Apart from the obvious measurement of the amplitude and phase of the
individual signals, which I do, I only have access to two ways of
visually monitoring surround signals.
I have always found a phase meter very informative in stereo. There
is the centre zero "correlation" meter type, either analog or with
LED bars, and the oscilloscope L/R or M/S method which I find less
useful. Having written that, I must say that I find the "Vector
scope" in RME's Digicheck works well. This is an oscilloscope
display but there is the option of AGC, and the rise and fall times
are adjustable.
Digicheck's surround visualisation includes phase meters between all
the channels of the "correlation" type and a synthesized two
dimensional display which assumes five channels in the directions of
5.1. If there is sound on one channel, one sees a line pointing in
the direction of the relevant loudspeaker. Two adjacent channel
produce a triangle, one apex at the centre, four a quadrilateral,
etc. Thus the space between the channels is filled in, although to
me this conveys no real information. One can read the individual
phase meters, which are mostly of use with tones, or read the
position of the corners of the display to see the relative magnitude
of the levels in each channel. (There are also separate level meters
on the same panel.)
The other surorund display that I have is in Samplitude, and also
assumes 5.1. This produces cigar shaped signals for individual
channels, coming to a point at the origin, but very rounded at the
outer end. Two front signals will fill in the space between the L&R
cigars, etc. Other than that, I have been uinable to discover how it
works. With this display, one can see if a single channel is low or
high in level, and gauge the relative levels of F and B. But there
is no indication of the coherence, or lack of it, between channels.
On a stereo phase display, such as that in Digicheck, one can readily
see if a mono signal has been placed in the stereo by means of a
panpot; but this cannot be seen in either of the surround
visualizations that I have.
What might work would be the Digicheck stereo display modified such
that signals in the front half on the soundfield are placed in the
top half of the display, while the rear half is in the lower
part. Then it might be possible to distinguish between panpotted
signals and coherent pairs.
I'd be very interested to know about other methods of visualizing
surround -- in the horizontal plane, at least to start with. In my
experience I can tell a lot about a stereo signal by watching the
level and phase meters, and I would like to be able to do also in surround.
David
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