Omnidirectional ≠ non-localizable.
It depends on the absorption happening in your room. In my open living room with wooden floors, I can almost never localize by subwoofer, but in my carpeted bedroom I can localize it a good deal below 80Hz.
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Stereo Bass using subwoofers
- Thread starter dkinric
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It depends on the absorption happening in your room. In my open living room with wooden floors, I can almost never localize by subwoofer, but in my carpeted bedroom I can localize it a good deal below 80Hz.
Not my experience.
Btw, science is saying that our localization capability is only dependent on the relation between frequency and diameter of the driver producing it. If we would have really large LF drivers we would be able to localize them down to 20Hz without any problem.
Driver diameter in relation to frequency effects directivity (it is near/at 0 at low frequencies as shown in the Spinoramas; the Neumann is so small it’s ~0 even at 200Hz).Not my experience.
Btw, science is saying that our localization capability is only dependent on the relation between frequency and diameter of the driver producing it. If we would have really large LF drivers we would be able to localize them down to 20Hz without any problem.
Low directivity (insane amount of reflections) will naturally decrease localization.
If you were in a true anechoic chamber, you of course would have no issue localizing down to 20Hz.
True, you said it more precisely than I did and we certainly agree on that.
This certainly is not true. The main problem to localize frequencies below 80Hz aren't reflections but the fact that distance between our ears is too small so we can't detect neither difference in level nor difference in phase which is necessary for localization.
From Wiki:
"As the frequency drops below 80 Hz it becomes difficult or impossible to use either time difference or level difference to determine a sound's lateral source, because the phase difference between the ears becomes too small for a directional evaluation. "
That also means that your ability to localize frequencies beow 80Hz doesn't depend on densitiy of walls/ceiling/floow (which affects reflected to absorbed ratio). In other words your ability to localize frequencies below 80Hzin your living room and in your bathroom is the same and it pretty much equals 0.
Pio2001
Senior Member
Jazz bass guitar goes down to 32Hz, pipe organ down to 20Hz. With electronic music bass can go as deep as musician want.
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Yes, but only if the composer wrote that note on the score, which is rarely the case.
And the amplitude of the fundamental is important too. 32 Hz by a piano or a harp delivers much less Energy at that frequency than 32 Hz from an organ.
No offense, but what is the point in stating the obvious?
Sound localization ability of humans and animals depends mostly on interaural distance. Two ears should get different spl and phase to be able to localize. Some of the effect comes from transients and harmonics of the signal (Many bass instruments have louder harmonics than the fundamental!)
Griesinger is a nice source http://www.davidgriesinger.com/
Griesinger is a nice source http://www.davidgriesinger.com/
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However, all that is said is valid only for men - every wife of HiFi enthusiast can easilly pinpoint any SW playing 20Hz tone even from the kitchen.
This has been very well researched. If you are localising the sub its probably due to other higher frequency noises its creating or stimulating in near objects. It's not due to the level of absorption.
Also don't forget that at low frequencies, below 80Hz, it is actually quite difficult to absorb. The wavelengths are too long. The deadened sound of your bedroom is due to the higher frequencies being absorbed not the low.
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Pio2001
Senior Member
Because I've been involved in discussions where it was not obvious for everyone
How many times have I been told that piano could go as low as 16 Hz (Bösendorfer imperial C0), and that therefore piano was perfectly suited to test subwoofers ?
I have recently measured the localisation of frequencies below 80 Hz in a 4-subs system, with a DIY dummy head. Unfortunately, the processor was not configured to play the low frequencies in stereo, but only in experimental mid / side configurations (some subs playing L+R, while the others play L-R or R-L).
However, this was enough to show that the difference of spaciousness heard at the listening position, between a mono and a stereo pink noise lowpassed at 80 Hz, was confirmed by analyzing the recording.
After lowpassing again the recording with a very sharp filter (-100 dB @ 100 Hz), the XY phase correlation diagram is still wider with the stereo pink noise than with the mono pink noise, measured at the ears of the dummy head.
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Because I've been involved in discussions where it was not obvious for everyone
How many times have I been told that piano could go as low as 16 Hz (Bösendorfer imperial C0), and that therefore piano was perfectly suited to test subwoofers ?
I have recently measured the localisation of frequencies below 80 Hz in a 4-subs system, with a DIY dummy head. Unfortunately, the processor was not configured to play the low frequencies in stereo, but only in experimental mid / side configurations (some subs playing L+R, while the others play L-R or R-L).
However, this was enough to show that the difference of spaciousness heard at the listening position, between a mono and a stereo pink noise lowpassed at 80 Hz, was confirmed by analyzing the recording.
After lowpassing again the recording with a very sharp filter (-100 dB @ 100 Hz), the XY phase correlation diagram is still wider with the stereo pink noise than with the mono pink noise, measured at the ears of the dummy head.
As I said, this has already been very well researched. I'm not sure you are going to be able to contradict that. I think you may be conflating hearing something that's out of phase with localisation. Try it again with people under controlled conditions with music.
Not to mention that few recordings have significant stereo content at low frequencies.
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Pio2001
Senior Member
With music ? No way. It works only with pure left / right signals, or decorrelated noise, as in the file that I posted above : Pink_80_abcd.flac
The file is not clean, by the way. Each sequence stops with a click, that I should remove.
I can't reproduce the experiment, as I have no more access to the subs, nor to the dummy head. I can post the XY phase correlation diagrams, though. They are here, by the way, but the picture is huge, and contains a lot of irrelevant diagrams for our discussion : https://www.homecinema-fr.com/forum/post180106863.html#p180106863
I can't do any listening test under controlled conditions, as having a perfectly identical frequency response under 80 Hz from two different locations would mean to be in true free field listening conditions.
Recording the phase correlation was the only rigorous way I found to measure the stereo separation at the listening position.
Best solution is speakers with controlled directivity in combination with acoustic treatment.
More realistic for most people is controlled directivity speakers, and little or no acoustic treatment. Getting good acoustic performance down to 100Hz requires much more effort than most can or are willing to do. Fortunately, it turns out that better speakers can increase performance to a level where many of us are pleased with the result.
Then you can use ordinary speakers, and try to place them so that problems are minimized. This means far away from boundaries - which can only be done in quite large rooms.
In most rooms, with most speakers, none of the above mentioned solutions are implemented. Because we live in the rooms we have, and we use the speakers that are available. Then we realize that most of us are used to sound that is very compromized in this upper bass - lower mid frequency range. When you hear a system with controlled behavior in this range, you realize what this means for sound quality, and that there is huge potential for improvement.
Ron Texas
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Anyone else have thoughts on this?
dshreter
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I agree with this statement only to the extent that subwoofers are being used for reproduction of frequency range that can be localized. For example, a multi-way speaker that has a "subwoofer" driver that extends from say 20Hz to 200Hz. If used exclusively <~80Hz as is typical, placing the subwoofers near the mains does not make sense unless this coincidentally corresponds to the preferred locations for evenness of frequency response.
I won't go so far as to say that subwoofers have zero localization, if for now other reason than distortion products at higher frequencies can exist. For this reason, I think there's merit to symmetrical placement if using multiple subwoofers. But even accepting that, I think the benefits of achieving even frequency response by running in mono at idealized subwoofer locations outweigh the potential benefits of running in stereo near the locations of the main speakers.
I agree. But if you did place them like that than you can drive them with stereo signal as that is how it would be if subs were integrated with mains.
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Jazz bass guitar goes down to 32Hz, pipe organ down to 20Hz. With electronic music bass can go as deep as musician want.
View attachment 47063
Jazz bass guitar (or stand-up bass or concert bass violin for that matter) generally goes down to the low E at 41 hertz. Not coincidentally, I think, this is a frequency where a lot of people really just start to have a lot of trouble discerning pitch. You can stick an extra low string on a jazz bass guitar and then you might get your 32 hertz. I know what this sounds like—LOW.
But anyway, I have found my stereo works much better for me subjectively if I cross over at 120 hz rather than 80 hz. If I cross over at 80 hertz there is something going on in the bass that literally makes me uncomfortable, like too much pressure or something. Cross over at 120 hertz and everything is nice and smooth and clear. Maybe it’s because I have two subs and my subs are much nicer than the rest of my gear and they are taking care of some issues that my speakers have trouble with—I’m not technical, I don’t know.
Correct. I listen mostly to jazz music so I'm aware of that.
Hard to tell why would that be as you are describing without knowing details about at least your main speakers. It may as well be that your SWs are simply doing a better job filling your room in the 80-120Hz region than your mains. Best thing to do will be to measure the FR in both scenarios, only that would show the real truth.
dshreter
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Agreed with Krunok you need to measure what is happening to have a real sense of what is going on. It’s easily possible your main speakers have a null, peak, or both in the 80-120Hz range at your listening position, and the sub has beneficial placement. There’s some danger in crossing too high and going mono at the higher frequency, but if it sounds better really who cares.
However, it’s also possible you could sort out the placement of your mains and listening position, in addition to some tone control to fix it too. Lots of variables, and no way to sort it without a mic.
I think the idea of "subs integrated with mains" is unfortunate. At low frequencies, it is extremely likely that the best place for a bass source is not the best place for imaging/soundstage and general balance across the rest of the audible spectrum. Thanks to physics, our reduced ability to localize bass sources allows us to place a sub where it belongs in any particular room.
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