"Don Pearce" wrote in message
...
On this audio extract, there are three segments.
The first is mono, the second is reprocessed stereo,
and the third segment is a good example of what happens
when the level difference of mono signal and the
out-of-phase pair is too small.

http://www.kolumbus.fi/iain.churches...StereoDemo.mp3

Mono for me.

For me too. But when the people upstairs decide there will be
no more mono, there will be no more mono. Fortunately, these
days we are more enlightened, and listeners expect mono archive
material to be preserved in pristine mono.

The second segment still has everything I want to hear at
centre front, but with some vague "stuff" round the sides.

Frequency analysis of the original mono, and the reprocessed stereo
track:

Mono
http://www.kolumbus.fi/iain.churches...requency01.png

Reprocessed Stereo
http://www.kolumbus.fi/iain.churches...requency02.png

Phase analysis

Mono
http://www.kolumbus.fi/iain.churches.../ESPhase01.png

Reprocessed stereo
http://www.kolumbus.fi/iain.churches.../ESPhase02.png

The third
part sounds like someone has got the phasing totally wrong somewhere
down the line.

Your analysis of the third segment was spot on, Don,
and illustrates well the importance of the relationship
of the mono centre signal to the out of phase pair.

"Overcooked"
http://www.kolumbus.fi/iain.churches.../ESPhase03.png

Iain






d


http://www.kolumbus.fi/iain.churches...requency01.png