise time, etc. Non-Linear distortions are important and much effort is expended to minimize them. In largish expensive loudspeakers it is rarely a problem. In inexpensive systems it is more common - good loudspeaker motors are expensive. The definitive evidence of a problem is subjective - distortion measurements commonly in use do not reliably correlate which what is audible in music. As I said, engineers aim for zero measured distortion, and get as close as possible within the cost, time and competence limitations.

Some discussions focus on a single factor, like diaphragm material, assuming that all audible differences are attributable to that. In fact, it is not uncommon for high priced tweeters using an exotic material, for example, to have superior motors yielding less non-linear distortion and reduced power compression. Differences may be heard that have nothing to do with the diaphragm - motors: the invisible variable. However, exotic materials have marketing attractions.

Waveform based factors are another popular topic of differentiation between loudspeakers. From an engineering perspective it is gratifying to see a clean impulse or step response, and to measure linear, or some other desired, phase response. From a listener's perspective it matters little or not at all. Humans are remarkably insensitive to phase shifts, many serious efforts to prove otherwise have not succeeded. Within drivers, which are minimum-phase devices, the time domain performance is predictable from the frequency response. There is no "speed" that is not explained by the frequency response and bandwidth at high frequencies.
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Originally Posted by Floyd Toole View Post

Some people find it a problem that so much information is embedded in "simple" frequency responses.
Usually the more they've already spent the more they seem to take offense to that statement! Surprisingly, it's no better in "professional" audio circles.
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post #2158 of 3084 Old 03-27-2018, 10:38 AM
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Usually the more they've already spent the more they seem to take offense to that statement! Surprisingly, it's no better in "professional" audio circles.
So true. And I was talking about high resolution anechoic frequency responses. If we look at in-room measurements - all bets are off!
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So true. And I was talking about high resolution anechoic frequency responses. If we look at in-room measurements - all bets are off!
I guessed as much - having read your book!

On a 7-series related note. I went through the M2 vs Salon2 blind test thread with great interest.
One thing I'd like to see tested more extensively is how preference ratings vary over different listening distances - and how that correlates to the directivity index of the speakers.

Therefore In about a week I'll be doing a little blind testing of my own where I'll be putting the 7 series against another brand of studio monitor who also do quite a bit of scientific research and testing (they have a nice anechoic chamber) but focus more on controlled directivity and optimise their models for different listening distances. It will be fun to compare their own models to see if that holds up behind the screen, and also to put the 705i or 708i in the mix to see if it reigns supreme, and under what conditions. I've been sent some of their anechoic data, and it'll be an interesting test. And yes - we'll be doing it in mono and with a switch box the change is instant. Not exactly the MLL but it'll have to do.
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post #2160 of 3084 Old 03-27-2018, 01:37 PM
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[QUOTE=TimVG;55929440]I guessed as much - having read your book!

"One thing I'd like to see tested more extensively is how preference ratings vary over different listening distances - and how that correlates to the directivity index of the speakers."

There are several interesting topics that could benefit from more investigation, but there are very, very few people in the world with the competence, interest, time and money to do the tests. Frankly, as I look back, we are damned lucky to have the experimental evidence we have - in my case thanks to the NRCC and Canadian taxpayers for the formative first 25 years and Harman's generosity over almost as long. As can be deduced from references in my book, not many others have involved the scientific method in understanding loudspeakers and rooms. Opinions, though, are countless and all over the map.

The tests I did in 1985 (pp.174-183 in the third edition) looked at lateral reflections in some detail. Admittedly the loudspeakers we would use now are better than these, but the scatter in the opinion ratings in various categories of imaging and space suggest that personal opinion and/or random factors are substantial influences. It turned out that the recordings themselves were powerful determinants. Listening distance was not a variable, but differences in loudspeaker directivity were significant - dipole vs cone & dome. An additional underlying problem is higher order reflections as listening distance increases and these are less well correlated with speaker directivity. The shape, size and acoustical performance of the room then is a significant factor. I wish you luck in your experiment.
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