M/S Decoding Technique

Discussion in 'Microphones (live or studio)' started by lorenzo gerace, Oct 1, 2002.

  1. lorenzo gerace

    lorenzo gerace Active Member

    Jan 27, 2002
    Hi everybody

    I'm about to record a string quartet for a composer who's been commisioned a soundtrack for a movie. In an everyday recording session like this I'd put up an ORTF stereo pair with some spot mics, but being the material to be recorded destined to a movie soundtrack I want to make sure it will be mono-compatible, so I'm thinking about setting up the stereo pair as an M/S pattern.

    Now the question: I'm using a Focusrite Octopre and a pair of AKG 414 TLII for my stereo pair: how do you decode the M/S inside Pro Tools? I mean, is there a way to record the two mics already decoded (thus recording three tracks)? I was thinking about assigning two tracks to the figure 8 mic and flipping the phase of one (as in the analog world), but how do you do this without affecting the tone of the selected track? Waves include their MS decoder plugin, but I never get it to work, anybody can expand on this?

    Thanx for your feedback
  2. mapostel

    mapostel Guest

    Hi Lorenzo,

    You don't have to record 3 tracks. You can actually leave the decoding to the mixdown by recording the M-signal on one track and the S-signal (fig. 8) on another.
    During mixdown you can send the S-track in PT to a bus, and use 2 Aux inputs fed by that bus. One of the Aux inputs gets phase reversed (you'll just have to compensate the delay in the other Aux input and in the M-channel). Both Aux inputs get panned hard left and right. M-signal stays centre and of course the original S-track must not be routed to L-R.
    If you want 3 tracks you'd need to make this setup during recording already.

    hope this helps,

  3. lorenzo gerace

    lorenzo gerace Active Member

    Jan 27, 2002

    Thank you for your reply

    I know I have to record 2 tracks for the M/S setup, however I won't be able to monitor them without a decoding matrix; my concern is precisely that: is there a way or workaround to record an already decoded M/S setup without a hardware device, leaving the decoding part in the software domain?; without listening how can I know if my mic placement will be right?

    Thanx for your feedback :)
  4. lorenzo gerace

    lorenzo gerace Active Member

    Jan 27, 2002

    I just red your post again: maybe I can use this same routing scheme for the recording session: recording 2 tracks but only listening to a pair of aux tracks whose input is fed by the original S track (plus the M track obviously). Do you think that could be feasible with Pro Tools?

    I'm going to try this setup in a minute.

    Thanx for the tip
  5. RecorderMan

    RecorderMan Distinguished Member

    Mar 28, 2001
    Hi Gerax,
    What he said on the m/s monitoring.
    As far as recording with m/s becuase of mono compatibillity issues, I'd say just listen to your normal mic'ing setup in mono and fine tune the adjustment of said mic''s. Then move them around with a set of cans on - monitoring in stereo - works for me....you can hear when the "hole" goes away and when your image comes into "sharp focus". Also, when any of you cam afford it, I highly recommend the Little Labs IBP ( In Between Phase) box. I recently purchased a pair, and any "two mic on single source" recording that I've been doing lately (like A singer & his/her a-gtr at the same time with two mic's, single drum percuccion w/ 2 mic's, a-piano, ect) has been a new experiance. you just put the mics where you want; throw an IBP on one of them, and adjust it in the control room. It sucks any "anti-phase" (at whatever degree) right out of the sound....instant phat..... :c:

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