You can see my 2 subs are very close to my mains now--to the inside and on the floor. My third is located underneath Jimi Hendrix. 🙂
Dan
I don't know if decorrelation has a "perception" per see - I mean at low frequencies, but decorrelated LF sources (assuming multiple sources) do provide a smoother spatial and frequency response than correlated ones. That's how I cam across this idea. A "decorrelation" filter turns out to be a sort of "reverberation" process (decorrelation filters are widely used in some areas). Adding this "reverb" (just to the subs) makes them appear louder than without, but the "reverb" is not heard that way because the frequencies are too low. It just seems to make it louder and more "enveloping".
Can you elaborate on the details of the reverb tail? I would like to do some experiments with my system, implementation of the impulse response for each subwoofer independently is very easy in BruteFIR.
You might want to try sampling the IRs of DSP sowftware plugins that emulate early reflections and reverb. That's what I do, VST-plugins in realtime, that is (Windows-based active system, using Herman Seib's "VST-Host" as the patchbay/platform for "everything"). Also I use a sort of crosstalk canceling for some of the reverb signals, in order to decorelate them in localization from the main signal, too. My system is conventional, main-skeakers-only setup.
The plugin mainly used ar "RoomMachine844", "Ambience" and "KR-Reverb FS.dll", all are Freeware. The latter is special as it jitters the early reflection, the modulated a bit in arrival time.
I'm aware that is not exactly the thing Earl does as I use this method full-range, not only below 100Hz (as inspired by David Griesinger paper, http://www.davidgriesinger.com/ , look for the two items "The Theory and Practice of Perceptual Modeling" ).
Therefore I'm interested in his specific findings as well. My guess is that his approach -- at least in part -- would be classic decorrelation with some "arbitrary phase shifter" impulse kernels, something like this : http://www.garykendall.net/papers/Decorrelation1995.pdf
- Klaus
The plugin mainly used ar "RoomMachine844", "Ambience" and "KR-Reverb FS.dll", all are Freeware. The latter is special as it jitters the early reflection, the modulated a bit in arrival time.
I'm aware that is not exactly the thing Earl does as I use this method full-range, not only below 100Hz (as inspired by David Griesinger paper, http://www.davidgriesinger.com/ , look for the two items "The Theory and Practice of Perceptual Modeling" ).
Therefore I'm interested in his specific findings as well. My guess is that his approach -- at least in part -- would be classic decorrelation with some "arbitrary phase shifter" impulse kernels, something like this : http://www.garykendall.net/papers/Decorrelation1995.pdf
- Klaus
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I don't listen much to elephant foot steps in sneakers, what happens to this bass localization when you have normal music content?
Anybody try the localization with other than a sealed box or ported, like a horn or dipole sub?
Personally I've never experienced sub localization that wasn't artifact related, nor do I recall anybody guessing Dr Hsu's typical trick demo where he lets the listeners think its the big sub out front running when its some smaller unit tucked away in a corner.
Anybody try the localization with other than a sealed box or ported, like a horn or dipole sub?
Personally I've never experienced sub localization that wasn't artifact related, nor do I recall anybody guessing Dr Hsu's typical trick demo where he lets the listeners think its the big sub out front running when its some smaller unit tucked away in a corner.
How could you test that? Bass instruments have harmonics that go up high enough to smudge the test. Maybe leave the harmonics in one place (high pass) and move the fundamentals around? (low pass)
That would be the point for music playaback, does it matter if the location of the fundamentals doesn't match the harmonics.
Pano et al,
Here's a little test. Put in earplugs (good ones) then do the LF localization tests.
I'd mention my results and theory, but I don't want to influence your results.
rev.
p.s. after the first session then also pinch/close your nose.
Here's a little test. Put in earplugs (good ones) then do the LF localization tests.
I'd mention my results and theory, but I don't want to influence your results.
rev.
p.s. after the first session then also pinch/close your nose.
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Thats sort of question, when listening to a bass solo, where fairly strong upper harmonics exist, does the location of the sub effect the perceived location of the instrument?
The overall point would be does a subwoofer located other than aligned with the main speakers have audible effects that outweigh optimal location benefits.
What also makes me wonder a bit is that I used to use a dipole sub with a pair of ESL speakers, and it was real tweaky about getting all three of the panels on the same arc of a circle. I would do the setup with a string held in the listening chair and each front corner of the speakers and sub aligned to the same spot on the other end of the string. Crossover was around 100 hz, and mid bass was totally seamless. But I never tried it otherwise, so see what various positions might do.
And it's not just the split position of the fundamentals and harmonics that worries me - the harmonics do have a strong localizing effect - but the overall ambiance is also a concern. The big speaker rigs I've listened to can do an uncanny job of reproducing a feel of the recording venue be it concert hall, sound stage, jazz club, rock concert, etc. That's very important to me.
I worry that might go away with the bass placed somewhere else. The worry is founded in the fact that I've never heard split systems do it well. I don't know if the location split was the cause, or something else.
I worry that might go away with the bass placed somewhere else. The worry is founded in the fact that I've never heard split systems do it well. I don't know if the location split was the cause, or something else.
I agree, correct bass seems to be the critical element for a sense of space.
OTOH a bass guitar may exist as sound for the first time during playback. It has no space, its a mono electrical signal that is mixed in some ratio between left and right channels to give the illusion of location.
Worse I am wondering about listening comparisons of similar multi mono signals vs distant microphone stereo recordings and how placement of the subwoofer effects the perception of location and space.
OTOH a bass guitar may exist as sound for the first time during playback. It has no space, its a mono electrical signal that is mixed in some ratio between left and right channels to give the illusion of location.
Worse I am wondering about listening comparisons of similar multi mono signals vs distant microphone stereo recordings and how placement of the subwoofer effects the perception of location and space.
My old Velodyne ULD-15 servo sub (< 1% distortion) is almost impossible to localize with the stock 85hz crossover point when properly matched. A foundation is just 'there'. It does sound much 'drier' than many, many other subs I've heard.
The first time I played a particular track with a very low and transient synth effect on 'Windham Hill Chill' after getting the ULD-15, I was literally startled out of my desk chair by what I thought was the pressure wave from a car accident that had taken place on the street outside my open window. It was the sub, behind me and on the other side of the room from the window.
Directional bass
The last conversation I had with Neville Theil (several - many? - years ago) was about his work disproving the "mono bass" myth. We hear directional bass fine. Go to any big auditorium, concert hall, or outdoor rock gig and you will hear it. Have you not all felt your clothes "flap" at a concert because of directional bass!
Ambisonics tries to recreate this directional plane wave by having one set of speakers push whi the others pull or 'suck' the sound pressure across the room.
The problem is reproducing bass in a small room. Below a certain fraction of a wavelength the room becomes pressure loaded - ie mono. This is a room acoustics problem, not a psychoacoustic or hearing problem! We hear directionally at all frequencies -yes, some more than others, but still directionally across the whole spectrum...
The last conversation I had with Neville Theil (several - many? - years ago) was about his work disproving the "mono bass" myth. We hear directional bass fine. Go to any big auditorium, concert hall, or outdoor rock gig and you will hear it. Have you not all felt your clothes "flap" at a concert because of directional bass!
Ambisonics tries to recreate this directional plane wave by having one set of speakers push whi the others pull or 'suck' the sound pressure across the room.
The problem is reproducing bass in a small room. Below a certain fraction of a wavelength the room becomes pressure loaded - ie mono. This is a room acoustics problem, not a psychoacoustic or hearing problem! We hear directionally at all frequencies -yes, some more than others, but still directionally across the whole spectrum...
An interesting thread, but I am unconvinced that bass strictly below 100 hz can be localized, or that multiple subs is the #1 solution.
Ok, what tests have you performed to lead to this?
All of the tests I've made, and when listening to live music and even (undistorted) LF test tones in large spaces, tell me that bass is directional. Of course, bass is encoded as mono on vinyl records, so there's no difference there.
Additionally, multiple sub woofers excite the room modes in a less disturbing way, providing better bass in more listening positions.
It's really a room acoustics issue, not a hearing issue. Oh, and of course it's a marketing issue for manufacturers, but they would not lie to us would they? The ITU standard, as bad as it is, still specifies 5 full-range speakers and a sub for low frequency effects. The sub is not for the bass, it's for the dinosaur footsteps etc. The bass is supposed to go through the 5 channels and that's how it is properly recorded and mastered. It is manufacturers and replay bass management which has sold the idea that you only need one sub, to make it acceptable for the average living room. Does it work? Hell yes, but it is a compromise on the same order as MP3 is a compromise. Convenience usually trumps quality, it's the world we live in. But this does not stop us hearing bass directionally if the circumstances will allow it.
From the Orphanage
Even though my statement has been excised from the context to which it belongs; the fact remains, that higher frequency components must be present in the signal you are auditing for subwoofer origin to be determined. As you already know where the woofer is placed, your assertion comes from a biased observer as well. To further confuse the issue, signal wave lengths below 100 Hz. are many times larger than the room in which the subwoofer(s) are operated while the audit is being performed.
Regards,
WHG
Even though my statement has been excised from the context to which it belongs; the fact remains, that higher frequency components must be present in the signal you are auditing for subwoofer origin to be determined. As you already know where the woofer is placed, your assertion comes from a biased observer as well. To further confuse the issue, signal wave lengths below 100 Hz. are many times larger than the room in which the subwoofer(s) are operated while the audit is being performed.
Regards,
WHG
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