Re: [Sursound] Ambisonics rig - loudspeakers directivity
On 08.07.2014, at 00:36, Jörn Nettingsmeier wrote: On 07/08/2014 12:20 AM, Gregorio García Karman wrote: How about using loudspeakers with cardioid characteristic in the bass range? http://www.me-geithain.de/index.php/en/studio/products/active-loudspeaker/rl901k I've used that speaker a couple of times, and it's fantastic. I sure would like to build a third-order periphonic rig with those, but for the tiny little obstacle that is the (entirely justified) price tag Joachim Kiesler puts on those. It's a good addition/correction to what I said before about directivity vs. radiating area - you can of course also obtain directivity by wasting some energy to the rear to actively cancel unwanted sound, and that is a bit easier to do for very low frequencies. Taken to the extreme, you end up with dipole basses, as discussed by, among others, Siegfried Linkwitz. If you have some flexibility as to speaker positioning, they must be very nice indeed. Thanks for your reply. These are fine speakers indeed. I am actually mulling over the idea of setting up an TOA rig with eight of those in an acoustically treated room (55 m2). They could be, e.g., arranged in a ring hanging at ca. 2.5 m. height (ring diameter ca. 5 m). In this room we are currently working with a quadraphonic setup with four venerable RL900 at the ear level (ring diameter ca. 8 m). I was wondering whether it would make sense to combine the lower ring of four RL900 and the higher ring of eight RL901 with a view to with-height ambisonics. Cheers Gregorio ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
On 07/01/2014 07:05 PM, Marc Lavallée wrote: Hi Fons. Tue, 1 Jul 2014 16:45:31 +, Fons Adriaensen f...@linuxaudio.org wrote : * If your room acoustics are bad, using directional speakers will not necessarily help, they could even make things worse. Unless maybe when you're building a PA system in a sports hall. What sort of problem would cause a directional speaker in a room? since speakers are only directional for higher frequencies (basically as a function of the radiating waveguide/column length in terms of wavelengths), a directional speaker will cause a muddy or boomy diffuse field (because it is dominated by the uncontrolled low frequency). a speaker tailored for wide dispersion will have proportionally more HF in the diffuse field, which may be more pleasant in the end. the overall tone color of a massive multichannel speaker systems in any reverberant room can easily be dominated by the uncontrolled leakage to the sides. add to that the fact that it is very easy to control high frequencies by wall treatment, and prohibitively complicated/expensive to absorb low frequencies, and directional speakers are suddenly a lot less desirable than they look on paper :) -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
On Mon, Jul 07, 2014 at 09:24:14PM +0200, Jörn Nettingsmeier wrote: On 07/01/2014 07:05 PM, Marc Lavallée wrote: Hi Fons. Tue, 1 Jul 2014 16:45:31 +, Fons Adriaensen f...@linuxaudio.org wrote : * If your room acoustics are bad, using directional speakers will not necessarily help, they could even make things worse. Unless maybe when you're building a PA system in a sports hall. What sort of problem would cause a directional speaker in a room? since speakers are only directional for higher frequencies (basically as a function of the radiating waveguide/column length in terms of wavelengths), a directional speaker will cause a muddy or boomy diffuse field (because it is dominated by the uncontrolled low frequency). a speaker tailored for wide dispersion will have proportionally more HF in the diffuse field, which may be more pleasant in the end. the overall tone color of a massive multichannel speaker systems in any reverberant room can easily be dominated by the uncontrolled leakage to the sides. add to that the fact that it is very easy to control high frequencies by wall treatment, and prohibitively complicated/expensive to absorb low frequencies, and directional speakers are suddenly a lot less desirable than they look on paper :) Exactly. Now if you control the room acoustics by HF damping only you're back to the muddy diffuse field. If you include an amount of scattering (i.e. diffusers), this will break up flutter echos while preserving tonal balance. 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 - unsubscribe here, edit account or options, view archives and so on.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
On 08 Jul 2014, at 00:14, Fons Adriaensen f...@linuxaudio.org wrote: On Mon, Jul 07, 2014 at 09:24:14PM +0200, Jörn Nettingsmeier wrote: On 07/01/2014 07:05 PM, Marc Lavallée wrote: Hi Fons. Tue, 1 Jul 2014 16:45:31 +, Fons Adriaensen f...@linuxaudio.org wrote : * If your room acoustics are bad, using directional speakers will not necessarily help, they could even make things worse. Unless maybe when you're building a PA system in a sports hall. What sort of problem would cause a directional speaker in a room? since speakers are only directional for higher frequencies (basically as a function of the radiating waveguide/column length in terms of wavelengths), a directional speaker will cause a muddy or boomy diffuse field (because it is dominated by the uncontrolled low frequency). a speaker tailored for wide dispersion will have proportionally more HF in the diffuse field, which may be more pleasant in the end. the overall tone color of a massive multichannel speaker systems in any reverberant room can easily be dominated by the uncontrolled leakage to the sides. add to that the fact that it is very easy to control high frequencies by wall treatment, and prohibitively complicated/expensive to absorb low frequencies, and directional speakers are suddenly a lot less desirable than they look on paper :) Exactly. Now if you control the room acoustics by HF damping only you're back to the muddy diffuse field. If you include an amount of scattering (i.e. diffusers), this will break up flutter echos while preserving tonal balance. How about using loudspeakers with cardioid characteristic in the bass range? http://www.me-geithain.de/index.php/en/studio/products/active-loudspeaker/rl901k G ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
On 07/08/2014 12:20 AM, Gregorio García Karman wrote: How about using loudspeakers with cardioid characteristic in the bass range? http://www.me-geithain.de/index.php/en/studio/products/active-loudspeaker/rl901k I've used that speaker a couple of times, and it's fantastic. I sure would like to build a third-order periphonic rig with those, but for the tiny little obstacle that is the (entirely justified) price tag Joachim Kiesler puts on those. It's a good addition/correction to what I said before about directivity vs. radiating area - you can of course also obtain directivity by wasting some energy to the rear to actively cancel unwanted sound, and that is a bit easier to do for very low frequencies. Taken to the extreme, you end up with dipole basses, as discussed by, among others, Siegfried Linkwitz. If you have some flexibility as to speaker positioning, they must be very nice indeed. -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio) Tonmeister VDT http://stackingdwarves.net ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
I'll just add my comments to the other excellent replies you've had. Experience of rather more years than I care to remember (of rigs in concert halls) leads me to suggest that amongst the best in terms of imaging (though, unfortunately not sound quality) are the Tannoy Dual Concentric designs. I think that there are two factors coming into play that result in this - one is the fact that all parts of the spectrum come from the same place due to the dual concentric design, the other is the relatively well controlled polar diagram. The unfortunately poor acoustic performance compared to modern designs like Genelecs is the only thing which stops me from going with them for everything. This sound quality seems to be related to the basic designs because when we had to audition some new ones a few years ago with the intention of using them to replace our flood damaged Tannoy 15 Monitor Golds which we had acquired in around 1970, we found the new ones sounded exactly like the four decade old ones - and bought Genelecs instead. Dave On 1 July 2014 15:28, Sero bassi...@gmail.com wrote: Hello All, First, thank you very much for this amazing and very useful mailing list. I have a query that might look like it is very newbie but it has created a big confusion in my head when someone asked that to me recently. What is the best loudspeaker directivity (polar pattern) for an ambisonics listening rig? I am very confused about this because I cannot find any reference on this on any pubblication or discussion on the net. My feeling is that the larger directivity angle the best (up to omnidirectional) but I am still not sure about this. We have a lot of discussion on decoding coefficient, decoding directivities (in phase, max Re etc) but not on the best solution for the transducer directivity. I hope you can solve my uncertainty. Thanks Serafino *Serafino Di Rosario* *MIOA MAES CENG* *28A Haycroft Road* *SW2 5HZ London(UK)http://expochirp.tumblr.com/ http://expochirp.tumblr.com/* -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140701/1f7cb2f9/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. -- As of 1st October 2012, I have retired from the University. These are my own views and may or may not be shared by the University Dave Malham Honorary Fellow, Department of Music The University of York York YO10 5DD UK 'Ambisonics - Component Imaging for Audio' -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140704/a3f59ec8/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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
We had a rig in our original Music Technology room consisting of four Quad electrostatics (the original ones!) suspended about a metre and a half below the sloping wooden ceiling so they were above head height but angled so they were directed at a central head height point. The array worked very well at reproducing 1st order pieces on the horizontal but generated spurious 'up' (and 'down') images which we traced to reflections of the radiation from the back of the speakers from ceiling nd walls. I suspect Richard Furse will remember the surprise at the way images of sheep bleeting in Don Quixote seemed to go up and down when they should just have been horizontal. Don Quixcote was one of the first, possibly the very first, fully digital Ambisonic compositions, thanks to Sile OModhrain's Atar ST based software, SurroundSound *. Dave *0'MODHRAIN, SILE 'Surroundsound, A B format Sounndfield processing program for the Composer's Desktop Project Soundfile system', ICMC Glasgow 1990 Proceedings, pp.121-123 On 2 July 2014 17:18, Martin Leese martin.le...@stanfordalumni.org wrote: Sero wrote: ... What is the best loudspeaker directivity (polar pattern) for an ambisonics listening rig? I am very confused about this because I cannot find any reference on this on any pubblication or discussion on the net. The only work I know on this is a study by Dermot Furlong using a simulator. He discussed his work on the sursound list in 1996; I have it preserved at: http://www.ambisonia.com/Members/mleese/dermot/ Dermot considered only first-order Ambisonics. Here is an extract: I am very well aware that ideal point source loudspeakers are usually specified for ambisonic reconstruction, but their directivities are not generally commented on, so perhaps this is of interest. And yes I know that most loudspeakers have frequency dependent directivities - I was trying to address the more basic question as to what was the effect of loudspeaker polar response on reconstruction. What I found was that for reasonably dead listening rooms, loudspeaker directivity was not a major issue - as long as omni radiation patterns were not used! However, for more live listening spaces the effect of loudspeaker directivity did play a significant role. Curiously perhaps, in cases of more 'dead' listening rooms, dipole loudspeaker directivities were found to lead to reconstruction of Listener Preference Indices which was as good as that of more directional loudspeaker polar patterns. Furthermore, as the room was made more lively, the reconstruction with dipole loudspeakers was consistently and significantly better than was the case with more directional loudspeakers! This was a surprise to me, and I did look at the implementation very closely to check everything was working properly... but this remains a consistent observation... for all reconstruction formats! Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ 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. -- As of 1st October 2012, I have retired from the University. These are my own views and may or may not be shared by the University Dave Malham Honorary Fellow, Department of Music The University of York York YO10 5DD UK 'Ambisonics - Component Imaging for Audio' -- next part -- An HTML attachment was scrubbed... URL: https://mail.music.vt.edu/mailman/private/sursound/attachments/20140704/cd59314f/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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
Dave Malham wrote: We had a rig in our original Music Technology room consisting of four Quad electrostatics (the original ones!) suspended about a metre and a half below the sloping wooden ceiling so they were above head height but angled so they were directed at a central head height point. The array worked very well at reproducing 1st order pieces on the horizontal but generated spurious 'up' (and 'down') images which we traced to reflections of the radiation from the back of the speakers from ceiling nd walls. In fairness to Dermot, I should point out that elsewhere in his 1996 post (in a part I did not quote) he wrote: It would appear that, in general, lively listening environments are preferable as long as strong early reflections are avoided. and: Use of reflecting diffusors would therefore appear to be recommended such that strong specular reflections are avoided but significant liveness is maintained. Dermot's post is preserved at: http://www.ambisonia.com/Members/mleese/dermot/ Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
Sero wrote: ... What is the best loudspeaker directivity (polar pattern) for an ambisonics listening rig? I am very confused about this because I cannot find any reference on this on any pubblication or discussion on the net. The only work I know on this is a study by Dermot Furlong using a simulator. He discussed his work on the sursound list in 1996; I have it preserved at: http://www.ambisonia.com/Members/mleese/dermot/ Dermot considered only first-order Ambisonics. Here is an extract: I am very well aware that ideal point source loudspeakers are usually specified for ambisonic reconstruction, but their directivities are not generally commented on, so perhaps this is of interest. And yes I know that most loudspeakers have frequency dependent directivities - I was trying to address the more basic question as to what was the effect of loudspeaker polar response on reconstruction. What I found was that for reasonably dead listening rooms, loudspeaker directivity was not a major issue - as long as omni radiation patterns were not used! However, for more live listening spaces the effect of loudspeaker directivity did play a significant role. Curiously perhaps, in cases of more 'dead' listening rooms, dipole loudspeaker directivities were found to lead to reconstruction of Listener Preference Indices which was as good as that of more directional loudspeaker polar patterns. Furthermore, as the room was made more lively, the reconstruction with dipole loudspeakers was consistently and significantly better than was the case with more directional loudspeakers! This was a surprise to me, and I did look at the implementation very closely to check everything was working properly... but this remains a consistent observation... for all reconstruction formats! Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ 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.
Re: [Sursound] Ambisonics rig - loudspeakers directivity
Hi Fons. Tue, 1 Jul 2014 16:45:31 +, Fons Adriaensen f...@linuxaudio.org wrote : On Tue, Jul 01, 2014 at 09:28:47AM -0500, Sero wrote: I am very confused about this because I cannot find any reference on this on any pubblication or discussion on the net. My feeling is that the larger directivity angle the best (up to omnidirectional) but I am still not sure about this. Regardless of whatever 'suspected', 'hopefully correct' and 'unproven' theories you way find in the wild, there are a few basic facts to take into account: * Each speaker should cover the intended listening area as uniformly as possible. * Almost all speakers will be omni up to to few hundred Hz. Above that the best ones tend to have a fairly broad pattern. * If your room acoustics are bad, using directional speakers will not necessarily help, they could even make things worse. Unless maybe when you're building a PA system in a sports hall. What sort of problem would cause a directional speaker in a room? * LF room effects are much more related to *where* the speakers are than to how they radiate. Ciao, I use three subs in my small listening room, to activate more modes; it helps to distribute the bass frequencies in the room. -- Marc ___ 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.
