How to Choose a Loudspeaker -- What the Science Shows - Page 63 - AVS Forum | Home Theater Discussions And Reviews
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post #1861 of 5320 Old 02-20-2019, 05:37 PM - Thread Starter
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Poor Spinorama Results

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Originally Posted by drewTT View Post
Revel founder, bashing the competition. Nice.
drewTT,

No, I am simply stating a fact.
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post #1862 of 5320 Old 02-20-2019, 06:06 PM
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How to Choose a Loudspeaker -- What the Science Shows

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Originally Posted by Floyd Toole View Post
As elaborated on in many papers and my book, the measurable evidence that correlates with perceived sound quality is dominated by frequency response - IF sufficient anechoic data are accumulated, processed and presented - the spinorama is a good example. This is addressed early in my book, Chapter 5, Section 5.7 where it is shown that these data alone can provide very high correlations with double-blind subjective evaluations of sound quality. It is important to remember that transducers are minimum-phase devices - i.e. the time domain behavior is predictable from the amplitude response.



Those other factors are important only if the loudspeakers are appropriately stressed.


So to the point of the Salon2 and F228be comparison (and possibly even smaller speakers that measure equally well), as long as both are played at reasonable volumes, and supplemented with a subwoofer (since otherwise the Salon2 has a lower range and also just to reduce the stress on the F228be), they should sound essentially the same. And I'm guessing the F228be can actually be pushed pretty far itself without distorting. So the point of diminishing returns at that point may be completely negligible.

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post #1863 of 5320 Old 02-20-2019, 07:28 PM
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Quote:
Originally Posted by Scotth3886 View Post
I'm amazed how many of Gordan Holt's terms that I still use. Plus, I've added a few to his list such as 'scale' and 'resolve'.

"data retrieval" though? Ewww, that sounds so digital …. double ewww.
Scale and resolve sound like good old engineering terms to me. But once it gets started there's no end to how creative the wordsmithing will get.
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post #1864 of 5320 Old 02-20-2019, 07:31 PM
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Originally Posted by Scotth3886 View Post
Thanks. I knew you or someone would say that. I've used REW maybe three times, and had great difficulty getting the graphs a size that I could screen shot 20hz to 20k and fit in one photobucket screen size without running off of the page. I'll try this again at some point when I have time to figure out how to experiment with the x and y coordinates and be able to screen shot that into one screen page. Otherwise, I can't post it.
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Originally Posted by Scotth3886 View Post
Yeah, I saw that I could do that, but that's what I was trying to avoid. I was trying to get it on one page even if one had to scroll right and left. Photobucket (when it works) won't let me do that.
REW is a great tool, and it has some built-in options to do exactly what you want to do.

Pick a graph you want to use, and then click on the Overlays button:



That will open up a new window with just your graph. Then you can click on the Set graph limits button:



That will open a small dialog box that lets you select your limits; it's real-time interactive, so you can adjust the left and right limits either by typing them in or clicking on the up and down buttons until you get your response to fit the graph the way you want it. Most of the REW guys like to see the Y axis in 5 dB increments.



Once you have the graph set the way you want it, hit the Apply Settings button. Then click on the Capture button:



And REW will let you pick a picture width in pixels, and resize the image for you.

And there's not need to use Photobucket if you don't want to. You can simply drag the images from your computer to the AVS forum post when you reply by using the Drag and Drop File Upload section, and then use the forum's inset image function to add them to the post.

It may sound like a lot of steps, but becomes second nature after you do it a couple of times. You can click on the quote button on this post to see what the posting code looks like.

Scott
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post #1865 of 5320 Old 02-20-2019, 07:37 PM
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Quote:
Originally Posted by Dave in Green View Post
Scale and resolve sound like good old engineering terms to me. But once it gets started there's no end to how creative the wordsmithing will get.

I don't think there's too much of it I haven't used at one point or another.
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post #1866 of 5320 Old 02-20-2019, 07:43 PM
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Quote:
Originally Posted by srw1000 View Post
REW is a great tool, and it has some built-in options to do exactly what you want to do.

Pick a graph you want to use, and then click on the Overlays button:



That will open up a new window with just your graph. Then you can click on the Set graph limits button:



That will open a small dialog box that lets you select your limits; it's real-time interactive, so you can adjust the left and right limits either by typing them in or clicking on the up and down buttons until you get your response to fit the graph the way you want it. Most of the REW guys like to see the Y axis in 5 dB increments.



Once you have the graph set the way you want it, hit the Apply Settings button. Then click on the Capture button:



And REW will let you pick a picture width in pixels, and resize the image for you.

And there's not need to use Photobucket if you don't want to. You can simply drag the images from your computer to the AVS forum post when you reply by using the Drag and Drop File Upload section, and then use the forum's inset image function to add them to the post.

It may sound like a lot of steps, but becomes second nature after you do it a couple of times. You can click on the quote button on this post to see what the posting code looks like.

Scott

Thanks for your help. One of these days before too long, I'll have an all-day rain when I have nothing else to do, and I'll give it a try again.
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post #1867 of 5320 Old 02-20-2019, 07:54 PM
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I'll try it with one of the graphs. I think I need to fix those things you mentioned in REW to make this moar better.

The first few of the scans were playing with very small changes in toe-in to a little bit of toe-out and the last few were sub woofer phase. The green line a 0 phase and 1/2 degree or so of toe-out seemed to be the best.
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post #1868 of 5320 Old 02-20-2019, 08:45 PM
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Quote:
Originally Posted by Scotth3886 View Post
I'll try it with one of the graphs. I think I need to fix those things you mentioned in REW to make this moar better.

The first few of the scans were playing with very small changes in toe-in to a little bit of toe-out and the last few were sub woofer phase. The green line a 0 phase and 1/2 degree or so of toe-out seemed to be the best.
Try changing the dB limits of your graph from the current -100 dB - 180 dB to 40 dB -100 dB. That should give you a clearer picture of the frequency response of the toe-in positions. That's a pretty good application for REW, by the way.

Scott

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Quote:
Originally Posted by srw1000 View Post
Try changing the dB limits of your graph from the current -100 dB - 180 dB to 40 dB -100 dB. That should give you a clearer picture of the frequency response of the toe-in positions. That's a pretty good application for REW, by the way.

Scott

I'll try it next time and hopefully I can remember where to find these posts showing me how.

Got distracted already looking into who is going to be at Woodstock 50 (to be renamed Resthome Unhinged). Let's see, Canned Heat, Eric Burdon maybe John Mayall, Ringo. Let's see how this all works out. I'm game to go if they make it worth it.
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post #1870 of 5320 Old 02-21-2019, 12:18 AM
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Quote:
Originally Posted by drewTT View Post
Speakers have to work in a million different rooms. We don’t listen in anechoic chambers. Do you honestly think Paradigm is that incompetent that they couldn’t design a flat measuring speaker if they really wanted to?

But the science shows that the nature of the room doesn’t matter. The best speakers sound the best in all rooms. As for Paradigm, there speakers used to measure fairly well, but that changed a few years ago.


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Quote:
Originally Posted by Floyd Toole View Post
It may or may not be, but whatever the cause, it should not be there. Woofers operating up to those frequencies would be an odd decision.



The transition frequency, as described in my book in Section 6.1 is down around 200-300 Hz. It is sometimes rounded up to around 500 Hz, for reasons not well defined but likely related to adjacent boundary effects. But, the phenomenon we are discussing with this loudspeaker is higher than that, and as shown in Figure 5.4, off-axis performance is influential to the final impression well into the 500 Hz frequency range. Figure 5.4(d) shows that the direct sound is a dominant physical factor only at quite high frequencies. Perceptually it is more important at lower frequencies, but one cannot ignore off axis performance, especially when the indiction is of a low-Q resonance - the most easily perceived of all.
Thank you for elaborating. The information in your book is vast and invaluable, much appreciated that you're putting in the time to refer us to specific parts in reference to the remarks and questions asked by us in this topic. There's so much information in your book, for mere enthousiasts like most of us here, it's simply too much to fully comprehend after reading it through only once.
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post #1872 of 5320 Old 02-21-2019, 05:23 AM
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Quote:
Originally Posted by Steve Goff View Post
But the science shows that the nature of the room doesn’t matter. The best speakers sound the best in all rooms. As for Paradigm, there speakers used to measure fairly well, but that changed a few years ago.


Sent from my iPad using Tapatalk

I looked back through my AXPONA pics from 2018 and I see that I was in their room. I don't recall anything especially bad, but mostly in the vast middle. I tend to remember the really good and the really bad as the rest is mostly a blur now.

Edit: I did remember how bad the ML15a were shoved up against the front wall like that. I bet that unsold a few speakers.
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Once you get a ways away from NCAA football, nothing much registers here.
So true! And, I'm a Buckeyes fan. You have to leave the city for anything relevant.

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Quote:
Originally Posted by Steve Goff View Post
But the science shows that the nature of the room doesn’t matter. The best speakers sound the best in all rooms. As for Paradigm, there speakers used to measure fairly well, but that changed a few years ago.


Sent from my iPad using Tapatalk

Thats a bit of a misinterpretation. A neutral speaker with good polar plot will have most balanced/natural response in virtually all rooms. But that doesn't necessarily mean it will sound good, due to the acoustic problems in room, SBIR, room modes and placement. Its not really speakers but rooms fault. Same way when you enter different room, your voice will sound different. Unbalanced speaker on the other hand has greater chance of highlighting the rooms problems.
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post #1875 of 5320 Old 02-21-2019, 07:26 AM
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So true! And, I'm a Buckeyes fan. You have to leave the city for anything relevant.
Yep. Columbus has been sort of a downer for my two big hobbies: the high end audio and collector cars.

I went seven years to that school and three Rose Bowls, but frankly, I get real tired of the fanaticism in re OSU football.

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post #1876 of 5320 Old 02-21-2019, 08:24 AM
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Such things bother me, too, but readers need to take it in a chronological context. Had I reviewed them in the reverse order, I might have had and reported different reactions. (BTW, I reviewed a Performa speaker, not a Concerta.)
Hi!

yes i understand but you also praised the B&W D3 wich also is a poor performing speaker! like i said before the Revel Concerta2 M16 for 900 bucks is a better speaker.

I wonder if you would say that if you would review those speakers

what really bothers me is that Atkinson said in your review that it measures very well....but it really doesn't!

//Mike
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post #1877 of 5320 Old 02-21-2019, 08:59 AM
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Hi All,
A quick question that has been running in the back of my mind regarding multichannel speaker selection. Sorry if it has been answered already but did a quick search with limited success.

Since we are not sensitive to absolute phase (if a stereo speaker pair has equal phase wrap over frequency in both speakers) then we get a phantom centre presentation and it sounds good. If one were to invert 1 of the tweeters then it sounds for lack of a better term phasey. If we invert both tweeter (crossover problems aside), it sounds more normal so one would conclude we are more sensitive to relative phase.

Taking this question to multichannel, is there benefit to having all speakers exhibit the exact same phase shift throughout the frequency bands (at least above say 300hz or so), or do surrounds and atmos channels not matter as much. I suspect the LCR is more critical for proper front channel panning or is relative phase shift between speakers not an issue with multichannel? I can't escape the feeling that ALL speakers relative phase shift should be the same for multichannel. If not, what are the variables at play that exclude this?

The above question assumes we are not using tools like Dirac that change the speakers relative phase response.

Thank you in advance,
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post #1878 of 5320 Old 02-21-2019, 09:11 AM
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Originally Posted by Rex Anderson View Post
Even the best home theater systems pale in comparison to large scale PA systems in great venues. I set up and tuned 8.4 systems in concert halls and played back compositions by composers who wrote music specifically for those systems. Sound would move around the concert halls and create images that would blow your mind. One of the electronic music composers I worked with created the sound of a ball in a roulette wheel going around the venue. That was just one part of the composition, but it was amazing.

Personal anecdote...I saw many concerts at New York's Madison Square Garden in the 1970s and 1980s, when it was notorious for bad sound, despite bands paying lots of money to companies like Clair Bros. to provide state-of-the-art PA rigs. The venue itself, like many sports arenas serving double duty as concert venues, was just a bear, acoustically.

Fast forward to last year, my first MSG concert in awhile, Radiohead. Even sitting on the *side* (not facing the stage directly) the sound was astonishingly good and detailed. The venue itself had certainly upgraded, but it's still a big oval sports arena, and I suspect modern DSP and PA technology has just gotten that good now.

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post #1879 of 5320 Old 02-21-2019, 09:36 AM
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Originally Posted by epetti View Post
So to the point of the Salon2 and F228be comparison (and possibly even smaller speakers that measure equally well), as long as both are played at reasonable volumes, and supplemented with a subwoofer (since otherwise the Salon2 has a lower range and also just to reduce the stress on the F228be), they should sound essentially the same. And I'm guessing the F228be can actually be pushed pretty far itself without distorting. So the point of diminishing returns at that point may be completely negligible.
I have to say I heard both, same room same gear same positions and I bought the salon 2. To be fair in hindsight it is possible the f228be could sound better in comparison with more modest amplification, but I didn't get to check that out.

The f36 with a sub isn't going to sound like the salon2 with everything else being equal, but a $22k pair is for the more fanatical of us that obviously put a very high value on reproduction and get off on the finer details and the point of diminishing returns is an individual choice.

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post #1880 of 5320 Old 02-21-2019, 09:44 AM
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Quote:
Originally Posted by mlee1 View Post
Hi All,
A quick question that has been running in the back of my mind regarding multichannel speaker selection. Sorry if it has been answered already but did a quick search with limited success.

Since we are not sensitive to absolute phase (if a stereo speaker pair has equal phase wrap over frequency in both speakers) then we get a phantom centre presentation and it sounds good. If one were to invert 1 of the tweeters then it sounds for lack of a better term phasey. If we invert both tweeter (crossover problems aside), it sounds more normal so one would conclude we are more sensitive to relative phase.

Taking this question to multichannel, is there benefit to having all speakers exhibit the exact same phase shift throughout the frequency bands (at least above say 300hz or so), or do surrounds and atmos channels not matter as much. I suspect the LCR is more critical for proper front channel panning or is relative phase shift between speakers not an issue with multichannel? I can't escape the feeling that ALL speakers relative phase shift should be the same for multichannel. If not, what are the variables at play that exclude this?

The above question assumes we are not using tools like Dirac that change the speakers relative phase response.

Thank you in advance,

First of all, you are actually inverting polarity. Inverting polarity is generally speaking much more destructive then phase shift. Phase shift is basically same as if you would move speaker at another location in room. But inverting polarity on one speaker, assuming that both speakers are equidistant from you will cause much more destructive interference in portions of program which both speakers share.
Contrary to that, although phase shift (so basically speaker placement) can be destructive it can also be alleviated via typical distance tweak on AVR and some EQ (if needed). So, yeah, keep polarity same on all speakers.

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Originally Posted by krabapple View Post
Personal anecdote...I saw many concerts at New York's Madison Square Garden in the 1970s and 1980s, when it was notorious for bad sound, despite bands paying lots of money to companies like Clair Bros. to provide state-of-the-art PA rigs. The venue itself, like many sports arenas serving double duty as concert venues, was just a bear, acoustically.

Fast forward to last year, my first MSG concert in awhile, Radiohead. Even sitting on the *side* (not facing the stage directly) the sound was astonishingly good and detailed. The venue itself had certainly upgraded, but it's still a big oval sports arena, and I suspect modern DSP and PA technology has just gotten that good now.

Could you please fix your post? You have attributed the wrong quote to me. Thanks.


(BTW, apparently you replied to another post of mine yesterday, though your reply didn't seem to show up in this thread).
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post #1882 of 5320 Old 02-21-2019, 10:24 AM
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Phase shift is basically same as if you would move speaker at another location in room.
Hi thanks for the response but let me clarify my question. This is just a theoretical question regarding speaker phase over frequency and selecting a multichanel speaker system as a whole.

Assume Speaker 1 and Speaker 2 have the exact same frequency response, both on and off axis (I know not realizable in the real world ).

Speaker 1 is a 2-way speaker and Speaker 2 is a 4 way+ multiway speaker. Notice the phase shift differences over the frequency sweep (it is not important that the provided phase measurements are not taken correctly only that the phase response over frequency shows differences).

For multichannel systems is it better to have ALL speakers exhibiting the same phase response? Or does it not matter? Is only frequency response a concern? Can I mix and match these 2 speakers for a multichannel speaker system?

For a stereo pair, if using speaker 1 for the Left speaker and using speaker 2 for right speaker, the presentation will sound strange even though the frequency response is the same. Intuitively would expect that there are advantages in sound presentation for a multichannel system to use all of the same speakers. On the other hand it would be nice to not have to worry about it and simply select speakers based on frequency response assuming the on and off axis measurements are close to each other.
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post #1883 of 5320 Old 02-21-2019, 10:34 AM
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Originally Posted by mlee1 View Post
Hi All,
A quick question that has been running in the back of my mind regarding multichannel speaker selection. Sorry if it has been answered already but did a quick search with limited success.

Since we are not sensitive to absolute phase (if a stereo speaker pair has equal phase wrap over frequency in both speakers) then we get a phantom centre presentation and it sounds good. If one were to invert 1 of the tweeters then it sounds for lack of a better term phasey. If we invert both tweeter (crossover problems aside), it sounds more normal so one would conclude we are more sensitive to relative phase.

Taking this question to multichannel, is there benefit to having all speakers exhibit the exact same phase shift throughout the frequency bands (at least above say 300hz or so), or do surrounds and atmos channels not matter as much. I suspect the LCR is more critical for proper front channel panning or is relative phase shift between speakers not an issue with multichannel? I can't escape the feeling that ALL speakers relative phase shift should be the same for multichannel. If not, what are the variables at play that exclude this?

The above question assumes we are not using tools like Dirac that change the speakers relative phase response.

Thank you in advance,
You are basically right -
--From a single loudspeaker phase response does not matter; we don't hear it.
--From a stereo pair, for amplitude panned phantom images to be well perceived the amplitude and phase responses of L & R speakers must be the same, but what it is does not matter. Of course, the phantom images are only properly perceived from the symmetrical sweet spot.
--In multichannel, the only amplitude panned images likely to be presented are in the L,C.R plane. There, in theory, all three speakers should be identical. In practice a slight mismatch in the center may or may not be noticed - it depends on the program. In my observation, high precision is not a requirement for the majority of movies where the center channel operates substantially independently of the L & R most of the time (done so that editing is simpler). Some music videos deliver the featured artist through all three fronts (dumb!) and in this case it may matter for the listener in the sweet spot. However, I cannot recall hearing any "panned" images among the other base or immersion channels. Movement, yes, but deliberate panning with credible intermediate stable locations, no. In any case, all such panning can only work for a single listener in the sweet spot (the mixer's seat), for all other listeners in the room there is no reliable amplitude panning. Consequently closely matched transfer functions (amplitude and phase) for all speakers in a surround system would not appear to be a requirement.
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post #1884 of 5320 Old 02-21-2019, 10:47 AM
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Could you please fix your post? You have attributed the wrong quote to me. Thanks.


(BTW, apparently you replied to another post of mine yesterday, though your reply didn't seem to show up in this thread).

Fixed.
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post #1885 of 5320 Old 02-21-2019, 10:48 AM
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In any case, all such panning can only work for a single listener in the sweet spot (the mixer's seat), for all other listeners in the room there is no reliable amplitude panning. Consequently closely matched transfer functions (amplitude and phase) for all speakers in a surround system would not appear to be a requirement.
Thank you for the detailed response! This greatly relaxes the choice loudspeaker for me. Your new version Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms should arrive today or tomorrow. Looking forward to reading it .
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post #1886 of 5320 Old 02-21-2019, 11:11 AM
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Hi thanks for the response but let me clarify my question. This is just a theoretical question regarding speaker phase over frequency and selecting a multichanel speaker system as a whole.

Assume Speaker 1 and Speaker 2 have the exact same frequency response, both on and off axis (I know not realizable in the real world ).

Speaker 1 is a 2-way speaker and Speaker 2 is a 4 way+ multiway speaker. Notice the phase shift differences over the frequency sweep (it is not important that the provided phase measurements are not taken correctly only that the phase response over frequency shows differences).

For multichannel systems is it better to have ALL speakers exhibiting the same phase response? Or does it not matter? Is only frequency response a concern? Can I mix and match these 2 speakers for a multichannel speaker system?

For a stereo pair, if using speaker 1 for the Left speaker and using speaker 2 for right speaker, the presentation will sound strange even though the frequency response is the same. Intuitively would expect that there are advantages in sound presentation for a multichannel system to use all of the same speakers. On the other hand it would be nice to not have to worry about it and simply select speakers based on frequency response assuming the on and off axis measurements are close to each other.

If you want ideal system, all speakers should match.
However I think you are kinda overestimating the "problem." Significant phase mismatch is most likely very audible only to parts of a signal which are common to multiple speakers at exactly the same time, so its more likely to be noticed in stereo music then multichannel movie. Basically, the issue will be present if you have mono signal on multiple channels or if you have sound/instrument/voice sharing (usually) 2 speakers because that sound is located on soundstage between them. That of course doesn't mean you will necessarily recognize the problem or hear it, unless its really bad.
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post #1887 of 5320 Old 02-21-2019, 11:14 AM
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Personal anecdote...I saw many concerts at New York's Madison Square Garden in the 1970s and 1980s, when it was notorious for bad sound, despite bands paying lots of money to companies like Clair Bros. to provide state-of-the-art PA rigs. The venue itself, like many sports arenas serving double duty as concert venues, was just a bear, acoustically.

Fast forward to last year, my first MSG concert in awhile, Radiohead. Even sitting on the *side* (not facing the stage directly) the sound was astonishingly good and detailed. The venue itself had certainly upgraded, but it's still a big oval sports arena, and I suspect modern DSP and PA technology has just gotten that good now.

Being a guitar player since 1965 and a recording and live sound engineer since 1974, I not only attended a lot of live music concerts, I was also the front of house mixing engineer for thousands. Even with the best systems, it's hard to overcome bad acoustics. It's difficult to achieve good sound for most arena rock IMO. I prefer smaller venues with good acoustics. In venues with good acoustics, PA systems and a skilled mixing engineer, great sound can be achieved. Current systems are better than ever. The biggest problem I hear these days is what mix engineers think is "good sound".
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post #1888 of 5320 Old 02-21-2019, 11:35 AM
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Thats a bit of a misinterpretation. A neutral speaker with good polar plot will have most balanced/natural response in virtually all rooms. But that doesn't necessarily mean it will sound good, due to the acoustic problems in room, SBIR, room modes and placement. Its not really speakers but rooms fault. Same way when you enter different room, your voice will sound different. Unbalanced speaker on the other hand has greater chance of highlighting the rooms problems.


I didn’t say good speakers will always sound good in bad rooms, I said that the ranking of speakers doesn’t change. Rooms do sound different, and some have big problems with room modes, but listeners hear through room differences.

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post #1889 of 5320 Old 02-21-2019, 11:43 AM
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I didn’t say good speakers will always sound good in bad rooms, I said that the ranking of speakers doesn’t change. Rooms do sound different, and some have big problems with room modes, but listeners hear through room differences.
Got it. I was actually quoting you out of context.

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post #1890 of 5320 Old 02-21-2019, 11:52 AM
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Being a guitar player since 1965 and a recording and live sound engineer since 1974, I not only attended a lot of live music concerts, I was also the front of house mixing engineer for thousands. Even with the best systems, it's hard to overcome bad acoustics. It's difficult to achieve good sound for most arena rock IMO. I prefer smaller venues with good acoustics. In venues with good acoustics, PA systems and a skilled mixing engineer, great sound can be achieved. Current systems are better than ever. The biggest problem I hear these days is what mix engineers think is "good sound".

Such as my trip a few years back from C-bus to Charleston, West by gawd Virginia to see the Moody Blues at the beautiful Clay Center https://www.theclaycenter.org/

9th row seats with fellow oldsters, and the sound engineer thinks he needs to turn it into EDM. And so bad that you couldn't hear the lyrics. I read the warnings in reviews of prior performances in the tour.
During the intermission I ended in a big argument with him and thankfully a several fellow geezers joined in. It pretty well ruined the event for me.

Last edited by Scotth3886; 02-21-2019 at 12:17 PM.
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