Having only thought of EQ in terms of frequency adjustments, I was intrigued at the prospect of how Mid/Side processing could be used to enhance the 'stereotomy' of a mix.  Also my research indicated that on Scope, one of the best tools for this purpose was the MASTERIT EQ from DIGITALAUDIOSOFT, simply because each of the five bands had multiple modes of operation, so it could cover all of the jobs done by various other Scope mastering equalizers, plus a few that the others did not cover.

So having purchased the device never having done Mid/Side processing before, I hooked it up to a project I had been working on the day before.  A suitable starting project because it basically consisted of a vocal, bass and drums all center mix, and two rhythm guitars playing the same part but panned hard left and hard right for a stereo spread affect. 

The guitars needed to be 'lifted' in the mix, and I found I was able to boost the guitar frequency in the mix without boosting the same frequencies of any center material.  Something not possible with the standard EQs I had been used to working with.

So it occurred to me that the simplest way to think of Mid/Side EQ was to think of two separate EQ devices.  One that worked on the material at the center of the mix without affecting the sides (A), and the other that worked on the left and right side material without affecting the center material (B). 
 

  1. Select M/S for mode

  2. Select L/R for MODE-INPUT

  3. Select L/R for MODE-OUTPUT
   

  1. Turn 'EQ IN' on

  2. Turn 'Filter IN' on

  3. Select A & B as the EDIT MODE

  4. Select the starting values you desire to apply to the overall mix for LOW-SHELF, LO-MID, MID, HI-MID and HI-SHELF.  This step is just to get close to what you want, as you will be making further adjustments to the MID then SIDE separately.  Note that 'A' and 'B' values for each of the five bands will be set in tandem.

     The EQ IN button engages the inner three band settings.

The FILTER IN button engages the LO and HI CUT/SHELF outer band settings.

     Edit Mode A&B will link the MID and SIDE together, so there will be no difference between MID and SIDE initially.  This is just to get your basic sound.  Note: if you select A & B after making separate adjustments to 'B' side parameters, then the 'B' side parameter values will be reset to the same values as the 'A' side.
 

  1. Select 'A' as the EDIT MODE

  2. Select 'B' in the OUTPUT MUTE section

  3. Engage the small EQ IN buttons for the MIDDLE ranges you want to adjust.

  4. Select the values you desire to apply to the middle of your mix for LOW-SHELF, LO-MID, MID, HI-MID and HI-SHELF

 

    

Selecting 'A' means that the EQ settings will be represented by and applied to the 'inner A' ring of values around the main EQ parameters.

    

Muting 'B' will allow you to work on the middle (mono) material in your mix, without hearing the side material.
   

  1. Select 'B' as the EDIT MODE

  2. Select 'A' in the OUTPUT MUTE section

  3. Engage the small EQ IN buttons for the SIDE ranges you want to adjust.

  4. Select the values you desire to apply to the sides of your mix for LOW-SHELF, LO-MID, MID, HI-MID and HI-SHELF

 

     Selecting 'B' means that the EQ settings will be represented by and applied to the 'outer B' ring of values around the main EQ parameters     Muting 'A' will allow you to work on the side (stereo) material in your mix, without hearing the mid material.

Each of the five bands work like a Parametric EQ in that each has a frequency control (top knob) and a matching boost/cut control (lower knob).  The lower and upper band are referred to as 'FILTER' and are activated with the 'FILTER IN' button.  The three middle bands are referred to as 'EQ' and are activated with the 'EQ IN' button. 

Note in the DAS diagram below that the frequency ranges of the LOW MID, MID and HI MID range have some overlap to give best overall coverage.

MASTERIT features seven bands of EQ (represented by the seven red squares above).  LOW-CUT and HI-CUT, LOW-SHELF and HI-SHELF, these two bands can also become LOW-CUT and HI-CUT (with variable slope) or (and) two full parametric EQ bands. In addition there are three full parametric bands of EQ, that can also been switched into three modes of BAND PASS and two modes of NOTCH (with variable slope).

 

From time to time you should listen to how the separate sections of the MASTERIT are affecting your mix as follows:
  • Unmute both A and B to check your overall sound
  • Turn off the EQ-IN whilst FILTER-IN is turned on to see how the LOW and HI SHELF filters are affecting your mix.
  • Turn off the FILTER-IN whilst EQ-IN is turned on to see how the LOW-MID, MID and HI-MID EQ are affecting your mix.
  • Turn off all frequency ranges and turn them on one at a time to see how each is affecting the mix.  Best to do this with Edit Mode 'A' whilst 'B' output is muted and vice versa.

I found KIM LAJOIE'S BLOG excellent reading as it details four example applications of the MID/SIDE technique, including Mono Bass, Top End Dimension, Focused Vocals and Giant Lower Mids, the focus being on modification of the side levels leaving the mid levels untouched in a way that maintains the overall balance of the mix.

Using MASTERIT whilst listening on headphones, I noticed I was able to bring elements of the mix either forwards or backwards in a 3D audio space, for example adjusting the top end of the MID side seemed to move hi-hats further or closer to the front of the sound stage.  This type of psychoacoustic effect is just a subjective observation though, and would depend on each individual mix, MASTERIT settings and listening conditions.

Further applications are explained by this Blue Cat Audio PDF.
 

 
The MASTERIT has two more important parameters, the M/S MODE-INPUT and the M/S MODE-OUTPUT buttons.  These buttons allow MASTERIT to encode and decode signals with Mid/Side information as follows:
   

M/S MODE-INPUT:  Select this if you wish to process signals that are already M/S encoded, such as an M/S microphone or M/S encoded Digital Audio file.
   
M/S MODE OUTPUT:  Select this if you wish to output a signal encoded with M/S information.  For example you may want to output to another device such as a compressor that accepts an M/S encoded signal.
 
Mastering a Stereo Signal Recording a M/S Microphone Encoding a M/S Stereo File Using Double Mono EQ
       

  1. Mode M/S

  2. Input L/R

  3. Output L/R

  1. Mode M/S

  2. Input M/S

  3. Output L/R

  1. Mode M/S

  2. Input L/R

  3. Output M/S

  1. Mode L/R

  2. Input L/R

  3. Output L/R
     

 
Below we have included our showcase track firstly on the left, un-mastered, and then on the right after mastering with MASTERIT.
 
 

"Luc Pont Eyes" A Jon Luc Ponty Tribute written and mixed by Dante

 

"Luc Pont Eyes" now mastered by Eric with DAS MASTERIT
 
 

VIEW TWO VIDEO DEMONSTRATIONS OF RECORDING AND MASTERING SESSIONS FEATURING MASTERIT HERE
 

Dante and Eric September 2010