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Square One: Going, Going, Gone

1/1/2008

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FIG. 1: After selecting an audio clip in Steinberg Cubase, you can apply a fade-out using this dialog box. Preset curve shapes can be selected using the lower row of buttons, and the shape can be edited by adding breakpoints to the fade envelope. When you click on the Process button, the data in the audio file will be altered: this is a destructive edit operation, so you may want to make a backup copy of the audio file before proceeding.

Unless your music consists of a single phrase that loops repeatedly, your recordings will include transitions — places where one section or texture ends and another starts. If you've mastered the art of making transitions, your listeners will experience the music as dramatically coherent. Like a theatrical lighting designer, you'll be able to bring up a spotlight in one corner of the stage while dimming out other areas to allow the stage crew to scurry in and unobtrusively move the furniture. But if your transitions aren't working, the musical drama will contain moments that are jarring or confusing.

Transitions can be abrupt or gradual, and both can be musically useful. In the days of tape recording, abrupt transitions were handled with a razor blade and a splicing block. The tape would be physically cut apart and taped back together in as many as a dozen places in a single master multitrack recording. One careless slip, and days of expensive sessions would be ruined. Today we can do the same thing safely (nondestructively) by moving chunks of audio data with the mouse.

Gradual transitions are called fades. To create fades, tape operators would push the gain attenuation sliders (called faders) up or pull them down while recording the output of the mixing console onto a new tape track or a different reel of tape. The computer makes this process much easier and gives us more options. For one thing, we can experiment with different fade shapes until we're satisfied, without needing to worry about wearing out a strip of magnetic tape.

Beware the Curves

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FIG. 2: By clicking-and-dragging a fade handle in Mackie Tracktion, you can create a smooth linear fade-in or fade-out.

Everybody has heard fade-outs at the ends of recorded songs. At a strategic moment (usually when the last chorus starts to repeat), the level begins to drop. The music transitions smoothly to silence. But there's more to programming a satisfying fade-out than grabbing an amplitude envelope point with the mouse and dragging it down; a good editor will take advantage of the various fade shapes available to him or her.

A song fade-out should usually begin with a definite-enough drop in loudness that listeners will notice it, but it may end with the last faint notes lingering for quite a while. In other words, the fade will have a concave shape (see Fig. 1). If it has a convex shape, beginning very gradually and then finishing with a more abrupt drop, listeners may feel less satisfied.

When one section of a song transitions to another, individual tracks from the first section may fade out while tracks from the second section are fading in. Such a transition is called a crossfade. With crossfades, a slightly convex shape (called an equal-power crossfade) is often the right choice for both the fade-in and the fade-out. For technical reasons, if you use a straight linear fade-out of one track at the same time as a straight linear fade-in of another, the ear will perceive a drop in loudness during the middle of the fade. In an equal-power crossfade, the overall loudness will remain constant throughout the transition.

This is also true when a track is being panned across the stereo field. Stereo panning is a type of crossfade between the left speaker and the right speaker. If the crossfade is linear, the panned signal will get quieter as it passes through the center position. An equal-power crossfade, which is implemented by default in many mixers, solves the problem.

On occasion, you may want an abrupt transition from one texture to another, but simply jumping from one audio clip directly into another may be too abrupt. You may even hear a pop, click, or thump at the transition point. The solution is a quick fade, also known as a de-click envelope. An audio clip can be given a fade-in or fade-out that's only a few milliseconds in length. The ear won't hear it as a fade, but the transition will be smoothed.

Fadeology 101

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FIG. 3: Each audio clip in Ableton Live can have its own volume envelope. Here, a 6-segment convex envelope is being programmed to create a fade-in.

The manual for your multitrack recorder will help you understand the features it provides for creating fades. Several methods are in common use. You may be able to drag a fade handle at the beginning or end of an audio clip using the mouse (see Fig. 2). If you drag one audio clip so that it overlaps another, the recorder may crossfade between them automatically and allow you to choose a crossfade type from a dialog box.

More-complex fades can be handled using track automation. For instance, at the end of a song, you might want all the instruments to fade out smoothly while the vocal starts to fade out and then fades in again (perhaps with different effects processing) for a final moment of intimacy. To accomplish this, you would need to control the instrument fades with one automation envelope, perhaps by assigning those tracks to a mixer group for convenience, while controlling the vocal with separate automation envelopes.

Recording your fades as automation data is a good technique if you prefer to “play” the fade intuitively rather than relying on a visual analysis. With a hardware fader box, you can mix fade-ins and fade-outs exactly the way tape operators did in the days of analog recording, yet retain the ability to edit the fades afterward (handy if someone jogs your elbow in the middle of a sensitive move).

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FIG. 4: In Image Line FL Studio, volume envelope segments can be given a positive or negative curvature. Here, a convex fade-in envelope requires only one segment.

Some DAWs provide a multisegment amplitude envelope for each audio clip. A multisegment envelope can be used to program a fade-in or fade-out of any required shape (see Fig. 3). Some DAWs allow the curvature of each envelope segment to be adjusted (see Fig. 4). In that case, you can create curved fades using fewer segments.

If an instrument is fading in at the beginning of a new section, you might find an EQ fade or an effect fade useful. Try applying a lowpass filter to a track, and then produce the fade-in by raising the filter cutoff frequency so that the track starts as a low rumble and then emerges into the foreground as the high frequencies are added.

For an effective reverb fade-in, use a prefader send to route the track to a reverb. At the beginning of the fade-in, only the reverb return will be heard, so the track will sound distant or ghostly. As the dry signal fades in, bring the reverb return down (using another fade envelope) so that the wet and dry signals are balanced the way you want them.

As these examples show, the humble fade can be turned into a potent dramatic tool. With a little experimentation, you'll discover an unlimited number of uses for this handy function.

Jim Aikin is a frequent contributor to EM. His new interactive fiction novella, Lydia's Heart, is available for download from his Web site (www.musicwords.net).

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