No, not at all, Marc. I didn't pickup the specifics on the 'eggs' - sorry about that. But i wasn't implying a hard cutoff at 80Hz. 120hz is ok. It's the higher end for the crossover but is acceptable and the same ideas apply.
> > > > > 2011/6/7 Marc Lavallée <[email protected]> > >> >> 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 >> > > > > -- > 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. (Multimedia and Electronic Music Experiments) -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110607/15a9ed96/attachment.html> _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
