07:50 PM 7/24/2012 +0100, Paul Hodges wrote:
--On 24 July 2012 12:40 -0600 Martin Leese
<[email protected]> wrote:
and download the file:
Ambisonic_stereo_decoding_equations_1981.pdf
This gives the most recent (1981) equations
for Super Stereo. (Once again, thanks to
Geoffrey and Larry.)
Presumably the unexplained k1 and k2 relate to shelf filtering in some form.
Paul
--
Paul Hodges
From my delving into this awhile back, this is the best I can offer.
Again referencing Martin's site:
https://sites.google.com/site/mytemporarydownloads/
<https://sites.google.com/site/mytemporarydownloads/Ambisonic_stereo_decoding_equations_1981.pdf?attredirects=0>Ambisonic_stereo_decoding_equations_1981.pdf
Kindly provided by Dr. Geoffrey Barton (1/26/2011).
K1 & K2 are the two frequency magnitudes for the shelf filters
K1 < 800 Hz.
K2 > 800 Hz.
p is the degree of "phasiness" (e.g. 0.0 to 0.25) which, in a note from
Geoffrey, relates to the degree of accuracy of the phase difference networks.
My presumption then is that a tighter tolerance phase shifter ( < 1 degree
error from 20 to 20k Hz) reduces the degree of phasiness (which can be
"pushed" to the rear with the forward preference control--fed by the 'b'
node) and would "allow" for a slightly steeper slope on the shelf
filters. (The WW '77 decoder probably exhibited a significant degree of
phasiness, and a tighter tolerance pair of phase shifters will also
probably provide better imaging for SS decoding.)
and,
j of course is the 90 degree phase difference in the two pairs of phase
difference networks.
w is stereo width (I believe 1.0 : 1.6 max recommended, ratio of L+R
to L-R)
--Larry Gruber
_______________________________________________
Sursound mailing list
[email protected]
https://mail.music.vt.edu/mailman/listinfo/sursound
