|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
63.87.108.184
In Reply to: The Welti paper is not worth the paper it is printed on if good bass at one seat is your goal posted by Richard BassNut Greene on March 5, 2007 at 09:45:03:
...the data speaks for itself.
Follow Ups:
Welti explains his priorities up front.Most readers don't get his message.
His priorities only make sense for surround sound in a small auditorium or in a very large home theater.
His top priority is reducing bass frequency response variations from seat to seat among 16 seats in the middle of a small theater, or in a very large home theater.
The data do not address the bass frequency response at ONE two-channel sweet spot seating position and the subjective integration of subwoofer(s) and two main speakers (our top priorities and/or only priorities for two-channel audio).
This article has nothing to do with the sweet spot in two-channel audio.
I regret that the article fooled you into that assumption -- it fools most readers because it is poorly written.
In my opinion it is the worst article ever written about subwoofers because the author appears to be articulate, but he is incompetent as a writer because so many readers are fooled into believing his conclusions apply to two-channel audio. They do not.
.
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
I didn’t realize my paper(s) had caused such a commotion! A few comments:“I regret that the article fooled you into that assumption -- it fools most readers because it is poorly written.”
I don’t know how it could have been stated any clearer…
"1 INTRODUCTION
This paper concerns low frequency optimization in small to medium sized rooms with multiple subwoofers and multiple listeners. "The paper is relevent in cases where there are more than one listener, with their heads not occupying the same space. Of course it is more relevent when they are a couple of feet apart or even more if there are several seats covering a substantial portion of the seating area. Yes, its true that this would most often be the case in a home theater situation. If you are only concerned about the “stereophile sweetspot”, you shouldn’t have much to worry about. Get a good parametric eq.
“No real room measurements for Welti”
Reread the paper please. (“How Many Subwoofers are Enough?”,)“Only one virtual room used by Welti to represent all real rooms!”
Reread the paper please. (“How Many Subwoofers are Enough?”,)
“No concern about bass quality (or even measurements) in the ONE sweet spot for two-channel audio”
Stated clearly in the paper.“No concern about subwoofer-front speaker integration.”
Lots of concern, but for the multiple seat situation where that is really a PROBLEM.“It may be possible, after months or even years of trial and error, to find positions for multiple subwoofers that are optimal for ONE seating position in ONE room ... but ONLY if you ignore the quality of subwoofer/main speaker integration (the quality of the front soundstage), which is the most important attribute when using a subwoofer(s) in a two-channel audio system, IMHO.”
Please read ““In-Room Low Frequency Optimization”, Sept. 2003, AES preprint 5942.” It is possible. There are consumer devices coming out soon.
“(3) Full excitation of the first-order axial floor to ceiling room mode (as every subwoofer on the floor fully excites that room mode) causing a NASTY bass peak in the 69 to 73Hz. range (eight-foot ceiling).”This is part of the typical misunderstanding of room modes: thinking only of the excitation, and forgetting the second part – where the ears are (closer to the null of that first axial mode than not in this case).
"I didn’t realize my paper(s) had caused such a commotion! "RG
Nah, just me and the Duke causing a commotion ... and somehow your paper got thrown into the commotion ... I mean "debate".
Many two channel audio owners read your paper and decide what they need is to be surrounded by four subwoofers for the best possible bass frequency response, and the best possible subwoofer-main speaker integration, at their ONE sweet spot seat. I have no idea why so many readers extrapolate your home theater conclusions to their two-channel audio systems, but it must have something to do with your writing.
.
.
.
.
"I don’t know how it could have been stated any clearer"
RG
I've been writing a financial newsletter ECONOMIC LOGIC as a hobby since 1977 and there have been a number of times subscribers have misinterpreted what I thought was very clear writing. I always take the blame -- could have said it a different way..
.
.
.
.
"If you are only concerned about the “stereophile sweetspot”, you shouldn’t have much to worry about. Get a good parametric eq."
RG
Agree. I've been equalizing my DIY subwoofers since the early 1980's and pontificating about the subject online since 1996. A lot of two-channel audiophiles are anti-equalizer, unfortunately.
“No concern about bass quality (or even measurements) in the ONE sweet spot for two-channel audio”
Stated clearly in the paper.
RG
You say it is stated clearly.
It seemed clear to me when I read your paper many years ago.
But Duke and others just don't get it.
.
.
.
“No concern about subwoofer-front speaker integration.”
Lots of concern, but for the multiple seat situation where that is really a PROBLEM.
RG
Integration is much more difficult with two-channel audio as side and rear subwoofers are usually heard/felt as separate sound sources.
.
.
.
.“It may be possible, after months or even years of trial and error, to find positions for multiple subwoofers that are optimal for ONE seating position in ONE room ... but ONLY if you ignore the quality of subwoofer/main speaker integration (the quality of the front soundstage), which is the most important attribute when using a subwoofer(s) in a two-channel audio system, IMHO.”
Please read ““In-Room Low Frequency Optimization”, Sept. 2003, AES preprint 5942.” It is possible. There are consumer devices coming out soon.
RG
Front speaker - subwoofer integration is subjective and depends on so many factors that I couldn't list them all here. No matter what consumer devices are available, they will face the wraith of the high-end audiophile ("It doesn't sound right to me") and his wife ("You can't put your subwoofer THERE!")
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
Using scattered multiple low frequency sources smoothes the in-room bass response. Welti's data demonstrates that. So does Geddes'. So does Griesinger's. I could probably find more.Apparently you make the assumption that smooth bass only in the sweet spot is exclusively the province of two-channel, whereas smooth bass throughout the room is exclusively the province of multichannel. I don't make that assumption. Perhaps herein lies much of our disagreement.
Computer simulations in one virtual home theater to jump to conclusions for ALL two-channel audio rooms AND no subjective listening at all!If this is how you reach your audio conclusions, Duke, then you are a "lost audiophile".
No real room measurements for Welti
(not sure if Geddes used real measurements).Only one virtual room used by Welti to represent all real rooms!
(not sure if Geddes measured in a real room).Simulated frequency response averaged by Welti for 16 seating positions in four rows
(I don't recall precisely but think Geddes used three positions)No concern about bass quality (or even measurements) in the ONE sweet spot for two-channel audio
No concern about subwoofer-front speaker integration.
No listening panel testing the simulated (jump to a) "conclusion" in a variety of different listening rooms.
.
.
.
.
It's a rare room that will have bass frequency response, measured at one two-channel stereo sweet spot and including room effects, better than +/-10dB in the 20-100Hz. range.It may be possible, after months or even years of trial and error, to find positions for multiple subwoofers that are optimal for ONE seating position in ONE room ... but ONLY if you ignore the quality of subwoofer/main speaker integration (the quality of the front soundstage), which is the most important attribute when using a subwoofer(s) in a two-channel audio system, IMHO.
The sound quality at ONE SWEET SPOT is all that matters to most two-channel audio system owners. It could be all that matters to a particular home theater owner too.
But there is more than one sweet spot when a center speaker is used in a real theater, or in a home theater. That's why acousticians DO NOT CARE about the bass frequency response at any ONE seating position (contradicting the priorities of a two-channel audio system owner).
If you sit in a crowd of average Americans, the average IQ is likely to be about 100. Does that number "100" really mean anything for any one person in the crowd?
Well maybe it does for you!
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
Richard,My position is that scattered multiple subs done right (and it's not complicated) smoothes the bass everywhere in the room, including in the sweet spot. The data indicates that this is true.
Claims about what is or is not important to this or that group doesn't change acoustic reality. Claims about whether or not the messenger is a lost audiophile don't change acoustic reality.
One of your paragraphs I will respond to:
"It may be possible, after months or even years of trial and error, to find positions for multiple subwoofers that are optimal for ONE seating position in ONE room ... but ONLY if you ignore the quality of subwoofer/main speaker integration (the quality of the front soundstage), which is the most important attribute when using a subwoofer(s) in a two-channel audio system, IMHO."
You don't need to optimize the position of multiple subs. It's much easier than using only one sub, just as using two subs is easier than using only one.
The blend with the main speakers is improved (assuming steep-slope lowpass filters) because the bass is smoother, so there's less discrepancy between what's happening in the bass region and what's happening up above.
How about either you or I start a thread asking two-channel system owners if they agree or disagree with this statement: "The sound quality at ONE SWEET SPOT is all that matters."
At least we could settle that issue.
Duke
When all the "experts" have different recommendations, then it's obvious none have "the answer" ... or there is no "answer" that applies to every room!For two-channel audio: If subwoofers are NOT placed near the two main speakers (two subs) or between the two main speakers (one sub), at a similar distance from one's ears as the two main speakers, then the stereo image/soundstage is not likely to match the image/soundstage quality from a pair of full-range expensive loudspeakers, which is the primary goal when using small relatively inexpensive main speakers plus a subwoofer or two.
.
.
.
Simulated rooms just don't work.And you don't have all the data and details of the measurment methodologies from any experiments -- you have just the conclusions and a limited amount of data presented in a white paper or book -- conclusions that don't match from "expert" to "expert".
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
I didn't think so. That's why I've given references, so that it's not just you and me saying "Oh yeah??" to each other.It's always possible to find a way to question someone else's work, especially if we disagree with him. But assuming the author isn't an outright liar, the real question is this: What useful information is in there and what does it tell us?
That's my point.You could buy an extra subwoofer or two ... and hear no improvement, or hear a deteriorated bass frequency response ... meaning your money should have been used for upgrading the front speakers ... or upgrading some other components ... or given to your favorite charity.
Measuring bass by using frequency response standard deviations is not going to tell you whether the bass frequency response at YOUR SEAT sounds good.
It only takes one bass peak to ruin the reproduction of one bass guitar note or one bass drum strike -- the rest of the bass frequency response could be ruler flat causing a pretty good standard deviation measurement ... but the bassline won't sound right (and could sound horrible if the bass drum excites that one bass peak)!
Tom Nousaine found that fully exciting every room mode with a corner subwoofer is usually a good thing for bass if the resulting bass peaks are well distributed ... because our ear's one-third smoothing ability can work well on well-distributed bass peaks.
If you had three bass peaks under 80Hz. from standing waves (typical room) and could eliminate two of them, you might think the bass would sound better.
In reality, the one remaining bass peak is likely to be more audible and more annoying than it was before, possibly making the overall subjective bass quality worse than it was with three bass peaks.
The most serious bass problem in small rooms is insufficient modal density under 100Hz.
There are not enough bass peaks and nulls under 100Hz. for our ear's one-third octave smoothing ability to smooth out.
Above 200-300Hz there are so many standing wave and 1/4 wavelength cancellation peaks and nulls that they can be blended together by our one-third octave smoothing ability and we can't hear them.
Most common among people who try more than two subwoofers is placing ALL the subwoofers on the ground where they will ALL excite the very important first-order axial floor-to-ceiling standing wave (71Hz, boom with a 8 foot ceiling ... 56.5Hz. boom with a 10 foot ceiling).
Tom Nousaine found this to be the main reason five "surround" subwoofers did not outperform one subwoofer in a corner (other than having higher maximum SPL).
All the five "surround" subwoofers were located on the floor and caused a huge boom at 71Hz. -- the last thing you want when trying to reproduce a bassline just as the bass musician played it.
.
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
The only time adding an additional subwoofer would not result in smoothing is if its pattern of in-room peaks and dips exactly overlapped the pattern of the original sub(s). And the only way that would happen is if it was placed in exactly the same location occupied by another sub, which is physically unlikely if not impossible. Remember that when you add another subwoofer, you turn down the volume of the previous one(s) so that the average bass SPL stays the same. Spatial and to a certain extent frequency response smoothing goes up as the number of bass sources in the room goes up, according to Geddes, as I have previously cited.There are plenty of 1/4 and 1/2 wavelength peaks and nulls below 100 Hz, but they are the result of reflections off of walls far away from the subwoofer, not the wall close to it. I said that before. This is one reason why each subwoofer's in-room pattern of peaks and dips will be unique.
You also already brought up the floor-to-ceiling mode issue, and I acknowledged that vertical scattering would be beneficial, and pointed out that mulitple subs on the floor would be no worse than the one or two subs on the floor you advocate - and at least my way gives you the option to scatter vertically. And if vertical scattering is benefical, then likewise scattering in the horizontal plane would be beneficial - which my technqiue calls for and yours does not.
First lend me $10,000 so I can bet you.When will I pay you back?
On payday.
When's payday?
You ought to know, you're the one who's working.
I can eliminate all bass peaks for one listening seat with a $150 digital parametric EQ.
You go spend thousands for additional subwoofers.
Put any of your "scattered" subwoofers far from the two main speakers and you will distort the intended stereo image/soundstage from the FRONT of the room.
Put all of your "scattered" subs on the floor (typical placement) and you will cause maximum excitation of the dreaded 71Hz. floor to ceiling standing wave bass peak -- often excited by bass guitar notes and kick drums.
Put two subs on the floor, and put two subs near the ceiling, and you will most likely hear a buzzing / rattling plasterboard ceiling that will make the bass sound worse than a distorted $100 Radio Shlock subwoofer in a back corner of your room!
1/4 wavelength cancellations off nearby walls are not important at subwoofer frequencies because subwoofer wavelengths are 15 feet and longer.
While 1/4 wavelength cancellations can be serious problems in the upper bass (over 80Hz.), that's above a subwoofer's range.
Tom Nousaine says the sub scattering (5 surround subs located near the five surround speakers) theory does not work for two-channel or surround sound based on measurements in real rooms.
And let's not forget the experts who don't agree with you ... not to mention the fact that no two subwoofer placement "experts" agree with each other!
.
.
.
.
But first, quit dogging me and help me sell some subs so I'll have ten grand to loan you!! ;0)My guess is your equalized sub would measure smoother than my mulitple small subs at one optimized locaion in 10 out of 10 rooms.
I would also guess that my multisubs would be smoother across a wide range of listening positions in 10 out to 10 rooms if we drew that "wide range" circle big enough.
But note that it's NOT an either/or choice between multisubs and one equalized sub. In fact, because there's far less variation from one location to another with multisubs, equalization would then be likely to produce benefits everywhere in the room. Best of BOTH worlds.
I really don't understand why you keep coming back to the floor to ceiling mode as if that's some unique weakness of a multisub system that isn't vertically scattered. It is every bit as much a weakness of a single sub system. All the bass coming from near the floor = all the bass coming from near the floor, no matter how many cones are reproducing it.
I also don't understand why you keep talking about the 1/4 wavelength reflection off the nearby wall. I have told you several times now that's not what I'm talking about. Please go back and re-read every single one of my posts (okay, just kidding about that part - but I have explained it to you several times).
You haven't given me any reasons why scattered multiple subs would have poorer imaging. I can cite at least one source that says they would give you better imaging if done properly (Griesinger). If you have more than just assertions, I'm interested in what you have to say.
The thousands of dollars on additional subs isn't really true if you start out intending to do multiple subs from the beginning. You can do a nice four-sub system for under two grand.
Can you give me the Tom Nousaine reference? I'd like to read it.
Duke
p.s. - Richard, do you think anyone else is still reading this thread?
"I really don't understand why you keep coming back to the floor to ceiling mode as if that's some unique weakness of a multisub system that isn't vertically scattered. It is every bit as much a weakness of a single sub system. All the bass coming from near the floor = all the bass coming from near the floor, no matter how many cones are reproducing it."RG responds:
With scattered multiple subwoofers all located with drivers near the floor, you will have:(1) Less than full excitation of some side-wall-to-side wall room modes
(2) Less than full excitation of some front-wall-to-rear-wall room modes
(3) Full excitation of the first-order axial floor to ceiling room mode (as every subwoofer on the floor fully excites that room mode) causing a NASTY bass peak in the 69 to 73Hz. range (eight-foot ceiling).
One really loud bass peak in the 69-73Hz. range is much more likely to be audible and annoying than the three or four bass peaks that you would typically get when using one corner subwoofer (causing maximum excitement of all room modes), as one alternative.
If the three or four bass peaks from one corner subwoofer are not stacked, or at adjacent frequencies (from square or near square rooms), they will be somewhat smoothed by our ear's one-third octave smoothing ability.
Any subwoofer located to the side or rear of a listener deteriorates the stereo two-channel image from the front of the room.
.
.
.
Think about the best speakers you have ever heard in your life.Most likely they were large very expensive full-range speakers.
No separate subwoofer(s) were needed.
They sounded great with ALL the bass coming from the left front and right front speakers -- similar to having left-front and right-front stereo subwoofers (which you seem to think is such a bad idea!)
The goal with subwoofers is to replicated the sound quality of expensive full range speakers by using relatively inexpensive main speakers plus one or two subwoofers to extend their bass frequency response.
Changes from adding a third or forth subwoofer could benefit or deteriorate the bass quality at any one listening seat and the changes would vary from room to room.
.
.
.
.
The studies that I have cited (which you reject) demonstrate that scattering subs in the horizontal plane smoothes the bass everywhere in the room.Geddes advocates locating one subwoofer closer to the ceiling than to the floor. I agree. But even if that isn't practical, multiple low frequency sources is still demonstrably an improvement.
You even admit that horizontally scattered subwoofers will smooth the side-to-side and front-to-rear room modes. That would be an improvement, would it not?
Apparently you are arguing that it would not, because of the remaining floor to ceiling mode - which is now easily addressed by elevating one sub (multiple subs are likely to be much smaller than a single sub), or by applying as single band of parametric equalization, or by an appropriately tuned Helmholtz absorber (since now we'd only have one peak to deal with). In each of these cases, we're better off with the benefits accruing from having scattered multiple low frequency sources.
And even if we did none of these things to address the floor-to-ceiling mode, we'd be down from having a major imbalance in three 1/3-octave-wide critical bands to having it in only one. And I'm sure you're aware that the most extreme in-room peaks and dips are formed by the combining of two or three modes, so we will have taken a major step towards smoothing the in-room frequency response by reducing the modal excitation in two dimensions, even if the third is not directly addressed.
As far as what the goal of a subwoofer system is, mimicing live music in a good recital or concert hall is my goal - NOT mimicing two fullrange stereo speakers. Small room acoustics being what it is, there is very significant room for improvement in the bass region over using two speakers as you well know from your frequent citation of plus or minus 10dB as being typical of stereo in-room bass response.
I didn’t realize my paper(s) had caused such a commotion! A few comments:
“I regret that the article fooled you into that assumption -- it fools most readers because it is poorly written.”I don’t know how it could have been stated any clearer…
"1 INTRODUCTION
This paper concerns low frequency optimization in small to medium sized rooms with multiple subwoofers and multiple listeners. "The paper is relevent in cases where there are more than one listener, with their heads not occupying the same space. Of course it is more relevent when they are a couple of feet apart or even more if there are several seats covering a substantial portion of the seating area. Yes, its true that this would most often be the case in a home theater situation. If you are only concerned about the “stereophile sweetspot”, you shouldn’t have much to worry about. Get a good parametric eq.
“No real room measurements for Welti”
Reread the paper please. (“How Many Subwoofers are Enough?”,)“Only one virtual room used by Welti to represent all real rooms!”
Reread the paper please. (“How Many Subwoofers are Enough?”,)
“No concern about bass quality (or even measurements) in the ONE sweet spot for two-channel audio”
Stated clearly in the paper.“No concern about subwoofer-front speaker integration.”
Lots of concern, but for the multiple seat situation where that is really a PROBLEM.“It may be possible, after months or even years of trial and error, to find positions for multiple subwoofers that are optimal for ONE seating position in ONE room ... but ONLY if you ignore the quality of subwoofer/main speaker integration (the quality of the front soundstage), which is the most important attribute when using a subwoofer(s) in a two-channel audio system, IMHO.”
Please read ““In-Room Low Frequency Optimization”, Sept. 2003, AES preprint 5942.” It is possible. There are consumer devices coming out soon.
“(3) Full excitation of the first-order axial floor to ceiling room mode (as every subwoofer on the floor fully excites that room mode) causing a NASTY bass peak in the 69 to 73Hz. range (eight-foot ceiling).”This is part of the typical misunderstanding of room modes: thinking only of the excitation, and forgetting the second part – where the ears are (closer to the null of that first axial mode than not in this case).
Show me blind comparisons of a typical left-right "stereo" subwoofer position versus four mid-wall subwoofers in a variety of typical two-channel stereo listening rooms by audiophiles, where the listeners generally agree that that four mid-wall subwoofers are a better choice for two-channel stereo.These data do not exist.
Therefore the conclusion that four mid-wall subwoofers will sound better than the typical left-right subwoofers is nothing more than JUMPING TO A CONCLUSION.
That's not objective.
That's not science.
If there are no blind listening evaluations, at least show me measurements of sine waves, at the ONE stereo sweet spot seat preferred by the stereo's owner, in a variety of two-channel stereo listening rooms that SUGGEST four-mid-wall subwoofers measure significantly better than left-right subwoofers.
These measurements would not help us evaluate subjective satellite speaker- subwoofer integration, and they may not correlate with subwective auditions, but they might at least suggest POTENTIAL audible benefits of four mid-wall subwoofers.
Your white paper fails only because so many two-channel stereo owners read it and then believe four mid-wall subwoofers is the right answer for the highest quality bass at their ONE sweet-spot seat.
Of course your paper does not specify this goal, and your goals obviously apply to home theaters with multiple rows of seats, but when so many readers get the wrong impression over many years, it is ALWAYS the writer's fault. Can we blame George W. Bush for this?
Tom Nousaine posted online several years ago that he tested your four mid-wall subwoofer recommendations in a real room, versus a corner subwoofer, and does not agree.
In fact, it appears that no two speaker "experts", from Tom Nousaine, Earl Geddes and Dave Clark in Michigan ... to Sigmund Linkwitz and Floyd Toole in California, etc. agree on four on the floor mid-wall subwoofers, based on what is in their homes, or what they recommend in their articles and papers!
So there is clearly no agreement among "experts" on the number of subwoofers, much less their "optimum" locations.
I could stop right here with the obvious conclusion that optimum subwoofer placement and quantity for two-channel audio may vary from room to room, may vary with different measurement methodologies, may vary depending on listener priorities, and may not apply to surround sound audio in the same room!
But no one here ever stops arguing, or allows another inmate to get in the last word, on these LIFE and DEATH issues!
The important question for readers here at the Asylum is whether buying a third or fourth subwoofer would be a good investment for TWO-CHANNEL AUDIO. And never mind the added cost, or opportunity cost of failing to upgrade more important components.
A primary goal of two-channel audio owners is perfect subwoofer-satellite speaker integration at the stereo sweet spot position. This is entirely subjective, but is not helped by side and rear subwoofers.
A second goal is a decent bass frequency response at the stereo sweet spot position. At least no worse than a pair of expensive full-range speakers. This is somewhat subjective because bass peaks and partial nulls can be measured at any listening position, but their subjective effect on the bassline is affected by our ear's one-third octave smoothing, and bass peaks are much more noticeable than partial nulls while listening to complex music.
The correct answer to the question is that buying a third or fourth is a "flip a coin" gamble for two-channel audio.
If all the three or four subwoofers were placed on the floor, and all included the first-order axial standing wave center frequency in their range, then the liostener will most likely hear a bass peak from that room mode with typical ear heights in an 8-foot tall room ... and with all ear heights in a 10 foot or taller room.
Tom Nousaine's AES paper comparing five surround subwoofers with one corner subwoofer first identified this problem. It would apply just as much to your "four on the floor" subwoofer recommendations in a typical two-channel audio room.
Ears would have to be close to the partial null of the first-order floor to ceiling axial standing wave to avoid a bass boom. With a typical listening chair ,and a listener of average height, the ears are not close enough to avoid coupling with that room mode. Even more coupling if the listener is below average height, his chair is below average height and the listener doesn't sit up straight.
So if none of my arguments convince you that your surround sound subwoofer placement recommendations do not apply to two-channel audio in a typical two-channel audio room (much smaller than the room you used) ... if for no other reason than you did not test this goal, then I must resort to my ultimate rational argument:
Your Mother wears Army boots!
.
.
.
.
Richard BassNut Greene
Subjective Audiophile 2007
Well, general responses first. Let's get something straight, it's not an issues of two channel vs multichannel audio. It's simply whether or not you have more than one listener position, as I explained.I am all for controlled listening tests, which most "audiophiles" eschew. In fact, I have done a series of controlled listening tests comparing "stereo" subwoofer setups and mono setups (several configurations). It is publixhed as an AES preprint (Subjective Comparison of Single Channel versus Two Channel Subwoofer Reproduction, Oct 2004, preprint 6322.). Though I biased the experiments strongly towards finding differences, it was extremely hard for the subjects to tell the difference. So much for stereo bass.
As for experts disagreeing, of course people disagree. You can read the comments by Earl on the May 2006 AES, regarding a later journal paper conver the subwoofer thing. If you do read it, you see that he really doesn't disagree with the core concepts. He is doing some stuff with vertical displacement of the subs (which might be especially interesting considering raked seating area - whoops there I go with the "not audiophile" thing again!)
I have talked to Tom Noussaine, and he did not disagree with my ideas. He may have tested it in one room and it didn't work, but I neven said it would work in every room.
What is typical seated ear height? Around 3 1/5 feet - hmmm thats puts it fairly close the the null for the first axial floor/ceiling mode (4 to 4 1/2 feet). In any case this part of the response should not vary from seat to seat (for a flat seating area anyway), so is amenable to equalization.
I will not respond further here, as I can see you have made up your mind.
Thank you for the opportunity for getting in the last word.You wrote:
"Let's get something straight, it's not an issues of two channel vs multichannel audio. It's simply whether or not you have more than one listener position, as I explained."
RG
Two channel audio has one sweet spot.
There is no averaging of 16 seats.
For some two-channel audiophiles who sit far enough from the speakers, two side by side chairs may provide two sweet spots.
The sweet spots are usually half way between the side walls in the null for the first-order axial room mode. This is far different than four four-seat rows crowded together in a 6' by 6' space in the middle of a 20' BY 24' room.
.
.
.
You wrote:
I am all for controlled listening tests, which most "audiophiles" eschew. In fact, I have done a series of controlled listening tests comparing "stereo" subwoofer setups and mono setups (several configurations). It is publixhed as an AES preprint (Subjective Comparison of Single Channel versus Two Channel Subwoofer Reproduction, Oct 2004, preprint 6322.). Though I biased the experiments strongly towards finding differences, it was extremely hard for the subjects to tell the difference. So much for stereo bass.RG:
I'm playing the part of a subjective audiophile online this year in an attempt to view audio from another point of view. From 1985 through 2005 I was objective.I agree there is no stereo bass at subwoofer frequencies -- our ears are too close together for a stereo effect with 14 feet and longer wavelengths.
The main purposes for left right subwoofers is easier integration with the two main speakers ... and to prevent a first order axial standing wave (most two-channel audiophiles sit half way between the side walls right in the partial null of this standing wave).
Of course preventing one standing wave can make the remaining bass peaks and partial nulls easier to hear and more annoying than before.
There's no guarantee that two subwoofers will sound better than one.
.
.
.
You wrote:
As for experts disagreeing, of course people disagree. You can read the comments by Earl on the May 2006 AES, regarding a later journal paper conver the subwoofer thing. If you do read it, you see that he really doesn't disagree with the core concepts. He is doing some stuff with vertical displacement of the subs (which might be especially interesting considering raked seating area - whoops there I go with the "not audiophile" thing again!)RG
Add in REL and HSU corporate subwoofer location recommendations and we have even less agreement among "experts"!
Earl has the best home theater I have ever experienced. But using more than two subwoofers are much more likely to benefit a large home theater than a relatively small two-channel listening room for two reasons:
(1) You can't suboptimize for one "sweet spot" seat in a home theater
(2) Side and rear subwoofers are much more likely to be sonically invisible when listeners are surrounded by five speakers in a home theater, versus only two up-front speakers for two-channel.You wrote:
I have talked to Tom Noussaine, and he did not disagree with my ideas. He may have tested it in one room and it didn't work, but I neven said it would work in every room.
RG
Tom Nousaine uses eight 15" subwoofer drivers mounted on a wood plenum in his basement firing up through a vent in the corner of his room. That doesn't sound like a vote for four mid-wall subwoofers to me!You wrote:
What is typical seated ear height? Around 3 1/5 feet - hmmm thats puts it fairly close the the null for the first axial floor/ceiling mode (4 to 4 1/2 feet). In any case this part of the response should not vary from seat to seat (for a flat seating area anyway), so is amenable to equalization.
RG'
I'm 5' 10" tall = the average male height. My ears are not 3 1/5 feet off the ground when seated at home.I've been harping about subwoofer parametric equalization online for ten years ... but most two-channel folks would be upset if their next-door neighbor used an equalizer, much less them! A subwoofer position recommendation has to be acceptable without equalization to be useful at this two-channel forum (unfortunately)
You wrote:
I will not respond further here, as I can see you have made up your mind. Have fun with it!
RG:
In fact it is YOU who have made home theater subwoofer location recommendations without ever verifying whether your recommendations correlate with the subjective experiences of real human listeners. You mentioned that fact in your paper -- I'm not accusing you of hiding anything.My points are:
- No other "experts" have made the same subwoofer recommendations as you have
- Your research can not be blindly applied to a two-channel audio sweet spot, where listener priorities differ from a large 16 seat home theater, and equalization is not likely to be used.Of course you never claimed to have answers for two-channel non-equalized audio, because that was not your goal. So there is no need to defend yourself here.
The correct answer for this forum:
No one knows whether adding a third or fourth subwoofer will usually improve the bass at two-channel sweet spot because no one has ever asked real two-channel audiophiles to answer that question!That's my fancy way of saying "I don't know"
If there's one thing you can infer from my "I don't know", it's that I have not made up my mind at all.
.
.
.
Hello Todd,Thank you for taking the time to comment. Just for the record, your comments are addressing statements made by Richard BassNut Greene, not myself - I want to mention that in case someone comes along and thinks that your comments are in reply to something I wrote because they immediately follow one of my posts.
It had crossed my mind that the ears of seated listeners would be in neither a node nor an anti-node of that floor-to-ceiling mode, but I wasn't confident that was the correct way to analyze it. Thank you for specificially addressing that that issue.
It's rare that we get real professionals here. Earl used to hang out some, especially over on the High Efficiency forum, but he was attacked so regularly over there that he finally stopped coming to the Asylum altogether.
Hi Duke, I understand. It was just some general comments based on your (rather heated) exchange. I also got burned once or twice on forums, so i generally stay away. It can be very time consuming...
We may have set a new record for two-inmate "debates" without serious character attacks!If you think this is "heated", you should read the blind test / wire debates!
Your study ends with the obvious caveat that you have no idea if the measurement methodology used correlates with listener preferences in a home theater ... much less with a listener's preferences at his preferred sweet spot for his two-channel audio system.
This post is made possible by the generous support of people like you and our sponsors: