Mastering: Mid-Side Compression

The stereo mix is routed to a bus for example bus 1 and 2. Bus 1 and 2 then goes through two auxs basically getting duplicated. As the stereo track has now been duplicated, one of the two versions is going to get a polarity flip. This polarity flip is done only on the right hand side of the stereo mix, this means that the left and right hand sides of the track are 180 degrees out of phase with each other. 

The right track that has been flipped is routed out through a mono output therefore the right and left hand sides are summed together. The parts of the music that are in the centre of the stereo filed will be cancelled out due to the fact that they are common to both the left and the right channel and due to the polarity flip. The widely panned sounds will not be cancelled as they are on the extremes of the stereo field and will only be in either the left or right channel and they are not common to both. This track is labelled ‘Side Encode’ and routed through Bus 4.

The next track will be labelled ‘Mid Encode’ which will be routed out through Bus 3, this is the parallel duplicate track that has not be changed at all but is summed to mono.

The two duplicates are sent to the left and right hand sides of a pair of stereo auxes. The ‘Mid Encode’ track goes to the left side in each case and the ‘Side Encode’ goes to the right side in each case.

There are two stereo aux tracks with the same input of Bus 3 and 4. These two aux tracks are ‘Left Mid Decode’ and ‘Right Side Decode’. The signal at this stage has now been flipped 180 degrees twice therefore bringing it back to the original. The ‘Left Mid Decode’ track is being sent out on A1 which is the left hand side of the main output and the ‘Right Side Decode’ track is being sent out through A2 which is the right hand main output.

The ‘Right Side Decode’ and the ‘Left Mid Decode’ track’s faders should be turned down to -6dB as there is a risk of overloading the master fader.

Everything on the output is the same as the original however you have the option of being able to control the levels of the music thats panned centrally separately o the music that is panned to the left and right. Pull down “mid-encode”‘s fader to reduce centrally placed sounds.