I think frequency response is pretty important - most important? maybe. Most of the articles in the bibliography are addressing frequency response. It can get severely distorted at low frequencies in real rooms.
And there is bass and there is bass. As for 'boring mono bass' of pop music - that is the result of production practice that places the bass guitar and kick drum dead center, and this includes the higher frequency overtones of those sounds that can dominate those mixes up to about 200 to 400Hz - 2 to 4 octaves above the sub woofer crossover. The 'bass' a sub woofer produces is (or should be) only the energy below 80Hz or so. So in a system with good bass management, a wonderful big bass tone (organ, designed sound, whatever...) will still have overtones, that fuse cognitively with the fundamental, produced in stereo or multichannel sound. I think our localization of energy below 80Hz is ambiguous at best and is complicated even more by the reality of room modes (that provide their own spatial effect). But the bass range from about 100Hz to 600Hz is important to provide a good sense of stereo width and envelopment. (There's an old technique of using a 'shuffler' or 'spatial equalization' to enhance stereo width in this range ( http://www.audiosignal.co.uk/Resources/Stereo_shuffling_A4.pdf)). Certainly, having a system with no separate sub woofer and all speaker locations at full range (and full power for bass transients) is most ideal (assuming you also have good control of the room acoustics). If that's not possible (and it often isn't), optimize the crossovers so your 'mains' do most of the work and your sub (or subs) stays out of the way as much as possible - just providing support for the lowest frequencies. jim 2011/6/7 Marc Lavallée <[email protected]> > > > The Harman article basically says that bass in pop music is usually mono > and therefore we should care mostly about the frequency response. Using > multiple subs does helps to smooth the frequency response, but is it > what's most important? There are recordings with stereo bass, so I'd > prefer to hear some directional bass than the usual boring mono bass of > pop music. When I listen to music and sound art, I don't care much if > some bass tones are missing. It's easy to switch from stereo bass to > mono if required. I prefer to leave all options open, even if a small > room is a limiting factor. The type of sub-woofer is also an important > factor (omni vs dipole vs cardioid). Ambisonics can supposedly reproduce > bass from all directions; is it true? I won't know until I try. > > I found a bibliography with a good section on bass reproduction : > http://www.aktives-hoeren.de/downloads/LiteraturlisteKleineRaeume.pdf > > I hope that my amateurish comments are not too noisy for this list; > as a listener (or music consumer), I have much to learn (and try). > > Le Mon, 6 Jun 2011 09:31:43 -0400, > jim moses <[email protected]> a écrit : > > > The idea that one can manipulate standing waves with multiple subs is > > pretty well studied. It's separate from the idea of localizing low > > frequencies but does imply the usefulness of have multiple subs to > > improve frequency response and avoid bass peaks and nulls at > > locations throughout a space. Harmon ( the JBL division), who would > > like to sell a lot of subwoofers, has studied this - here's a > > reference article (AES 2006): > > > http://www.wghwoodworking.com/audio/low-frequency_optimization_using_multiple_subwoofers.pdf > > a quick google search will yield a good handful of derivative > > articles like this one: > > > http://www.bgradia.com/PDFs/Better%20bass%20through%20multiple%20subwoofers.pdf > > > > best, > > jim > > > > 2011/6/5 Marc Lavallée <[email protected]> > > > > > Le Fri, 03 Jun 2011 10:47:23 +0100, > > > dw <[email protected]> a écrit : > > > > > > > > I did a basic experiment with twos subs and a sound generation > > > > > software (PureData with the equal_power_pan extension). I > > > > > panned a bass sine tone from left to right and back, changing > > > > > the frequency between 40Hz and 160Hz. I was able to localize > > > > > the sine tone at certain frequencies, depending on my position > > > > > in the room; at 70Hz the tone was very easy to localize. So > > > > > it's definitely possible to create a sound field with > > > > > directional bass, intentionally or not. > > > > > > > > I suspect you are just modulating the standing wave pattern.. > > > > > > Yes, I was probably just doing that. > > > Room modes, standing waves, etc. But... > > > > > > The consumer audio industry stated with authority that bass should > > > just fill the room, and that that's what sounds good. I was not > > > supposed to buy a second sub, I was supposed to stick one in some > > > corner and be happy forever. > > > > > > One paper caught my attention: "Spatial auditory display using > > > multiple sub-woofers in two different reverberant reproduction > > > environments" (easy to google). It studies our ability to localize a > > > pair of left/right subs and front/back subs, in an anechoic room > > > and a small domestic room, for frequencies ranging from 40 to > > > 100Hz. In both rooms, our ability to localize front or back bass > > > tones is very bad (about 40% accuracy). In a anechoic room we can > > > localize the left/right bass tone without error. In a domestic room > > > the results are not as good, but we are still able to localize L/R > > > bass tones down to 80Hz with 80% accuracy. I suppose that the same > > > test in a small room with bass traps would give better results. > > > > > > I once asked Fons A. what kind of speakers I should get for > > > Ambisonics and he replied that full range speakers are mandatory. > > > With my small room and small budget it was a challenge. It took me > > > a while to figure how to build lots of bass reflex enclosures for > > > small full-range drivers, and I was ready to build them. Then I > > > learned that a dedicated decoder can be used with three subs. > > > Someone mentioned the KEF "Eggs" as good domestic speakers, and I > > > was lucky to find three sets of discontinued KEF home theatre > > > speakers at a very good price (with the smallest "Eggs" and the > > > "Kube-1" sub). The Eggs are excellent. The Kube doesn't have much > > > bass extension, but it works. So now I am playing with my new toys, > > > but I'm not ready to install an ambisonics setup (I need to find a > > > sound card with 16 outputs). > > > > > > In the meanwhile I am adapting my XTC setup in order to use two > > > satellites and two subs. I must admit that your filter is my > > > favourite right now, although I should compare it with the others > > > (RACE, BACCH) later this summer. > > > > > > > Here is the 'uncut' version, if you would like to compare. I > > > > think it is less suitable for general use, so don't want it to be > > > > the offical distributed version. You seem to be the only one > > > > interested. The file will be removed in a day. > > > > > > There's a bit more bass coming out of your "uncut" filter, but > > > there's some cancellation when the bass signal is mono (equal in > > > both channels). I still prefer when the stereo signal is sent > > > directly to a pair of subs at +-30 degrees. > > > > > > -- > > > Marc > > > > > > _______________________________________________ > > > Sursound mailing list > > > [email protected] > > > https://mail.music.vt.edu/mailman/listinfo/sursound > > > > > > > > > > > _______________________________________________ > Sursound mailing list > [email protected] > https://mail.music.vt.edu/mailman/listinfo/sursound > -- Jim Moses Technical Director/Lecturer Brown University Music Department and M.E.M.E. (Multimedia and Electronic Music Experiments) http://jimmoses.wordpress.com/ -- Jim Moses Technical Director/Lecturer Brown University Music Department and M.E.M.E. 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