Re: [Sursound] Construction of purpose built ambisonic studio. (Aaron Heller)
Hi Aaron Thanks for your response. What I meant by 'angle errors', was that if the speakers are placed in a different part of the room that was structurally different, the sound waves would not be the same as the any of the others (due to reflection/absorbs-ion phase errors altering frequency/transient response). This can be improved through dsp, but it is never as good as getting it right at source. Maybe 'angle errors' was not the correct term. Stanford's CCRMA room does look (and undoubtably sound) good, but the space below is maybe a bit over board for what I want to achieve, in the space I have. The actual area of the build space is probably around 180 square foot within a bigger space of 700 square foot on two floors. It does have high ceiling though, with an apex over 4 metres (6.8 metres from ground floor to apex). This does dictate to a certain extent the shape of the room, as the room will be built on a mezzanine above the ground floor. This means the 'front' already slopes down to1.80 metres, rising to the back 4.5 vertical wall (that meets the apex). A box could still be constructed though, ignoring the slopes, but as I mentioned earlier this would actually be beneficial in front dominant mixing. I will probably go for a raised listening position to achieve more down positions, although to get a fully central head position standing may be required. I will be very interested in your forth coming paper on partial coverage speaker arrays, as to date I have only used the platonic solids, or only horizontal decodes. Cheers Steve Message: 10 Date: Sat, 8 Mar 2014 20:26:17 -0800 From: Aaron Heller hel...@ai.sri.com To: Surround Sound discussion group sursound@music.vt.edu Subject: Re: [Sursound] Construction of purpose built ambisonic studio. Message-ID: CA+MMR5BuP=iCrgw+YOKhoKkSk=y3rspyu0fjsaj+ezk9+ww...@mail.gmail.com Content-Type: text/plain; charset=utf-8 Steve, I'm not sure I follow everything you're saying about angle errors, but there are a few installations that work well here in the SF Bay area that I have personal experience with. The Listening Room at Stanford's CCRMA is a 3rd-order periphonic facility, described here https://ccrma.stanford.edu/room-guides/listening-room/ The others are in private homes, so I'll let the owners to chime in if they please. They're good sounding rooms, but without special acoustic treatment. (unlike my living room, which is glass on three sides). There are several accounts of Ambisonic reproduction not working well in very dead rooms, such as an anechoic chamber. Also, for 3rd order periphonic you need to place a number of speakers below the listener, which can be a challenge. The acoustically transparent floor in CCRMA's Listening Room is one solution.Eric Benjamin and I have a paper in the upcoming Linux Audio Conference on designing HOA decoders for partial coverage speaker arrays, such as domes and rings. Aaron (hel...@ai.sri.com) Menlo Park, CA US -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140308/a123ed5c/attachment.html -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140310/d8afee27/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Construction of purpose built ambisonic studio (J?rn Nettingsmeier)
to the best of their abilities, and puts the missing bass frequencies in the correct direction. $DEITY help you if anything is not perfectly phase-aligned, though. disclaimer: i've toyed with such hacked-up multiband setups, but none of them ever went to production (or had to), so there may be pitfalls i've overlooked. First order decode for the four subs in the corners was what I was thinking. Didn't think about going to fourth order on everything else though, as I didn't think the increase in channel count was worth the little improvement. I also want to leave some processing power for mixing plugs (I use a lot) :) Agreed on the full range horizontal ring. I was more thinking of a dodecahedron for the satellites, either only 20 on the vertices, or get 5 more, and would it be possible to use the edges? Is it better to use platonic solids, or doesn't it matter? The Satellites actually go down to 80hz really, i've just been using them at 120 in the current set up, generally due to the response of the room, so I could actually cross them all here. This is of course where I may get some dodgy response. I will also delay compensate to the sweet spot Thanks again, and needless to say I will be asking a few more questions as I progress. The build won't start for another month, and when it's finished I would love for all you ambisonic heads to have a listen. Cheers Steve -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140310/8173e2f6/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] [ot] 4 D sound (!)
On 2014-03-09, Fons Adriaensen wrote: There are four basic forms of the theory used in signal processing, which are all connected but also subtly different. The Fourier transform is continuous time and continuous frequency. The Fourier series is periodic time and discrete frequency. The discrete time Fourier transform is discrete time and periodic frequency. And finally the discrete Fourier transform is both discrete and periodic in both frequency and in time. There are just two, the FT and the DFT. The only difference between the last three forms you mention is only a matter of interpretation. You can easily interpret even the FT into the whole. All it takes is topological completion, and then working with suitable equispaced delta distributions. Discrete time Fourier transform drops off very naturally from there and vice versa, you can recover a dense basis essentially equivalent to the full FT one simply by passing the period of the DTFT to the null limit. No wiggle-room, nothing. But of course that wasn't what I was talking about. In a certain sense they're all the same, which is why I said already that they're intricately connected. In the sense I was talking about, which is the more trivial kind, they're nothing of the sort. They really can be separated by the kind of systematic I laid out in talking about periodicity and discreteness, and that's pretty much what governs their actual usage in the mathematical and engineering disciplines. I also think that way to looking at the Fourier methods is rather useful as such, *because* of the practicality of the viewpoint. -- Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front +358-40-3255353, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2 ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Construction of purpose built ambisonic studio. (Aaron Heller)
On Mon, Mar 10, 2014 at 09:50:43PM +, Steve Boardman wrote: Stanford's CCRMA room does look (and undoubtably sound) good, but the space below is maybe a bit over board for what I want to achieve, in the space I have. The actual area of the build space is probably around 180 square foot within a bigger space of 700 square foot on two floors. As an example of what can be done without digging holes in the ground have a look a this: http://www.rossinispace.org/. This is at the conservatory of Pesaro, Italy, and the best sounding and most accurate higher order Ambisonics studio I know of. Size should be comparable to your 180 sq.ft. Shape is approximately a square, but with no parallel walls. The space has a very low RT60 down to LF (bass traps are planned but not yet operational), the idea being that in AMB mixes most of the space should be provided by the signal and not by the room (which makes sense, creating virtual spaces is one reason to use full surround). The control desk, shown against the wall in the panaromic picture, can be moved to the center. The speaker system consist of * a ring of six at elevation -33 degrees (ideally this should be -45 degrees, but this requires an elevated listening position), * a ring of eight at ear height, * a ring of six at +45 degrees * a speaker at the zenith. * one subwoofer for a total of 21+1 speakers. This is an excellent setup for third order, in the sense that the decoder matrix is very well-conditioned (it doesn't rely on signals that would cancel acoustically). If you have four subs there's no reason for not using them (put them in the corners, with a dedicated decoder). One thing that could be improved is that the current ring of eight is oriented such that there is no front speaker. The alternative, rotating it 22.5 degrees, would provide a layout that is more compatible with formats such as 5.1 or 7.1. One point not yet mentioned in the replies so far is that for lower order (and in particular first) you should use less speakers. Also for this the rotated ring of eight would be better - the subset used for first order at the moment does not have L-R symmetry. Ciao, -- FA A world of exhaustive, reliable metadata would be an utopia. It's also a pipe-dream, founded on self-delusion, nerd hubris and hysterically inflated market opportunities. (Cory Doctorow) ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
