> Hi everyone, > > I've been lurking for only a day, but Sampo's note gives me the courage to > go ahead and ask the first question I was hoping this group might help me > answer. > See you've already had some good replies. But, I'll throw in my experiences ... some of which have been at the really cheap end of things ;-(>
> I am interested in experimenting with periphonic sound synthesis using > Ambisonics and (likely) Matlab, for research purposes. I've got a grasp on > the software side of things to do this, and already can pipe multichannel > sounds generated in Matlab to a standard 5.1 receiver. > Beware Condon-Shortley Phase and Matlab. Ambisonics doesn't use it, quantum physics does. (You get some of the rotations oing backwards ...) > Now I would like to construct a higher-order sound system, ideally with > consumer-level (and consumer-priced) components. I don't need a big > dynamic range, high power, or the best sound fidelity possible, I just > need a working prototype. This is the part I have found very little > information on in my research� > > My understanding is that 8 channels is the minimum needed for stable 3-D > Ambisonics (rather than planar surround). There was a recent reminder, on this list, within the last month, that one could use 6 channels (the mid points of the faces of a cube). I've never heard anyone say they've done it, let alone say it was 'nice'. (The engineering would, also, not be fun ... though you are not obliged to place speakers mid-wall/ceiling/floor ... you can tilt the cube!) So I'd stick to eight unless you are really adventurous. > From my Mac, I can easily output > up to 8 channels of lossless PCM audio over HDMI or optical Toslink. So it > seems like it should be possible, in principle, to assemble a budget > system -- the question is what kind of affordable receiver/amp would be > appropriate? > > The home cinema/gaming market offers several 7.1 systems these days, but I > imagine the subwoofer channel would likely be band-limited with different > amplifier circuitry than the other channels. In my early days I used a USB 5.1 card. Subjectively I concluded all six channels were identical ... but never measured them. > There are also some 9.2 > receivers available. I'm not clear how to input more than 8 channels to > these receivers, given that they all take HDMI/Toslink inputs, Dolby > TrueHD etc are all 7.1, as far as I know, and they don't normally have > discrete analog inputs. So I'm not sure if an 8-channel digital input > would imply one channel is destined for a subwoofer as expected for a 7.1 > system. And, otherwise, if these systems do funky in-receiver processing > to generate 9.2 sound from 8 input channels, then that certainly seems > incompatible with Ambisonics� > > Are any of these receivers an option? Any other suggestions? Of course, I > don't care about the video switching capabilities, etc., the multiplexed > digital input just needs to be decoded and sent to 8+ speakers somehow. > > Otherwise, if there's a Firewire or USB solution, I'd be happy to hear > more about those as well. I use a MOTU Traveller. An expensive firewire solution. (The reason is that it is good for TetraMic recordings ...). That gives 8 analogue outs, with another 8 by ADAT (you need a cheap (dare I say Behringer?) AdAT->-analogue box). If I was staring again, just for playback, I'd probably grit my teeth and buy a 24 channel ?Hammerfall card to use on Linux ... but that just proves the point that so many of the answers depend on what Operating System you put in the question ;-)> _______________ My first set-up was ... just to show how naff one can be ... four pairs of computer monitors. The results were pleasant (pleasant enough, that i was disappointed when I heard some of the same pieces on a professional/research system;-)> But that did iliustrate the 'infrastructure' expense ... I decided to install a mains socket in each corner of the ceiling: I did that myself, but the materials cost more than the speakers. Recently, with a student, we created a whole variety of rigs. The bottom end one was a 'kiosk': A free-standing set of tubes, that gives a 1.1 metre cube (on legs) that you can 'walk into'. The idea is not original, was on this list some long time back (apologies to inventor, I've forgotten who!). Again, using computer speaker pairs. We tried DRC techniques on that to 'improve' performance, but the corrections were worse than au naturel. Still it gives a interesting experience. Certainly for non-music (non classical music) such as jet planes buzzing about, firework displays --where the listener expectation is not of delicate harpsichord playing-- it is very good. ____________________ If you want to play --sorry, do preliminary studies-- then computer speakers are 'fun'. After that, I think you hav two big questions to answer: - What OS am I wiling to use. (I think there is only one answer to that, but I won't start an OS-war on this thread;-)> - Do I want to build _a_ system (e.g. a cube), or is that just stage one? If the latter, you have to think about extensibility, as well as immediate needs (and that ups the short-term costs). Michael (PS Written quickly, if you want detail / references / etc. just ask off-list.) _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
