EQ8 M/S mode - how does it work?

Discuss music production with Ableton Live.
Post Reply
sinnatagg
Posts: 137
Joined: Sat Mar 19, 2005 7:45 pm
Location: Oslo, Norway
Contact:

EQ8 M/S mode - how does it work?

Post by sinnatagg » Tue Aug 16, 2011 10:23 am

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


sinnatagg
Posts: 137
Joined: Sat Mar 19, 2005 7:45 pm
Location: Oslo, Norway
Contact:

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

Post by sinnatagg » Tue Aug 16, 2011 10:40 am

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

siliconarc
Posts: 2836
Joined: Mon Jul 16, 2007 12:27 pm
Location: UK
Contact:

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

Post by siliconarc » Tue Aug 16, 2011 10:49 am

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.

sinnatagg
Posts: 137
Joined: Sat Mar 19, 2005 7:45 pm
Location: Oslo, Norway
Contact:

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

Post by sinnatagg » Tue Aug 16, 2011 10:53 am

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

sinnatagg
Posts: 137
Joined: Sat Mar 19, 2005 7:45 pm
Location: Oslo, Norway
Contact:

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

Post by sinnatagg » Tue Aug 16, 2011 11:25 am

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

3dot...
Posts: 9996
Joined: Tue Feb 20, 2007 11:10 pm

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

Post by 3dot... » Tue Aug 16, 2011 2:36 pm

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)
Image

bicarbone
Posts: 385
Joined: Tue May 09, 2006 6:31 pm
Location: Switzerland
Contact:

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

Post by bicarbone » Tue Aug 16, 2011 3:37 pm

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!
|soundcloud|

MBP 2.2 GHz i7 quad 10.7.5 8GB ram | Live9suite | Reaper | Metric Halo ULN-2 + DSP | PSI A21-M active monitors | Littlepapercones passive speakers | Studer 169 analog mixer

3dot...
Posts: 9996
Joined: Tue Feb 20, 2007 11:10 pm

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

Post by 3dot... » Tue Aug 16, 2011 4:01 pm

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:
Image

rosti
Posts: 280
Joined: Fri Aug 21, 2009 5:23 pm
Location: HELLsinki

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

Post by rosti » Wed Aug 17, 2011 12:03 pm

LOL! I never realized that EQ8 can do mid/side EQ'ing :lol:

Thaks for helping the blind man.

Post Reply