The EM Poll

Sound Design Workshop: Imaginative Processing

Dec 1, 2007 12:00 PM, By Brian Smithers

           

How to make the most of multimono surround plug-ins.

BONUS MATERIAL
Web Clips: Hear audio examples of delay and divergence

FIG. 1: Sonar’s SurroundBridge makes any mono or stereo plug-in available as a selectively linked set of processors on a surround bus.

Once you start creating in surround, working in stereo feels like painting with half your palette missing. With an immersive sound field, you have many more ways to craft a sound or to frame a musical thought. Cakewalk Sonar Producer's surround capabilities offer plenty of creative options. I'll assume you know the basics — how to create and use a surround bus, how to assign audio channels to outputs, and so forth. Here I'll focus on the sound.

Although my examples use Sonar Producer 6, you can accomplish the same thing in the other major digital audio workstations that support surround mixing. (Digidesign Pro Tools LE is a notable exception; surround is an HD-only feature.) Each DAW has its own implementation and terminology, but the basic principles are universal.

Multiple Choice

Effects in surround can be multichannel, in which case they work across all channels in a unified way, or multimono, which is like having a separate mono processor on each channel. Although the multichannel method might seem more appropriate, especially for natural-sounding effects, each approach has its place.

I like to put a short multimono delay on lead instrumental or vocal sounds to give them a sense of space before adding reverb. In Web Clip 1, you'll hear short single-tap delays (10 to 15 ms) on the left and right channels, slightly longer delays (20 to 30 ms) on Ls and Rs, and no delay on center. In Sonar, you use SurroundBridge for this (see Fig. 1), which makes any mono or stereo effect available as linked processors on a surround bus. When the effect is bypassed, the center-panned sound just sits there in the middle of the room, but then the delays move it out of the center by simulating reflections from the walls.

The sound appears to be everywhere without being anywhere in particular, because the delays are decorrelated (no two delay times are the same). To allow this, go to the SurroundBridge tab and uncheck Controls Linked To Groups for all channels.

Once the sound sits in the surround field the way I like, I can apply reverb. I often prefer multichannel reverbs because they behave like a real space, allowing the sound to bounce from channel to channel as nature intended. Sometimes, however, decorrelating a multimono reverb is good for distancing the reverb from the dry signal.

Near or Far

In stereo, you control proximity of a sound by using EQ and time-based effects. In surround, it's possible to move a signal from the perimeter of the room to the center merely by panning. In surround parlance, this is called divergence, although the use of that term is not as tightly standardized as one would hope. High divergence values move a sound closer to the speakers, whereas lower values do the opposite and make the sound converge in the center of the room, right in the listener's lap. Divergence allows the signal from one speaker to bleed into adjacent speakers. In Sonar, this is called Focus.

In Web Clip 2, the sound walks around the perimeter of the surround field, first at maximum distance (Focus = 100), then in a smaller circle (Focus = 60), and finally in a small circle around the listener (Focus = 30). You can lock the radius of the circle by holding Alt as you drag the cursor.

To create a spiraling-in effect, automate several rotations at the perimeter, then go back and automate the Focus control from 100 down to 0. For a more even effect, draw the envelopes. Create an Angle envelope, and using the Saw envelope shape, drag from the top of the track to the bottom to create a clockwise spin (or vice versa), then drag to the right for the duration of the desired effect. The sound will pan one complete circle for every cycle of the Snap to Grid value. Halve the frequency by holding the Ctrl key as you drag; double it by holding Alt. To spiral in, create a Focus envelope, add a node at the top of the track for the beginning and another at the bottom for the end of the effect, and choose a linear curve from the envelope's right-click menu.

Brian Smithers is course director of audio workstations at Full Sail Real World Education and the author of Mixing in Pro Tools: Skill Pack (Thomson Learning, 2006).

BONUS MATERIAL
Web Clips: Hear audio examples of delay and divergence