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I'm looking to add a subwoofer to my 2 channel system for some extra bass. Currently I have Klipsch RF5s paired with a symfonia opus 10 power amp and symfonia opus 8 pre. I only use the system for music and the sub will never be used for HT. The setup is in a fairly large room with high ceilings.Also, I've read conflicting statements about what woof
I'm looking to spend around $1000AU. These are the choices I have within Australia:
$954 - Sonique Thunderbox (standard) (Aus)
$995 - Legend Kurlette Powered (Aus)
$995 - SVS PB10-ISD
$999 - Whatmough Tornado (Aus)
$999 - LSK S250 Kit (Aus)
$999 - Monitor Audio Radius r360
$1049 - Klipsch RW-10
$1200 - Epos ELS
$1250 - Equinox Equator 0.I (Aus)
$1,290 - Osborn T12 (Black) (Aus)
$1295 - SVS PB12-NSD
$1299 - LSK S350 Kit (Aus)
$1,299 - B&W ASW600
$1299 - Klipsch RW-12
$1328 - Sonique Thunderbox 1200SE (special edition) (Aus)
$1350 - SVS SB12-Plus
Follow Ups:
You have Klipsch floorstanding speakers, with two 8 inch woofers. And 100 watts too!Dude, you should have plenty of bass! Try moving things around first. Especially move yourself. Bass likes to hang out in corners and also against the wall. Move yourself to where the bass is. Much cheaper and better sounding than adding a sub.
Then you will hear all of the awesome bass that your speakers are already producing. No joke. Try it just for fun some day. BTW, what ARE your main speakers? Maybe you could do better in the long run by upgrading your main speakers.I completely agree with hukkfinn with regards to enjoying music without a sub. Take a good look at this thread for instance. If the bass experts cannot agree on how to integrate a sub, how successful do you think you and I will be when WE try? Once you start messing with a sub, the best thing you will do with it is get rid of it. That's what I did anyway.
I've tried to add a sub (or two subs) a few times on this audio journey, and I always come to the same conclusion as hukkfinn. If you do buy one, have fun with it. But keep the original box and packing material for when you get tired of it and want to sell it.
Best of luck!
Okay... so out of all of that does anyone have any subwoofers from that list to recommend over any of the others?No, I don't want two subs and no, I don't want to get one from overseas.
They muck up your sound.Seems like a good idea at first.
After a while you'll notice yourself not enjoying the music as much.
Just my experience.
I have tried many many different subs just for comparison sake. I ended up have a local cabinet builder build me the bass section of the ElectroVoice Partrician cabinet and loaded it with the Klipsch K-33. It is a full horn loaded sub and is VERY VERY musical vs Home Theater rumble. I drive it with a 9 watt 300B SET amp. The other option is to order the Seismic Sub from Dr. Edgar in flat kit form. I think he sells them for $400.00. That is the best music sub I've every heard. JMOOC
There's also the Home Theater Horn plans in the current Audioxpress, which uses the Adire Tempest. If you don't like the sound of the horn, the Tempest will work fine in a sealed or ported box (see the plans at Adire).
Hello Apokalypse,As you've probably noticed, most subwoofers are designed for loudest-deepest-possible-bass in the smallest-possible-box. That's great for home theater, but not necessarily the best set of priorities for music reproduction.
My suggestion is to get two less expensive subs, preferably with 4th order low-pass filters. Avoid models with ultraheavy cones - in my experience they tend to sound like rumblemotors instead of like music.
Let me explain my reasoning behind suggesting two subs:
Consider the situation with a single subwoofer. There will be one path length from the sub to the listening position. There will be another path length from the sub to the wall behind you and then back to the listening position. At the frequency where the path length difference is equal to one-half wavelength, the energy reflecting off the back wall will arrive 180 degrees out-of-phase with the direct energy and a cancellation dip will result. At the frequency where the path length difference is equal to one wavelength, the reflection will arrive in-phase and a reinforcement peak will result. There will be additional peaks and dips at harmonic intervals, and others related to alternative reflection paths in the room.
Now the problem in the bass region is not that there are too many of these path-length-related peaks and dips; it's that there are TOO FEW of them! They are spaced widely enough apart to be audible. At midrange and high frequencies we also have path-length-related peaks and dips, but they are so many and spaced so close together that they are not heard as separate and distinct peaks and dips.
I propose using two (or more) subs, scattered around the room in an attempt to maximize the variance between their respective peak and dip patterns. For instance, maybe place one sub near (but not in) the front left-hand corner, and the other sub along the right-hand wall a little bit behind the listening area. A fourth order low pass filter will help conceal the location of that second sub. Barring that, cross over any subs that aren't near the main speakers as low as possible.
There will be a tradeoff: One supersub will go deeper than two half-the-price subs, and probably play louder too. You must resist the temptation of ultralow and ultraloud bass - for it usually comes at the expense of sound quality.
The multisub approach will give you a low frequency sound field more reminiscent of what you'd get in a much larger room. What I'm proposing is an acoustic solution to what is fundamentally an acoustic problem. Equalization would be an electronic solution, and may or may not be more practical - but in this case is probably out of your price range.
Just my $.02. Best of luck to you.
1/4 wavelength cancellations are minor issues in subwoofer bass frequencies (under 80Hz.) but do affect the upper bass above 80Hz.
Remember how long the wavelengths are at these frequencies compared to the distance between the subwoofer and nearby walls (relatively close for most people).Standing waves are major issues at subwoofer frequencies (under 80Hz.) because they can cause easy to hear bass peaks and nulls.
Using left-right subs prevents a side-wall-to-side-wall standing wave that makes the bass more consistent across a couch. But don't confuse 'more consistent' with a flat frequency response that can never happen without bass traps/parametric EQ in the relatively small rooms that we use for home audio.
For two channel audio, subwoofers have to be located near main speakers (or between them if there is only one sub) for good integration with those speakers.
With two subwoofers in use, a bass note is played by four (two-way main speakers) to six (three way main speakers) different drivers in four different enclosures!
If you want a realistic reproduction of a bass note using two-channel audio, all the drivers involved with a bass note (the attack of the note comes from a mid-range driver or vass/mid driver!) must be located relatively close together -- not on different sides of the room.
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Richard BassNut Greene
Subjective Audiophile 2007
Just curious, how does "two-channel audio" differ from multi-channel in the bass?Why I ask is the recent article in TAS about multi-channel where they tried several set-ups and although some felt the directional cues from the rear were hokey, they seemed to agree that "the bass was great with five near full-range speakers.
Richard,If I understand you correctly, you are saying that standing waves are the dominant problem in the deep bass region, and that subwoofers need to be located near the main speakers to integrate properly.
If standing waves are the dominant problem, then changing the subwoofer's location shouldn't make such big difference because the standing wave patterns are a fxed function of room dimensions. But as we all know, changing the location of a subwoofer has clearly audible and even dramatic effect. The reason it does is the path-length-induced peak and dip pattern that I've described (and which Roy Allison described long before me, but he focused on the reflections off the wall closest to the speaker whereas I'm assuming the subwoofer starts out up against that wall).
I believe one key to good subwoofer integration with the main speakers is generating a low frequency sound field that is similar to that generated by the main speakers at higher frequencies. Scattered multiple subs addresses this. Given that the ear is very poor at judging the direction of a low frequency sound source without upper freqency cues (hence the steep crossover), and that the ear is obviously pretty good at hearing large peaks and dips in bass energy, I place the higher priority on getting the soundfield right.
Bass varies in every room -- I can only offer theory (and experience for typical rectangular "plasterboard on 2x4" rooms):YOU WROTE:
If I understand you correctly, you are saying that standing waves are the dominant problem in the deep bass region, and that subwoofers need to be located near the main speakers to integrate properly.RG:
Correct summary of bass theory ... but never forget that measurements of the room and listening rule, not theories.The best sub location for the bass frequency response may not be the best location for excellent integration with the main speakers. My first priority is near-perfect integration with the main speakers. That forces sub locations to "close to the main speakers" (two subs) or between the main speakers "one sub".
There are tricks to allow locating one mono sub near either speaker rather than between them (sharply cutting output over 80Hz.).
And if the sub has very little output over 40Hz. it can theoretically be located anywhere as no experiment I've ever read suggests localization is possible with sound under 40Hz.
... although with loud music content under 40Hz. it is possible to "hear" a sub is located behind you, or to your side, solely from the feel of bass pressurization on the side or back of your body.
That may be okay with surround sound but with two channel I don't want to hear the illusion that a bass player is stnding in front of me and that's not helped by feeling pressurization from the lowest notes on my back from a rear subwoofer.I know I'm extra picky about hearing at home the bassline that the bass musician intended. The bass player almost always plugs his bass into the recording console because even a recording studio is too small a room for a good bass frequency response.
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If standing waves are the dominant problem, then changing the subwoofer's location shouldn't make such big difference because the standing wave patterns are a fxed function of room dimensions.
RG
Sub location determines how strongly a standing wave is excited, and listener location determines how well his ears will couple with the standing wave. Subs and listeners located far from walls/corners of rooms have a much different bass frequency response than subs and listeners located near walls/corners.
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.But as we all know, changing the location of a subwoofer has clearly audible and even dramatic effect. The reason it does is the path-length-induced peak and dip pattern that I've described (and which Roy Allison described long before me, but he focused on the reflections off the wall closest to the speaker whereas I'm assuming the subwoofer starts out up against that wall).
RG
Not true.
Subs tend to be located near walls, or no more than a few feet from walls. This is too close to affect 14 feet and longer wavelengths?
Well ... it wouldn't be a good idea to locate two subs so their drivers were 4 feet from the side walls, 4 feet from the front walls, and 8 feet apart. That could cause a deep narrow null.
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I believe one key to good subwoofer integration with the main speakers is generating a low frequency sound field that is similar to that generated by the main speakers at higher frequencies.
RG
Impossible
Bass is omnidirectional.
Sound gets more directional as the frequencies rise.
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.Scattered multiple subs addresses this. Given that the ear is very poor at judging the direction of a low frequency sound source without upper freqency cues (hence the steep crossover), and that the ear is obviously pretty good at hearing large peaks and dips in bass energy, I place the higher priority on getting the soundfield right.
RG
I wish scattered multiple subwoofers smoothed the bass response.
The soundfield is never right if there are any bass peaks +3 to +6dB from standing waves (because +6dB can means a bass note fundamental tone sounds twice as loud as the bass musician intended!) Add in a null or two and you hear a different bassline than the musician intended in our small rooms (compared to listening to headphones or listening to speakers or a live bass musician in a nightclunb or auditorium.) Very large home listening rooms tend to have reasonably accurate basslines unless the ceiling is under 10 feet tall.Listen to s slow sinewave frequency sweep tone (at least 20 seconds from 20 to 100Hz.) and you'll hear whether the bassline is reasonably flat. It usually is not without many bass traps and/or parametric EQ.
The oddest thing about people experimenting with multiple subwoofers is they tend to place all the subwoofers on the floor where they fully excite the very important floor-to-ceiling standing wave (70 Hz. in 8 foot tall rooms, and I'm assuming the sub has full output at 70Hz). There are theoretical advantages with four subwoofers (left floor, left ceiling, right floor, right ceiling) if the ceiling doesn't rattle from the bass (it will) and the wife doesn't send you to the funny farm (she will) and you can afford FOUR subwoofers.
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Duke
Richard,Thanks for taking the time and energy to answer. I'll only comment on a few areas, but brevity isn't one of my gifts.
Duke wrote: "But as we all know, changing the location of a subwoofer has clearly audible and even dramatic effect. The reason it does is the path-length-induced peak and dip pattern that I've described (and which Roy Allison described long before me, but he focused on the reflections off the wall closest to the speaker whereas I'm assuming the subwoofer starts out up against that wall)."
Richard BNG replied: "Not true. Subs tend to be located near walls, or no more than a few feet from walls. This is too close to affect 14 feet and longer wavelengths? Well ... it wouldn't be a good idea to locate two subs so their drivers were 4 feet from the side walls, 4 feet from the front walls, and 8 feet apart. That could cause a deep narrow null."
Duke comments: I must have communicated poorly. In assuming that the subs are placed close to one wall, I'm ignoring the reflection off of that wall. It's the reflection off the other walls - in particular the wall on the other side of the listener - that I originally wrote about. Those walls are plenty far enough away to affect 14 foot wavelengths.
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Duke wrote: "I believe one key to good subwoofer integration with the main speakers is generating a low frequency sound field that is similar to that generated by the main speakers at higher frequencies."
Richard BNG replied: "Impossible. Bass is omnidirectional. Sound gets more directional as the frequencies rise."
Duke comments: Actually the directionality of sound is related to a combination of factors, wavelength being one of them. It is quite possible to have a directional woofer and an omnidirectional tweeter. The soundfield is a combination of direct and reverberant energy. At midrange and high frequencies, we don't get audibly significant room-induced requency response anomalies (though we do get speaker-induced ones that carry over into the room). If the speakers are flat in the midrange and treble, the combination of direct and reverberant sound will not measure flat but the peaks and dips will be close enough together that they won't be audibly apparent. The asymmetrical subwoofer placement I suggest will result in dissimilar peak-and-dip patterns, and the closer the peak-and-dip spacing the less audible individual peaks and dips are because the ear integrates the sound within roughly 1/3 octave wide bandwidths (called "critical bands"). I'd have to put on my thinking cap to explain this psychoacoustic phenomena, but will do so if it would be of benefit to you.
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Duke wrote: "Scattered multiple subs addresses this. Given that the ear is very poor at judging the direction of a low frequency sound source without upper freqency cues (hence the steep crossover), and that the ear is obviously pretty good at hearing large peaks and dips in bass energy, I place the higher priority on getting the soundfield right."
Richard BNG replies: "I wish scattered multiple subwoofers smoothed the bass response. The soundfield is never right if there are any bass peaks +3 to +6dB from standing waves (because +6dB can means a bass note fundamental tone sounds twice as loud as the bass musician intended!) Add in a null or two and you hear a different bassline than the musician intended in our small rooms (compared to listening to headphones or listening to speakers or a live bass musician in a nightclunb or auditorium.) Very large home listening rooms tend to have reasonably accurate basslines unless the ceiling is under 10 feet tall."
Duke comments: Scattered multiple subs helps audibly. The reason the bass is reasonably accurate in very large rooms is in part because the peaks and dips are spaced close enough together that they don't have serious audible consequence. That's exactly what I'm doing with scattered multiple subs, but in smaller rooms.
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Richard wrote: "The oddest thing about people experimenting with multiple subwoofers is they tend to place all the subwoofers on the floor where they fully excite the very important floor-to-ceiling standing wave (70 Hz. in 8 foot tall rooms, and I'm assuming the sub has full output at 70Hz). There are theoretical advantages with four subwoofers (left floor, left ceiling, right floor, right ceiling) if the ceiling doesn't rattle from the bass (it will) and the wife doesn't send you to the funny farm (she will) and you can afford FOUR subwoofers."
Duke comments: I absolutely agree! This is an example of exactly the principle I'm advocating. I only spoke about scattering the subwoofers within the horizontal plane, but they should be scattered in the vertical plane as well. Ideally, at least one sub should be located above the centerline height of the room (over 4 feet off the gound in an 8-foot room).
I could point you to comments made by people who have heard a scattered multiple subwoofer system, but it would be somewhat self-promitional.
Best regards,
The proof of superior bass response is in the measurements and in the seamless integration with two main speakers. Scattered multiple subwoofers, other than their obvious disadvantages of extra cost and extra space required, tend to have less seamless intergration with the two main speakers compared with the very common left subwoofer - right subwoofer set-up. This is obviously much less of an issue with surround sound.1/4 wavelength cancelations are not important concerns in the lower bass (20 to 80 Hz.) because almost all of the significant bass frequency response deviations are related to standing waves between opposing room surfaces.
From 80 to 200Hz. the 1/4 wavelength cancellations can become very important as they can make a bass note fundamental frequency completely inaudible if the cancellation is at just the right frequency. That's really changing the bassline.
There are very few directional woofers and omnidirectional tweeters.
The most directional (somewhat directional) woofers are dipole configurations. Tweeters are not omidirectional -- and having a second tweeter on the back of a speaker enclosure doesn't count.
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Richard BassNut Greene
Subjective Audiophile 2007
"The proof of superior bass response is in the measurements and in the seamless integration with two main speakers."I couldn't agree more.
Computer modelling and actual in-room measurements indicate that scattered multiple subs will measure better than two subs located near the speakers, and therefore would also be expected to integrate better when done properly (steep slope crossovers).
"How Many Subwoofers Are Enough", Todd Welti, JAES Convention Papar #5602, May 2002
"In-Room Low Frequency Optimization", Todd Welti, JAES Convention Paper #5942, October 2003
Welti's second paper very clearly demonstrates that the more low frequency sources, and the more widely scattered, the smoother the bass response. I have other references that I haven't bothered to dig up and cite here - hopefully this should be sufficient.
"1/4 wavelength cancelations are not important concerns in the lower bass (20 to 80 Hz.) because almost all of the significant bass frequency response deviations are related to standing waves between opposing room surfaces."
This is incorrect. Significantly changing the subwoofer location will very dramatically shift the in-room pattern of peaks and dips, which would not be the case if your statement was correct. "Subwoofers in Small Listening Rooms", Tomas Salava (I don't remember where I found this paper but I do have a copy of it).
Of course narrow pattern low frequency sources are not the norm but they are no more uncommon than Maggies and Quads and Martin Logan CLS & Odyssey & Prodigy (and there are many others). I think you got me on the tweeters though. Magnat may have made a true point source ionic tweeter at one time, but they no longer do. Most so-called "omni" tweeters (MBL, Duevel, Wolcott) have a torus-shaped radiation pattern, so you are right about that.
Welti averages bass frequency responses at 16 seats located in the middle of a very large listening room.If your room is similar and you can place your ears in 16 locations simultaneously, then the Welti paper is just for you.
I want to know the frequency response for my two ears with no averaging, and I want a subjective judgement on two-channel suybwoofer/satellite speaker integration from my one seat.
Welti does not provide any of these answers.
(Nor does he claim to)His paper could be applied to surround sound in a small theater.
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...the data speaks for itself.
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.
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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.
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"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..
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"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.
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“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.
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.“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!")
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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.
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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!
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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.
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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".
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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.
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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!
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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.
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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.
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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!
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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.
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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.
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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.
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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.
Not everyone has access to the AES library, so let me cite something that's more readily available.Addressing the issue of multiple low frequency sources vs a single low frequency source, Earl Geddes (a physicist specializing in small room acoustics and consultant specializing in loudspeaker design) wrote this in a Speaker Asylum post on October 30, 2005:
"At a single point in space, one can EQ the response, of course, but that has been shown to actually make the problem worse at other points, so it is not a global solution. To some, like myself, it is not a solution at all. 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. In your example above the main channels having two woofers and then two subs goes a long ways towards a smoother response, about 1/4 the variation or four times better than one sub."
So here we have a case made for the use of multiple subs (and four is probably approaching the point of diminishing returns). But, where should they go?
Below is a link to a very short (two page) informal paper posted by Earl on his website. This documents the difference between placing four subwoofers one in each corner, and four subwoofers randomly, in a rectangular room. The different colored curves on the graphs are for different listening positions. This is not an in-depth study but is useful as a comparison of symmetrical vs asymmetrical positioning.
As you will see, scattering the subs results in significantly smoother bass at each of the three listening positions modelled in the simulation.
Duke
p.s. - If you ever want to do some educational casual reading, do an "advanced search" of Speaker Asylum posts by "egeddes".
Earl and I disagree on bass EQ.How one measures the bass (sine waves for RG) and whether there is any averaging (2 mikes located 8" apart for RG) will determine the "best" subwoofer locations.
Since it is only possible to EQ one seat, EQ is best suited for two channel audio -- and that's what I recommend.
EQ can be counterproductive for surround sound ... EXCEPT for eliminating a bass peak caused by a floor-to-ceiling standing wave (that can similarly affect every listening seat in the room, so one EQ setting benefits every listener whose ears are a similar distance from the floor).
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An acoustic solution to the problems of bass reproduction in small rooms is applicable to both two-channel and home theater.
Two sub location alternatives.One room
That does not lead to any conclusion about optimum subwoofer placement for audiophiles in general.
It also may be that Earl's data are from a computer simulation rather than from measurements in a real room. That would make the data further removed from reality.
And there was no listening panel to report whether or not they could hear differences (measurements under 80Hz. were similar).
Earl did come to one conclusion that placing all subs in corners made the bass frequency response rougher than his alternative This is because corners cause maximum excitement of standing waves in rectangular rooms and this is also well known without any measurements.
Earl does not compare front-speaker - subwoofer integration differences among his two alternatives -- this is the top priority for two-channel audio, IMHO, but of course Earl's work concerns surround sound home theater, not two-channel audio.
It is also well-known that placing one sub near the ceiling and one near the floor can prevent an important floor-to-ceiling standing wave ... assuming the ceiling doesn't rattle and make the bass sound worse!
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Richard BassNut Greene
Subjective Audiophile 2007
Earl's work is not only applicable to multichannel. You are putting words into his mouth. I have had many conversations with Earl about bass reproduction within the context of a two-channel system. As I keep telling you, the acoustics are the same.
A high priority for real theater and home theater audio is consistency from seat to seat. This can be estimated using standard deviations of frequency response measured at many seats.You seem unable to realize that the priorities for home theater sometimes have little correlation with the priorities of a two-channel audio system owner sitting in his "sweet spot".
I bring you two of the five Welti "Limiting Assumptions" (not one of the five applies to two-channel audio, except for the assumption of a rectangular room!):
(1) "System is equalized"
(2) "We are interested in acoustical response in a seating area (averaging 16 seats located in four different rows), not at one particular seat."Well Mr. Duke, very few Asylum readers, or two-channel audio system owners in general, equalize their speakers .... and almost all are interested in the acoustical response at THEIR SEAT ... not at some seat three rows back ... or the frequency response averaged among 16 different seats!
Earl's work is also for home theater = so front speaker / subwoofer integration (preserving the front of the room soundstage) is not an important factor as it would be with two-channel audio.
Both Welti and Geddes "solutions" require buying more than two subwoofers = expensive
Both "solutions" use ONE room to generate conclusions for all rooms (bad science)
Both "solutions" appear to use computer models rather than measurements in a variety of real rooms (bad science).
Both "solutions" contradict one another!
They both are untested theories Duke, not "solutions" for all two-channel listening rooms.
Subjective comments: Neither "solution" has subjective human input from a listening panel in a variety of listening rooms (bad science).
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Richard BassNut Greene
Subjective Audiophile 2007
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."
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.
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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. 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?
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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,
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.
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)
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!!"
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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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!
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.
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.
Except Welti who took his toys and went home mad.
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Richard BassNut Greene
Subjective Audiophile 2007
You Da Man!
Duke,I think Richard is more concerned with arrival time anomalies. That wasn't something I worried about when I bought my REL for placement in my system a few years ago. After moving it a few times I came up with a location where I was happy with the results and there it sat, at least for 2 years.
Then one day I decided to move it to my second system, a 2 channel system built around my TV. That system has a Denon receiver with Audyssey room EQ functions and it also time compensates for different distances from the listener to the driver. I was amazed at how much difference that time compensation made and how much sharper transient attack became. I also noticed that the receiver's calculation of the distance from listening position to the sub was longer than the physical distance with the difference, according to the manual, being caused by time delays in the sub's filters and active circuitry.
I was also surprised to find that, although I missed the bass extension the sub provided in my audio system, I preferred to leave it in the TV system because not only did I think that the results sounded better there but I also appreciated the cleaner and sharper transient attacks I was now getting in the audio system without the sub.
I never heard anything from the sub that I thought was bass components of a chord arriving last, preceded by the sound from the mains, when I had the sub in the audio system, even though it was probably around a metre further away from me than the mains, yet though the sub wasn't perceived as delivering a sound that lagged the mains, I'm forced to conclude that there was enough of a difference to blunt the effect of transient attacks and lose a little clarity.
These days I'm a lot more appreciative of Richard's view on placing subs close to a main speaker. In fact I'd probably prefer to see them placed a fraction closer than the main because of the inbuilt time lag in the circuitry. I have toyed with the idea of moving the sub back into the audio system and trying such a location but still haven't gotten around to it and I've slowly readjusted to the sound of my audio system without it. Since my speakers there deliver quite useable bass into the low 30 Hz area and I don't listen to much music with content lower than that, there isn't a musically compelling reason for me to try the shift. Admittedly the sub would add some useable cues and flesh out the acoustical space of the recording venue a bit more but I've also added a bit more acoustic treatment to the listening room which has meant that I'm getting more from the mains on their own than I did previously and that has helped 'compensate' for the loss of the sub.
While I agree with you on the importance of getting the soundfield right, I also agree with Richard on the timing issue. I think you really need to attend to both in order to get the best results.
Assuming a second order crossover between the mains and the sub, the sub's output would lag by 1/2 wavelength if I recall correctly. With a fourth order crossover, the sub's output would lag by 1 wavelength. In either event, there is indeed a case to be made for either using a compensating time delay or digitial time/phase correction on the main speakers or, if that's not available, locating the subs 1/2 to 1 wavelength closer to the listening position at the crossover frequency (which may not be physically possible).Locating the subs at the same distance as the main speakers would not address the phase lag resulting from an analog crossover - unless it was a true first order crossover.
Unless there's digital equalization or other digital processing circuitry involved, the subwoofer's internal electronics will impose negligible time delay. So in almost all cases, it's only the phase lag we would be concerned with. And locating two subwoofers in the same plane as the main speakers is doesn't address the phase lag. Placing them closer to the listening position than the main speakers would to a certain extent. I would suggest doing so asymmetrically.
I don't understand the theory of crossovers and phase lags, or anything about crossover theory for that matter, so I won't get into a discussion on that.For time compensation purposes, the receiver in the HT system calculates that my sub is about a meter further away than it is in fact. In the audio system it was about a meter and a half further away than the closest main speaker. Add those 2 distances together and the combined 'time lag' or whatever you want to call it was about equal to or slightly more than the distance/time from the mains to the listening position. I would think that irrespective of crossover slope, placing the sub much closer to a main speaker, and even slightly closer to me than the main speaker if possible, would have to have beneficial effects. The sub also has a phase control and that might well end up on a different setting.
I'm not suggesting that simple physical placement can achieve perfection, but I definitely do think that I could get better results with physical placement alone than I did when I originally had the sub in the audio system. One thing that moving it into the HT system where the receiver compensates for arrival time of sound from each driver actually did for me is to give me an idea of just how well a sub could integrate into a system. The receiver's auto setup process and the Audyssey EQ it provides have definitely produced a better result than I ever got by ear in the audio system.
I think there are a few things that would benefit pure audio systems that could very easily be stolen from the HT area and the automatic setup and EQ functions are definitely worth introducing into purist audio in my view.
David Aiken
I can see what you're getting at with this, however there are some limitations and it doesn't really suit what I'm looking for.The problem with cheap subwoofers is that they sound cheap. I don't want something to make boom noises, I want something musical. I'm not getting a sub for bass extension, I'm getting it more for bass reinforcement. The Klipsch speakers go very low. In this case I think having 2 cheap subs booming over the klipsch speakers would not sound as good as a single musical sub, despite all the points that you raise.
Apart from this cost and space are a consideration. As well as practicality. I live in a rental house and moving my stereo is enough of a job as it is.
Does anyone have any recommendations from the list I posted?
"In this case I think having 2 cheap subs booming over the klipsch speakers would not sound as good as a single musical sub, despite all the points that you raise."I think you misunderstand me.
My suggestion is not to choose two low-quality subs over one high-quality one.
What I'm suggesting is two small high-quality subs instead of one larger high-quality one. I'm suggesting a different philosophy about bass reproduction, which would be applicable to a "music only" system. There are several possible two-small-subwoofer configurations that offer advantages, and I'm advocating one of them.
As far as I have seen, Bag End, Rel and Vandersteen are the three names which can be found as the best sounding music subs in various subwoofer surveys of several reviewers (At least there is some consensus here!). They are reasonably priced too. Unfortunately they are not in your list and I wonder why.
Good luck.
Because, aside from importing them, they're relatively impossible to get in Australia.From what I've read the REL and Vandersteen sound like exactly what I want, it's just finding the damn things...
I live in India where Rel is available but Vandersteen isn't. Still I bought the Vandersteen (2Ce Sig) main speakers all the way from USA, spent a fortune on shipping and duties but don't regret. Also, I am quite happy with two Rel Strata-5 subs which integrate quite well with the Vandys and spared me of another costly overseas purchase. So you can consider the option of buying the subs from outside Australia if genuinely interested in a musical sub.
Every time I've seen someone mention multiple subs, they use multiples of the same sub. I own two very different subs. One has two high efficiency 10 inch drivers (Zu Mini-method) and the other has one big 15 inch driver (DIY 3 cubic foot enclosure with Dayton 15" DVC, 1000 watt plate amp). Has anyone ever tried to use two completely different subs together? I may just give it a try and see what happens.
Duke is arising several interesting aspect of the subwoofer field. I agree with him, Dual Subwoofers are better than just one. And several subwoofers are better than Dual. Of course real life limitations are an issue: budget, available space, etc. My opinion would be then Dual Subwoofers. The list you wrotte in your post includes several good ones. Another suggestion: do not get brand new ones from factories, you would be paying a lot more. Instead browse every day Audiogon, you'll find many bargains, mint condition, 1/2 price. Good luck, best, Antonio Machado.
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