>You definitely can't successfully sum 2-omni stereo to mono.
I do not agree with the above, Tom.
You only get comb filtering artifacts
if the mics are fairly close together.
If I use just two omni mics I use a
spacing of around 60 cm for a nice
stereo spread with no apparent
hole in the middle.
Each mic will get sufficiently different
amplitude and time differences so when
you mono them no comb filtering can be heard.
Goes for the 3 mic omni one, M3, Mercury
style mic set up too.
Also the Decca tree, M5, with outriggers are free
of audible comb filtering too.
Comb filtering can only be heard IF there is
enough correlation with a time delay between
mics and that is not true of spaced mic techniques.
Here the correlation between the mics are
low so the sum together in mono fairly well
> I think the Europeans who used MS or other crossed-matrix
> methods were able to use one channel for mono (although
> there were crosstalk phase-cancellation issues with that method).
In M/S we have M-S = L and M+S = R when
you matrix M and S to get stereo or L & R.
When you have stereo or L & R when you mono L + R
you get (M-S) + (M+S) = 2M.
So the difference signal (-S) + (+S) cancels completely
100 percent and we are back to the original M signal
only for 100 percent mono compatibility.
One never ever use only L or R only just mono, L+R,
the thing and we are back to the original M mic.
Very simple in fact.
No wonder that M/S is so popular in some quarters.
The Mastering Room AB
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