Bass direction is audible

[gnarly]

A few 2c thoughts/observations....

The assessment of bass directionality needs to be considered, firstly, independent of room. Room vary too much, and tend to be often be used as cop-out with regard to all kinds of audibility assessments, imo.

I think a single sub imparts recognizable directionality in two ways: audible and tactile.

Audible. Steady state tones are the hardest to detect directionality. But that can be true for much higher than sub frequencies too. Sine waves simply don't work at all indoors.
Pink noise low-passed however the sub is set up, sub playing only, is a good test.
Unless the sub is low passed at 80Hz or below, and with at least a 4th order slope, localization is quite easy ime.
I typically use a 96dB/oct low-pass @100Hz. And localization is still easy. But, I'm certain only to a degree that gets masked once main speaker is playing too.
Tone bursts, are super easy to locate.

Tactile. From transients like a bass drop or kick.....again, sub alone. It's a vector from sub's radiating area. It even matters which way the cone(s) are aimed, etc.

I test larger subs a lot, both indoors and out. And room is pretty large, so there are points of circumstance/bias in my assessments.
But honestly, I could care less about studies etc....been doing this too long...and in a bigger perspective than just home audio.
Directional bass rocks.

 

[kemmler3D]

A few 2c thoughts/observations....

The assessment of bass directionality needs to be considered, firstly, independent of room. Room vary too much, and tend to be often be used as cop-out with regard to all kinds of audibility assessments, imo.

I think a single sub imparts recognizable directionality in two ways: audible and tactile.

Audible. Steady state tones are the hardest to detect directionality. But that can be true for much higher than sub frequencies too. Sine waves simply don't work at all indoors.
Pink noise low-passed however the sub is set up, sub playing only, is a good test.
Unless the sub is low passed at 80Hz or below, and with at least a 4th order slope, localization is quite easy ime.
I typically use a 96dB/oct low-pass @100Hz. And localization is still easy. But, I'm certain only to a degree that gets masked once main speaker is playing too.
Tone bursts, are super easy to locate.

Tactile. From transients like a bass drop or kick.....again, sub alone. It's a vector from sub's radiating area. It even matters which way the cone(s) are aimed, etc.

I test larger subs a lot, both indoors and out. And room is pretty large, so there are points of circumstance/bias in my assessments.
But honestly, I could care less about studies etc....been doing this too long...and in a bigger perspective than just home audio.
Directional bass rocks.

Tend to agree. I have my sub crossed too high (almost 200hz) and it's not like it throws the stereo image off entirely, but it's noticeable on some tracks. And, I might be imagining it, but I feel like there's a slight sensation of pressure coming from the direction of the sub but not the other side, even for really low notes. I'm thinking I might add another sub to the other corner to even it out and just go for stereo bass because at that point, why not.

 

[staticV3]

How is that conclusion, that it hardly seems relevant to home audio applications not jumping to a conclusion?

Because it is a direct inference of the author's statement:

The psychoacoustic experiment was conducted in an anechoic room with minor room resonances which caused a significant change in the directional judgement for the affected frequencies, demonstrating how strongly room resonances can interact with directional hearing in the low-frequency spectrum.

 

[Duke]

If this study is correct, it would have implications as to how we should position subwoofers in our listening rooms. Maybe Griesinger's "stereo sub" idea may have some merit. Subwoofer positioning schemes such as Geddes' 3 sub method, or two subs in diagonal corners would need rethinking. Opinions?

I don't think the anechoic perceptual thresholds in the bass region translate to our non-anechoic listening rooms.

My understanding is that the ear cannot even detect the presence of bass energy from less than one full cycle. Considering the length of bass wavelengths relative to normal listening room dimensions, by the time the ear detects the presence of bass energy it has already begun arriving from multiple directions. So there is no perceptual (time-domain) separation between the first-arrival sound and the subsequent reflections in the bass region, and therefore the ear/brain system cannot determine the arrival direction(s).

My (sighted) observation has been that the more bass sources we have intelligently distributed around the room, the less localizable they each are, assuming none are distorting or passing audible upper bass/lower midrange energy due to inadequate lowpass fitering.

 

[Justdafactsmaam]

I don't think the anechoic perceptual thresholds in the bass region translate to our non-anechoic listening rooms.

This study suggests there is spatial information in the bass region we are missing due to room reverb in the bass region.

Me? I’d rather find out what the aural effect of that masked information is to determine if it has value and if it does then find out how much absorption/cancelation is needed to retrieve that information.

Declaring it unobtainium and dismissing the findings as irrelevant to home audio seems like the convenient short sighted conclusion

 

[gnarly]

This study suggests there is spatial information in the bass region we are missing due to room reverb in the bass region.

Me? I’d rather find out what the aural effect of that masked information is to determine if it has value and if it does then find out how much absorption/cancelation is needed to retrieve that information.

Declaring it unobtainium and dismissing the findings as irrelevant to home audio seems like the convenient short sighted conclusion

Amen. That is exactly why I listen outdoors.....to know what indoors is masking.
And then to work on how to get indoor bass to sound as good as outdoors.

 

[pablolie]

In my room and my listening tests, even 100Hz seems to have zero directionality. I'm always ready to deploy two subs (I have an identical spare one), but as of now I am fine with a single one x-overed at 70Hz. For my listening levels and patterns, that's my sweet spot. Easy enough to establish these days.

But as noted, it is hugely room dependent and also big-time preference dictated. Some people like a lot of bass, linearity be d*mned, and hey, they can get their fix these days. For my listening preferences, there doesn't seem much to care about under 32Hz or so - I never claim my personal preferences should suit everybody else.

 

[Titurel]

How is that conclusion, that it hardly seems relevant to home audio applications not jumping to a conclusion?

"Hardly relevant" is hardly jumping to a conclusion when prefaced with "For typical home audio applications." It does not preclude the possible implications of the study in atypical home environments. You ought to see my room. (imagine a gurning smiley)

 

[KSTR]

IMHO, the only way to consistently reproduce truly directional low bass in a real room would be what I call an orthogonal double-bass array. Not exactly a simple/cheap solution, that is.

If you have a fairly quadratic room, one can set up two equal DBAs with 90deg between their design axis, when looked at it diagonally -- which is also the listening axis.
For example, a L-channel-only signal will form a realistic (and flat) wavefront passing around your head, coming from 45deg to the left.

And a well-tuned DBA kills most room mode problems so I would expect exceptional bass quality overall, in all regards. One could still mix down the low bass to mono and do a compare with full stereo. Obviously, we need to find source material which has true stereo low bass signals as mixing/mastering engineers usually avoid stereo (sub-)bass for a number of reasons (vinyl cut, notably).

 

[Duke]

This study suggests there is spatial information in the bass region we are missing due to room reverb in the bass region.

Me? I’d rather find out what the aural effect of that masked information is to determine if it has value and if it does then find out how much absorption/cancelation is needed to retrieve that information.

Declaring it unobtainium and dismissing the findings as irrelevant to home audio seems like the convenient short sighted conclusion

My understanding is that relatively few recordings have stereo information below 80 or 100 Hz.

I would be surprised if the amount of absorption/cancellation needed to retrieve that information (when it exists) versus the real-world perceptual benefits adds up to a cost-effective use of resources for most people, but "cost-effectiveness" is of course a judgment call. I am under the impression that eliminating "room reverb in the bass region" is not a trivial undertaking, and wish you well should you decide to do so.

Imo there are more cost-effective paths to a spatially convincing presentation.

 

[Sokel]

My understanding is that relatively few recordings have stereo information below 80 or 100 Hz.

I would be surprised if the amount of absorption/cancellation needed to retrieve that information (when it exists) versus the real-world perceptual benefits adds up to a cost-effective use of resources for most people, but "cost-effectiveness" is of course a judgment call. I am under the impression that eliminating "room reverb in the bass region" is not a trivial undertaking, and wish you well should you decide to do so.

Imo there are more cost-effective paths to a spatially convincing presentation.

Most classical has stereo bass,no matter how old,I have posted numerous works and their analysis.
But it's not only about stereo bass,it's about proportions.

Every classical/opera listener expects baritones to sounds humane and defined in the scene for example.These proportions go out of the window,with some high-crossed set-ups these voices is like coming for a truck,not a man and they are diffused all over the room.

And I'm talking big rooms like mine too,even bigger so,not just small ones.And no one usually refers to that,is maybe that the genre is not so popular in HT or audiophile setups.
Even PA horns with high SPL ability respect these proportions.

 

[Duke]

Most classical has stereo bass,no matter how old, I have posted numerous works and their analysis.

Imo two subwoofers are significantly better than one, and imo it makes sense to configure them for stereo.

 

[Thomas_A]

There is a (phase?) trick to move bass around in the room, but I don't remember how it worked. A friend did a demo in my home long time ago.

 

[Yorkshire Mouth]

A few points/notes/questions.

Firstly, we’re mainly objectivists here, but I think even most of us would say that subjectively we have experienced, and have at least some sympathy with the concept of bass being non-directional.

Secondly, perhaps it’s not either/or; it’s not binary. I suspect bass isn’t non-directional, so much as less-directional. And, I suspect, less directional the lower it goes.

Perhaps it doesn’t become completely non-directional until it’s at 50, 40, 30, or even 20Hz (so not at all within the audible band), but slopes towards non-directionality as frequencies lower.

Thirdly, given the above, I’m sure we’re all aware of the concept of masking, where distortion (as an example) is hidden when the frequency is too close to the un distorted sound. I’d suggest there are very few sounds we hear from our speakers which are (as an example) pure 35Hz tones. And if the higher frequencies in the sound are greater than lower, then we’ll be more drawn to them (the higher), in relation to directionally.

If this is true, then the situation is very much “as you were”. Just because non-directionality isn’t proven (or is actually disproven) as an absolute, doesn’t mean that the general principles we’ve held all along lose all validity.

 

[pablolie]

The takeaway is: bass is complicated. It's hugely impacted by room modes, listening SPL (lots of non-linear stuff) and -as always- personal preference. The one-size-fits-all approach is doomed. And it doesn't matter if it's directional or not if room modes cancel it out and such.

I'd say that in most rooms:

(1) It's pretty impossible for full range speakers to cover 20Hz to 20kHz accurately
(2) It's hard enough to optimally position a single sub
(3) Two or more subs are ever harder to set up

There are many established platitudes about bass out there. Ignore them. Get yourself a Dirac kit or such, and leverage to explore optimal positioning.

 

[AdamG]

Eventually I completely moved away from having an additional subwoofer in the rear and had better bass quality with subs only in the front.

I experienced this same conclusion. I tried several location arrangements and what sounded best and surprisingly measured best at the MLP was front stage L&R subs just outside the the Main L&R front speakers. I suspect that this is very room dependent and my living space is all open floor plan that includes Living Room/Dining/Kitchen/Den and main hallway. I had a greater sense of Tactile energy and chest bass sensation. I lost that feeling when the subs were moved to other perimeter walls. Of course add in a sensible amount of listener & visual bias. The subs are pretty big @ 41″ x 20.5″ x 22.5″ (DxWxH) making them all but Impossible to hide.

 

[Titurel]

The takeaway is: bass is complicated. It's hugely impacted by room modes, listening SPL (lots of non-linear stuff) and -as always- personal preference. The one-size-fits-all approach is doomed. And it doesn't matter if it's directional or not if room modes cancel it out and such.

I'd say that in most rooms:

(1) It's pretty impossible for full range speakers to cover 20Hz to 20kHz accurately
(2) It's hard enough to optimally position a single sub
(3) Two or more subs are ever harder to set up

There are many established platitudes about bass out there. Ignore them. Get yourself a Dirac kit or such, and leverage to explore optimal positioning.

Regarding point 3 above, do you mean as summed subs or stereo subs or both cases? My experience with the second sort (stereo subs) is that they're easier to set up than either single and multiple summed subs. But I stress, my AVP's bass management allows for an array of sub strategies.

 

[Titurel]

I experienced this same conclusion. I tried several location arrangements and what sounded best and surprisingly measured best at the MLP was front stage L&R subs just outside the the Main L&R front speakers. I suspect that this is very room dependent and my living space is all open floor plan that includes Living Room/Dining/Kitchen/Den and main hallway. I had a greater sense of Tactile energy and chest bass sensation. I lost that feeling when the subs were moved to other perimeter walls. Of course add in a sensible amount of listener & visual bias. The subs are pretty big @ 41″ x 20.5″ x 22.5″ (DxWxH) making them all but Impossible to hide.

My subs aren't quite as visually imposing as yours, but my set up is similar - just outside of and slightly set back from the R & L mains, time corrected for the subs' built in room correction's latency and for the set back. Don't know if it's sensible, but it seems to work.

 

[Duke]

(3) Two or more subs are ever harder to set up

Well... ime, in practice, such seems to not be the case. Let me try to explain:

The more intelligently-distributed bass sources you have in the room the less critical the location of any one of them becomes. To put it another way, the more subs you have spread around the room, the less effect any one of them has on the net outcome. And that net outcome starts out significantly improved by the distributed multi-sub approach itself. I have been manufacturing and selling a four-piece distributed multisub sub system for eighteen years, and in practice a few general guidelines are almost always been sufficient.

That being said, ime there are definitely worthwhile refinement dividends that come optimizing the location of each sub. But it's not like you're going to get worse results by using multiple subs unless there's something anomalous going on.

 

[pablolie]

...
That being said, ime there are definitely worthwhile refinement dividends that come optimizing the location of each sub. But it's not like you're going to get worse results by using multiple subs unless there's something anomalous going on.

There undoubtedly IS something anomalous going on if you need multiple subs to get a satisfactory result. You're addressing it with multiple subs. Fine. There are other ways.