We've just started our surround mixing tutorials this week and today we had a brief primer on surround mixing techniques. I thought some of you might be interested and may have some of your own techniques as well.
Considerations
These also apply when mixing in any format: Mono, Stereo, Surround
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- A louder sound will mask a softer sound that occupies the same frequency ranges.
- Original sound may become fused with reverb; increasing pre-delay allows the reverb to be isolated and thus more distinguishable from the original sound.
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- Any delay/reverb <= 40ms will fuse with the original sound
- In stereo or surround, the first sound you hear dictates the sound's placement; even if the delay/reverb is louder than the original sound.
1 foot = 1ms
- A more accurate sense of space can be achieved by applying this rule to reverbs and delays.
The Magic Surround
- When mixing music in surround, delaying the output to the surround speakers will give a larger sense of space to the sound.
Sound Positioning
These conventions mainly apply to film surround sound. But they are also relevant for surround music mixing.
Center - Dialogue and Sync FX
Left & Right - Music & Atmos FX
Surround - Atmos FX
Low Frequency Effects - Specific low frequency effects.
Cinema Mixes
Surround sound operates with a discrete center channel and not a phantom center as you find in stereo. A discrete center channel has its own audio track. Whereas a phantom center is implied by an even positioning between left and right.
Having a discrete center channel ensures that an accurate positional image is maintained regardless of where somebody is sitting in the audience. If surround sound relied on a phantom center, someone sitting close to the left or right of the cinema would perceive any dialogue or sync fx as coming from the left or right. The discrete center channel ensures that these elements will always be heard from the center of the screen.
The low frequency effect (LFE) is essentially a sub. However, like the center channel, this has its own discrete channel instead of employing the use of a crossover. Most cinema left, right and center speakers have a full range so a crossover is not necessary. In a home theater environment, a sub with crossover will usually be used to compensate for this lack of range.
DVD Mixes
The major advantage of mixing for cinema is that the soundtrack will always be played at 83dB spl. Mixing for DVD tends to be more difficult because you cannot mix for a specific
[ Only registered and activated users can see links. Click here to register ]. For audiences, this means that you'll either have to watch dvds with full sound, or deal with the fact that some sound may be obscured when playing back at lower levels.
Domestic surround systems usually don't have a matched front row of speakers. That is, the Left & Right tend to have the best range and output while the center is smaller and lower-range so that it can sit on top of the television. Some surround mixers thus choose to pan some of the center channel to the left and right channels. However, mostly they don't bother.
The best solution to this problem is to make sure the next surround system you purchase has full level control over each speaker set so that you can turn the center up and the left and right down in order to get a fuller sound.
Concert Mixes
Although mixing to vision, the vision doesn't necessarily determine sound positioning. Some conventions in practise today involve positioning the band in the Left & Right speakers, vocals in the Center and crowd noise in the surrounds. In addition to this reverb and effects sit nicely in the surrounds, enhancing the live feel of the performance. Extreme surround effects should be avoided - ie: if a guitarist is standing to the far left of stage, soft-pan to the left instead of hard-panning.
Music (not to vision)
Obviously, there are a lot less conventions and rules with surround music mixing. The most common thing to find is that engineers will avoid using the center channel and instead rely on phantom center unless they are applying a specific effect.
Defining Space
- There is usually less use of surrounds for interior shots as this creates a smaller sense of space. If surrounds were used on an interior space it would be either to imply a larger space, or to define wall sounds and atmospherics (like muffled traffic or cafe noise).
- Center dialogue can be left dry, with reverb adding space in other channels. Much like in the real world where direct sounds do not have reverb present.
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