Hi Jörn (found it:) This all makes sense.
I forgot that a sphere would refocus sound back to the centre position. It would probably make the sound more mono! I was concentrating on the least amount of reflections to the listener, from a stereo point of view, with the listener and speakers non central. Of course if the speakers are tangential on a sphere, the sphere will reflect energy back through the centre position. This is probably why it is used to an advantage in some speaker designs, as the driver is never centre, and it is obviously open at the driver end. I will ask you first when shares become available :) A few diffusers at the back will keep the vibe sweet I think, it will also help when I start recording drums.... Looking back at your speaker positioning, it seems that this set up would be the best (fourth order) set up for what I have. I wasn't planning on having a separate decode for the full range horizontal ring, unless thats a good idea? The less decoding the better I think. It may take a lot of eq to get both sets to sit together, but the full range set is definitely of better quality. Do you think it would still be fine to decode 3rd order to this rig? I think I have been reading to many old papers that obviously push home the platonic solids being the best for decodes. I wish I had explored the idea of 'rings' earlier, I had just presumed that they weren't optimal, even though I had read and seen everyone here talk about them. It just goes to show that It is quite easy to go down a less than optimal path with ambisonics, even though I have been researching or mixing in the format for 3 years! The studio is based in East London, you are welcome, as is everyone on the list. I will post when finished and peeps can arrange off list for a listening session. Kind regards Steve On 12 Mar 2014, at 16:00, sursound-requ...@music.vt.edu wrote: > Message: 4 > Date: Wed, 12 Mar 2014 13:19:20 +0100 > From: J?rn Nettingsmeier <netti...@stackingdwarves.net> > To: sursound@music.vt.edu > Subject: Re: [Sursound] Construction of purpose built ambisonic studio > (J?rn Nettingsmeier) > Message-ID: <532050c8.20...@stackingdwarves.net> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 03/10/2014 11:50 PM, Steve Boardman wrote: >> Hi J?rn (not sure what the character '?' is as it always displays >> that way) > > an o with double dot. > >>> 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. >> >> This is interesting, as I have had various opinions on this. Some >> people say that spheres are the best as they have no parallel sides, >> so reflections are reduced. > > the center of a sphere is absolutely unusuable. all kinds of weird stuff > from in-head localisation to total collapse of localisation, changing > rapidly and erratically with just a few inches of head movement. > > the curvature of the walls does not mean that reflections are reduced, > only that they are focused towards the center. > there can even be a flutter echo. > >> They also only have one room mode, that >> can be predicted and treated. Or not excited (depending on the size). > > i'd love to hear a spherical room that is not totally abysmal, and be > proven wrong. but i won't buy shares of your studio when you go for a > sphere :) > >> I do know of speaker box technology that uses this thought to it's >> advantage, but I have never considered it for studio construction, >> due to complexity and space. It would also have to be very large for >> the lowest fundament not to excite it! > > think whisper gallery. do you want that in your control room? > >> I must say, I like dead rooms, although I do agree that they are not >> the best places to work. In fact quite disorientating. Listening to >> ones own body internally is very off putting. As a consequence I >> generally make the front complete dead with absorb-tion materials and >> then have the back handle for reflections via random breakup >> reflectors. Is this still a good idea? > > i guess so. my (modest) experience tells me that overly dead rooms often > call for "freshening up" by thin layers of HF-diffusing surface on top > of the bass absorbers... > >> A little room correction will of course be needed, especially for >> bass. >> >>> 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. >> >> 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) :) > > well, i started from the number of speakers you said you had available. > >> 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? > > you mean you want to create entirely separate horizontal and full-sphere > systems? > >> Is it better >> to use platonic solids, or doesn't it matter? > > with the recent advances in optimizing for irregular layouts by zotter > et al and heller et al, there is no longer a compelling reason to go for > platonic solids, except that they are kind of pretty :) > layouts based on a horizontal ring have the big advantage of better > horizontal-only performance, without much degradation in the 3d case. > >> 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. > > can't wait to. where is your studio located? > > > > -- > J?rn Nettingsmeier > Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 > > Meister f?r Veranstaltungstechnik (B?hne/Studio) > Tonmeister VDT > > http://stackingdwarves.net > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140319/3c24a4c7/attachment.html> _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
