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In Reply to: Still clueless Duke (home theater computer simulations don't identify best sub location for ALL 2-channel audio rooms!) posted by Richard BassNut Greene on March 7, 2007 at 09:15:32:
Hi Richard,Well before I get into replying to the points you raise, I have enjoyed this exchange and appreciate your efforts to keep it from entering the all-too-common internet thread death-spiral. And I'm sure you've wanted to be a bit more emphatic at times!
I'm not arguing for or against Welti's position. I'm only interested in what his data shows.
Acoustic principles established in one room can indeed be applied to other rooms. I bet all of the acoustic principles that come into play in your room were first established somewhere else. When a pattern is seen among several researchers indicating that scattered multiple subs results in smoother in-room response, maybe there's something to it.
You are right about the expense: Four small subs will be more expensive that one or two larger ones of equal quality and summed output capability. But some people are more interested in quality than quanity, and will make trade-offs accordingly.
If I might sum up your position, perhaps it would be, "Bass measured in the sweet spot is the only bass important to a two-channel system owner." Correct me if I'm wrong.
If I might sum up my position, it would be, "Scattered multiple subwoofers done right improves the bass everywhere in the room, including the sweet spot."
Duke
Follow Ups:
Forum thread "death spiral"? You mean like when I compare your family to farm animals and then compare you to Hitler? I was saving that for a future post!Forget averages -- at every INDIVIDUAL seat the bass frequency response is still uneven no matter how many subwoofers you use (unless every listener gets his own near field subwoofer).
Computer simulations are not data from real rooms.
They merely suggest subwoofer set-ups that ought to be measured, and more important -- listened to in real rooms.Side and rear subwoofers have no place in two-channel audio -- they upset the intended up-front stereo image/sound stage.
Averaging bass measurements hides reality.
Two-channel audiophiles care about their one-chair sweet spot.
Bass frequency response elsewhere is mainly irrelevant.The sweet SPOTS for home theater are usually considered to be at least three locations across a couch or three/four seats in one row.
Consistency (standard deviations) among the seats are considered more important than sub-optimizing the frequency response at one seat (which is the primary goal for a two-channel sweet spot).Why not add Tom Nousaine to your list of "experts":
Nousaine recommended one or two subwoofers in the nearest room corner based on a comparison with five surround sound subs (details and real measurements in his AES paper in the late 1990's).
Welti recommended four subs at mid-wall positions -- Nousaine tested Welti's theory in a real room and reported on-line that all subs in one corner were better!
Geddes recommended three subs -- one near the ceiling.
The other guy, I forget his name, recommended left-right subwoofers connected out of phase, the last time I read his paper.
Linkwitz goes for dipole bass which reduces excitation of most room modes -- perhaps the best advice of all for those unwilling to parametrically equalize their subwoofer, or buy a batch of bass traps.
Note that all these recommendations are different and all (except Linkwitz) are for home theater where sound comes at the listener from the front left, front right, front center, left side, right side, and sometimes from the rear.
The home theater is energized from at least 5 different locations versus two locations for typical 2 speaker two-channel audio -- the room acoustics are absolutely not the same as two-channel with the need to sit equal distances from the two stereo speakers to get the proper "phantom center image".
There is no evidence from real rooms that more than one subwoofer in one location is needed for decent bass under 80Hz. (other than SPL requirements that require more than one subwoofer)
Using two (left-right) subwoofers simplies subwoofer-main speaker integration by preventing potential integration problems possible with one mono subwoofer located off-center.
Sometimes using left-right subwoofers, which prevents a the first order axial side-wall-to-side-wall standing wave, makes the bass sound better at the sweet-spot listening position, and sometimes it does not.
There is a potential for improved bass frequency response at the sweet-spot position from using left-right ceiling subwoofers and left right floor subwoofers (4 in total) to prevent the very important first-order axial floor-to-ceiling standing wave in addition to the first-order axial side-wall-to-side-wall standing wave.
Unfortunately ceilings usually rattle from a nearby subwoofer, even assuming there is no WAF problem.
Much more can be accomplished with one subwoofer and a $150 digital parametric EQ which will completely eliminate all bass peaks at one sweet-spot listening position.
A lot of bass traps will reduce the partial nulls too, particularly above 80Hz. where bass traps work best (not that they are ever efficient tools at any frequencies).
As soon as you scatter subwoofers beyond positions that are close to the two main speakers, you start deteriorating the intended stereo image soundstage.
And the closest thing to a bass transient, the slap of a hammer on a kick drum, will not have the best possible sound quality if the two to three drivers in each channel (subwoofer driver, bass driver and mid-range driver ... or subwoofer driver and bass-mid-driver) that reproduce its sound are not located near one another.
Whether adding an additional subwoofer (beyond two) will improve the bass frequency response at the sweet spot seat (or at any other seat)is like flipping a coin. The correct answer is "maybe".
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Richard BassNut Greene
Subjective Audiophile 2007
Good one on Hitler & the Farm Animals. And I will concede that the average of my weight, my age, and my IQ is roughly 100.I hate it when people go through and quote me and then shoot me down piece by piece. Quote 'n shoot, quote 'n shoot. So my apologies for using that format, but I tried writing this another way and it was hard to keep it all straight. I'm an old fat guy - do the math.
Richard BNG wrote: "Forget averages -- at every INDIVIDUAL seat the bass frequency response is still uneven no matter how many subwoofers you use (unless every listener gets his own near field subwoofer)."
Duke replies: Still uneven, but definitely improved.
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Richard BNG wrote: "The other guy, I forget his name, recommended left-right subwoofers connected out of phase, the last time I read his paper."
Duke replies: Griesinger is the guy, and he recommended left-right subs based on maximizing the interaural phase difference to maximize the psychoacoustic sense of "envelopment". The recommendation of 90 degree out-of-phase operation of one sub was to synthesize envelopment in recordings with monaural bass by maximally de-correlating the in-room low frequencies. I haven't tried it yet but plan to.
* * *
Richard BNG: "Linkwitz goes for dipole bass which reduces excitation of most room modes -- perhaps the best advice of all for those unwilling to parametrically equalize their subwoofer, or buy a batch of bass traps."
Duke: Now we're on some common ground. I like dipole bass - it tends to be very natural sounding, with excellent pitch definition. The reason for the naturalness of dipoles is not that they excite fewer room modes - you see, the initial figure-8 pattern is immediately swamped by the reflections, so the room modes get excited anyway. And if anything the more modes excited the smoother the perceived in-room frequency response (this because the ear integrates sound over roughly 1/3 octave wide "critical bands" - room modes are plentiful above the bass region, but aren't an audible concern because they're bunched up enough to average out across a 1/3 octave interval). Rather, the dipole's naturalness arises because the in-room bass is effectively de-correlated. You can think of a dipole as two monopoles displaced in phase (or time, if we only look at one frequency) rather than displaced in space. My proposal displaces the monopoles in space, which is an other technique for de-correlating the in-room bass energy.
It is rare that owners of dipole speakers are happy with the way a single sub integrates into their system. This is because the output of a single sub in as small room is well correlated, and has a very different "feel" from the dipoles' output which is highly de-correlated in-room. Dipole owners are more likely to be happy with two subwoofers than one, this based on my own observations of posts by dipole owners. I believe the reason is improved de-correlation of the bass so that there's less discrepancy between what the subwoofers are doing and what the dipoles are doing. In my opinion the next logical step is scattered multiple subs.
I use dipoles and have built diople subs, and while they can sound very good in some ways dipole subs do have disadvantages. The disdvantages include large size required to go down deep, reduced power handling at low frequencies, and an absence of the impact that characterizes a good monople system. I can go deeper with better impact and still get good smoothness and pitch definition by using scattered multiple small monopole subs.
* * *
Richard BNG: "There is no evidence from real rooms that more than one subwoofer in one location is needed for decent bass under 80Hz. (other than SPL requirements that require more than one subwoofer)."
Duke: So why do you use and advocate two subs, if only one is needed?
* * *
Richard BNG: "As soon as you scatter subwoofers beyond positions that are close to the two main speakers, you start deteriorating the intended stereo image soundstage."
Duke: That's true unless you do it the way I recommend: Steep slope crossovers, preferably below 80 Hz. If you have to use a highe crossover or shallower slope, then put the multiple subs over closer to the main speakers. So if there's problem, the solution is easy.
* * *
Richard BNG: "And the closest thing to a bass transient, the slap of a hammer on a kick drum, will not have the best possible sound quality if the two to three drivers in each channel (subwoofer driver, bass driver and mid-range driver ... or subwoofer driver and bass-mid-driver) that reproduce its sound are not located near one another."
Duke: Excellent objection, as intuitively the loss of impact seems obvious. This is the objection that kept me away from trying scattered muliple subs for a long time.
In reality, the ear doesn't hear the initial wavefront of a bass signal. In tests where a single bass frequency cycle was presented to listeners, it was difficult to even detect. It takes several cycles for the ear to detect the presence of bass energy, and several more for the ear to correctly hear the pitch. So by the time the ear is detecting bass, the outputs of all subs in the room is being integrated.
The only data I have examining whether or not there is a loss in perceived bass impact from scattering the subs (as opposed to placing them next to the main speakers) is my own listening. I don't like to cite myself as a source and then ask you to take my word on faith alone. Especially given what you've uncovered about my family's rich genetic diversity.
Cheers,
Duke
Richard BNG wrote: "Forget averages -- at every INDIVIDUAL seat the bass frequency response is still uneven no matter how many subwoofers you use (unless every listener gets his own near field subwoofer)."Duke replies: Still uneven, but definitely improved.
RG
If all the subwoofers are on the floor and their frequency range includes the first-order floor-to-ceiling axial standing wave (71Hz. with 8 foot ceiling, and lower Hz. with taller ceilings), then listener is most likely to hear a bass boom from that room mode = not good.
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.Richard BNG wrote: "The other guy, I forget his name, recommended left-right subwoofers connected out of phase, the last time I read his paper."
Duke replies: Griesinger is the guy, and he recommended left-right subs based on maximizing the interaural phase difference to maximize the psychoacoustic sense of "envelopment". The recommendation of 90 degree out-of-phase operation of one sub was to synthesize envelopment in recordings with monaural bass by maximally de-correlating the in-room low frequencies. I haven't tried it yet but plan to.
RG
This idea has potential for reproducing low frequency room ambience if included in a surround sound recording. Not useful for two-channel audio (where connecting front left front and right front subs in-phase prevents a first-order axial side-wall-to-side-wall standing wave, making bass frequency response more uniform from left to right across a couch.)
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Richard BNG: "Linkwitz goes for dipole bass which reduces excitation of most room modes -- perhaps the best advice of all for those unwilling to parametrically equalize their subwoofer, or buy a batch of bass traps."Duke: Now we're on some common ground. I like dipole bass - it tends to be very natural sounding, with excellent pitch definition. The reason for the naturalness of dipoles is not that they excite fewer room modes - you see, the initial figure-8 pattern is immediately swamped by the reflections, so the room modes get excited anyway.
RG
Floor-to-ceiling and side-wall-to-side-wall standing waves get excited about 4.8dB less using dipole subwoofers versus monopole subwoofers. Period.
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You Wrote:
It is rare that owners of dipole speakers are happy with the way a single sub integrates into their system. This is because the output of a single sub in as small room is well correlated, and has a very different "feel" from the dipoles' output which is highly de-correlated in-room.
RG
This is because the dipoles excite many standing waves less than monopole speakers and this causes better quality bass in most rooms.
The monopole sub doesn't have this advantage.
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Dipole owners are more likely to be happy with two subwoofers than one, this based on my own observations of posts by dipole owners. I believe the reason is improved de-correlation of the bass so that there's less discrepancy between what the subwoofers are doing and what the dipoles are doing. In my opinion the next logical step is scattered multiple subs.RG
Bass on almost all two-channel recordings is mono -- there is no out-of-phase bass information in the left and right channels.
Bass problems are caused by multiple in-room reflections that may be in-phase or out-of-phase with the direct signal from the subwoofer
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Richard BNG: "There is no evidence from real rooms that more than one subwoofer in one location is needed for decent bass under 80Hz. (other than SPL requirements that require more than one subwoofer)."Duke: So why do you use and advocate two subs, if only one is needed?
RG: I use one subwoofer placed behind my left speaker.
That room position is near one main speaker because nearby upper bass output from the main speakers helps make a subwoofer sonically invisible.The sub is about 7 feet from the front wall and 5 feet from the left wall.
The driver is 4 feet above the floor, for reduced excitation of a strong concrete floor to stiff ceiling standing wave, and aimed at the ceiling for some additional "mechanical" low-pass filtering.
The crossover is 70Hz. & 24dB/octave. The turnover frequency would be lower than 70Hz. if my EPOS ES11 satellite speakers could handle that.
If it were possible to fit two 18 inch diameter 4 foot tall tube subwoofers "in the middle of my living room", then I'd have two.
Just yesterday the wife gave me her annual "You don't know how lucky you are to have a wife who allows you to place two speakers and that phallic symbol subwoofer in the middle of our living room" speech.
My response is the same:
I guess I should buy tiny Blose Acoustimess Sheikers and put all five of them BEHIND the large screen TV set where they sound awful ... like our P-whipped friend xxxxxx's wife makes him do?
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Richard BNG: "And the closest thing to a bass transient, the slap of a hammer on a kick drum, will not have the best possible sound quality if the two to three drivers in each channel (subwoofer driver, bass driver and mid-range driver ... or subwoofer driver and bass-mid-driver) that reproduce its sound are not located near one another."Duke: Excellent objection, as intuitively the loss of impact seems obvious. This is the objection that kept me away from trying scattered muliple subs for a long time. In reality, the ear doesn't hear the initial wavefront of a bass signal. In tests where a single bass frequency cycle was presented to listeners, it was difficult to even detect. It takes several cycles for the ear to detect the presence of bass energy, and several more for the ear to correctly hear the pitch. So by the time the ear is detecting bass, the outputs of all subs in the room is being integrated.
RG
Baloney.
The attack of a bass guitar note (the "pluck") and the attack of a kick drum note (the "slap") are in the mid-range frequencies and are reproduced by the bass-mid-driver or mid-range driver.If the bass note fundamental frequency that follows comes from anywhere but near the bass-mid driver or mid-range driver, then the note will not be reproduced correctly.
If a bass note's fundamental frequency excites a standing wave bass boom, it will be typically be +3 to +6dB louder than the musician intended (+6dB is subjectively twice as loud for bass under 50Hz.), so the note will not be reproduced correctly.
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The only data I have examining whether or not there is a loss in perceived bass impact from scattering the subs (as opposed to placing them next to the main speakers) is my own listening. I don't like to cite myself as a source and then ask you to take my word on faith alone. Especially given what you've uncovered about my family's rich genetic diversity.RG
I've been experimenting with one vs. two subwoofers and different subwoofer locations in my room for 20 years.Here's my conclusion:
One subwoofer parametrically equalized for my seating position sounds better than any one, two or three unequalized subwoofers in any locations I've ever tried.The results are not even close in my room.
Richard BassNut Greene
Subjective Audiophile 2007
I was mistaken to assume that you were using two subs, so thanks for correcting me on that.I misunderstood what you were saying about bass transients. You are correct that the impact harmonics are not reproduced by the subwoofer. But if the deep bass is indeed non-directional as you have previously stated, then the deep bass does not need to be reproduced from the same physical location as the upper frequencies.
With your single subwoofer closer to one speaker than the other, you are doing exactly what you just objected to - namely, not reproducing the deep bass from the same location as the upper frequencies. And it works fine because the deep bass doesn't need to be reproduced from the same location as the upper frequencies.
You misunderstood what I was saying about Griesinger's 90 degree out-of-phase technique, rather than repeat myself I'll suggest you take another look at what I wrote.
The 4.8 dB you mention regarding dipoles is related to the directivity index, and not modal excitation characteristics. 100% of the reflected energy ends up bouncing around the room, whether the source is a monopole or a dipole. Monopoles and dipoles excite the room modes differently but dipoles do not excite fewer room modes. Dipoles do have a smoother in-room bass characteristic (James M. Kates, "Dipole Loudspeaker Response In Listening Rooms"). So do scattered multiple subwoofers, for the reasons given in my previous post.
If you are happiest with a single equalized subwoofer, that's fine. I am suggesting an alternative that will offer a significant improvement throughout the room, not just in one place.
Duke
Bass from a solo subwoofer is directional above 40Hz.
If you use a 40Hz. 24dB or more per octave slope low pass filter you can probably place a subwoofer anywhere in the room and not hear its location.But if you place a subwoofer next to a main speaker, the bass will not be directional until about one octave higher (about 80Hz)
Wwhen the upper bass is coming
So you can usually use a turnover frequency up to 80Hz. with a 24dB/octave slope and still keep the subwoofer sonically invisible almost all the time.
For two-channel audio, any bass frequency response improvement from using scattered subwoofers (not predictable and not guaranteed) will be more than offset by deteroration of the front soundstage caused by placing subwoofers far away from the main speakers.
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Richard BassNut Greene
Subjective Audiophile 2007
You've conveniently moved the frequency where bass can be localized from 80 Hz down to 40 Hz.That's baloney.
Find me one source that supports your 40 Hz localization threshold.
Also, your assertion that my statement is "balony" isn't an argument; it's just an unsupported assertion. If you're going to use that as the subject line for a post, don't disappoint by not following up with some well thought-out arguments. Explain why my proposal will not offer a significant improvement throughout the room. I have zero desire to trade assertions with you. Make a good argument and I'll reply to it.
Duke
Not that there's anything wrong with wearing comfortable shoes."You've conveniently moved the frequency where bass can be localized from 80 Hz down to 40 Hz. That's baloney. Find me one source that supports your 40 Hz localization threshold."
RG
All tests I've ever read in the past 40 years using sine wave tones have shown that bass becomes directional above 40Hz.Those data are applicable to the audible effects from placing subwoofers to the side or rear of a two-channel audio listener.
They explain why side and rear subs are often heard/felt as separate sound sources with two-channel audio.
But real bass notes are not sine wave tones.
They have harmonics.
A Fender Jazz Bass note, for one example, will create more energy in the harmonics than in the fundamental bass tone.
That means quite a bit of bass energy will be coming from the two front satellite speakers in two-channel satellite speaker/subwoofer stereo ... and their upper bass output helps mask the location of nearby subwoofers.
When placed near the front speakers, subwoofers are usually sonically invisible up to about 80Hz. ... and that's why an 80Hz. 24db/octave crossover became the surround sound industry standard.
But that does not mean an 80Hz 24dB/octave crossover works to make subwoofers sonically invisible with two-channel audio when you place subwoofers FAR AWAY from the two main speakers ... such as near the side walls to the left and right sides of your listening chair ... or near the rear wall of the room.
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Richard BassNut Greene
Subjective Audiophile 2007
"...[W]ith enough subwoofers, it is theoretically possible to cancel out all modes in a room." - Todd Welti, "How Many Subwoofers are Enough""The spatial variations, and to a certain extent the frequency response variations, will go down (get smoother) as 1/N, where N is the number of independent sources." - Earl Geddes, Speaker Asylum Post 10-30-05
"An wuss rong wit Army Boots??" - Momma
So Welti tells us in which direction scattered multiple subs take us, and Geddes give us an idea of how far in that direction each additional sub takes us. I have no idea what Momma's point was.
You didn't provide a source backing up your claimed 40 Hz threshold for low frequency source localization. Asserting that "all tests I've ever read in the past 40 years using sine wave tones have shown that bass becomes directional above 40Hz" isn't citing a source.
I'll back up my claim. Here's a quote from an AES paper by Antti Kelloniumi et al entitled "Detection of subwoofer depending on crossover frequency and spatial angle between subwoofer and main speaker":
"It is generally known that when we raise the crossover frequency between main speakers and subwoofer or move the subwoofer away from the main sound source location, it gets easier to localize the the subwoofer as a source of the low frequency content. The maximum crossover frequency applicable has been evaluated to be somewhere between 100 Hz and 200 Hz. EVEN LOWER CROSSOVER FREQUENCIES BELOW 85 HZ HAVE BEEN USED, NOTICING THAT THEN THE POSITIONING OF LOW-FREQUENCY SOURCES IN A LISTENING ROOM GETS NON-CRITICAL." (emphasis mine)
Duke
Blind tests?
You have none.
Sighted tests?
You have none.
Measurements of a specific sweet spot listening position in a variety of rooms?
You have none.Measurements of a specific sweet spot listening position in ONE room?
You have none.All you have is a variety of "experts" with contradicting subwoofer advice for surround sound audio in print (and no similarities seen in the homes of those who have invited me into their homes).
You cherry pick very general conclusions from experts who do not agree with each other, and then extrapolate them to ALL two-channel audio sweet spot listening positions in ALL rooms?
Don't make me laugh!
This is nothing more than desperate data mining to defend a strong belief about subwoofers ... or to elevate a subwoofer quantity/locations choice that works well in your room into a broad audio rule of thumb for all two-channel audiophiles!
= jumping to conclusions
= baloney
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Richard BassNut Greene
Subjective Audiophile 2007
Richard,In my opinion it is much more productive to put our energy into discussing acoustics instead of arguing about arguments. But this is the direction you have chosen to take the discussion.
You insist on data that is not yet available. Controlled listening tests are expensive, and deliberately asymmetrical placement of multiple subwoofers is a new paradigm.
Yet when I do produce data and quotes from genuine experts in the field that clearly supports my position, and you accuse me of "desperate data mining".
Seems I can't win with you.
In some circles, my having produced expert data and references to support my position would actually mean something. You have not rebutted any of the expert testimony I've introduced - you've merely called it "BS". I assume if you had a better argument than that, you'd have made it.
You wrote:
"You cherry pick very general conclusions from experts who do not agree with each other, and then extrapolate them to ALL two-channel audio sweet spot listening positions in ALL rooms?
"Don't make me laugh!"
Mocking me isn't the same as making an argument. Show me some evidince or construct a good argument based on linking together acoustic principles to demonstrate that, as a general principle, scattered multiple subwoofers does not result in smoother in-room bass response as compared to conventional (symmetrial) placement of one or two subwoofers.
Maybe there is a room where a certain asymmetrical placement of multiple low frequency sources would result in less smooth bass than symmetrical placement of one or two low frequency sources. If it's possible, it will be because of acoustics. So give me a well thought-out acoustics-based argument on how and why that could happen.
If you undertake this exercise, I think you will find that scattered multiple subs are more likely to have exactly the results I have claimed.
Turning up the emotional volume with things like "don't make me laugh", "quotes can be BS too", and "baloney" will definintely score you points with some people. Some will read it and say, "Duuuuude, BassNut sure body-slammed the Dukester with that one!" And some will be reading for information rather than WWF-style entertainment, and will be interested in the evidence presented and arguments made on the subject of acoustics.
Duke
"This isn't an argument!"
"Yes it is."
"No, it isn't!!"
"Yes it is." - from a Monty Python skit
This is a two-channel audio forum.Subwoofer recommendation for home theater may not apply to a single two-channel audio sweet spot.
Subwoofer recommendations vary among experts and among manufacturers such as REL and HSU.
The Welti research makes assumptions that rarely apply to two-channel audio (equalization) and he admits in writing there is no way of knowing if his measurements correlate with subjective impressions of real audiophiles!
So the obvious answer to whether adding a third or fourth "scattered" subwoofer will benefit the sweet spot seat in a two-channel audio room is "I don't know".
That has been my answer all along.
From a transcript of: "Multiple Subwoofers for Home Theater" originally presented by Tom Nousaine at the 103rd Convention of the Audio Engineering Society, September 1997 (preprint 4558)
" ... in the subwoofer range, a single one (subwoofer) in the corner beats the pants off five-in-the-round ... So in summary, at least this experiment showed that one sub in the corner beats any combination placed elsewhere. ... If you have two or three subwoofers and you want the best performance, stack them all up in the same corner ... So the best thing you can do is to put your subwoofer in the corner and excite as many of the modes as you can as hard as you can!! What that does is give you the smoothest possible response in that room, although it may not be perfect."
So which expert is right?
You seem to know.
I don't.
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Richard BassNut Greene
Subjective Audiophile 2007
Hi Richard,Thank you very much for the Tom Nousaine reference.
I printed out a copy of AES Preprint number 4558 and could not find that quote you gave anywhere in the paper.
However, Nousaine does clearly state that one subwoofer in a corner measured smoother than five placed where his left, right, center, and two surround speaker normally go in his home theater system.
Nousaine is showing in-room measurements of plus or minus 3 dB from corner placement of a subwoofer. Richard, that simply does not sound right to me! Does that sound right to you? Is it really that simple - just put the subwoofer in the corner??
I once tried designing a speaker specifically for corner placement, and I am absolutely convinced that any speaker measuring plus or minus 3 dB from 100 Hz on down when placed in a corner had to be designed (or equalized) specifically for corner placement. Imagine moving a Klipschorn out into the room like a normal speaker. What would happen to the bass response?
The only way I can see Nousaine's subwoofers measuring so smooth in a corner is if they were designed specifically for corner placement. If that is the case, then no wonder they measured poorly when placed elsewhere (weak lower bass, as would be expected).
Also, you earlier made a strong case for scattering subs in the vertical plane (if multiple subs are used) to smooth out the floor-to-ceiling mode. Did you notice that the shape of the frequency response curve did not change when Nousaine stacked five subs in a corner? Only the amplitude changed. That is very, very strange - the implication would be that changing the height of a low frequency source has absolutely no effect on the floor-to-ceiling mode. With apologies to the bald-headed bad guy in The Princess Bride - inconceivable!
I did a search to see how widely Nousaine's paper is being cited as a source. Since its publication in 1997, one paper mistakenly attributes a statement on "envelopment" to Nousaine's paper, and another cites him as a "supplemental source". No papers are citing Nousaine's amazing "discovery" that corner placement results in the smoothest possible in-room response. Zero. If Nousaine was considered a credible source on the subject of subwoofer placement by the academic community, you'd think someone would have used his monumental findings in the ten years since his paper was published.
In contrast, Welti's "How Many Subwoofers Are Enough" has been cited in 17 papers since it was published in 2002.
So... my expert's friends can beat up your expert's friends!
Duke
The Nousaine quotes were all taken from an 11-page Nousaine article in the February 1988 issue of the Prairie State Audio Construction Society newsletter SOUND BYTES. The article was said to be a transcript of Nousaine's presentation to the audio club a few weeks after his AES presentation on the same subject.I can't find my 4558 preprint to quote from it.
If I wanted the loudest bass possible in my room, then one or more subwoofers in a corner with parametric EQ to eliminate all bass peaks at my sweet spot would be the answer. But my main speakers are 8 feet from the front wall and five feet from the side wall, so using a one corner subwoofer makes it sound like a bass player is standing alone in the front corner of my room!
Subs "stacked" in a corner may really be side by side in a corner rather than all stacked vertically to the ceiling.
All the measurements we have don't mean much if they are not confirmed by real audiophiles experimenting with subwoofer locations/quantities in their own rooms.
The ONLY conclusions I have from 25 years of experimenting iare:
(1) parametric equalizers are great "band aids" for subwoofers,
(2) a dozen bass traps are good if the wife will allow them (two don't make much difference), and
(3) side and rear subwoofers are much less likely to be sonically invisible than front subwoofers located near or between the two front speakers of a two-channel audio system.I can't even say for certain that adding a second subwoofer will benefit the two-channel sweet spot seat in a particular listening room, much less a third or fourth!
I'm sure "experts" who claimed the world was flat were cited many times ... before people found out they were completely wrong!
My current tube subwoofer places a 15" driver behind my left speaker, four feet off the floor, firing up at a slanted ceiling that is about nine feet tall above the driver. This location requires three bands of parametric EQ. If I reverse the subwoofer 180 degrees so it is downfiring at my cement slab floor, the frequency response becomes so bad that after an hour of trying to equalize it, I just gave up.
This worst sub driver position I'd found since 1987 ... was a mere 4 feet away from the best sub driver position I had found.
Who could have predicted that?Okay it's long past time for us to reverse positions and start a new argument. My new theory is that if your home has a street address that is an even number, then you should use an even number of subwoofers. I could cite many studies for this hypothesis ...
if there were any.
Richard BassNut Greene
Subjective Audiophile 2007
Well Richard, my horse has long since been beat to death, and yours ain't lookin' too healthy neither.Seriously, I learned a lot from this. Thank you.
Duke
Except Welti who took his toys and went home mad.
,
,
,
Richard BassNut Greene
Subjective Audiophile 2007
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