Jim, what you are telling me (indirectly) is that the smallest KEF "Eggs" I got are inadequate. Their crossover frequency is 120Hz. The others models can go down to 80Hz and 70Hz (they are also more expensive and not on sale). So my initial project of building lots of small bass reflex enclosures is still valid, because I can make them go down to 70Hz for a decent price (and some work). Oh well... -- Marc
> 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 > > > > > _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
