mid-side (phase invert) removing guitars

[bkkornaker]

heres a new question......

a buddy of mine brought a song to me, and asked me if i can remove the guitars on the song. The song itself is a standard stereo file, and the guitars are panned hard left/right. I know its possible with converting it to a Mid-side and possible inverting phase......but ive never done that before. got any tips or work arounds for someone who has never done this before?

this person does understand that once its done, probably the only thing left in the song, ....will be things panned directly up the center (vocals,snare,kick,bass)....but he is fine with that.

where do i start?

[kubeek]

I think that you can only end in complete opposite of you want. Unless the guitars is only one guitar and inverted on one channel, you can just achieve removing all the vocals, snare kick and bass and leaving the guitars untouched.

[punkin]

Yeah, and I'm thinking you can't do it unless you've got access to the raw tracks...I mean, the idea of phase cancelling requires that you mix two identical signal together but out of phase. Unless you've got the original guitar tracks, I don't see how you could do it.

Maybe someone else will shoot me down...gawd I hope they get me in the head...I don't do pain with any degree of dignity

[masteringhouse]

As was said you will need to isolate the guitars first. If you have the original tracks of the guitars then I would assume a remix is possble and would be the best way to remove them (obviously). I'm going to assume that you don't.

I haven't tried this but just trying to think logically. First you will need to isolate them the best that you can. Set up and M/S matrix and encode to M and S. The S component should contain the guitars and everything else closer to the sides. The M will have everything. Feed the S component into another channel and reverse polarity to cancel the sides out. Then decode the M and S components back to stereo.

Let us know if this works. I haven't done the math, but some sort of combination like this or variant may work to some degree.