On 03/24/2011 04:15 PM, david monacchi wrote:
Dear all,
we're planning to build in Pesaro-Italy a small ambisonic studio with
13 loudspeakers (full 3D - 4@-45°, 4@0°, 4@+45°, 1@90°)..
knowing your field-recording work, i can see how you'd focus on first
order, but i can't help noticing how 12 speakers would make a lovely
second-order dodecahedron (with a bit of wasted floor space, obviously),
which would also be nice for plain old first order. and it could be
simplified to "triangle, hexagon, triangle", which would also be a far
superiour horizontal-only setup for first order than your square.
> We're now
in the process of moving walls, treating acoustically the room, etc..
The room will be 5.00 x 4.60 x 3.20h and we are planning to treat it
to be as more 'dead' as possible..
i've had the pleasure to work in two rather dead ambisonic studios, one
was the IEM cube in graz, and the other the SPIRAL at the university of
huddersfield.
dead acoustics are great in that you can get very convincing renderings
of semi-anechoic or free-field conditions. but it can be a bit tricky to
keep phasing artefacts under control, because there are no early
reflections to mask and average them out.
the cube is particularly fussy in this respect (which is probably why
the graz folks report a strong preference for non-delay-compensated
decoders in some of their listening tests). the spiral was totally
unproblematic for some reason: it's three stacked octagons plus zenith
(i used a 3h2v decoder designed by fons), and there was no phasing
whatsoever, even though the room has an rt60 of 0.3s and is so quiet
that you begin to notice the hiss of the genelec 8240s (which are pretty
quiet to begin with).
but phasing can usually be fixed by hand-tuning the delays a bit.
In order to have a 'pleasant' space, we're thinking to put a wodden
floor which, to a certain degree, will also help absorbing some low
frequencies..
My question is: considering that the room will be semi-anechoic, is
the reflection from the wodden floor really compromizing for the
correct soundfied reconstruction? Are there studies that you know
with experimental data, or simply your direct experience on this?
it will have some impact on the rendering, but i doubt it will be
distracting, unless you wanted to specifically reproduce
vertigo-inducing audio scenes with no floor, like dangling off a crane
or something.
i'd say as long as your recording has floor reflections, the added ones
won't hurt.
best,
jörn
--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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