Setting Up a Mid-Side Matrix In Logic

Decoding Method using a M-S Plug [jump]

Decoding Method using Mixer Patching [jump]

Note: The below steps in Logic Audio are deemed necessary unless we find a way to directly perform M-S decoding with “plugs” within video Editors like FCP, Premiere, AvidDV etc. Should you come across a simpler M-S decoding solution, please email Rob D. <type@uwm.edu> so we can update the resources. It would, of course, be much better to be able to create the stereo image and make adjustments to it within the video editing application.

Currently in the Film Department, one can generate M-S stereo recordings with the “Backpack” and the Stereo Boom Mic Kits. The former use a Rode NT1-A Cardioid Mic as the “Mid” and a CAD M-179 Mix as the Figure 8. The Boom Kit uses Sennheiser MKH60/MKH30 mics. The below steps assume you have generated your field recordings on Hi-MD with a 44.1K native sample rate.

For sound-only project in Logic, the same matrix set-up are used. In this case, there’s no need to export the M-S recordings as a normal “Left-Right” stereo file and re-import them—just use them in the Logic Sessions as described and they’ll be part of the stereo (or surround) mix.

After making and transferring a field recording with the ”Mid” Cardioid Mic plugged into the Left/Ch 1 input of the recorder and the “Side” (Figure 8) Mic plugged into the Right/Ch 2 input of the recorder, you must create a standard Left-Right stereo sound file in Logic to get stereo in FCP, Premiere or AvidFreeDV.

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There are two ways to create a normal “Left-Right” stereo sound file. The first method described below is much simpler and its versatile if used with Tom Erbe’s Matrix plug recommended at the end.

Decoding using a simple M-S Plug

1. If you are going to use your recording in FCP, its best to convert the sample rate of the Hi-MD recording to 48K first. The instructions for this using QuickTime Pro are here.

http://www.uwm.edu/~type/FilmDept/TechWkshpManuals/ImportingHiMD_WavN2_FCP.pdf

2. Import your interleaved stereo, 48K, .wav file into Logic Audio. (f you get a prompt asking if you want to split the recording into “split stereo files,” select “load”). Under Hardware in the menu, check->Sample Rate-> 48 000. (If you are not importing the file into FCP, you can put the Logic Session in the Hi-MD native format: 44100 K)

3. In the mixer/environment window, set Input channel 1 to STEREO. STEREO is indicated by two circles “OO” at the bottom. If there is one circle (mono), click o the “O” and it will change to “OO.”

4. To insert the M-S decoding “Plug” into this channel and produce stereo playback, click-hold on an empty rectangle under the “Inserts” and select “DirMixer” with these contextual menu selections:

5. The insert shows like this:

6. Double click on the “Dir Mixer” button. In the window that opens, click-hold on the “L-R” and select “MS” from the pull-down window.

7. Drag you stereo interleaved file into the start of the Arrange Window on Track #1

Play the sound file and you should hear it in stereo. You can modify the image balance with the direction and Basis sliders if you wish.

8. Tom Erb has made a freeware, M-S decoding plug called, Matrix that might also be in the plug-in options or can be downloaded and installed in your personal OS X install:

Tom’s Matrix interface allows one to adjust the mid and side volume separately:

9. To export the normal “Left-Right” you are monitoring in Logic, click-hold-drag on the top half of the time scale at the top of the Arrange window to select the duration of the sound recording:

10. Play the sound file. Make sure the playback levels in the meters are extending near the top without causing the red over-load lights to come on. If the level is low, move the Input Siider for Track 1 up.

11. The button for outputting the mix is called “Bounce” in Logic. You can “jump: to th Channel 1/2 output channel of the Mixer by double clicking on the “OutPut 1-2” button:

Or scroll the bottom handle on the Mixer window to the right:

12. To create the new file, Click on the “Bounce” button at the bottom. In the window that opens, make these selections:

and click on “Bounce.”

13. In the file navigation window that opens, give your file a name that indicates that it is a normal stereo file and select the storage location:

14. Note that you have created a new, unique, sound file that should be backed-up on CD-R or other medium in case something should go awry with your FCP or Logic project at some future point. If your unique sound files are backed-up, you can rebuild your edit as it was with little loss of time.

Decoding using Mixer Patching

Note: The following method is considerably more involved. Its main advantage is that it permits one to perform equalization on the Mid and Side mics separately when very careful EQ is desired.

1. If you are going to use your recording in FCP, its best to convert the sample rate of the Hi-MD recording to 48K first. The instructions for this using QuickTime Pro are here.

http://www.uwm.edu/~type/FilmDept/TechWkshpManuals/ImportingHiMD_WavN2_FCP.pdf

[Note that you can also change the sample rate within Logic by double-clicking on the imported sound file and opening it in the Sample Editor. From the Sampler Editor sub-menu select, Factory->Sample Rate Convert and under Destination enter “48000.”]

2. Launch Logic. Under Audio -> Preferences, make sure the bottom two items are checked:

2. Import your interleaved stereo, 48K, .wav file into Logic Audio. When you get the prompt asking to convert the recording, select “CONVERT.” Note that the imported sound file is split into a Left “.L” channel and a “.R” channel.

3. Note that the imported sound file is “split” into Left, “.L and Right, “.R” channels

4. Under Hardware in the menu, check->Sample Rate-> 48 000. (If you are not importing the file into FCP, you can put the Logic Session in the Hi-MD native format: 44100 K)

5. Set Mixer input channels 1-3 of the Mixer/Environment Window into mono mode which looks like this:

6. Pan Input Channel 1 “Hard Left.” P an Input Channel 2 to “Center. ” Pan Input Channel 3 to “Hard Right” which looks like this:

7. To create the “decode” patch, the phase of the Right side channel must be inverted. To do this, click on an empty insert rectangle below the word, ”Inserts” in Mixer Channel 3 and select, “GAINER,” following these contextual menus:

8. Double click on the blue “Gainer” insert button. In the window that opens, click-hold on Normal and select “Invert” for the “Phase” cell.

9. The “split” tracks must be first be disconnected before that can be loaded separately into the Arrangment window. To do this Highlight both the left and right associated files:

10. Under EDIT in the AUDIO window submenu, select “Disconnect Selected Split Stereo Files.”

11. Drag-Drop just the Right channel (with .R suffix) into BOTH Tracks 1 and 3 of the Arrange Window:

12. Drag just the Left Channel (with “.L” suffix) into Track #2, the center or “Mid” track:

13. Click-Hold-Drag or “Scrape” across the top half of the timeline in the arrange window to select the duration of the file for loop play.

14. Press on the Space Bar to set the sound into loop play.

Note that you can adjust the volume of the “sides” with the sliders for Tracks 1 and. Normally, these are set at the same level. The volume in the center or middle is adjusted with the Track 2 slider.

As stated at the outset, the main advantage of this mixer patch method is that it permits one to perform equalization on the Mid and Side mics separately. In most cases, the same equalization should be used on the Left and Right “side” channels (tracks #1 and #3) and different EQ, needed to address the “mid” mic can be inserted on Track #2.

15. The button for outputting your Normal Left-Right Stereo mix (with or without EQ) is called “Bounce” in Logic. You can “jump” to th Channel 1/2 output channel of the Mixer by double- clicking on the “Output 1-2” button:

Or scroll the bottom handle on the Mixer window to the right:

16. To create the new sound file, click on the “Bounce” button at the bottom. In the window that opens, make these selections:

and click on “Bounce.”

17. In the file navigation window that opens, give your file a name that indicates that it is a normal stereo file and select the storage location:

18. Note that you have created a new, unique, stereo sound file that should be backed-up on CD-R or other medium in case something should go awry with your FCP or Logic project at some future point. If your unique sound files are backed-up, you can rebuild your edit as it was with little loss of time.

Rob Danielson 11.2006