Dear all, finally here at LEMS, we're now starting to move walls and treat acoustically the room for a good sounding multichannel studio with Ambisonics capabilities..
After all the thoughts raised, we decided to go for building a semi-anechoic space with wodden floor on elastic material, with removable thick carpets. Few other concerns are now on the list between me and my colleague, regarding the position of the speakers and their characteristics. All the ambisonic tests I've done over the last few years where never comparative tests between different configurations of speakers. So any experience that any of you may report would be important, cause we build a studio not so many times in life ;-)) As I wrote few months ago, the reason we imagined a 4+4+4+1 system (vertexes of an exahedron plus center of 5 faces) was mainly because such an array would give the possibility of enlarging the radius as much as possible, rotating the cube and placing the elev.0° speakers in the angles, having actually the room almost inscribed onto the ideal sphere (see the 4+4+4+1 jpeg here). Widening the radius, the available listening area would be enlarged and that's essential for a small room, where we would like to do not only production but also listening sessions with few peoples.. Another small advantage is that in this position all the speakers would have a corner behind (2 walls) and so the sound pressure radieted at the low-end would be almost identical.. But, even if our studio will immediately concentrate on first order field recordings, we're trying to build a facility that is ready for HOA uses, of course.. Being aware that the ideal isotropic array would have a 12-speaker (vertexes of an icosahedron) or 20-speaker (vertexes of a dodec) setup, in this perfectly equallly spaced arrays although, there's not an elevation 0 ring.... So some considerations: 1) since the azimuthal information is, as we know, much more important; 2) a ring of more than 4 speakers in the elev 0° plane could also be used for other 4-8 channels stardard formats; 3) since from the same ring it would be desiderable to have a 2.0 or 5.0 already placed or easily derived by slightly moving the speakers; 4) since a higher order is prefearable; we're considering to switch to a 4+6+4+1 (as Fons was suggesting) - but in this case the speakers are really un-equally spaced among each other's ring - or eventually a 4+8+4+1 setup - more equal distances and ready for a standard planar 8-ch, but in this last case the radius would actually be the room radius resulting in a smaller listening space.. The 3+6+3 (icosahedron suggested by Jörn and Joseph) with the staggered 6 adjusted to a ring would be a great solution also for having a 2.0 ready, but in that case the 3 floor speakers would be quite near the mix board loosing floor space, and we would need to inscribe the system into the room resulting in a very small listening area, + the total 12 speakers would confine the system to 2nd order also.. As always, a trade off is needed (also considering costs...), but few questions that may help us to decide: 1) based on your listening experience, would you prefer to enlarge the radius and have a wider listening area or to have a smaller area more isotropic and with more speakers for a full 3rd order? 2) since we can slightly augment the number of speakers: - which could be a good trade off, also considering that 16 loudspeakers would numerically open a full 3rd order capability? - Is the 4+4+4+1 really uncapable of reproducing efficiently 3rd order? - Is the 4+6+4+1 (16 speakers minus the bottom one) almost able to do a 3rd order? - Would it be practical and efficient to decode on these arrays through mixed orders 3rd on azimuth and 2nd on elevation? 3) do you think that the compensations to be done in the decoder (uneven dimensions of our room 5.05L 4.35W 2.95H) would affect much the 3D reconstruction.. In the 4+4+4+1 the compensation would actually be much less for the height since we're not using the bottom speaker and we'll compensate the zenit speaker, resulting in a truncated sphere which is larger than the room.. 4) does anybody have a comparative experience with coaxial speakers vs 2way ones in small ambisonics arrays?. Of course a set of meyer HM-1 would be everybody's dream but they're not even anymore in stock.. We're also trying to avoid Genelec and to go toward a more transparent speaker, more importantly a 20-20k phase-coherent one, but there's not so many choises out there... Active or passive is also another choise to be taken.. Anything to recommend? 5) We would of course prefer to have full range speakers and to add a sub just for the area 20-40 hz.. In case we go for more and smaller speakers, what would you recommend to be the higher low-end frequency for a good ambisonics? Aware that this is a long mail :-(, any comment or suggestion from the community would be appreciated at this stage.. Thank you in advance for your time ! All the best, David Monacchi Eugenio Giordani LEMS - Laboratorio Elettronico per la Musica Sperimentale State Conservatory of Music of Pesaro Piazza Olivieri 5, 61122 Pesaro - Italy Possible other configurations: David Monacchi Performer, Eco-Acoustic Composer Professor of Electroacoustic Music, State Conservatory of Pesaro (Italy) Adjunct Professor, Faculty of Communication Sciences, University of Macerata (Italy) www.davidmonacchi.it [email protected] Mobile: +39 328 7562307 Studio: +39 0722 328407 -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110625/0fe86258/attachment.html> -------------- next part -------------- A non-text attachment was scrubbed... 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