[Scott Dorsey]

wrote:
I'm guessing you all probably know why I need to create one of the above - =
to trick a Pro Logic Surround decoder.

Why not use a pro logic encoder, then?

Problem is, I know what a 90 - and 180 - deg phase shift looks like on a pu=
re sinewave, but how to I achieve 90 degrees phase shift on "real world" ma=
terial - a clip of ducks quacking or a 1890s locomotive roaring by? There =
is no simple wave - ducks, trains, and of course music - are anything but s=
imple!

All-pass networks are discussed extensively in the Audio Cyclopedia.
--scott

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