Hi,
I am not sure if it would make a lot of practical sense to re-map
+-30º stereo recordings. (to +-45º etc.)
If a recording was made with a crossed cardioid pair of microphones
(usually +-45 degrees or wider), or using sine/cosine panpots, it is
now generally +-45 degrees re-mapped to +-30 degrees.
We can also analyze stereo with the loudspeakers at +/- 30
degrees, and see that rE in the center is now 0.87, which is a
significant improvement over 0.71 obtained with speakers +/- 45
degrees. In general, with two speaker stereo, for sounds in the
center, rE = cos(theta/2), where theta is the angle between the
two loudspeakers.
If the two speakers were to have a separation of zero degrees, rE
would be 1, a further "improvement". This is basically an argument
for a centre speaker, or rather for a derived centre speaker as in
Trifield.
Ciao,
Dave Hunt
From: Stefan Schreiber
Date: 31 March 2016 17:20:20 BDT
To: Surround Sound discussion group
Subject: Re: [Sursound] OT Stereo stage width - Was: Static stereo
source in rotating soundfield, possible?
Aaron Heller wrote:
Marc Lavallée, Eric Benjamin, and I put together a Trifield (three
speaker
stereo) plugin and demo'ed it a Burning Amp last fall. It is
hosted at
https://bitbucket.org/ajheller/trifield/overview
It is written in Faust so can be compiled for a number of
different hosts,
but we provide precompiled VST plugins for Windows and MacOS in the
download folder.
There are also some plots that use Gerzon velocity and energy
localization
vectors (rV and rE) to analyze, +/-45 deg stereo vs Trifield vs
+/- 30 deg
stereo that shed some light on why "the +/- 30 deg stereo
triangle" works
well.
This is not a direct response, just an observation:
Wide stereo (so +-45, or +-60º deg) would easily be possible with L-
C-R stereo, native recordings. (s. Gerzon,1990.)
However and in practical terms, 5.1 does most of the same.
I am not sure if it would make a lot of practical sense to re-map
+-30º stereo recordings. (to +-45º etc.)
You basically say the same:
We can also analyze stereo with the loudspeakers at +/- 30
degrees, and see that rE in the center is now 0.87, which is a
significant improvement over 0.71 obtained with speakers +/- 45
degrees. In general, with two speaker stereo, for sounds in the
center, rE = cos(theta/2), where theta is the angle between the
two loudspeakers.
But:
How can rV > 1 be true??! (second last image...)
Best,
Stefan
P.S.: I have always seen 5.1 as stereo + ambiance system, which is
the historical development as well.
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