How to Prepare for the Coming Storm of 5.1-Surround Projects

How to Prepare for the Coming Storm of 5.1-Surround Projects
You're Surrounded

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You need to route the recorded tracks into a mixing console that lets you pan them between five output channels. (There should also be a sixth output for the LFE channel, but you don’t pan anything from the main tracks to this output.) If you have a Yamaha O2R or O1V, Panasonic DA7, Tascam TDM4000, or Mackie Digital 8-Bus, you’re already in business. Each of these digital consoles lets you patch the outputs from the surround matrix (outputs) to an 8-channel mixing deck (more on this shortly).

If you don’t have a console with built-in surround panning, it’s relatively simple to patch the equivalent using sub- groups or aux sends (see the sidebar “Mixing Surround Without a Matrix”). But for ease of mixing, nothing beats a screen with a picture of the room and a cursor that shows where the sound ends up. Some consoles, such as the DA-7, provide a pair of controls on the work surface to pan left/right and front/rear, while others, such as the Mackie D8B, use a trackball or mouse.

Patch the console’s outputs to an 8-track deck, where your final surround tracks will reside (see Fig. 1). The Tascam DA-88 has become the standard multitrack deck for surround due to its popularity in the film industry, but any common 8-track format will work, including a computer workstation. You don’t need a Dolby Digital or DTS encoder to mix surround tracks; encoding is the last part of the process. Whatever you record your mix on, carefully note the track assignments. Unlike stereo, surround gives you many different track-assignment methods to choose from. The table “Surround Track Assignments” shows a list of the most common track-assignment systems, or modes.

Often you won’t be able to choose which channels end up on what tracks. For instance, both the Panasonic DA7 and the Mackie D8B mixers are set up in mode 4, whereas many large-format consoles and some mixing programs (such as Minnetonka’s MX 51 for Windows) are designed to be used in Mode 1. Try to pick one output format and note it on the label of every 5.1 tape you make. Eventually, someone will have to figure out your track assignments to encode them on a disc, and you don’t want your sloppy work habits to jeopardize a project.

Surround Track Assignments No standard has been established for assigning channels to tape/disk tracks for surround mixing. However, these six modes are the most commonly used. Make sure to mark every mix tape or file so the track assignments are clear to all who need to work with them. Note that tracks 7 and 8 can be used for recording a separate stereo mix. That way, if the end users choose to listen in stereo, they will hear a real stereo mix rather than a downmixed version of the 5.1 mix.
Track	1	2	3	4	5	6	7	8
Mode 1	L	R	Ls	Rs	C	LFE	Lt	Rt
Mode 2	L	C	R	Ls	Rs	LFE	Lt	Rt
Mode 3	L	Ls	C	Rs	R	LFE	Lt	Rt
Mode 4	L	R	C	LFE	Ls	Rs	Lt	Rt
Mode 5	L	C	Rs	R	Ls	LFE	Lt	Rt
Mode 6	C	L	R	Ls	Rs	LFE	Lt	Rt
Key: L = left, C = center, R = right, Ls = left surround, Rs = right surround, LFE = low frequency effects. Lt and Rt = left and right stereo mix.

Speaking Of Speakers
You’ll need to upgrade your monitoring system to include five speakers and a subwoofer so you can hear what you’re doing in 5.1 surround. The speakers are arranged in a circle around the listener’s head (see Fig. 2), and the channels are labeled L (left), C (center), R (right), Ls (left surround), Rs (right surround), and LFE. Feeding these speakers requires six channels of amplification. Keep the channel definitions in mind as I discuss patching options.

FIG. 2: According to the AES standard for 5.1 monitoring, the front left and right channels should be 30 degrees from center, and the two surround channels should be 110 degrees from the center.

The simplest and perhaps best setup for music mixing is five matched near-field reference monitors used with a subwoofer. I like the JBL LSR-28P and M&K 150 speakers, but I’ve heard some great mixes on the little Alesis Monitor Ones and Yamaha NS-10s.

Try to match the main speakers as closely as possible, because the relationships between the center, left, and right levels are critical, and the relationships between the front and surround levels affect the final mix much more than you might imagine. You could mix and match speakers—many excellent surround mixes have been done with mismatched center and rear-surround speakers— but I recommend you use a matched set to avoid putting yourself at a disadvantage.

The physical speaker layout is pretty simple (see Fig. 2). Just put a mic stand at the mix position and measure the distance from that position to the location of the center-channel speaker. Then cut a piece of string to the same length and tie one end to the mic stand. Mark the center-speaker position and go 30 degrees to the left and right for the front L/R speaker positions. Next, go 110 degrees to the left and right of the center for the Ls and Rs (surround) channels. This setup is the AES standard for monitor placement.

There is one exception to the “five matched speakers” rule. When mixing movie soundtracks, you don’t want direct-radiating, point-source surround speakers, because most movie surround effects need to be diffuse. As a result, the surround speakers should be dipole designs, which have drivers that fire forward and backward, creating a diffuse sound field. In this case, the surround speakers should be placed directly to the sides of the mixing position, 90 degrees from the center-speaker location. If you’re mixing multichannel music, use a pair of direct-radiating speakers matched to the front three speakers and placed at the 110-degree positions.

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