[Scott Dorsey]

Les Cargill wrote:

I have no idea how you do it in analog or in real time. But a
Hilbert Transform will provide a very good 90 degree phase
shift.

It will. Unfortunately when you run it through a Dolby CP-50 which uses
an all-pass filter (which is NOT a very good 90 degree phase shift), it
doesn't sound so good. You need to use filters on the encoding side
which are more or less the opposite of the ones on the decoding side.

I think that there are real time and analog versions of them;
I only know how to do to in the not-real time way.

As to the surround decoder - turn that off and do it
stereo. People still know how to do that.

Go to film-tech.com. Download the Dolby CP-50 manual. Look at the
phase shift networks on the Cat 146/150 card. Build the same networks
in reverse for encoding.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."