Science on low frequency quality?

[FrantzM]

I'm 64, have never used subs. Part of that for me is room issues - and what my ear is used to. IMO, it's quite possible to enjoy music with a system that cleanly reproduces 50 - 20,000 hz...

I got you.

I (and likely most music lovers) enjoy music from any source , as example I enjoy it from my SONOS Beam and sometimes from my iPhone Pro speakers...

Great Audio reproduction mandates 30 to 15 KHz IMHO , however.

Peace.

 

[FrantzM]

Regarding science about perceptions of bass and "quality" (which I interpret as subjective impressions, could be potentially described along specific parameters like https://www.aes.org/e-lib/browse.cfm?elib=16323), there are some interesting papers and models that have been discussed here but not very often.

1. Fazenda et al. Subjective preferences of modal control methods JAES 2012: https://www.aes.org/e-lib/browse.cfm?elib=15734 (can download free copy at https://www.avsforum.com/attachments/jaes_v60_5_perception_modal_control-pdf.2273992/)
2. Martens et al, SPATIAL AUDITORY DISPLAY USING MULTIPLE SUBWOOFERS IN TWO DIFFERENT REVERBERANT REPRODUCTION ENVIRONMENTS, ICAD 2005, and the related SUBJECTIVE EVALUATION OF AUDITORY SPATIAL IMAGERY ASSOCIATED WITH DECORRELATED SUBWOOFER SIGNALS ICAD 2002
3. Griesinger (http://www.davidgriesinger.com/), specifically

but can find other papers on his linked page

I interpret these loosely to suggest that:
A. Although bass reproduction is generally considered as a minimum phase phenomenon, perceptual testing suggest possible benefit of prioritizing modal decay time reduction over simple frequency response approaches (#1 above, also https://www.semanticscholar.org/pap...ivet/c60956bb7ae27df063100c5431f738c7225667ef)
B. Laterally decorrelated bass may positively contribute to spatial perceptions (envelopment or spaciousness) in certain situations with certain listening materials, perhaps with certain recording techniques (this has been discussed a fair amount in the past, but my speculation is that perhaps many stereo classical music recordings might benefit more than, say, pan pot stereo recordings). Since many listening rooms are not perfectly symmetric on the left and right in terms of construction, including window and door placement, reality does not perfectly reflect the mathematical model for modes, so I wonder to what degree sidewall placement of subs might excite room modes a little differently. The other aspect I wonder is whether placing the subwoofers wider than the left and right speakers might act like Blumlein shuffling in the low bass (can see discussed https://www.flyhighwaves.com/studio/stereo-shuffling-new-approach-old-technique/ and https://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf, but again, spatial perceptions are referenced here)

Two aspect of Geddes' approach (which has been described in different ways at different times but generally involves reasonably full-range speakers run full-range, one ultra-low frequency subwoofer located in a corner, one bass source above the midline of the room, and at least one other subwoofer due to point of diminishing returns) that potentially differ significantly from the Welti approach (which has also evolved somewhat from the typically linked "multisub" paper to https://hometheaterhifi.com/technic...n-interview-with-todd-welti-and-kevin-voecks/):
i. The degree of overlap between the subs and the main channels
ii. My speculation that his approach of multiple decorrelated bass sources may end up incorporating some aspects of A and B above, even if unintentionally so, since highly asymmetric bass source placement may be expected to differentially "drive" room modes, also phase and level of each additional bass source are sequentially adjusted to reduce peaks, which may involve phase cancellation at modal frequencies, essentially acting somewhat like a "sink" or electroacoustic absorber, as well as possibly contributing to what I discussed above in point B. Perhaps @Duke could comment further.

Anyway, since you asked about science and bass quality, I thought the above references might serve as a possible starting point to explore further on your own.

Young-Ho

I t have been of that opinion (but it was only an inkling) for a while. I also have noticed that in my room, I could move my head or my position ever so slightly and lose (or gain) a good amount of bass; half a foot, could make a difference. Better in my opinion to have 2 subs than one for the same cash outlay...
I am 2/3 Geddes , I use 2 subs now but will move to 3 very soon.

Thanks for the links, excellent post.

Peace.

 

[DonH56]

@DonH56

I knew you were a gentleman, and admit that you didn't rub more salt on the wound.
But... , you failed to mention that you hit 8 Hz, (!!!) in your room and that you have the more than potent, JBL equivalent of the Trinnov Altitude Processor... so ,
Duly noted ...
you are still on my Hate List.




As usual , great info.
Peace.

Thanks, I am impervious to jealousy. And, it was 7 Hz at -3 dB, please pass the salt...

 

[jsilvela]

Regarding science about perceptions of bass and "quality" (which I interpret as subjective impressions, could be potentially described along specific parameters like https://www.aes.org/e-lib/browse.cfm?elib=16323), there are some interesting papers and models that have been discussed here but not very often.

1. Fazenda et al. Subjective preferences of modal control methods JAES 2012: https://www.aes.org/e-lib/browse.cfm?elib=15734 (can download free copy at https://www.avsforum.com/attachments/jaes_v60_5_perception_modal_control-pdf.2273992/)
2. Martens et al, SPATIAL AUDITORY DISPLAY USING MULTIPLE SUBWOOFERS IN TWO DIFFERENT REVERBERANT REPRODUCTION ENVIRONMENTS, ICAD 2005, and the related SUBJECTIVE EVALUATION OF AUDITORY SPATIAL IMAGERY ASSOCIATED WITH DECORRELATED SUBWOOFER SIGNALS ICAD 2002
3. Griesinger (http://www.davidgriesinger.com/), specifically

but can find other papers on his linked page

I interpret these loosely to suggest that:
A. Although bass reproduction is generally considered as a minimum phase phenomenon, perceptual testing suggest possible benefit of prioritizing modal decay time reduction over simple frequency response approaches (#1 above, also https://www.semanticscholar.org/pap...ivet/c60956bb7ae27df063100c5431f738c7225667ef)
B. Laterally decorrelated bass may positively contribute to spatial perceptions (envelopment or spaciousness) in certain situations with certain listening materials, perhaps with certain recording techniques (this has been discussed a fair amount in the past, but my speculation is that perhaps many stereo classical music recordings might benefit more than, say, pan pot stereo recordings). Since many listening rooms are not perfectly symmetric on the left and right in terms of construction, including window and door placement, reality does not perfectly reflect the mathematical model for modes, so I wonder to what degree sidewall placement of subs might excite room modes a little differently. The other aspect I wonder is whether placing the subwoofers wider than the left and right speakers might act like Blumlein shuffling in the low bass (can see discussed https://www.flyhighwaves.com/studio/stereo-shuffling-new-approach-old-technique/ and https://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf, but again, spatial perceptions are referenced here)

Two aspect of Geddes' approach (which has been described in different ways at different times but generally involves reasonably full-range speakers run full-range, one ultra-low frequency subwoofer located in a corner, one bass source above the midline of the room, and at least one other subwoofer due to point of diminishing returns) that potentially differ significantly from the Welti approach (which has also evolved somewhat from the typically linked "multisub" paper to https://hometheaterhifi.com/technic...n-interview-with-todd-welti-and-kevin-voecks/):
i. The degree of overlap between the subs and the main channels
ii. My speculation that his approach of multiple decorrelated bass sources may end up incorporating some aspects of A and B above, even if unintentionally so, since highly asymmetric bass source placement may be expected to differentially "drive" room modes, also phase and level of each additional bass source are sequentially adjusted to reduce peaks, which may involve phase cancellation at modal frequencies, essentially acting somewhat like a "sink" or electroacoustic absorber, as well as possibly contributing to what I discussed above in point B. Perhaps @Duke could comment further.

Anyway, since you asked about science and bass quality, I thought the above references might serve as a possible starting point to explore further on your own.

Young-Ho

Looks super interesting, thank you! A bit over my head, but I'll go slow.

 

[jsilvela]

I'm 64, have never used subs. Part of that for me is room issues - and what my ear is used to. IMO, it's quite possible to enjoy music with a system that cleanly reproduces 50 - 20,000 hz...

Yep!
The science-based approach of Toole et. al. is based on correlating the average preference of listeners in blind tests with some objective measurements.
Finding fault with the system you like because it fails to meet some objective measurement would basically amount to telling you to "join the crowd", IMO.

 

[jsilvela]

Regarding science about perceptions of bass and "quality" (which I interpret as subjective impressions, could be potentially described along specific parameters like https://www.aes.org/e-lib/browse.cfm?elib=16323), there are some interesting papers and models that have been discussed here but not very often.

1. Fazenda et al. Subjective preferences of modal control methods JAES 2012: https://www.aes.org/e-lib/browse.cfm?elib=15734 (can download free copy at https://www.avsforum.com/attachments/jaes_v60_5_perception_modal_control-pdf.2273992/)
2. Martens et al, SPATIAL AUDITORY DISPLAY USING MULTIPLE SUBWOOFERS IN TWO DIFFERENT REVERBERANT REPRODUCTION ENVIRONMENTS, ICAD 2005, and the related SUBJECTIVE EVALUATION OF AUDITORY SPATIAL IMAGERY ASSOCIATED WITH DECORRELATED SUBWOOFER SIGNALS ICAD 2002
3. Griesinger (http://www.davidgriesinger.com/), specifically

but can find other papers on his linked page

I interpret these loosely to suggest that:
A. Although bass reproduction is generally considered as a minimum phase phenomenon, perceptual testing suggest possible benefit of prioritizing modal decay time reduction over simple frequency response approaches (#1 above, also https://www.semanticscholar.org/pap...ivet/c60956bb7ae27df063100c5431f738c7225667ef)
B. Laterally decorrelated bass may positively contribute to spatial perceptions (envelopment or spaciousness) in certain situations with certain listening materials, perhaps with certain recording techniques (this has been discussed a fair amount in the past, but my speculation is that perhaps many stereo classical music recordings might benefit more than, say, pan pot stereo recordings). Since many listening rooms are not perfectly symmetric on the left and right in terms of construction, including window and door placement, reality does not perfectly reflect the mathematical model for modes, so I wonder to what degree sidewall placement of subs might excite room modes a little differently. The other aspect I wonder is whether placing the subwoofers wider than the left and right speakers might act like Blumlein shuffling in the low bass (can see discussed https://www.flyhighwaves.com/studio/stereo-shuffling-new-approach-old-technique/ and https://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf, but again, spatial perceptions are referenced here)

Two aspect of Geddes' approach (which has been described in different ways at different times but generally involves reasonably full-range speakers run full-range, one ultra-low frequency subwoofer located in a corner, one bass source above the midline of the room, and at least one other subwoofer due to point of diminishing returns) that potentially differ significantly from the Welti approach (which has also evolved somewhat from the typically linked "multisub" paper to https://hometheaterhifi.com/technic...n-interview-with-todd-welti-and-kevin-voecks/):
i. The degree of overlap between the subs and the main channels
ii. My speculation that his approach of multiple decorrelated bass sources may end up incorporating some aspects of A and B above, even if unintentionally so, since highly asymmetric bass source placement may be expected to differentially "drive" room modes, also phase and level of each additional bass source are sequentially adjusted to reduce peaks, which may involve phase cancellation at modal frequencies, essentially acting somewhat like a "sink" or electroacoustic absorber, as well as possibly contributing to what I discussed above in point B. Perhaps @Duke could comment further.

Anyway, since you asked about science and bass quality, I thought the above references might serve as a possible starting point to explore further on your own.

Young-Ho

Looking at the first reference, the Abstract is mighty interesting.

Using objective measures to correct these modes often fails because they do not correspond to the subjective experience of listeners.

I'll look at the next one you post which is downloadable, and will keep learning. Thanks again.

 

[youngho]

Looking at the first reference, the Abstract is mighty interesting.

I'll look at the next one you post which is downloadable, and will keep learning. Thanks again.

Yep!
The science-based approach of Toole et. al. is based on correlating the average preference of listeners in blind tests with some objective measurements.
Finding fault with the system you like because it fails to meet some objective measurement would basically amount to telling you to "join the crowd", IMO.

I think the latter may be a bit unkind. Toole, Olive, and others have demonstrated that listeners can listen through rooms, so to speak, and they have also written about some listeners having different preferences than others (lateral reflections, tone controls, target curves, etc), but I feel like a lot ends up getting oversimplified here in ASR: Harman curve (even though there has been more than one over time), steadily rising directivity is ideal (as opposed to the relatively flat directivity from a few hundred to several thousand Hz demonstrated by so many Harman speakers), the importance of measurements that don't show IMD that was described as audible by Toole in the third edition of his book (in reference to a Kef speaker, model unknown), etc.

You might start with Griesinger's YouTube video.

 

[jsilvela]

My room is not large and I do not need large subs; four 12" (Rythmik) subs do just fine. I am not using a miniDSP (or MSO) but tweaked things myself (using room measurements, e.g. REW) in my AVP to get decent bass response.

FWIWFM - Don

This was very helpful, thanks.
I think I've become a bit wary of all the complexity with MSO, miniDSP etc. In machine-learning parlance, it seems to me a case of over-fitting.
If 2-4 subs help fill in cancellations, and also add more discrete modes at more listening positions, then I can understand, informally, that an AVR has a better building block to play with, shall we say.

 

[miha]

In Toole's work small monitors with response to about 100 hz had an almost 100% correlation with their model of preferred sound. It was less with full range speakers. My guess is that is mainly because full range speakers in a real room are uneven at low frequencies. Even in their test circumstances. So at least it seems to me a really flat result is going to be better and preferred.

How important is that? I think they surmised from their research that bass response was responsible for 30% of preference. So an outsized importance despite our relative insensitivity to bass. When you think about it, nulls and resonances in a room can result in huge differences in response. Some instruments can nearly disappear in nulls and others can be heavily overblown masking other frequencies even with our reduced sensitivity at sub 100 hz frequencies. So something of a dichotomy that we are insensitive to bass yet in smaller domestic spaces the response is usually by far the most uneven in the whole frequency range.

So one fortunate circumstance is we stop hearing position around 80 hz and below. So one sub EQ'd is fine. You cannot EQ out nulls, but we are more sensitive to resonances and peaks. So just flattening peaks is very helpful. Optimally having more subs, fewer nulls etc is better. Or alternatively having a large enough room all these effects are pushed way down in frequency which is not usually the case in domestic sized listening rooms.

"So one fortunate circumstance is we stop hearing position around 80 hz and below."
I've experienced this myself but I don't understand why this happens? If I put a sub on my left side, the sound will reach my R ear later than my L ear. So, I would assume that phase localisation would be possible...

 

[FrantzM]

This was very helpful, thanks.
I think I've become a bit wary of all the complexity with MSO, miniDSP etc. In machine-learning parlance, it seems to me a case of over-fitting.
If 2-4 subs help fill in cancellations, and also add more discrete modes at more listening positions, then I can understand, informally, that an AVR has a better building block to play with, shall we say.

Hi

The issues of small room acoustics (of Acoustics In general) are very complex. The mathematics to model and understand acoustics are perforce complex. The solutions mirror that complexity. We are not yet at a point where we get a system, and at the press of a button, it works well and to our satisfaction. Accurate and (interestingly), thus satisfying audio reproduction (Science backs up that assertion), at this point in time is complex, complicated. We are fortunately living in a time when the audio enthusiast has at his/her/their disposal, high performance tools, many of those happen to be free. To put things in perspective, think about getting the power of a tool such as REW , 30 years ago... or finding a measurements microphone with the accuracy of a UMIK-1 ($100) or equally inexpensive equivalent (Dayton Audio EMM-6? , etc) would likely be in the multi-thousand dollars region.. As for software there weren't any that would not have cost a year salary... REW with all its power and, yes complexity, is free. The miniDSP 2x4, it is a fabulous piece of engineering with a relatively gentle learning curve, it doesn't require months of study. MSO is in my opinion complex, there are few (no?) alternatives and... none as performant.. There are very few software that approach its performance and that do not cost or incur serious disbursement. I am not certain for example that the often heralded DIRAC DLBC outperforms MSO... The question is asked with all seriousness: does anyone know of a software that performs the same functions at any price? The few that come to mind are proprietary or for a closed system... What is an MSO equivalent?

One can with REW and with (several ) reiterations find a good response with 2 subs even 4. It will take time... Lot of time and or luck. The response using only REW and iterations could be good, likely better than that of many commercial or AVR DRC. It is unlikely to be as good, as that you would obtain with MSO, I would daresay impossible.

There is the alternative to hire a serious acoustician. For many who frequent this and other forum, the combination of REW + MSO + hours of their time (and frustration) is worth the results.

To conclude. An AVR in my opinion is the necessary building stone of any audio system even when you wee the remove the multiple subwoofer setup, From what I think I know few of the usual AVR are as good as REW+MSO + miniDSP in optimizing multiple subwoofers. Perhaps the Trinnov or Storm or ... By then, you are talking about units costing upward of $15,000.oo for the PrePro...

Please try to @bodhi, suggestion if you have a pair of subs, even inexpensive ones or even of different models and types (sealed or closed or both) ...The minDSP 2x4 and the microphone about $350.oo on Amazon for both... The YouTube video, A free afternoon, just do what the video says...

You'll be glad you did.

Peace.

 

[jsilvela]

[...]

Please try to @bodhi, suggestion if you have a pair of subs, even inexpensive ones or even of different models and types (sealed or closed or both) ...The minDSP 2x4 and the microphone about $350.oo on Amazon for both... The YouTube video, A free afternoon, just do what the video says...

You'll be glad you did.

Peace.

Thank you. I'm very much paying attention to what you and @bodhi have been saying.
I don't want either of you to think I'm beating around the bush and trying to get papal benediction for my existing setup to stop experimenting.
I am pretty much decided on getting a second sub in the next few days (likely Kef, which is easier for me to get than SVS).
I am going to try a slower approach though. First compare single/double sub with REW measurements, understand what happens, repeat, re-position etc.
As I learn more I'll see about eventually going the MSO / miniDSP route.

I have been failing at expressing myself, I think. The multi-sub / MSO / miniDSP route is relatively sophisticated. I was hoping for more science to back that up.
This earlier response from @youngho https://audiosciencereview.com/foru...e-on-low-frequency-quality.41064/post-1451035
The second paper cited is freely available. It sets up a blind test with two sample tracks, and several configurations of subwoofers, from a single sub to 4.
It is a very interesting read. One juicy quote from it:

One very clear result is that one single subwoofer positioned in the corner of the room, with no equalization, is not advisable. Simple control steps such as moving the subwoofer toward nodal lines of offending modeshapes or applying magnitude equalization will improve reproduction quality noticeably.

The "winning" configurations use 2 and 4 subs respectively, in a "source/sink" configuration. The gist seems to be to lower the modal energy.
This was the kind of "persuasion" I was wanting more of.
Mind you, it's a single paper and there seem to be several schools of thought w.r.t low frequencies. I'll keep learning.

 

[bodhi]

Thank you. I'm very much paying attention to what you and @bodhi have been saying.
I don't want either of you to think I'm beating around the bush and trying to get papal benediction for my existing setup to stop experimenting.
I am pretty much decided on getting a second sub in the next few days (likely Kef, which is easier for me to get than SVS).
I am going to try a slower approach though. First compare single/double sub with REW measurements, understand what happens, repeat, re-position etc.
As I learn more I'll see about eventually going the MSO / miniDSP route.

Just to clarify, I don't use MSO myself. I have smooth enough response with just two subs and XT32 and I see no need to tweak any more. I'm only concerned of single listening position though and haven't measured other positions. But just from walking around the room the bass response feels to be good everywhere. And the improvement from one to two subs is very, very audible (again, outside the MLP). I think there were 10dB peaks before.

 

[DonH56]

"So one fortunate circumstance is we stop hearing position around 80 hz and below."
I've experienced this myself but I don't understand why this happens? If I put a sub on my left side, the sound will reach my R ear later than my L ear. So, I would assume that phase localisation would be possible...

Hand-waving: At 80 Hz a wavelength is about 14 feet (169", 4.3 m). Your ears are maybe 8" apart, or about 0.047 of a wavelength at 80 Hz (a delay of about 0.6 ms). At low frequencies the wavelength is so large relative to our head that the sound appears to arrive at both ears at (nearly) the same time, making it difficult to impossible to resolve phase differences, so we lose the ability to determine direction. Our hearing sensitivity is also much lower (look up equal loudness curves and see how much louder 80 Hz needs to be to be heard as loud as 1 kHz).

See e.g. https://en.wikipedia.org/wiki/Sound_localization for a discussion of ITD and IID (time and intensity differences used to determine direction) and some of the math describing how small an difference we can localize. At higher frequencies, we can resolve down to the microsecond level, but at low frequencies wavelengths are too large to distinguish direction. From the Wikipedia article:

"The lowest frequency which can be localized depends on the ear distance. Animals with a greater ear distance can localize lower frequencies than humans can. For animals with a smaller ear distance the lowest localizable frequency is higher than for humans."

HTH - Don

 

[sigbergaudio]

I have been failing at expressing myself, I think. The multi-sub / MSO / miniDSP route is relatively sophisticated. I was hoping for more science to back that up.

What kind of science are you looking for exactly? Thousands people have tested this in their own homes and shared the measurements, there's no dispute over the fact that you will get a more even response with more than one sub and/or DSP. The difference is very easy to hear as well.

 

[jsilvela]

What kind of science are you looking for exactly? Thousands people have tested this in their own homes and shared the measurements, there's no dispute over the fact that you will get a more even response with more than one sub and/or DSP. The difference is very easy to hear as well.

I see lots of anecdotal evidence at ASR, to be sure. Many of us can and do post REW before/after etc.
Blind tests with hopefully non-specialist test subjects were the kind of thing I wanted to see more of.

There was a previous response in this thread: https://audiosciencereview.com/foru...e-on-low-frequency-quality.41064/post-1451035
I've read one of the papers cited and seen a presentation. Pretty interesting.

I hope I don't appear dismissive. I really appreciate many comments you and others at ASR have given me. Learning lots.

 

[DonH56]

Posting measured results is not anecdotal, it is empirical evidence.

Many authors were referenced previously that delve into the science. Look up papers by Geddes, Welti, and so forth. I don't have Geddes bookmarked, but here again is Todd Welti's presentation -- I think the papers behind it are referenced: https://www.harman.com/documents/multsubs_0.pdf

There are many articles on the AES site but you may have to pay for them. Toole's book gets into it but I don't think it has all the math. There are many decades of research into this subject and it is somewhat complex, far too much for a few forum posts. One of the problems with this subject is that it is accepted as well-known theory and so the basic theory and references are pretty old, so details are mostly in places like books on acoustics and such. I do not know just how much science you are looking for, how deep you want to go, and so forth. My ancient grad text covers wave theory for multiple sources but does not explicitly cover subwoofers (that is a subset): Fundamentals of Acoustics by Kinsler et. al.

It is a good question, but expecting a treatise on acoustics on an Internet forum is a bit beyond what you're likely to get. You can be dismissive of the posts here, that is fair, but you are going to have to dig in and do the research to get an answer if you really want the science behind it. I for one do not want to try to reproduce decades of research and a couple of grad courses in a forum post.

 

[jsilvela]

Posting measured results is not anecdotal, it is empirical evidence.

Many authors were referenced previously that delve into the science. Look up papers by Geddes, Welti, and so forth. I don't have Geddes bookmarked, but here again is Todd Welti's presentation -- I think the papers behind it are referenced: https://www.harman.com/documents/multsubs_0.pdf

There are many articles on the AES site but you may have to pay for them. Toole's book gets into it but I don't think it has all the math. There are many decades of research into this subject and it is somewhat complex, far too much for a few forum posts. One of the problems with this subject is that it is accepted as well-known theory and so the basic theory and references are pretty old, so details are mostly in places like books on acoustics and such. I do not know just how much science you are looking for, how deep you want to go, and so forth. My ancient grad text covers wave theory for multiple sources but does not explicitly cover subwoofers (that is a subset): Fundamentals of Acoustics by Kinsler et. al.

It is a good question, but expecting a treatise on acoustics on an Internet forum is a bit beyond what you're likely to get. You can be dismissive of the posts here, that is fair, but you are going to have to dig in and do the research to get an answer if you really want the science behind it. I for one do not want to try to reproduce decades of research and a couple of grad courses in a forum post.

hm, I think I've put my foot in my mouth.
In no way did I mean to be dismissive. Nor do I want to waste anyone's time. I'm sorry that's what's coming off.

I have seen the Welti presentation, as well as Geddes. And I have read the first edition of Toole's book that presented the Welti work.
The solutions to the LF conundrum they propose, are complex. More complex than appeals to me.
I may end up going exactly that route (I think MSO is an implementation of the Welti idea?)
I'll start slow, though. First get a second sub. Play with location, take measurements, repeat.

Of course I'm aware this is a forum, I was hoping for links, references, not a dissertation. The Fazenda et al. paper cited in a previous post here, for example, has been super interesting.

 

[sigbergaudio]

I see lots of anecdotal evidence at ASR, to be sure. Many of us can and do post REW before/after etc.
Blind tests with hopefully non-specialist test subjects were the kind of thing I wanted to see more of.

There was a previous response in this thread: https://audiosciencereview.com/foru...e-on-low-frequency-quality.41064/post-1451035
I've read one of the papers cited and seen a presentation. Pretty interesting.

I hope I don't appear dismissive. I really appreciate many comments you and others at ASR have given me. Learning lots.

I would understand that for something like cables, but unless your room is somehow perfect to begin with, there's no mistaking the difference between a smooth and uneven response in the 20-100hz area. You're asking for "proof" for something that no one is disputing or questioning, and the reason for that is that the difference is obvious for anyone who tries. And yes I know there are lots of people who can hear "night and day" difference between cables as well, but on this topic I think your struggle to find "evidence" is actually because the difference is so obvious there's no reason to produce such evidence.

Please also note that I'm not saying "there's no dispute with regards to the difference between one or multiple subs", I'm saying "there's no dispute with regards to the difference between a smooth and uneven response." - For all we know you already have a smooth response with your single sub, then the difference will not be obvious when you add another.

TL;DR:

• Smooth response is audibly better than an uneven response: No dispute
• Adding more subs will even out the response: No dispute
• DSP will even out the response: No dispute
• You (jsilvela) will get an audible difference by adding more subs or DSP: We have no idea, since we don't know you current response.

 

[jsilvela]

You're asking for "proof" for something that no one is disputing or questioning, and the reason for that is that the difference is obvious for anyone who tries.

I was not expecting "proof". I have not managed to express myself properly.
My second sub is already ordered and on its way.
I did not want to make this thread about "should I jsilvela buy another sub".

TL;DR:

• You (jsilvela) will get an audible difference by adding more subs or DSP: We have no idea, since we don't know you current response.

Again, the reason I did not is I did not want to make this thread about my installation in particular.
I did post my REW readings in another thread, and you were very helpful there. See https://audiosciencereview.com/foru...subwoofer-specs-and-brands.40468/post-1437371

I seem to be digging myself into a bigger hole by saying more, so I will stop here.
Again, please know I appreciate I respect your comments and those of others here.

 

[sigbergaudio]

So if you are not looking for science (studies?) that proves that it works, are you looking for studies explaning WHY it works? If you are asking for blind tests it sure seems like you're looking for evidence that there is an audible difference? What else would they be doing in the blind test?