On 03/20/2011 07:25 PM, Dave Hunt wrote:
The whole PA world has gone rather line-array mad since the idea was
re-introduced and re-engineered by L'Acoustique and Intellivox (Duran
Audio) some 10-12 years ago.
mostly for two reasons:
* they are cheaper than designs with delay towers
* with their better directivity, you can get reasonably good sound out
of mediocre or outright bad-sounding halls, where stacks would be very
hard to get right (since you can effectively reduce room excitation or
even steer around problematic walls altogether)
my subjective view is that you can also scale them higher than stacked
systems before they start to sound really funny.
and of course they are a lot easier and safer to rig, and to get really
high up in the air, which is totally uneconomical for stacks.
Now, every manufacturer has to have a
"line-array" system, though the use of the term is often barely
appropriate.
true. not the least because l'acoustic and a select few other players
have patented all the really clever bits, and the objective of the race
has changed to "whose patent workarounds are the least detrimental?"
I too, like J?rn, am curious to know at what point does ambisonics break
due to the non-simultaneity of arrival of sound from widely spaced
sources. Obviously lower order components will suffer most from this,
why do you think that?
With a widely spaced array, the "sweet spot" will be correspondingly
larger,
that's not really true. the sweet spot in the strict ambisonic sense is
a function of order and wavelength only. but intuitively, i think the
same. my rule of thumb to the question of how many tickets can be sold
without falling from grace is "two thirds of the array diameter at third
order", since it does indeed seem that large arrays are more lenient in
this respect.
even under lab conditions, the effect is obvious: fons once gave me a
"virtual ambisonic" demo with point sources rendered on the sala bianca
wfs system (using material i was intimately familiar with), and the
result was clearly improved by moving the virtual sources well behind
the physical wfs speakers.
i guess the explanation is that we get closer to the plane wave ideal.
and thus a bigger audience can be within it, but the ultimate
constraints will be size of venue and environmental noise concerns.
that's another thing worth exploring: the funktion one guys have
reported that ambi rigs have an advantage in this respect, because the
ratio of useful loudness inside to leaked emission outside of the array
is better than with stereo (or maybe even conventional four-point)
playback systems. i haven't experienced this yet and can't think of a
hypothesis to explain it, but i'd like to talk to the f1 guys at some
point about this observation.
--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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