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EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 10:23 am
by sinnatagg
EQ8 got this very cool stereo mode, but how does it work? Does it transform the stereo signal to three or more channels internally. How does it determine what is the center part of the stereo L/R signal?

-a

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 10:32 am
by garyboozy

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 10:40 am
by sinnatagg
Thanks for the link!

So I guess the inverse of one side is summed with the other to remove the center, and the you can do the some thing again to isolate the center. Then it's just mixing it back in the right proportions.

-a

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 10:49 am
by garyboozy
yea something like that...
wikipedia wrote:The left and right channels are produced through a simple matrix: Left = Mid + Side, Right = Mid ? Side (the polarity-reversed side-signal)
the details still baffle me somewhat. not stopped me using m/s processing all the time, though.

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 10:53 am
by sinnatagg
Reading closer, the article says the two sides are summed to generate the center and that the phase of one side is flipped. This makes the sides disappear in mono :?

I guess it's use with caution like all stereo tricks.


-a

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 11:25 am
by sinnatagg
garyboozy wrote:yea something like that...
wikipedia wrote:The left and right channels are produced through a simple matrix: Left = Mid + Side, Right = Mid ? Side (the polarity-reversed side-signal)
the details still baffle me somewhat. not stopped me using m/s processing all the time, though.
Thanks for looking this up. So the Side is phase flipped in the final L/R signal and only the Mid signal will remain in mono.

So the Mid is A+B, but I still haven't found any description of how the side signal is generated though. Perhaps it's just L or R or L-R.

-a

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 2:36 pm
by 3dot...
in-phase
1+1=2
anti-phase cancellation
1+(-1)=0 (one side is inverted)

the center cancels out...
(phaze cancelling as it's the same on both R and L...
one side is phase inverted..)

which leaves all the rest (the difference aka "side frequencies")

8)

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 3:37 pm
by bicarbone
Correct me if I'm wrong!

The Utility device in live's effects lets you hear what's going on in the Sides: just use the preset called "difference" and put the gain back to 0 db (it's boosted to 8 db or so because the side signal is usually pretty weak).

If you want to hear the Mid only, use the Mono preset.

Utility is your friend if you're tweaking EQ8 in M/S mode!

Re: EQ8 M/S mode - how does it work?

Posted: Tue Aug 16, 2011 4:01 pm
by 3dot...
yep
there's a "width" parameter on the utility plugin...

0% is mono (middle)
200% are the sides

and also ... you can use it to phase-shift any side of a stereo signal
:wink:

Re: EQ8 M/S mode - how does it work?

Posted: Wed Aug 17, 2011 12:03 pm
by rosti
LOL! I never realized that EQ8 can do mid/side EQ'ing :lol:

Thaks for helping the blind man.