On 07/09/2012 06:15 PM, Simon Edmonds wrote:
using first order for reverb is fine as the overall localisation is not critical. In the next incarnation of my system I will have a 3rd order mixer but still using a 1st order send and reverb
i used to say the same, but i have found it's not true as you scale up to larger numbers of speakers. natural-sounding reverb needs a low IACC, and to ensure that, you want very high-resolution reverb. not for its localisation benefit (obviously), but to ensure very low crosstalk between neighboring speakers.
using a first-order reverb on more than, say, twelve speakers periphonic will begin to add significant phasing artefacts as you move around even slightly, because neighboring speakers convey very similar signals. they will interfere in a nasty way without giving any benefit.
on a 40-channel speaker system which i built last year for the ICSA conference, we used two decoders designed by fons, one dedicated third-order, the other first-order, for native soundfield signals and reverb. the first-order decoder used only a subset of the available speakers, which improved the perceived quality a lot.
morale: low-order reverb doesn't scale. if you want to use it on massive systems, keep low-order content separate and pipe it through a dedicated decoder using fewer speakers.
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