Do you see much difference in the floor to driver distances between the floor-stander and the sub?
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Stereo Bass using subwoofers
- Thread starter dkinric
- Start date
And what about downward firing (Floor firing) subs?
Digital_Thor
Senior Member
Yep... we know history. But normally a narrow 3 way tower speaker is good for stereo image, and distributed subwoofers are better located along walls - preferably slightly hidden - in most cases. Because it looks better and fits most interiors too. Often, HIFI is split between looks and quality of reproduction.
It could be argued that multiple subwoofers are not needed, when you only sit in ONE spot. I must say, though. That it is a pleasure to walk around in my apartment, and hear very little difference in bass - in comparison to a lot that experience huge variance, when simply moving the head forth and back half a meter.
Multiple subwoofers can also create a way smoother response, than any stereo speaker. But I do agree that a larger 3 way is needed, to reach 40-60hz - because it creates an overlap, which makes the subwoofers and mains sum - so we don't experience dips and peaks.
Perhaps I should clarify: "Subwoofers are typically positioned on the floor, so lower than typical bass drivers on MANY (MANY DOES NOT MEAN ALL) floor-standing speakers. As such, they may possibly avoid or ameliorate one SBIR effect."
I don't think I have anything else to add here, besides this thesis, which I ran across earlier this year and posted elsewhere but not here: https://aaltodoc.aalto.fi/bitstream...tasa_Anamaria_2022.pdf?sequence=1&isAllowed=y
The thing is almost all floor standing speakers place the port near to the floor even if they have the woofers higher up. As we are talking sub-bass the port is the emitter.
The paper shows that even a 10 degree spacing is detectable, which means the subwoofers should be placed very near to the speakers, which in turn means you cannot move subwoofers freely to cancel room modes. You either use multiple subs to tame the room acoustics or use just two and have wide-band stereo. But, not both.
Actually, I was incorrectly thinking about floor bounce, which typically occurs well above meaningful port output but probably also above subwoofer output, as well, at least for typical listener heights and distances
The paper was conducted in a near anechoic environment, so-called free field conditions, with detections of angle of separation occurring relative to the median plane, so I don't see how apply the findings to typical domestic listening environments.
With respect to placement of subwoofers, opposing sidewall first-order length mode nodal placement of a pair of subwoofers could potentially address some of the odd-order axial modes, as well as possible enhancement of stereo perception (Blumlein conceived frequency-dependent stereo processing for perception of image width, which tends to be narrower at bass frequencies, so perhaps further lateralization of bass sources might compensate for that?) and envelopment (Griesinger, the Robin Miller paper I linked before), so I don't think that it's necessarily a trade-off.
You posted the paper, I commented on it. If it doesn’t apply to the discussion, what was your reason of posting it?
I thought chapters 1-3 were a fantastic review and discussion of existing research and understanding to date with references to guide further learning as desired. Did you read these parts? There was quite a bit of material that I found to be extremely relevant to the discussion at hand ("Stereo bass using subwoofers"), but it appears that I am wasting my time here.
Yes, I read the prior art sections but I prefer to refer to a paper for what it is about not for what others found historically.
It's too bad that you couldn't recognize the implications of the paper itself for what it was actually about nor its relevance to the discussion at hand. I don't have ready access to all the papers summarized, and my posting that link was not intended solely and especially for you but rather the forum as a whole. I'm also interested in history, and it's possible that other people besides you might be, as well, so please keep in mind that everything is not about you. Thanks.
Some additional perspectives from others that might be interesting to consider:
@j_j
Fundamentals of hearing 2004
https://www.aes-media.org/sections/pnw/ppt/jj/jj_aes04_ts1.ppt
“Various people have reported, sometimes anecdotally, that above 40Hz (and below 90Hz), although one can not localize a sound source, differences in interaural phase can create a sensation of space.. his suggests that for accurate perception of space, 2 or 3 subwoofers may be necessary. This also, as in many other places in audio, creates a situation where what one might consider the “optimum” solution (maximum bass flatness) does not in fact convey the perceptual optimum.”
Soundfields vs human hearing 2012
https://www.aes-media.org/sections/pnw/ppt/jj/soundfields_vs_human_hearing_edited.ppt
“Specifically, although one can not LOCALIZE signals below about 90 Hz, one can detect spatial effects from interaural phase differences down to about 40Hz. The AT&T Labs “Perceptual Soundfield Reconstruction” Demo, no longer available, contained a very nice example of these effects, and how they can change “boomy bass” in the 2-radiator case into “bass spread about a room” in the 5-channel case.”
@Thomas Lund
https://www.genelec.com/-/immersive-monitoring-a-perceptive-perspective
“From 50 Hz to 700 Hz, however, fast-firing synapses in the brainstem are responsible for localisation, employed in a phase-locking structure to determine interaural time difference (ITD). Humans can localise at even lower frequencies, but we will come back to that in a specific ultra low frequency blog.
The ability to position sound sources with precision spherically is a key benefit of immersive systems. Another is the possibility to influence the sense of space in human listeners. For the latter, the lowest two octaves of the ITD range (i.e. 50-200 Hz) play an essential role; but may be compromised in multiple ways”
https://www.genelec.com/-/blog/how-to-analyse-frequency-and-temporal-responses
“With both stereo and immersive, for your room and system to be able to reliably convey the envelopment latent in the content, perceived-direct sound should dominate in the 50 to 700 Hz range – where audible patterns characteristic of the recording space may have been picked up. If they have, you can be sure that the recording engineer has gone to great lengths in doing so. Fig 2 is a recording setup in Olavshallen in Trondheim, Norway, and shows a main mic array with sufficient distance between capsules to capture LF differences and moving patterns – two of the most precious qualities of a hall to preserve….Fig 3 shows the GRADE graphs from section 4.3 of the report, and reveals a monitor to the left which is able to convey envelopment latent in the content; and one to the right that is less able to do so. If listening to the latter, you are unable to judge recorded space precisely. Such ability may also be sacrificed when relying on bass management with only one subwoofer to reproduce all LF sound, rather than multiple channels and acoustic in-room summation. If possible with delicate content, don’t use a higher bass management cross-over frequency than necessary, and preferably below 60 Hz.”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1526313
“It's not primarily about localization, more about reproducing the swirling LF patterns a fine concert hall generates when music is being played. With acoustical summation in a reproduction room, there is a chance of hearing them, while electrical summation surely kills such joy. Also, we actually localize all the way down to a static pressure change (DC). It's indoor conditions messing up our senses”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1524620
“To faithfully reproduce great acoustic recordings, a flattish frequency response of perceived-direct sound is just one of the goals. More importantly, to me, the monitoring room and sound system need to convey moving patterns of sound latent in the recording, especially between 40 and 200 Hz. This is where to hear the soul of a concert hall or church, in case it has been recorded.
Collapsing discrete channels to a single sub channel should therefore be a last resort, e.g. if the reproduction room/placement is difficult and/or to accommodate multiple listeners.
Taking advantage of discrete channel reproduction at low frequency has even spread outside acoustic recordings. Top pop/rock productions now also make use of such perceptual excitement, which will remain a secret to “collapsers”
@j_j
Fundamentals of hearing 2004
https://www.aes-media.org/sections/pnw/ppt/jj/jj_aes04_ts1.ppt
“Various people have reported, sometimes anecdotally, that above 40Hz (and below 90Hz), although one can not localize a sound source, differences in interaural phase can create a sensation of space.. his suggests that for accurate perception of space, 2 or 3 subwoofers may be necessary. This also, as in many other places in audio, creates a situation where what one might consider the “optimum” solution (maximum bass flatness) does not in fact convey the perceptual optimum.”
Soundfields vs human hearing 2012
https://www.aes-media.org/sections/pnw/ppt/jj/soundfields_vs_human_hearing_edited.ppt
“Specifically, although one can not LOCALIZE signals below about 90 Hz, one can detect spatial effects from interaural phase differences down to about 40Hz. The AT&T Labs “Perceptual Soundfield Reconstruction” Demo, no longer available, contained a very nice example of these effects, and how they can change “boomy bass” in the 2-radiator case into “bass spread about a room” in the 5-channel case.”
@Thomas Lund
https://www.genelec.com/-/immersive-monitoring-a-perceptive-perspective
“From 50 Hz to 700 Hz, however, fast-firing synapses in the brainstem are responsible for localisation, employed in a phase-locking structure to determine interaural time difference (ITD). Humans can localise at even lower frequencies, but we will come back to that in a specific ultra low frequency blog.
The ability to position sound sources with precision spherically is a key benefit of immersive systems. Another is the possibility to influence the sense of space in human listeners. For the latter, the lowest two octaves of the ITD range (i.e. 50-200 Hz) play an essential role; but may be compromised in multiple ways”
https://www.genelec.com/-/blog/how-to-analyse-frequency-and-temporal-responses
“With both stereo and immersive, for your room and system to be able to reliably convey the envelopment latent in the content, perceived-direct sound should dominate in the 50 to 700 Hz range – where audible patterns characteristic of the recording space may have been picked up. If they have, you can be sure that the recording engineer has gone to great lengths in doing so. Fig 2 is a recording setup in Olavshallen in Trondheim, Norway, and shows a main mic array with sufficient distance between capsules to capture LF differences and moving patterns – two of the most precious qualities of a hall to preserve….Fig 3 shows the GRADE graphs from section 4.3 of the report, and reveals a monitor to the left which is able to convey envelopment latent in the content; and one to the right that is less able to do so. If listening to the latter, you are unable to judge recorded space precisely. Such ability may also be sacrificed when relying on bass management with only one subwoofer to reproduce all LF sound, rather than multiple channels and acoustic in-room summation. If possible with delicate content, don’t use a higher bass management cross-over frequency than necessary, and preferably below 60 Hz.”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1526313
“It's not primarily about localization, more about reproducing the swirling LF patterns a fine concert hall generates when music is being played. With acoustical summation in a reproduction room, there is a chance of hearing them, while electrical summation surely kills such joy. Also, we actually localize all the way down to a static pressure change (DC). It's indoor conditions messing up our senses”
https://www.audiosciencereview.com/...view-room-eq-setup.26397/page-21#post-1524620
“To faithfully reproduce great acoustic recordings, a flattish frequency response of perceived-direct sound is just one of the goals. More importantly, to me, the monitoring room and sound system need to convey moving patterns of sound latent in the recording, especially between 40 and 200 Hz. This is where to hear the soul of a concert hall or church, in case it has been recorded.
Collapsing discrete channels to a single sub channel should therefore be a last resort, e.g. if the reproduction room/placement is difficult and/or to accommodate multiple listeners.
Taking advantage of discrete channel reproduction at low frequency has even spread outside acoustic recordings. Top pop/rock productions now also make use of such perceptual excitement, which will remain a secret to “collapsers”
Personally, when I tried, I was never happy with the results. And that is despite the fact many swear the LS50 speakers do much better if you use 2 subs and offload anything under 200Hz to them. You need to DSP the heck of such a setup to get great results. So I stick to a single sub at 70Hz, and used Dirac for simple optimization.
I am aware I am potentially sacrificing distortion at higher SPL, but since I sit 7ft apart of my speakers thatbwould be wayntoo much SPL for my taste.
I will keep following this topic.
I am aware I am potentially sacrificing distortion at higher SPL, but since I sit 7ft apart of my speakers thatbwould be wayntoo much SPL for my taste.
I will keep following this topic.
Avoiding high SPL and high loudness (two different things, note) is a wise thing. We only get pair of inner hair cell rows each.
Trying to assess whether I should be going 4 way stereo or dual mono subs. The thread is quite interesting. I am used to listening to electronic in headphones with very good bass extension. Lots of synth based stereo data under 80hz and probably a decent amount under 30hz. It's pretty easy to set these up as 4-ways which I may try first.
As a side remark on stereo subs: I just bought the Marantz AV10. It can do the stereo bass routing for two subs (even for 4 if you have them
)Setup here is Neumann 2xKH810 + 2xO410 (KH420 previous gen) so the bass management is in the sub. Can do one per channel or sum as many as I wantAs a side remark on stereo subs: I just bought the Marantz AV10. It can do the stereo bass routing for two subs (even for 4 if you have them
The difference is subtle at best and not present at all on most recordings. But your mileage may vary so if you can test both that's of course the best.
In most recordings, the utility is intentionally destroyed.The difference is subtle at best and not present at all on most recordings. But your mileage may vary so if you can test both that's of course the best.
Now, if you have a good, well-designed acoustic recording that hasn't been treated with the "mono bass" routine, etc, you may get quite a bit from it, especially if you have 2 front, 2 back, properly (that word!) recorded.
Below 40Hz it's not as much of an issue, but between 40 and 90Hz, yes, there is "stereo content" possible in a good venue with a good recording.
Andysu
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Tom C
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