How to Choose a Loudspeaker -- What the Science Shows - Page 35 - AVS Forum | Home Theater Discussions And Reviews
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post #1021 of 5353 Old 01-26-2019, 06:05 AM
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Here is a question Ive been wondering about. The premise of this thread is that, basically, accurate speakers sound the best to most people. Another topic that comes up often in regards to sound quality is that room correction above the subwoofer bandpass is not desirable. However, it would seem to me that this assumes we are using speakers that are able to be placed in the room in such a way as to have a reasonably accurate frequency response. So here is my question. In my room due to placement restrictions, my frequency response is very poor....nowhere close to accurate. With Audyssey XT32, my response is very good and, to my ear, the sound is drastically improved. Although I understand that achieving a better response with ideal placement and perhaps better measuring speakers would be preferable, within the constraints of the speakers that I have, and without placement flexibility, wouldn't room correction to at least have a somewhat accurate response be the lesser of two evils compared to having a dreadfully inaccurate frequency response?

@Floyd Toole
So to clarify, given the speakers I have and placement restrictions, it doesn't sound right to me that no eq with a dreadful frequency response would be somehow superior to a more accurate response with eq. To illustrate:

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post #1022 of 5353 Old 01-26-2019, 07:16 AM
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Originally Posted by emcdade View Post
Not sure I entirely agree.

I think you could make a case that a speaker that specializes in huge dynamics without a ruler flat anechoic response still trumps, say, an audiophile monitor speaker with outstanding measurements for home theater usage.
I thought ht speakers were speakers that sacrificed fidelity to a small extent for pleasing ascetics, like waf and placement against a wall in a busy room? Thats what I think of when I hear 'good for ht'. A dedicated 2 channel system with a pair of full range speakers 5' away from any reflecting surface putting the highest regard towards to musical playback could, conversely sound like garbage tucked into a corner.
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post #1023 of 5353 Old 01-26-2019, 07:55 AM
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Originally Posted by craig john View Post
I didn't say I couldn't afford it. I said I didn't want to. Audio is not my profession. Since it appears you haven't read the whole thread, I've explained my profession here:
My memory is not what it used to be, but I could swear I read that you have taken that Audyssey Pro kit of yours and calibrated systems for people, perhaps even for money? If so, perhaps you should disclose that?
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post #1024 of 5353 Old 01-26-2019, 08:55 AM
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Originally Posted by steven59 View Post
I thought ht speakers were speakers that sacrificed fidelity to a small extent for pleasing ascetics, like waf and placement against a wall in a busy room? Thats what I think of when I hear 'good for ht'. A dedicated 2 channel system with a pair of full range speakers 5' away from any reflecting surface putting the highest regard towards to musical playback could, conversely sound like garbage tucked into a corner.
"Good for ht" and "good for music" always strike me as being marketing phrases. Wearing my cynical hat, there doesn't seem to be consistent usage except for the seller saying whatever moves more product.
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post #1025 of 5353 Old 01-26-2019, 09:01 AM
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Originally Posted by Bill-99 View Post
"Good for ht" and "good for music" always strike me as being marketing phrases. Wearing my cynical hat, there doesn't seem to be consistent usage except for the seller saying whatever moves more product.

I'd say there are speakers not so good for HT mostly because of placement requirements.
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post #1026 of 5353 Old 01-26-2019, 10:17 AM
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Originally Posted by Scotth3886 View Post
I'd say there are speakers not so good for HT mostly because of placement requirements.
Fair enough.

I'd also say there are speakers not so good for ht or for music because, well, they aren't very good.


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post #1027 of 5353 Old 01-26-2019, 10:29 AM
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I'm at the bottom of page 29 and would like to input my observation between the performa 2 and performa 3 line this my OPINION that the spinorama results are leading revel away from stereo reproduction towards a more ht bias, intended or not. The performa 2 specifically f32 and f52 along side the f208 where I spent a couple hours comparing them. I struggle with the words to describe the differences in imaging so i'm going to simplify my remark that the performa3's sounded and imaged like large speakers admittedly giving less clues to their origins, but still not creating the effect the 'fake' panning of sound? special effects? Dig out Lindsey Buckingham's from the cradle, we have his guitar filling the room with the accompanying instruments emanating from there. The f208 does this tonally as good as it gets, but somewhere the sound became separate from the whole, so difficult to explain, somewhere the seductive qualities of the music became an event. The depth and size became individualized instead of all the sounds being a part of the whole. I doubt I was able to express my experience concisely, but being a strictly 2 channel music lover the difference is obvious.


Spoiler!



I'm not sure what copy and paste from a post on page 30 is going to look like, but it is informative.
So this is with 1 speaker being tested in mono? and or general public. and I would suggest as small as the audiophile market is compared to HT or even boom boxes those of us that cherish our antique 2 channel delivery system aren't the target market.
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post #1028 of 5353 Old 01-26-2019, 10:40 AM
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Originally Posted by bear123 View Post
Here is a question Ive been wondering about. The premise of this thread is that, basically, accurate speakers sound the best to most people. Another topic that comes up often in regards to sound quality is that room correction above the subwoofer bandpass is not desirable. However, it would seem to me that this assumes we are using speakers that are able to be placed in the room in such a way as to have a reasonably accurate frequency response. So here is my question. In my room due to placement restrictions, my frequency response is very poor....nowhere close to accurate. With Audyssey XT32, my response is very good and, to my ear, the sound is drastically improved. Although I understand that achieving a better response with ideal placement and perhaps better measuring speakers would be preferable, within the constraints of the speakers that I have, and without placement flexibility, wouldn't room correction to at least have a somewhat accurate response be the lesser of two evils compared to having a dreadfully inaccurate frequency response?

@Floyd Toole
So to clarify, given the speakers I have and placement restrictions, it doesn't sound right to me that no eq with a dreadful frequency response would be somehow superior to a more accurate response with eq. To illustrate:

Pardon for my folksy interpretation of Dr. Toole...
Omni-directional microphones measure both the direct sound and reflections as one.
Human ears are capable of differentiating between reflections and direct sound.
Corrections make adjustments treating the indirect sound as an issue with direct sound but that is not what we hear.

A well designed speaker that has good anechoic direct response, when room corrected, is not longer producing flat response for direct sound.
The result of the correct results in inferior, degrading the perceived sound even though the chars look good.

Room correction systems are products which in themselves produce bias. They show the measurements and then the predicted response.
Without independent measurements, even measurement based systems have no verification.

The advise provided here is sound. For well designed speakers, limit room correction to below the Schroeder frequency.

- Rich
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post #1029 of 5353 Old 01-26-2019, 10:45 AM
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Originally Posted by Bill-99 View Post
"Good for ht" and "good for music" always strike me as being marketing phrases. Wearing my cynical hat, there doesn't seem to be consistent usage except for the seller saying whatever moves more product.
Clearly any speaker great for music is also great for HT.


However, video changes experience..
For example, watching a well recorded multi-channel concert is much more engaging with the display on.
The corollary is that when there is video (HT), the user is less critical of the audio.


- Rich

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post #1030 of 5353 Old 01-26-2019, 10:54 AM
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Originally Posted by RichB View Post
\


Pardon for my folksy interpretation of Dr. Toole...
Omni-directional microphones measure both the direct sound and reflections as one.
Human ears are capable of differentiating between reflections and direct sound.
Corrections make adjustments treating the indirect sound as an issue with direct sound but that is not what we hear.


A well designed speaker that has good anechoic direct response, when room corrected, is not longer producing flat response for direct sound.
The result of the correct results in inferior, degrading the perceived sound even though the chars look good.


Room correction systems are products which in themselves produce bias. They show the measurements and then the predicted response.
Without independent measurements, even measurement based systems have no verification.


The advise provided here is sound. For well designed speakers, limit room correction to below the Schroeder frequency.


- Rich
A speaker with a non-flat frequency response might be able to fit in the poor room and placement, whereas a flat response speaker might very well end up exaggerating and showcasing the poor environment. It is no wonder that different people love different speakers - for it depends upon their own room & placement.
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post #1031 of 5353 Old 01-26-2019, 11:33 AM
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Originally Posted by bear123 View Post
Here is a question Ive been wondering about. The premise of this thread is that, basically, accurate speakers sound the best to most people. Another topic that comes up often in regards to sound quality is that room correction above the subwoofer bandpass is not desirable. However, it would seem to me that this assumes we are using speakers that are able to be placed in the room in such a way as to have a reasonably accurate frequency response. So here is my question. In my room due to placement restrictions, my frequency response is very poor....nowhere close to accurate. With Audyssey XT32, my response is very good and, to my ear, the sound is drastically improved. Although I understand that achieving a better response with ideal placement and perhaps better measuring speakers would be preferable, within the constraints of the speakers that I have, and without placement flexibility, wouldn't room correction to at least have a somewhat accurate response be the lesser of two evils compared to having a dreadfully inaccurate frequency response?

@Floyd Toole
So to clarify, given the speakers I have and placement restrictions, it doesn't sound right to me that no eq with a dreadful frequency response would be somehow superior to a more accurate response with eq. To illustrate:

I had a quick look at your home setup using the link you provided. You definitely have problems. Both speakers are buried in a bookshelf with spaces around them (resonant cavities), and the right speaker is hard against a wall, which becomes part of that speaker, but not the companion Left speaker which is more in the open. There will be a L/R imbalance, that probably cannot be completely corrected.

I devote an entire chapter in my book to "adjacent boundary effects" including measurements of a "bookshelf" loudspeaker (the kind you have) measured as it is intended to be used (standing free, on a stand), and in various other placements with respect to a single wall, including on a shelf with space around it (Figures 9.7 thru 9.9). The differences are huge. Equalization can assist with the broadband bass boost, but cannot fix the cavity resonances and diffractions from the complicated bookshelf surroundings.

Without comprehensive anechoic data on the speakers it is impossible to estimate what an uncomplicated room curve should look like. Checking their specs in the manual it says: "fine tuning by Dr. Hsu to sound good to his ears". We can probably assume that the speakers were free standing, in the best possible locations, but we have no other guidance as to what might have influenced Dr. Hsu's personal tastes.

Your installation is acoustically "complicated", and EQ cannot fix all the complications. Can it make things better than they were? - almost certainly, especially at the very important frequencies below about 500 Hz. The non-flat response above that frequency could be due to uneven off-axis frequency response, but we have no anechoic data to tell us whether this is a performance attribute that can be compensated for or not.
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post #1032 of 5353 Old 01-26-2019, 12:20 PM
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Originally Posted by Floyd Toole View Post
I had a quick look at your home setup using the link you provided. You definitely have problems. Both speakers are buried in a bookshelf with spaces around them (resonant cavities), and the right speaker is hard against a wall, which becomes part of that speaker, but not the companion Left speaker which is more in the open. There will be a L/R imbalance, that probably cannot be completely corrected.

I devote an entire chapter in my book to "adjacent boundary effects" including measurements of a "bookshelf" loudspeaker (the kind you have) measured as it is intended to be used (standing free, on a stand), and in various other placements with respect to a single wall, including on a shelf with space around it (Figures 9.7 thru 9.9). The differences are huge. Equalization can assist with the broadband bass boost, but cannot fix the cavity resonances and diffractions from the complicated bookshelf surroundings.

Without comprehensive anechoic data on the speakers it is impossible to estimate what an uncomplicated room curve should look like. Checking their specs in the manual it says: "fine tuning by Dr. Hsu to sound good to his ears". We can probably assume that the speakers were free standing, in the best possible locations, but we have no other guidance as to what might have influenced Dr. Hsu's personal tastes.

Your installation is acoustically "complicated", and EQ cannot fix all the complications. Can it make things better than they were? - almost certainly, especially at the very important frequencies below about 500 Hz. The non-flat response above that frequency could be due to uneven off-axis frequency response, but we have no anechoic data to tell us whether this is a performance attribute that can be compensated for or not.
Thanks very much for the response. Be honest. Did you cringe a little?

Seems like if I want to improve things, I need to be willing to get the speakers out of the bookshelves and onto stands.
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post #1033 of 5353 Old 01-26-2019, 12:49 PM
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Thanks very much for the response. Be honest. Did you cringe a little?

Seems like if I want to improve things, I need to be willing to get the speakers out of the bookshelves and onto stands.
Yup. And aim them at you. This will deliver the best possible direct sound to you and will put the wall reflection farther off axis, attenuating its effects slightly. BTW, bookcases behind the speakers are useful absorber/diffusers.
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post #1034 of 5353 Old 01-26-2019, 12:51 PM
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Originally Posted by craig john View Post
Did you take any measurements before and after running Audyssey? Did you change anything based on those measurements? Neither did Dr. Olive.




Did you try Reference Level Offset?
Yes, I changed speaker location, sub location, measured which seats were too much variation from the others and excluded that seat/ or seats during calibration. Etc. I've followed the "master Audyssey" thread here on AVS and still didn't like the sound. I tried single seat calibration.

You make a lot of assumptions.

That said, I jumped Audyssey before the new app came out that allowed you to change cut off frequency. Regardless, there's better solutions out there.
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post #1035 of 5353 Old 01-26-2019, 04:07 PM
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Originally Posted by steven59 View Post
It seems pretty clear that Dr. Toole and many of the other Harman supporters in this thread prefer an open, spacious sound over pinpoint imaging. /SPOILER]
"Toole prefers room reflections/spatial sound" in many variations floats through the forums. I'm truly getting tired of slaying this "dragon" over and over again. Any stated "preference" for open, spacious sound reported in my writings is not a personal preference. If you read my book you will understand that much of the world shares this opinion. You are welcome to a different one, of course.

As for my personal feelings, as shown in my book in Section 7.4.6, I have lived with and enjoyed several variations of spatial rendering over the years, from a very spacious personal "concert hall" with essentially omni loudspeakers designed for classical works (Figure 7.19), through variations of direct sound dominated multichannel (Figures 7.18 and 7.21). Currently, my system would be described as being direct-sound dominated, as the first sidewall reflections don't exist, and I use multichannel upmixing to embellish stereo to whatever level of spatial envelopment I choose. So, I have a basic "pinpoint" localization system that can be "spatially" modified at will.

Kevin Voecks, a Revel/Harman supporter to be sure, listens in a room covered with fiberglass, and has stated here that he is a devotee of pinpoint imaging.

All that said, the advantage of loudspeakers designed to meet the criteria described in my book, and recognizable in comprehensive anechoic data like a Spinorama, is that the customer can choose. Allowing more room reflections can enhance the spatial presentation without destroying the timbre. Killing the room reflections puts you in a pristine direct sound field. Both sound timbrally neutral, differing only in spatial rendering. Because spatial effects are dominated by recording technique, it is nice to have alternatives.

This is not a new topic for me. 38 years ago I set up a listening room which had heavy velour drapes along the fronts of the side walls. When pulled out, the side wall reflections were absorbed, giving pinpoint, tight, imaging. When they were pushed back, they allowed for a more open, spacious soundstage. One tended to favor rock and pop, the other more spatially oriented classical recordings. Such an option only works well if one has well designed loudspeakers to begin with.

Harman is not the only company capable of designing such loudspeakers. The guidance is in the public domain, but not everyone knows about it or believes in it.
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post #1036 of 5353 Old 01-26-2019, 04:41 PM
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My memory is not what it used to be, but I could swear I read that you have taken that Audyssey Pro kit of yours and calibrated systems for people, perhaps even for money? If so, perhaps you should disclose that?
Your memory is definitely not what it used to be. I have NEVER charged ANYONE for helping them with their systems, whether it is in the design phase, the installation phase, the calibration and EQ phase, or in the post-cal tweaking phase, or any of those combined. I always use in-room measurements to assist with cal, EQ and tweaking, but I don't use an Audyssey Pro kit. (I own one, but it sits in the closet unused.) I've set up systems with YPAO, MCACC, (not impressed with eithe rof those), and with Anthem ARC, (very good system!)



I will say that there was one instance where I took money for a fairly extensive re-work of a friend's system, but it was only because he demanded that I take the money. The very next day, I donated the money to the American Cancer Society, (I had cancer myself a couple years ago, so it was an easy donation to make.)



To refresh your memory, you and I met at an AVS GTG about 5 years ago. You brought your M2's along, but due to some complication with the amps, your were only able to demo a single M2. IIRC it was set up with a dual mono signal, (a stereo signal upmixed to PLIIx Movie with just the center channel speaker playing), Appropo to this thread, I noted then that the mono nature of the demo limited the imaging to a central, distinct image. No phantom images were present in the demo. And I wasn't the only one who noticed. Another attendee called the sonic image "pencil-thin." I had forgotten that demo until now, but it reconfirms my thoughts that monophonic listening provides no insights into the imaging capabilities of a PAIR of speakers. Also, this was intended to be a blind demo of the 2 speakers in question, but it didn't turn out that way because of the amp situation:
https://www.avsforum.com/forum/89-sp...l#post30027377

Quote:
Since I am one of the... "participants that didn't even write about their impressions," I apologize for my tardiness in writing up my impressions of the GT. However, my tardiness is not related to any hesitation on my part, or any concern about being attacked by anyone. Nor is it because I have an untoward respect for JTR speakers. My first ever exposure to JTR speakers was to the 215's at this GTG, so I had no untoward bias about JTR speakers going into this event. Nor did I have any bias towards the JBL speakers. I have heard the JBL Everest system previously and have been critical of their price/performance ratio. In addition, I've been involved in a number of discussions on this forum about the Harman/JBL's research and it's, (IMO), very self-serving reporting. On the contrary, my tardiness in posting my impressions has been caused by things taking place in my life outside AVS forum. Things were absolutely insane at work last week. And then on Saturday I left to attend my son's graduation from ASU. (As an aside, he graduated Summa Cum Laude with a 4.0 in "Sustainability." He also gave the "Convocation Address" for his graduating class. My fatherly pride is positively BURSTING out of my heart as I write this!!! I can't even put into words how proud I am of my son!)

Nonetheless, to get back to the subject of the thread, I completely agree that, in this comparison, "...the M2's were a clearly superior speaker," and that "It wasn't even close." In spite of the fact that the M2's had one arm tied behind their back by the amp situation, the sound *quality* of the M2's was far smoother, more articulate and more detailed than the 215's. And the difference wasn't subtle. Where the 215's made Nora Jones sound like she had a sore throat, the M2's brought out the smoothness and harmonic texture and nasality of her voice. Where the 215's made the drums and bass guitars of the Fourplay piece sound like one big, VERY LOUD combined note, the M2's articulated each note as distinct and separate from every other note, and they articulated the drum kicks as distinct from the bass guitar. I was actually astonished by the articulation of the bass with the M2's, especially since so little effort was put into integrating their bass into Andrew's room.

The only thing I didn't get from the M2's was their imaging capabilities. Of course, this was due to the amp situation and the "dual-mono" nature of the signal they were receiving. All dual-mono setups exhibit a very precise central "phantom" image... but no other "front soundstage" imaging. That's just how dual-mono setups work. EVERYTHING sounds like it coming from the exact middle of the of the front of the room. In that respect, the M2's worked perfectly, as they presented exactly what Brandon described as a pencil-thin image in the center of the room. Nora Jones' voice is recorded in dual-mono, so it's presentation in dual-mono worked perfectly, and her voice imaged exactly where it was supposed to... in the middle. But so did all the other instruments, which, if presented in 2-channel, are supposed to surround her with music. That didn't work unfortunately.

I will say that I think we listened to the JTR's too loud. I think they may have sounded better if we had turned them down 6 dB or so. After the JTR demo, my ears were actually numb. I couldn't hear well and everything sounded muffled and muted for about 20 minutes. Fortunately we had some time between demo's and my ears recovered, but the excessive SPL's we were hearing with the JTR's definitely caused some strain on my hearing. Also, it made the comparison tougher because the SPL's we heard for each track were different.

I have yet to hear a speaker that would make me move away from my Triads, and I heard nothing this weekend that changed my feelings on that. However, I have discussed a trip to both Dave's and Mark's places to hear these speakers integrated into their own rooms. I will try to make that happen after the holidays, (and, depending on how far the Packers go in the playoffs, after the Superbowl.)

To summarize, it was a great, fun-filled day with a great bunch of guys, great sound and great food and drink. One of the highlights of the day for me came at the end of the day, after most people had left. We watched the UFC fights with ChopShop, who has trained with some of the UFC guys and knows some of the trainers and fighters. He offered some insights into the fighting that were a unique perspective. (Chop, I still think Hendricks beat Lawler for the title!)

Thank you Andrew for hosting this event. Your hospitality is first rate, and your theater is an ideal venue for this type of GTG, (and that Book of Eli demo was as amazing as the Metallica demo I had the last time I was at your place!!!). If you host anymore GTG's, I hope I'm invited!!!

Craig

You and I had several interesting exchanges before the GTG took place. One involved a calibrator name Mr. JBL, who calibrated your system by placing the mic on the floor halfway between the speakers and the LP: https://www.avsforum.com/forum/89-sp...l#post28078962 Funny stuff!



Another one where we discussed how to demo multichannel recordings on a 2-channel system: https://www.avsforum.com/forum/89-sp...l#post28247306 and https://www.avsforum.com/forum/89-sp...l#post28249122


In one post, you thought it was advantageous to intervene and EQ the speakers in the bass range before demo, so as not to superimpose the room's characteristics on the listening impressions listening, (interventions to level the playing field is something I've argued for in this thread):
https://www.avsforum.com/forum/89-sp...l#post28248466
and

https://www.avsforum.com/forum/89-sp...l#post28267138



Here we talked about some music choices for the GTG:

https://www.avsforum.com/forum/89-sp...l#post28768890
You responded on the next page.


Re-reading snippets from the thread was a walk down memory lane. Fun...


Craig
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post #1037 of 5353 Old 01-26-2019, 05:51 PM
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Originally Posted by craig john View Post
Your memory is definitely not what it used to be. I have NEVER charged ANYONE for helping them with their systems, whether it is in the design phase, the installation phase, the calibration and EQ phase, or in the post-cal tweaking phase, or any of those combined. I always use in-room measurements to assist with cal, EQ and tweaking, but I don't use an Audyssey Pro kit. (I own one, but it sits in the closet unused.) I've set up systems with YPAO, MCACC, (not impressed with eithe rof those), and with Anthem ARC, (very good system!)



I will say that there was one instance where I took money for a fairly extensive re-work of a friend's system, but it was only because he demanded that I take the money. The very next day, I donated the money to the American Cancer Society, (I had cancer myself a couple years ago, so it was an easy donation to make.)



To refresh your memory, you and I met at an AVS GTG about 5 years ago. You brought your M2's along, but due to some complication with the amps, your were only able to demo a single M2. IIRC it was set up with a dual mono signal, (a stereo signal upmixed to PLIIx Movie with just the center channel speaker playing), Appropo to this thread, I noted then that the mono nature of the demo limited the imaging to a central, distinct image. No phantom images were present in the demo. And I wasn't the only one who noticed. Another attendee called the sonic image "pencil-thin." I had forgotten that demo until now, but it reconfirms my thoughts that monophonic listening provides no insights into the imaging capabilities of a PAIR of speakers. Also, this was intended to be a blind demo of the 2 speakers in question, but it didn't turn out that way because of the amp situation:
https://www.avsforum.com/forum/89-sp...l#post30027377




You and I had several interesting exchanges before the GTG took place. One involved a calibrator name Mr. JBL, who calibrated your system by placing the mic on the floor halfway between the speakers and the LP: https://www.avsforum.com/forum/89-sp...l#post28078962 Funny stuff!



Another one where we discussed how to demo multichannel recordings on a 2-channel system: https://www.avsforum.com/forum/89-sp...l#post28247306 and https://www.avsforum.com/forum/89-sp...l#post28249122


In one post, you thought it was advantageous to intervene and EQ the speakers in the bass range before demo, so as not to superimpose the room's characteristics on the listening impressions listening, (interventions to level the playing field is something I've argued for in this thread):
https://www.avsforum.com/forum/89-sp...l#post28248466
and

https://www.avsforum.com/forum/89-sp...l#post28267138



Here we talked about some music choices for the GTG:

https://www.avsforum.com/forum/89-sp...l#post28768890
You responded on the next page.


Re-reading snippets from the thread was a walk down memory lane. Fun...


Craig
I quickly perused the GTG thread you linked. Looks like a fun way to spend a day. Regarding the mic on the floor, it’s a fairly common practice among live sound engineers when tuning systems in large venues like theaters and arenas. The logic is that the first reflection from the floor bounce can easily be stronger than the first reflection from a side wall because of the shorter distance between mic / floor vs. mic / wall. Placing the mic on the floor minimizes the effect of that reflection on the measurements. I’ve tried it a few times with varying degrees of success, but rarely have time to experiment with new measurement techniques in the middle of setting up for a show. You may have already deduced this, but I thought I’d put it out there.
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Originally Posted by craig john View Post
Your memory is definitely not what it used to be. I have NEVER charged ANYONE for helping them with their systems, whether it is in the design phase, the installation phase, the calibration and EQ phase, or in the post-cal tweaking phase, or any of those combined. I always use in-room measurements to assist with cal, EQ and tweaking, but I don't use an Audyssey Pro kit. (I own one, but it sits in the closet unused.) I've set up systems with YPAO, MCACC, (not impressed with eithe rof those), and with Anthem ARC, (very good system!)



I will say that there was one instance where I took money for a fairly extensive re-work of a friend's system, but it was only because he demanded that I take the money. The very next day, I donated the money to the American Cancer Society, (I had cancer myself a couple years ago, so it was an easy donation to make.)


......

Re-reading snippets from the thread was a walk down memory lane. Fun...


Craig
Ok, thanks for the clarification. It is a case of misplaced memory. After reading your post I recalled who it was that was doing the Audyssey Pro cals. Not you . Given your recent posts, I thought that should be divulged - if it were actually the case, but it's not.

Although almost without exception I enjoy reading your comments since they're typically well informed, your recent exchanges have been painful to read. I think skepticism in general is good, but uninformed skepticism...not so much. Especially when it involves decades old, freely published, freely available(at a small cost in some instances ), peer reviewed research that has been adopted as an ANSI standard. Have you stopped to think why ANSI has adopted the findings you're disputing as a standard for consumers to evaluate loudspeakers? That's a whole lot of very knowledgeable folks from across the audio industry that have accepted this body of research. Now granted, they could all be suckers with blinders on and maybe you'll be the one to expose the fraud, but somehow I doubt that.

Also, thanks for the links, they were fun to read

Quote:
Originally Posted by garygreyh View Post
I quickly perused the GTG thread you linked. Looks like a fun way to spend a day. Regarding the mic on the floor, it’s a fairly common practice among live sound engineers when tuning systems in large venues like theaters and arenas. The logic is that the first reflection from the floor bounce can easily be stronger than the first reflection from a side wall because of the shorter distance between mic / floor vs. mic / wall. Placing the mic on the floor minimizes the effect of that reflection on the measurements. I’ve tried it a few times with varying degrees of success, but rarely have time to experiment with new measurement techniques in the middle of setting up for a show. You may have already deduced this, but I thought I’d put it out there.
Yeah, he worked for Neil Diamond setting up his concert systems. He is a great guy who has helped me multiple times with support on the M2's.
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I don't believe he is arguing against any standards - just questioning the methods and results of a study on room correction systems.
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post #1040 of 5353 Old 01-27-2019, 08:55 AM
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Originally Posted by garygreyh View Post
I quickly perused the GTG thread you linked. Looks like a fun way to spend a day. Regarding the mic on the floor, it’s a fairly common practice among live sound engineers when tuning systems in large venues like theaters and arenas. The logic is that the first reflection from the floor bounce can easily be stronger than the first reflection from a side wall because of the shorter distance between mic / floor vs. mic / wall. Placing the mic on the floor minimizes the effect of that reflection on the measurements. I’ve tried it a few times with varying degrees of success, but rarely have time to experiment with new measurement techniques in the middle of setting up for a show. You may have already deduced this, but I thought I’d put it out there.
Interesting. I can see how that could work in a larger venue with little or no modal response issues, but how well does it work in a far smaller acoustic space where modal response is the primary issue? Virtually every RC system I aware of for small space room correction uses a mic at ear level at the PLP, or multiple locations around the PLP. Is that not how small space room correction should be performed?



Craig


PS. I need to get you together with a friend of mine who, in addition to being an HT enthusiast, is also a musician and he works for a sound reinforcement, public address company. You guys would probably have a lot to talk about and teach me.


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I have a few questions about room correction. First, I’d like to summarize how I understand things and ask a few questions that I’m hoping Dr. Toole can comment on. Second, I’d like to share my experiences with using room correction.

I had always thought that room correction offered benefits over the entire audible range. However, based on the insight shared here by Dr. Toole, it seems as though the science indicates that EQ can often help below the Schroder Frequency (~500Hz), but not so much above that.

If the loudspeaker being used already has excellent on and off axis frequency response, then any EQ above the Schroeder Frequency is likely to be detrimental. However, if the loudspeaker has some flaws in it’s frequency response, then EQ could fix it, however, it’s extremely difficult to accomplish this by using in-room measurements. This is because in-room measurements will show not only the direct sound, but it will also contain information on the room reflections. Binaural human hearing is very good at separating the direct sound from the reflected sound above the Schroeder frequency. So, if the speaker has a good frequency response, it may not necessarily show up that way in a room measurement (due to reflections), and room EQ software may EQ that area thinking there is a problem, when there is not. However, it didn’t need to be EQ’d because humans will be able to hear the direct sound from the speaker, separating it out from the reflection.

Therefore, the only way to reliably EQ a loudspeaker that has frequency response problems above the Schroeder frequency would be to have good anechoic measurement data on that speaker. For example, if a speaker has an uneven response around 2kHz (say it has a 5db dip in this area relative to the rest of the range, then it could work to EQ the speaker up in that area (with the appropriate Q). However, it would still be hard to do this in-room. You’d need to EQ it in an anechoic chamber to get the proper EQ adjustment.

Do I have the basics correct here?

Next, I’d like to share my experience with using room EQ.

I use Audyssey MultEQ and I always thought that it improved the sound. Subjectively, to my ears, I always thought that the most noticeable improvement was in the bass (by far). However, when I look at before and after measurements (using REW) to me the frequency response looks better across the entire audible range. I’ve posted some REW graphs to demonstrate (all graphs are smoothed to 1/12th octave).

If you look at the before and after for the left speaker and sub, there are some areas that look better with Audyssey, and others that look worse. However, overall I think it looks a little better. Certainly the left and right speaker average across three listening positions looks smoother.

However, if my understanding of the above is correct, then even if my REW graphs look smoother above the Schroeder frequency, they may not actually be giving me better sound above that frequency.

Now, subjectively, when I listen to music and switch back and forth between no Audyssey and Audyssey, it sounds better to my ears with Audyssey. However, this is with the subs. And as I said, the most noticeable improvement is in the bass. So, if I switch back and forth between full Audyssey and the “Bypass L+R” feature (this means Audyssey is still on for the subs, but removed for the left and right speakers, then the sound difference between the two is different. The way I would describe the sound difference between these two modes is that in the “Bypass L+R”, it sounds like there is more midbass. Just going by the sound, I would guess there is more energy somewhere in the 100hz to 500hz area. To my ears, it still sounds better with Audyssey (vs. the "Bypass L+R"). So, is it possible that Audyssey is improving the sound enough below the Schroeder frequency, that it is negating any detriments that it has caused above this frequency?

I will note that if I turn the subs off, put the speakers to full range, and switch between no Audyssey and Audyssey, but this time without dynamic EQ, I think it actually sounded better with Audyssey turned off. It sounded fuller this way, and thinner and brighter with Audyssey turn on. So perhaps the vast majority of improvement that Audyssey is making is in the sub bass range.

FYI – my main speakers are GoldenEar Triton 2s and I have two PSA V1500 subs. I’ve attached a few pictures of my room as well.

I can't find any anechoic measurements of my speakers online (only quasi-anechoic), so it's hard to tell just how good these speakers are. Based on the quasi-anechoic, and comparing those to the quasi-anechoic measurements of the GoldenEar Triton 1s, and to the Triton 1s anechoic measurements on soundstage.com, it seems to me like the Triton 2s probably have a good average on and off-axis frequency response, but maybe not great? Hard to tell.

https://www.soundandvision.com/conte...peakers-page-4

Attachments:
1) Left speaker + subs, main listening position, before Audyssey.
2) Left speaker + subs, main listening position, after Audyssey (dynamic EQ is also on).
3) Average of left and right speakers + subs, averaged over three listening positions, before Audyssey.
4) Average of left and right speakers, +subs averaged over three listening positions, after Audyssey (dynamic EQ is on).
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35 pages and how many Spinorama measurements so far?
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post #1043 of 5353 Old 01-27-2019, 10:19 AM
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Originally Posted by craig john View Post
Interesting. I can see how that could work in a larger venue with little or no modal response issues, but how well does it work in a far smaller acoustic space where modal response is the primary issue? Virtually every RC system I aware of for small space room correction uses a mic at ear level at the PLP, or multiple locations around the PLP. Is that not how small space room correction should be performed?



Craig


PS. I need to get you together with a friend of mine who, in addition to being an HT enthusiast, is also a musician and he works for a sound reinforcement, public address company. You guys would probably have a lot to talk about and teach me.



Craig
Averaging multiple measurement is generally best. In large venues, I use 3-4 mics in different parts of the venue and take multiple measurements simultaneously. It also allows me to see how changes in the response of the system effect different locations in the venue in real time. Then the audience shows up and changes everything.

Low frequency sound in small rooms with close boundaries creates a lot of problems with regards to even response across the space. It creates a similar but “scaled up” set of issues in large spaces. There are still room modes but they tend to occur at larger distances from each other, as the waves have to travel farther before they reflect off of a wall/floor/ceiling and crash back into each other out of phase, creating a null, or combine positively (in phase) and create a peak in the response at that position.

Boundary reflections in a typical home listening room are what allow placing multiple subs in different locations around the room to even out the response across a larger percentage of that room. If you tried to space subs like that outdoors you’d have a nightmare of cancellations and summations on your hands. I’m giving the “Cliff’s Notes” version here (are Cliff’s Notes even still a thing?) because it’s getting off topic for this thread. See the link for more info on that. It covers the basics, but their is much, much more out there on this subject. The linked article does not address the process of trying to get the crossover region in phase between the subs and main speakers, which are sometimes located more than 30 to 40 feet away from each other.

http://www.prosoundweb.com/article/i...he_power_alley

Why the engineer setting up the M2s chose that technique in that situation I can’t say with any certainty. It may be his SOP or he may have had another reason. Maybe he was tired and just wanted to lie down (LOL). I guess the most important thing is results. Wish I had a better explaination, but at this point, I do not.

Another reason for minimizing the floor reflection when measuring in large venues is to streamline the process of time aligning the sub systems that make up a larger concert scale sound system. Strong first refelections can cause errant measurements when calculating delay times in the software. Errant measurements take time to correct (no pun intended) and time is money and like money, often in short supply.

Those subsystems would include the main speaker array(s), front fills on the lip of the stage to cover the front rows of seats that are outside the coverage pattern of the main speakers, subwoofer arrays, under balcony fills, out fills to the sides of the stage and delay speakers (when necessary) to maintain SPL at long distances from the stage. All of these subsystems are fed by separate outputs of the mixing console or system processor(s) so that they can be manipulated individually. Getting all of these elements to play nice together is no small task and compromises are always made in an attempt to provide even coverage across the largest percentage of the audience area. Sorry... got on a bit of a tangent there.

I may know your friend. It’s a pretty small community of audio professionals / musicians around these parts. If not, I’d welcome the opportunity to meet him.

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I don't believe he is arguing against any standards - just questioning the methods and results of a study on room correction systems.
+1! I don't see how 1 system can be eq'd, win the comparison, and the test not considered to be biased. I don't care how old the test was done or who did the test. Either all systems be eq'd the same or test them as designed. You can't get any simpler than that.
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post #1045 of 5353 Old 01-27-2019, 11:33 AM
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Ok, thanks for the clarification. It is a case of misplaced memory. After reading your post I recalled who it was that was doing the Audyssey Pro cals. Not you . Given your recent posts, I thought that should be divulged - if it were actually the case, but it's not.

Although almost without exception I enjoy reading your comments since they're typically well informed, your recent exchanges have been painful to read. I think skepticism in general is good, but uninformed skepticism...not so much. Especially when it involves decades old, freely published, freely available(at a small cost in some instances ), peer reviewed research that has been adopted as an ANSI standard. Have you stopped to think why ANSI has adopted the findings you're disputing as a standard for consumers to evaluate loudspeakers? That's a whole lot of very knowledgeable folks from across the audio industry that have accepted this body of research. Now granted, they could all be suckers with blinders on and maybe you'll be the one to expose the fraud, but somehow I doubt that.
I'm sorry you found my posts painful to read. However, did you read the story I wrote about Aprotinin, (Trasylol)? As a medical professional yourself, you should be able to grasp the analogies between that story and the Harman story. Similar to Harman's research, EVERYONE bought into that drug. These were also very smart people who accepted the company's, (Bayer Pharmaceutical's), sponsored research on face value. The FDA approved it. Every heart surgery program in the world used it, especially on every high-risk patient at elevated risk for bleeding. For 13 years, (1993 to 2006), it was virtually the standard of care for high risk open heart surgery patients. It turned out the company sponsored RCT's were all small studies that weren't powerful enough to show the significance of the deleterious side effects of the drug. Over those ensuing 13 years, there were 63 more papers published, all of which showed a significant effect on perioperative bleeding. However, none of them were large enough to show a significant deleterious effect on mortality, (DEATH), or on Kidney failure. It wasn't until 2 independent groups of researchers performed meta-analyses on the data of much larger populations of patients, that these untoward effects were recognized. Once they were exposed by third party researchers, the FDA rescinded approval of the drug and it was eventually taken off the market. By 2011, The Society of Thoracic Surgery and the Society of Cardiovascular Anesthesiologists issued a statement on Blood Conservation Clinical Practice Guidelines which said the following:

Quote:
High-dose (Trasylol, 6 million KIU) and low-dose (Trasylol, 1 million KIU) aprotinin reduce the number of adult patients requiring blood transfusion, total blood loss, and reexploration in patients undergoing cardiac surgery but are not indicated for routine blood conservation because the risks outweigh the benefits. High-dose aprotinin administration is associated with a 49% to 53% increased risk of 30-day death and 47% increased risk of renal dysfunction in adult patients. No similar controlled data are available for younger patient populations including infants and children.
https://www.sts.org/sites/default/fi...Update0311.pdf
(You may not be familiar with this controversy because, IIRC, you're not a cardiac anesthesiologist and probably don't read the cardiac anesthesia literature.)



In any event, YES, I believe it's possible for a standards committee and whole bunch of very smart people to believe in, and invest in, research that is not fully vetted, performed by an entity that has a vested interest in the outcome of the research, and does not have high-powered, third party studies that totally support the findings. Harman's research may well be 100% correct, but I will view it through the lens of skepticism until it is verified by unbiased, third party investigators. I also believe there are enough question marks for me to remain skeptical.



I will make an attempt to get my hands on a full copy of the paper in question. I may even join the AES. Are you a member? Have you read the article in its' entirety? If so, what were your thoughts?



Craig



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+1! I don't see how 1 system can be eq'd, win the comparison, and the test not considered to be biased. I don't care how old the test was done or who did the test. Either all systems be eq'd the same or test them as designed. You can't get any simpler than that.
Are theese negative considerations about Room EQ above the Schroeder frequency also valid for manual EQ (measuring the response in the MLP with an omnidirectional microphone)?
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post #1047 of 5353 Old 01-27-2019, 11:36 AM
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I have a few questions about room correction. First, I’d like to summarize how I understand things and ask a few questions that I’m hoping Dr. Toole can comment on. Second, I’d like to share my experiences with using room correction.

I had always thought that room correction offered benefits over the entire audible range. However, based on the insight shared here by Dr. Toole, it seems as though the science indicates that EQ can often help below the Schroder Frequency (~500Hz), but not so much above that.

If the loudspeaker being used already has excellent on and off axis frequency response, then any EQ above the Schroeder Frequency is likely to be detrimental. However, if the loudspeaker has some flaws in it’s frequency response, then EQ could fix it, however, it’s extremely difficult to accomplish this by using in-room measurements. This is because in-room measurements will show not only the direct sound, but it will also contain information on the room reflections. Binaural human hearing is very good at separating the direct sound from the reflected sound above the Schroeder frequency. So, if the speaker has a good frequency response, it may not necessarily show up that way in a room measurement (due to reflections), and room EQ software may EQ that area thinking there is a problem, when there is not. However, it didn’t need to be EQ’d because humans will be able to hear the direct sound from the speaker, separating it out from the reflection.

Therefore, the only way to reliably EQ a loudspeaker that has frequency response problems above the Schroeder frequency would be to have good anechoic measurement data on that speaker. For example, if a speaker has an uneven response around 2kHz (say it has a 5db dip in this area relative to the rest of the range, then it could work to EQ the speaker up in that area (with the appropriate Q). However, it would still be hard to do this in-room. You’d need to EQ it in an anechoic chamber to get the proper EQ adjustment.

Do I have the basics correct here?
I'll give you an "A". Well done, you have done your homework. I would add that one can do quasi-anechoic - i.e. time windowed - measurements in a room and get useful data above 1-2 kHz. No doubt, truly anechoic measurements are best because they can have high resolution in the frequency domain over the entire frequency range.

A quick look at your measurements indicates to my eye that Audyssey has slightly boosted the bass. To test its success at smoothing the bass one needs to make the broadband bass levels more equal. A bass tone control should get you close. Because of the equal-loudness contours, a small change in level at bass frequencies makes a disproportionate impression on overall spectral balance. Most people like bass, and too much bass is often a "forgivable sin". It is a simple way to impress a customer.

A cautionary note for several people in this discussion: spatial averaging (multiple mic locations) at low frequencies yields smoother curves, but it does not describe what is heard at any one location. You need to make separate measurements at all important seat locations, using 1/6-octave or higher resolution, and compare them to see how much variation there is. This is where multiple subs, properly used, are hugely advantageous (Chapter 8 in my book).
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post #1048 of 5353 Old 01-27-2019, 11:51 AM
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Are theese negative considerations about Room EQ above the Schroeder frequency also valid for manual EQ (measuring the response in the MLP with an omnidirectional microphone)?
The "negative considerations" about broadband EQ apply to all measurements, but the ones you do yourself may be the most trustworthy. And the MLP is where performance matters most.

The first reason for the "negativity" is well described in my book. It shows that steady-state room curves are highly predictable from anechoic data - it is the off-axis radiation - early reflections - that dominate the curve shape. If there are irregularities in the room curve caused by an otherwise well designed loudspeaker having amplitude response problems, EQ can help. This is a rare event, as most competent designers aim for flattish, smooth on-axis response. If, as is more common, an irregularity is caused by frequency dependent directivity problems, EQ cannot fix it - you need a better loudspeaker, or an acoustically dead room.

The second reason involves discrete reflections that acoustically interfere at the measuring location, generating ripples. If these ripples are smoothed by EQ you have changed the on-axis - direct sound - performance of the loudspeaker which is the most important starting point for good sound. Two ears and a brain react very differently to acoustical interference than an omni mic. Humans distinguish between direct and reflected sounds on the basis of direction of arrival and timing. The mic and analyzer do not.
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post #1049 of 5353 Old 01-27-2019, 11:52 AM
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While the physics of sound (acknowledging that psychoacoustics does complicate things) is likely less complicated than human biology and pharmacology, the gist of what craig john is saying is reasonable. I do not have a reason to doubt the research of Toole et al, nor do I have the credentials to go toe to toe with them. However, generally, in science, when other researchers are able to duplicate your results, that is when they become believable and widely accepted. And even though this industry likely contains far fewer scientists and researchers than say climate and meteorology, I know this industry is still capable of peer review - if the will were there.
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post #1050 of 5353 Old 01-27-2019, 12:11 PM
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Quote:
Originally Posted by Floyd Toole View Post
I'll give you an "A". Well done, you have done your homework. I would add that one can do quasi-anechoic - i.e. time windowed - measurements in a room and get useful data above 1-2 kHz. No doubt, truly anechoic measurements are best because they can have high resolution in the frequency domain over the entire frequency range.

A quick look at your measurements indicates to my eye that Audyssey has slightly boosted the bass. To test its success at smoothing the bass one needs to make the broadband bass levels more equal. A bass tone control should get you close. Because of the equal-loudness contours, a small change in level at bass frequencies makes a disproportionate impression on overall spectral balance. Most people like bass, and too much bass is often a "forgivable sin". It is a simple way to impress a customer.

A cautionary note for several people in this discussion: spatial averaging (multiple mic locations) at low frequencies yields smoother curves, but it does not describe what is heard at any one location. You need to make separate measurements at all important seat locations, using 1/6-octave or higher resolution, and compare them to see how much variation there is. This is where multiple subs, properly used, are hugely advantageous (Chapter 8 in my book).
I agree with everything said here. In my own system, (and every system I have designed for others), I use multiple subs... in my room, 3 to be exact. I have based my sub placement off of Welti's work, (which, BTW, was all computer simulations and measurements, no preference testing.) I also used his approach of using identical subs with a mono signal to all of them. Unfortunately, my room doesn't lend it self to Welti's subwoofer placements, and instead I used a more random group of placements, more similar to Geddes' approach. I then gain-matched them like Welti, and I set the delays appropriately, based on the PLP. This lead to very similar measurements over the 3 important seats in my theater. I then applied Audyssey XT32 to the combined system. I ended up with flat and remarkably similar responses at all 3 important seats. I also have very short decay times of the bass. The bass in my room is very articulate, with every note being distinct and recognizable as it's own timbre and tonality. Using these same techniques, or small variations, I have achieved similar results in other rooms as well. I appreciate the work done by Welti and by others to help me optimize the bass in my own, and other systems.



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