From: Rob Danielson
Hi Andy,
Yes, several of the MS plugs including +matrix have the math ability
to reverse the process. I believe we determined in an earlier
discussion on this list, however, that one cannot reclaim the exact
same mid and side signals/tracks by this means. So, save your field
M-S original files; they are unique.
Not true, The process is 100% accurate, 100% reversible (if your doing thi=
s
digitally that is - kinda close with analog electronics) My demo "party
piece" to demonstrate this to my students is to take 2 signals; some music=
in mono and something nasty sounding like White noise or Timecode. Then Sum=
& difference these (IE MS encode them) then decode back to 2 very separate =
&
clean signals. If you listen to either just the M or the S you get loads=
of noise and barely audible music I tend to crank up the noise to emphasise=
how effective this all works.
BTW, Personally I tend to keep every generation, so I do save my MS
originals.
John Hartog Wrote
"How is MS considered mono compatible, if when you sum the stereo L&R
you are left with only the information from the original M channel? Is
that really true? "
The S chan is a record of what is DIFFERENT between the Left & Right.
If you mono any stereo recording any diffeence is lost (its Mono yeh)
In the case of MS this results in all the S info going, leaving you with
just a mic (the M) pointing on axis at the subject just as you would do if=
you if you had originally made a mono recording.
But
In the case of XY, ORTF etc the sum of L&R will be from 2 mics that can
never be tottally coincident, hense there will be some comb filtering
cancellantion because there will be some time delay of the same sound that=
is picked up by 2 mics spaced apart.
"Seems like the S channel that gets lost would normally contain a
majority of the information (like 2/3 or something considering a
cardioid M) of the original L&R mix (talk about phase cancellations!).
If so that would not really be mono compatible at all, would it?"
No the M picks up ALL the sound (it's just there is no info as to what
direction(s) the sounds came from.
The S only picks up what is DIFFERENT between L&R. A Fig 8 mic in a MS rig,=
does a rather good job of not hearing sounds from straight ahead in the
middle. IE for a sound that arrives at the same time & at the same level in=
both channels there clearly is no Difference, hence it doesn't get recorded=
.
But the S does record sound other than from straight ahead, the more they
get to either the extreme Left or Right the louder will be their
contribution to the S signal.
hope that helps
regards
JL
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