Hi Martin, HOA are not limited to icosahedra or only uniform arrangements (which exist also beyond the 5 platonic solids). It would be very hard to claim them flexible or universal if that was the case. Uniform arrangements though simplify decoder design significantly.
As I mentioned you would need some more recent decoder methods for a hemisphere, however these methods are available and not so sensitive to speaker placement (no need for quests for magical geometries). My two cents, start with a regular horizontal ring, covering the case of horizontal decoding too, and spread the rest of the speakers evenly at the hemisphere, covering roughly equal area partitions. You can also fix one straight above and work with the rest. I believe the system should be capable of decoding 3rd order signals to half-space for such an arrangement, but that needs some checking. I mentioned two publicly available resources for decoding to such a setup. I forgot to mention however that there exist also professional tools for that. I think Blue Ripple Sound’s decoder can handle hemispheres and irregular setups (haven’t tried it myself) and also the latest Spat from IRCAM has implemented the more advanced HOA decoders I mentioned. Best, Archontis > On 10 Feb 2016, at 00:16, Martin Dupras <martindup...@gmail.com> wrote: > > I have no objection to using fewer than 16 speakers; it's just the > maximum I have available to me. > > The reason I had not considered the icosahedron vertices setup is > because, according to the wikipedia page, it's capable of 2nd order, > not 3rd order. Is that not the case? > > Again from wikipedia: "Since stacked rings are somewhat wasteful at > higher elevations and necessarily have a hole at the zenith, they have > been largely surpassed by hemispherical layouts since mature methods > for decoder generation have become available. As they are difficult to > rig and require overhead points, hemispheres are usually found either > in permanent installations or experimental studios, where expensive > and visually intrusive trussing is not an issue." > > That's the whole reason why I was considering a hemispherical setup > originally. It talks about "mature methods for decoder generation" so > I (wrongly, perhaps) assumed that there were capable decoders, and > there would likely be already available "templates" or "typical > scenarios" to use as a starting point. > > Thanks, > > - martin > > > - martin > > On 9 February 2016 at 22:02, Augustine Leudar <augustineleu...@gmail.com> > wrote: >> I know Im treading on thin ice here around all these ferocious maths >> guys... but might it be that there is not a suitable array that uses 16 >> speakers? I know if you have 16 speakers you will want to use all of them >> but an Icosahedron is only 12 speakers (vertices) but it might be the best >> option. >> Also you could try ICST ambisonics plugins in max - they let you put the >> speaker array in and it adjusts accordingly. >> >> On 9 February 2016 at 21:51, Martin Dupras <martindup...@gmail.com> wrote: >> >>> Thanks for all the responses. Much appreciated. >>> >>> I'll re-phrase the question in light of some of the answers I've been >>> given. >>> >>> I will be using third-order Ambisonics. My aim mostly is to experiment >>> to get a good sense of what is possible with Ambisonics with height. I >>> have experimented successfully with 8-channel planar Ambisonics some >>> time ago. My primary intent is to spatialise multiple monophonic >>> (synthesised) sources using 3rd-order Ambisonics spatialisation, and >>> the playback of mixed sources (spatialised monphonic and stereophonic >>> sources as well as B-format 4-channel recordings.) >>> >>> At this moment in time, I have the opportunity to deploy (next week) a >>> 16-channel array, so I would like some advice on a configuration that >>> would be a good start to experiment with Ambisonics with height. >>> Someone suggested that I consult the wikipedia page on Ambisonics. >>> That is indeed where I got the idea that an "upper hemisphere" setup >>> might be suitable, since I only have on this occasion 16 speakers. >>> There is however no suggestion as to what a suitable hemispherical >>> configuration might be for a 16-speaker array, which is why I asked my >>> original question. >>> >>> So let me ask a new question. Given the constraint that I can only use >>> 16 speakers at the moment, and that I need to deploy this next week, >>> can somehow point me in the direction of what might be a suitable and >>> reasonable geometric configuration to try out? It seems to me that the >>> only really practical options here are two stacked rings (stacked >>> octagons) or a hemisphere. I would have thought that the hemisphere >>> would be the better choice, and in my scenario, a full lighting rig >>> allows me theoretically speaking to have speakers at the required >>> positions. >>> >>> Again, thank you for all the responses. >>> >>> - martin >>> >>> >>> On 8 February 2016 at 15:19, Martin Dupras <martindup...@gmail.com> wrote: >>>> Hi, >>>> >>>> I'm intending to try setting up a 16-speaker Ambisonics array next >>>> week in a small TV studio. I'm trying to figure out the practical >>>> arrangements for setting up the speakers. I was wondering if anyone >>>> with experience might be able to offer some advice or point me in the >>>> right direction? >>>> >>>> What I'm planning at the moment is a half-sphere arrangement which >>>> would likely consist of: >>>> >>>> - 8 speakers in a circle of radius 2m at a height of approximately 1.6m >>>> - 6 speakers in a smaller circle at an elevation of 45 degrees >>>> - 2 speakers at an elevation of approximately 75 degrees >>>> >>>> Alternatively, I would be happy with an arrangement similar to the >>>> first 16-speakers in this diagramme: >>>> >>> http://www.matthiaskronlachner.com/wp-content/uploads/2013/10/loudspeaker-plan-observatory.jpg >>>> >>>> I've been trying to find out if there is a convention or "most usual" >>>> arrangement but couldn't find anything. I'm not particularly attached >>>> to the actual arrangement, I just want to find an arrangement that >>>> will work well enough with 16 speakers. Any advice? >>>> >>>> The other thing I would welcome is advice on how to mount the speakers >>>> to lighting rigs in a manner that is practical enough to offer some >>>> good compromise between precision and ease of setup. I believe the >>>> speakers we'll be using for the upper tiers will be Genelec 8060s. >>>> >>>> Many thanks. Any advice will be greatly appreciated! >>>> >>>> Cheers, >>>> >>>> - martin >>> _______________________________________________ >>> Sursound mailing list >>> Sursound@music.vt.edu >>> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, >>> edit account or options, view archives and so on. >>> >> >> >> >> -- >> www.augustineleudar.com >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: >> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20160209/6d5ca824/attachment.html> >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit >> account or options, view archives and so on. > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit > account or options, view archives and so on. _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
