Finishing a Surround Mix

Working with music in surround sound is new to almost everyone, even veteran musicians, producers, and engineers. There are no rights and wrongs at this point. The picture you paint with a surround mix can be much more varied than with stereo. Do you create the illusion that the listener is watching a band that's up on a stage, or do you put the listener on the stage, in the middle of it all? Now that you know what the controls do, it's time to experiment with them. For this section, there is no formal exercisesimply play with your newfound surround toy and see what happens.

Filtering the LFE

Before bouncing your final mix, it's a good idea to remove frequencies higher than what your subwoofer can produce. The signal being sent to the LFE goes over a full-frequency channel, but the frequency response of the subwoofer generally limits what you hear to a low rumble. However, in some consumer 5.1 playback systems, users can indicate in their equipment configuration options that a subwoofer is not present, causing the LFE channel to be redirected into the main speakerswhich means the full-range signal of the LFE channel is heard through the main speakers. If that occurs with your song, the consumer will hear a mix that you never intended, and this could be quite disruptive to the overall sound of your song. By filtering the LFE output in Logic before bouncing, you eliminate any possibility that the full-range signal of the LFE will be heardregardless of a consumer's configuration.

So, let's go ahead and filter the LFE on your song's output.

1.	Open the Environment window and locate your surround Output Objects.
2.	Select the LFE Output Object.
3.	Click the Show EQs check box in the Object Parameter box. An EQ box appears at the top of the LFE Object.
4.	Double-click the LFE Object's EQ box. A Channel EQ plug-in is inserted into the channel and opens in a plug-in window.
5.	Click the Low-Pass Filter button in the top right corner of the Channel Equalizer window.
6.	By dragging up or down on the setting values as needed, set the Low-Pass Filter setting to 80 Hz, at 48 dB per octave. This frequency setting causes sounds with frequencies above 80 Hz to get quieter as their frequencies get higher. The setting of 48 dB per octave specifies how quickly the sounds above 80 Hz die away. You can see this filtering visually represented in the Channel Equalizer display. The filter point 80 Hz is common for the LFE channel (although some engineers set the LFE cutoff as high as 120 Hzit's a matter of personal preference). A subwoofer is designed to play only low frequencies anyway, so you don't want frequencies higher than 80 Hz in the LFE signal.
7.	Close the Channel Equalizer window.

Adjusting the Surround Mix Level

Currently, you have six Output Objects in the Environment. To raise or lower the volume of your surround mix, you need to raise or lower the volume of all six Output channels together, at the same time. You could group the channels and then adjust the volume, but there's an even slicker way. Logic provides a special Master Audio Object that controls the volume level of all outputs simultaneously.

1.	In the Environment's Audio layer, create a new Audio Object and position it as shown in the figure below.
2.	Assign the new Audio Object's channel to Master. The master fader affects the volume of signals going to any of the Output Objects in a song. If the master fader is turned down low, then the meters in the surround Output Objects will read low. If you raise the fader on the Master Audio Object, the volume of all the surround Output Objects will increase.
3.	Play your song.
4.	Raise and lower the Master Audio Object's fader. As you raise or lower the Master Audio Object's fader, the volume sent to the outputs is also raised or lowered.
5.	Set the master fader to a level that does not clip any of the Audio Output Objects.
6.	Close the Environment window.

TIP

When moving the output faders, select them all first, and then move one of them up or down. This links the faders temporarily to ensure that the relative fader positions remain the same.

Bouncing for Surround Sound

You've already learned in Lesson 1, "Exploring the Workspace," how to bounce a final mix when working in stereo. Bouncing in surround sound is basically the same thing, except you have to pay attention to more meters and change one simple setting.

1.	Choose File > Bounce. The Bounce dialog opens. Everything is properly set up with the exception of the Surround Bounce setting.
2.	From the Surround Bounce setting, choose 5.1. In this song, most channels are assigned to a 5.1 output, and the Bass channel is assigned to 5.1 without Center. When you use 5.1 for the Surround Bounce parameter, all Output channels and groups of Output channels that are part of a 5.1 mix are included in the bounced files.
3.	Type mySurroundStems into the Save As text box, and bounce the files to your desktop. TIP Since six files are going to be created, you may want to create a specific folder to keep them in.
4.	Look on your desktop. Logic has created six discrete "Surround Stems" files. Notice the extensions that are added to the end of the filename you chose. They indicate which speaker each audio file represents.

MORE INFO

At this point, the files you have are not capable of being heard by most consumers. They need to be encoded into a format that consumer playback systems understand, such as DTS or Dolby Digital. Logic does not have encoders built into it, but there are third-party programs that do. For example, Apple's DVD Studio Pro comes with a Dolby Digital encoder called A.Pack, which allows you to apply the 5.1 sound track you've created in Logic to your own DVD-Video discs! To learn more about A.Pack, check out Apple Pro Training Series: DVD Studio Pro 3, or visit macProVideo.com.