David Wyld wrote:
 
> The problem is that there are now two main Surround formats (I am really
> referring to the situation in UK and acknowledge that there may be
> others available in other places) The Dolby system is, as far as I can
> make out, a computer generated surround sound 'effect'.The system which
> we at Mirabilis have helped to promote since 1989 is UHJ Ambisonic
> Surround sound, which simply decodes the four original recorded signals
> (front left; front right; back left; back right) . I am not aware of any
> organ recordings in Dolby surround sound (- if anyone is, I would love
> to know).
 
I think that the "problem" is much more than this. Yes, especially with Dolby
AC-3 and
DTS (so that makes THREE systems, at least) the muslit channel directional can
be
effectively decoded. However none of the channels are full samples of the
original. If
memory serves me correctly Dolby AC-3 uses a flat 384kbs and DTS uses a variable
one of
slightly higher bandwidth to effect better use of the bits to prevent
'congealing' on
complex passages. BOTH of these formats for the full 5.1 channels use
significantly less
bandwidth than CD for two channels with a resulting loss of musicality.
 
I understand that there is a strong hope for the DVD (was Digital Video Disk and
I
think is now Digital Variable Disk) to provide AC-3, DTS and possibly 5 channels
of 20
bit with 2 channels of 24 bit sound on the ONE DISK! THIS multi layered solution
will
then cope with every possibility for the same programme on the one disk. YOU
then choose
your level of replay quality.
 
AC-3 and DTS (I have no exposure to Ambisonic) are primarily intended for highly
directional movie effects (foley, etc) NOT for music.
 
I have only one surround sound recording of a pipe organ and that is Hector
Olivera at
the Atlanta Fox which implements Pro-Logic which has "steered" monophonic rear
"channels". But, someone seems to have added some awful reverb that seems to be
single channel. However, at this point (at least in my experience) Pro-Logic is
VERY
superior for even movie music than AC-3.
 
Hope that assists.
 
Ian McLean in
Perfect Perth (well, so far!)