Configuring External Audio Monitors

The following section describes how to connect external audio speakers to your editing system and how to make audio level adjustments in Final Cut Pro and Mac OS X.

Connecting Speakers to Your Editing System

When you add audio speakers to your editing system, you need to make sure that the speakers are properly connected to your audio interface or built-in computer audio output and that the interface is properly configured in Final Cut Pro.

To connect self-powered speakers to your computer
  • Connect the main left audio output of your audio interface to the left speaker, and connect the main right audio output of your audio interface to the right speaker.

For more information about types of audio connectors and adapters, see Connecting Professional Video and Audio Equipment.

Monitoring 5.1-Channel Surround Sound

Final Cut Pro does not support multichannel surround sound mixing capabilities or editing of speaker assignments, but you can configure your system to monitor certain kinds of 5.1-channel surround sound audio files. If you have 5.1-channel surround sound files that have been mixed in another audio application such as Soundtrack Pro, you can import these files and then configure your audio outputs and hardware to monitor in surround sound.

Important: A multichannel audio interface and speaker system with at least six channels is required to monitor surround sound.

Figure. Diagram showing the relationship between audio tracks and an audio interface and speaker system with six channels.

There are two ways of configuring your sequence audio outputs for 5.1-channel surround sound monitoring:

  • Use the 5.1 Monitoring audio preset: If you know in advance that you are going to edit a 5.1-channel surround sound file into your sequence, you can assign the 5.1 Monitoring audio preset to your sequence.
  • Use the Match Audio Outputs command: This command automatically configures your sequence audio outputs and track output assignments based on the currently selected audio clip in your sequence. You can select a 5.1-channel surround sound clip in your sequence and use the Match Audio Outputs command to automatically configure your sequence outputs.
To configure Final Cut Pro for 5.1-channel surround sound monitoring using the Match Audio Outputs command
  1. Import a multichannel surround sound QuickTime audio file into Final Cut Pro.

    Note: Final Cut Pro supports only surround sound audio files that contain the MPEG_5_1_A QuickTime audio track tag and whose channels are ordered in the following sequence: left and right, center, LFE, and left surround and right surround.

  2. Edit the multichannel clip into the Timeline.

    In most cases, you should place the audio clip starting on track A1 in the sequence.

  3. A clip with six linked clip items appears in the Timeline.

  4. Choose Edit > Linked Selection, and make sure that a checkmark appears next to the Linked Selection menu item.

  5. Select the clip in the Timeline.

  6. Choose Sequence > Match Audio Outputs.

  7. If Final Cut Pro alerts you that your sequence’s audio outputs will change, click OK.

    Final Cut Pro alerts you that your sequence’s audio outputs have changed to match the stereo and mono groupings of the selected clip items.

  8. Verify the audio output assignment of each track by Control-clicking the Lock Track control or Auto Select control of each track and checking the audio output assignment in the Audio Outputs submenu of the shortcut menu.

    For more information, see Assigning Tracks in the Timeline to Audio Outputs.

  9. Connect your 5.1-channel surround sound speaker system to the appropriate channels of your audio interface.

Setting Monitoring Levels and Muting System Sound Effects

When you mix your audio, it’s important to monitor using a consistent volume setting. If a sound is too loud in the mix, you should adjust the level of the audio in Final Cut Pro, not the volume setting on the speakers themselves. Once you set up your audio monitoring levels, you should not need to adjust the overall volume setting of your audio very often.

If all of your audio is consistently too quiet or too loud, you should probably change the overall volume setting for your speakers and then keep it at this new level. There are a few different places to adjust the volume, including the volume knob on the speakers themselves.

If you are using the built-in audio output of your computer, you can adjust its volume in the Sound pane of Mac OS X System Preferences, by using the volume control keys on the keyboard, or by using the built-in volume slider in the menu bar.

To adjust the built-in volume of your computer using the volume slider in the menu bar
  1. Open System Preferences by choosing Apple menu > System Preferences, then click Sound.

  2. In the Sound pane of System Preferences, make sure the “Show volume in menu bar” checkbox is selected.

    When the checkbox is selected, a volume icon appears in the menu bar.

  3. Adjust the volume in the menu bar.

    You can also adjust the volume in the Sound pane of System Preferences.

To mute all alert and Mac OS X user interface sound effects
  1. Choose Apple menu > System Preferences, then click Sound.

  2. Click the Sound Effects button.

  3. Deselect the “Play user interface sound effects” checkbox.

  4. Deselect the “Play feedback when volume is changed” checkbox.

  5. Slide the “Alert volume” slider all the way to the left.

If you are using an audio interface other than the built-in audio, you can route the alert sound effects to the built-in speakers, but monitor Final Cut Pro audio from your audio interface.

To route Mac OS X alert sounds and sound effects through your computer’s built-in speakers
  1. Choose Apple menu > System Preferences, then click Sound.

  2. Click the Sound Effects button.

  3. Choose “Built-in Audio: Internal speakers” from the “Play alerts and sound effects through” pop-up menu.

While monitoring the audio of your program, avoid changing the volume setting of your speakers unless it is absolutely necessary. A consistent monitoring level allows you to get used to the average loudness you’re establishing for your mix, so that you can better judge how well the louder and softer sections of your mix are working together.

To adjust the volume setting of your speakers, try playing a signal that represents the average volume you want to monitor. Avoid setting speaker volume so high that it fatigues your ears or distorts in the speakers.

Some people use the 1 kHz tone of the Bars and Tone generator to set the volume of their speakers. However, you may find that the 1 kHz tone causes you to lower your speaker volume more than you would for normal audio because the tone is so incessant and your ears are particularly sensitive to this frequency. Generally, 1 kHz tones are useful for setting levels from device to device when looking at meters, but not as helpful for setting average listening levels.

Tips for Choosing Speakers and an Amplifier

Professional audio engineers have to be able to trust the sound coming from their speakers. When you mix your audio, you need audio monitors that can handle the full range of audio intensities and frequencies. Ideally, your monitors will have a flat frequency response from 20 Hz to 20,000 Hz (or 20 kHz). This means that they neither attenuate nor amplify any frequencies. Flat frequency response is important for critical listening because the speakers themselves are not “coloring” the sound.

In addition to the speaker quality itself, additional factors affect your audio monitoring environment:

  • Size and materials of the room

  • Placement of the speakers within the room, such as distance from walls and angle of speakers

  • Listener position between speakers

Frequency Response and Dynamic Range

The quality of speakers varies greatly depending on their purpose as well as their price. For example, speakers in a portable stereo or television are designed to play audio that has already been mastered by a mixing engineer. Mastered audio such as audio CD, radio, television, and movie sound has a compressed dynamic range (meaning levels are fairly consistent and loud).

Speakers and amplifiers that are designed for mastered audio often intentionally emphasize certain frequencies, as is done with the bass enhancement feature found on many systems. This may make an audio CD sound better, but it is not recommended for mixing production sound because you get a false impression of the audio signal. For example, if your speakers overemphasize frequencies around 2 kHz, you may compensate during mixing by reducing the intensity of audio around 2 kHz. If you then play your mix on a different set of speakers with a flat frequency response, the frequencies around 2 kHz will sound too muffled.

Figure. A diagram showing a flat frequency response and another showing a not flat response.

Self-Powered Versus Passive Speakers

Speakers powered by an external amplifier are called passive speakers. When you use separate amplifiers and passive speakers, a number of factors affect the overall frequency response and quality of your audio. Instead of using a separate amplifier and speakers, a simpler option is to use self-powered speakers (speakers with built-in amplifiers). These have become increasingly popular, especially for studio monitoring and video editing.

Self-powered speakers deliver more consistent performance because both components are designed to work together and are housed in a single enclosure. For video editing systems, self-powered speakers are a good, easy-to-use solution. Self-powered speakers accept line level inputs, so it’s fairly easy to connect them to your audio interface.

Amplifiers and Signal Levels for Unpowered Speakers

Unpowered speakers require signals with higher voltage than consumer and professional equipment can provide directly. These levels are known as speaker level audio signals, while audio devices such as tape recorders and audio mixers usually provide line level signals. An audio amplifier boosts line level signals to speaker levels to properly drive speakers. Wide-gauge speaker cables that can handle the higher electrical strength of speaker levels are used to connect the amplifier to speakers. For more information about audio signal levels, see Connecting Professional Video and Audio Equipment.

Setting Up a Proper Audio Monitoring Environment

Room shape and material are just as important as the quality of the speakers themselves. Every surface in a room potentially reflects sound, and these reflections mix together with the sound originating from the speakers. Rooms with parallel walls can create standing waves, which are mostly low-frequency sound waves that reinforce and cancel each other as they bounce back and forth.

Standing waves cause some frequencies to be emphasized or attenuated more than others, depending on your listening position. When you mix in a room that creates standing waves, you may adjust certain frequencies more than necessary. However, you may not notice until you play back your audio in a different listening environment, in which those frequencies may sound overbearing or nonexistent.

Tip: A much cheaper alternative to building new walls is to mount “bass traps” to the existing walls. Bass traps help to eliminate parallel surfaces in the room and absorb low-frequency energy.

If the material in a room is very reflective, the room sounds “brighter” because high frequencies are easily reflected. Mounting absorbing material (such as acoustic foam) on the walls can reduce the brightness of a room. A “dead room” is one that has very little reflection (or reverberation). Try to cover any reflective surfaces in your monitoring environment.

Speaker Placement and Listening Position

Most video editing suites use near-field monitors, which are speakers designed to be listened to at fairly close range. Speakers should be at least a foot or two away from any walls to prevent early reflections of sound, which combine with and muddy the original sound.

Position the speakers as far from your listening position as they are from each other (forming an equilateral triangle). For example, if the distance between the speakers is 6 feet, you should place yourself 6 feet from each speaker. The apparent width of the sound stage, or stereo image, increases as the distance between the speakers increases. However, if the two speakers get too far apart, sound information appearing in the center (between both speakers) starts to disappear.

Using Headphones

Many people use headphones as an alternative to monitoring speakers. Headphones provide isolation from ambient noise in the room where you are mixing, adding additional clarity that may not be obvious in your speakers a few feet from your ears. This clarity can be helpful for cleaning up low-level noise and pops created by misaligned edits. However, don’t rely solely on headphones when you mix because level and pan adjustments you make may be too subtle or delicate for the average viewer listening to your movie on speakers a few feet away. Headphones often have a different frequency response than full-range speakers, so if you mix using headphones your audio may sound bass-heavy when played back on speakers.