This is something I have alluded to before.
There is no need to have multiple transducers in the same box with
ambisonics.. In fact it should be more accurate, economical, aesthetic, and
space saving to have each transducer at its own separate point in space.
Tweeters are more directional so more are needed, they are also cheaper.
Going all the way down the frequency range to the least directional and
most expensive, woofers and subs.
Separate decodes could be done for each transducer bandwidth, rotating the
soundfield to align. This would also benefit the transducer crossover
point, as there would be less interference from proximity. It would also
help room response, as crossovers could be tweaked and balanced on the fly.
Which is also alot of fun!
Steve
On 16 Oct 2015 12:47, "Peter Lennox" <p.len...@derby.ac.uk> wrote:
> we used a much cruder version of this back in 2002 - decoding a
> hemispherical 32 speaker array to second order, but crossed over the
> B-format at 90Hz (I think) to a horizontal-only 8-sub array, decoded in 1st
> order. This was on the basis that we couldn't fly the subs, and anyway,
> elevation discernment, being largely due to pinnae affects, was not
> appealed to by the subs anyway. Had to work on the time alignment (the sub
> decoder was analogue, the mid'n'tops 32 speaker array done in software) and
> spatial alignment (rotating the subfield to match t'other, in the b-format
> feed). It worked well, though could have been further refined; it was a
> one-off installation.
> But the principle of using decreasing order with decreasing frequency made
> sense from the point of view of efficient use of transducers.
>
> It made me wonder whether the same principle extends the other way -
> increasing order with increasing frequency, to make up for the deficiencies
> in spatial resolution of lower orders at HF.
> Given that it should now be reasonably 'easy' to align the fields of
> multiple cells - even having differnt numbers of speakers for each
> frequency band, there might be less reason to assume that point source
> speakers are strictly necessary.
> We're still using speakers designed as stereo projection systems, and it
> could even be that starting again, thinking about real-world usages of
> ambisonics, that one could revisit the speaker design theories.
>
> Going off on a tangent, it might be that (as others have experimented
> with, before) that the trasnducer design for the programme material which
> is 'ambient' (reflected sound, from no particular source, and therefor not
> requiring precision in phantom imagery) might differ than that for
> the'virtual sources' ('images')
>
> So I experimented with 12 very modest nxt-type flat panels which were
> rotated thru' 90 deg. to what you'd expect, as it were - that is, they
> didn't 'face' the centre but were at right angles to it. The results (given
> the modest set up) were better than they had any right to be - most
> especially for ambient and distant sounds.
> I know they used to use multiple dipoles on the walls in cinemas for
> conveying the surround channels of 5.1 material (they might still do, I
> never go to the cinema because of the loud, poor sound) - so this seems to
> be a similar principle.
>
> Just a few ramblings
> cheers
> Dr. Peter Lennox
> Senior Fellow of the Higher Education Academy
> Senior Lecturer in Perception
> College of Arts
> University of Derby
>
> Tel: 01332 593155
> ________________________________________
> From: Sursound [sursound-boun...@music.vt.edu] On Behalf Of Jörn
> Nettingsmeier [netti...@stackingdwarves.net]
> Sent: 16 October 2015 12:15
> To: sursound@music.vt.edu
> Subject: Re: [Sursound] Advice on new loudspeaker array... Genelec 8010
> speakers?
>
> On 10/15/2015 10:51 PM, Dave Malham wrote:
> > One of the things that should be investigated in conjunction with higher
> > order Ambisonics material would be to "fade down" the higher order
> > components as the frequency drops, thus spreading the bass over more
> > speakers, reducing the strain on the individual speakers whilst
> maintaining
> > the spectral balance - hey, wasn't that Richard Lee's Powered Integrated
> > Sub concept from several years ago?? Doesn't help with first order
> materiel
> > but....
> >
>
> <ears pricked up>
>
> Intriguing idea, that. So we would apply zero-phase high-pass filters to
> the second and higher components?
> Should be nice for a test run, but how to keep latency down for live
> electronics and A/V sync? How would we phase-align an IIR filter?
> Allpasses on the lower components?
>
> The spectral balance would be maintained despite the filters, since
> we're in LF, where each new order "takes away" as much as it "adds", so
> to say. Unlike at HF, where we have to add energies and any such
> filtering throws the spectral balance of kilter, as Eigenmike users will
> know...
>
> --
> Jörn Nettingsmeier
> Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
>
> Meister für Veranstaltungstechnik (Bühne/Studio)
> Tonmeister VDT
>
> http://stackingdwarves.net
>
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