There are two ways to record MS (mid-side) stereo signals with the 7-Series recorders, record either discrete M and S signals and decode later, or decode MS in the recorder to Left-Right stereo.
When recording the inputs discretely, post production can use these signals and have full control of the stereo image. When using the on-board MS decoder on the recorders, the resulting L/R signals have a fixed stereo "width", or image. This will generate files with a fixed stereo image.
7-Series recorders offer a wide variety of headphone routing options, it is important to chose the correct headphone routing option for your setup.
Recording Inputs Discretely While Monitoring MS
If recording MS signals discretely, it is very useful to monitor that signal as Left-Right stereo. Use the MS stereo headphone monitoring options for this. MS stereo headphone modes sends discrete M and S signals to record tracks while sending Left-Right (decoded) audio to the headphones.
For the MS decoder to operate properly, the Mid signal is connected to input 1 and the Side signal to input 2. The amount of stereo “spread” is factory-fixed to a 50/50 percentage from Mid to Side signal using the MS stereo headphone routing options.
Decoding MS While Monitoring MS
If MS signal is decoded by the 7-Series to record Left-Right stereo, navigate to the Setup Menu option Input 1,2: Linking MS and select Linked 1,2 and M/S. This allows the user to control the gain of both microphone capsules from Input 1's gain pot and the mid-side control with Input 2's gain pot.
For the MS decoder to operate properly, the Mid signal is connected to input 1 and the Side signal to input 2. With this setup, the recorder decodes the MS signal; there is no need to use the MS stereo headphone monitoring option when decoding MS at the input. Recording the decoded MS signal and using a MS stereo monitoring option at the same time will decode the MS signal twice resulting in discrete M and S signals in the headphone monitor. The decoded MS signal is can be monitored by selecting Tracks A,B as the headphone monitor source.
Learn more about MS Stereo Basics.