Re: [Sursound] Construction of purpose built ambisonic studio.
On 03/08/2014 02:13 AM, Steven Boardman wrote: I have constructed many studios in the past but never one where all the speaker positions have equal importance. Normally with stereo it is beneficial for the sides of the space not to be divisible into each other. still holds for ambisonics. try to get as many different room modes as possible. The cube being one of the worst examples of this. It is generally better to have the mix position at one end of the longest side of a room too, which helps diffuse reflections before they return to the mix position. my setup has its front speakers close to a wall, and the remaining short reflections are compensated with FIR filters to some degree. the sides are against a bookshelf and free-standing in the room, with very different acoustic loading and hence vastly different FIRs. the rears are wedged between sofas. that makes my front direction the most analytical, and the system nowhere near isotropic. but it sounds very good. i just know that when i want to dissect something in detail, i rotate it to be in front. unless you can afford a purpose-built room like the (mostly heptagonal!) listening room at CCRMA (which, despite its very modest speakers, is quite amazing - goes to show the importance of the room), some pragmatism is called for :) Also completely parallel faces aren't good either, (but they also need to symmetrical and predictable) as of course this creates more reflections. symmetry between left and right of the most frequent listener orientation is still a good thing. Wider and higher at the back is generally a good thing. The general idea is to through all errors behind where they have less importance and where they can lose there energy more. This also applies to 5.1, where front has dominance. The problem I have is that this doesn't seem to a good idea with ambisonics, as the mix position needs to be central and all angle errors need to be equal. central to the speaker system, yes. there is no benefit to being in the exact center of the _room_, though. i'd go for some front-back asymmetry. This actually leans towards the construction of a perfect cube for simplicity of build, as creating a perfect sphere would be difficult and space would be lost. a sphere would be absolutely disastrous, unless it is anechoic, and then the shape does not matter anyways. and as aaron pointed out, overly dead listening rooms lack proper masking of interference artefacts and will be very irritating to work in. the way i approach it is: * keep the early reflection paths clean for every speaker, like you would for stereo. no reflections 10 ms is a good thing, if possible. * keep the diffuse field under control. off-axis mud adds up as you add more speakers, so proper bass absorption and diffuse reflection in the treble and upper midrange are important. * use mild digital room correction in addition to acoustic treatment, it can do wonders for bass problems, where mechanical measures are difficult. * if you have to make compromises, keep the frontal direction as perfect as possible, and use it as a magnifying glass to work on details even if the respective sound later moves elsewhere. It will basically be a third order set up, but not sure on the exact amount of speakers yet. I have 4 subs, 25 satellites (120hz roll off) and 10 nearly full range speakers (60hz roll off). Any advice on room shape, and speaker positioning would be greatly appreciated. an off-the-cuff suggestion: * four subs in the corners. * the fullrange speakers on a horizontal ring, with one speaker in front, for a decent approximation of ITU 5.1 and 7.1, if necessary. * the satellites in a lower ring-of-eight, an upper ring-of-eight, another ring of six, one zenith speaker. then you have two spares, and they will come in handy some day. the bass management will be tricky. first of all, each speaker needs to be perfectly delay-compensated to the listening spot. then i'd try to create different layers of decoding: * separate first-order decode for the subs, low-passed at 60, 24dB/oct * fourth-order decode for everything else * horizontal speakers high-passed at 120/24 * satellites high-passed at 120/24 * a separate horizontal-only decode (of the same full-sphere input signal) for the range from 60 to 120 hz, again at 24dB/oct this lets you drive all speakers 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. have fun, jörn -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ Sursound mailing list
Re: [Sursound] [ot] 4 D sound (!)
actually one of the best sound installations I ever hear was made in mono with a crap speaker that cost about a £5 . It was just some strange moaning noises coming out of a pile of rubbish in the corner of a gallery. Everyone loved it and it was so much more interesting than some of the stuff Ive hearn on a million dollars worth of Genelecs On 9 March 2014 01:49, Fons Adriaensen f...@linuxaudio.org wrote: On Sun, Mar 09, 2014 at 12:35:34AM +0200, Sampo Syreeni 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. Usually a discrete spectrum is interpreted as the exact spectrum of a periodic waveform. But it's equally valid to say its the sampled spectrum of a finite time signal. A discrete representation in the time domain (i.e. samples) is usually interpreted as a finite-bandwidth signal (which is the dual of the second interpretation above), but it's equally valid to say it's the exact representation of a signal that is periodic in the frequency domain (the dual of the first interpretation above). 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 -- 07580951119 augustine.leudar.com -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140309/1830a39d/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
[Sursound] Connecticut could be 1st state to curb loud movies... that exceeded 85 decibels
http://news.msn.com/us/connecticut-could-be-1st-state-to-curb-loud-movies NEW HAVEN, Conn. (AP) - Connecticut could become the first state to curb loud movies under proposed legislation that's drawing opposition from the Motion Picture Association of America. The legislature's Public Safety and Security Committee is considering the bill, which would prevent theaters from showing a film or preview that exceeded 85 decibels. The National Institute for Occupational Safety and Health recommends noise should be kept below 85 decibels for workers for eight hours to minimize hearing loss. -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140309/fd18e8fb/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Connecticut could be 1st state to curb loud movies... that exceeded 85 decibels
On 10/03/2014 00:34, Andrew Castiglione wrote: http://news.msn.com/us/connecticut-could-be-1st-state-to-curb-loud-movies NEW HAVEN, Conn. (AP) - Connecticut could become the first state to curb loud movies under proposed legislation that's drawing opposition from the Motion Picture Association of America. Ok The legislature's Public Safety and Security Committee is considering the bill, which would prevent theaters from showing a film or preview that exceeded 85 decibels. Hmm, 'exceed' xx dB implies to me a max temporary peak value. But this would be idiotic -- ok it would mean human babies and most music is 'illegal'. Is this a joke? guess not. JL The National Institute for Occupational Safety and Health recommends noise should be kept below 85 decibels for workers for eight hours to minimize hearing loss. -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140309/fd18e8fb/attachment.html ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Connecticut could be 1st state to curb loud movies... that exceeded 85 decibels
http://news.msn.com/us/connecticut-could-be-1st-state-to-curb-loud-movies NEW HAVEN, Conn. (AP) - Connecticut could become the first state to curb loud movies under proposed legislation that's drawing opposition from the Motion Picture Association of America. The legislature's Public Safety and Security Committee is considering the bill, which would prevent theaters from showing a film or preview that exceeded 85 decibels. The National Institute for Occupational Safety and Health recommends noise should be kept below 85 decibels for workers for eight hours to minimize hearing loss. But there is a long history of (US) state legislatures 'doing things' --Indiana : pi=3.2 http://www.youtube.com/watch?v=bFNjA9LOPsg --South Dakata : astrology, thermology NOW, THEREFORE, BE IT RESOLVED, by the House of Representatives of the Eighty-fifth Legislature of the State of South Dakota, the Senate concurring therein, that the South Dakota Legislature urges that instruction in the public schools relating to global warming include the following: (1) That global warming is a scientific theory rather than a proven fact; (2) That there are a variety of climatological, meteorological, astrological, thermological, cosmological, and ecological dynamics that can effect world weather phenomena and that the significance and interrelativity of these factors is largely speculative; and [etc.] http://thinkprogress.org/politics/2010/02/25/83917/south-dakota-legislators-tell-schools-to-teach-astrological-explanation-for-global-warming/ So ... Connecticut may have an []affect ... or not ... it's all speculative ... Michael ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
