Using Buses and Aux Channels:

You can automate several
channels together by using groups. Click on a track name, then shift-click on
any other track names that you’d like to treat the same, then hit “command G”
and name the group. Then, any automation will control all tracks in the group
together. But there are even more flexible and powerful ways to do the same
thing. Let’s say you have several tracks that all need to move up or down in
unison, such as layered tracks of ambience, or several overlapping voices, but
you’d like to retain the ability to easily tweak the individual elements as
well. Bouncing would eliminate your ability to change the balance among the
tracks. You could simply highlight the tracks and make a group, which would
let you write automation data to all the grouped tracks equally. But it can
get quite dizzying if you want to adjust an individual element’s volume, forcing
you to cancel the group, perhaps re-select a subgroup, make the change, re-activate
the group, and if you don’t like the change, you can’t easily get back to where
you started.

But if the outputs of the
tracks in question are sent to a “bus” instead of the main stereo mix, they
can be returned to the main mix through an aux channel. That aux channel can
then be automated or have effects applied to it, adjusting all sounds sent to
that bus equally. This is also an excellent, resource-saving method for processing
a group of tracks that need similar treatment. If several channels all need
the same kind of compression, or EQ, don’t insert a plug-in on every channel,
bus them together and insert one effect on the aux channel where they return.

A bus can be mono or stereo,
and which one is best will depend on what sounds you are busing. If all the
tracks are mono and can share the same pan position, choose a mono bus. If you
would like the tracks to have individual placements across the stereo spectrum,
or if you are busing stereo tracks, choose a stereo bus.
Forced Bussing:

Using buses creates an intermediate
grouping of tracks before the final output, which allows you to adjust several
tracks in one step. Buses are often used in music mixing to simplify control
of related inputs. For instance, if there are 8 or 10 mics on a drum kit, these
channels can be routed to a bus before the main outputs. Audio from those channels
can then be controlled by a single bus fader. That way each channel can be tweaked
separately, and the bus master can be adjusted to raise or lower the overall
level of the drums.

In the example below, tracks
3, 4 and 5 are routed to buses 1-2. Bus 1 and 2 are selected as the inputs for
an Aux channel. If you have found a balance of the three ambiences that you
like, but want all of the ambience to duck under the narration or acts, you
can pull-down the level of the Aux channel which will adjust all of the ambience
tracks at once. And if all of the ambience had rumble or hiss that needed EQ,
you could apply plug-ins to the aux channel rather than to each individual track,
saving processing power by reducing the number of plug-ins needed.

On the track’s channel strip
in the edit window, click on the “output” box and select a bus, or pair of buses,
rather than the main stereo outputs. Repeat this for all channels you want to
adjust together. Then create a new aux track, mono or stereo, depending on which
type of you need. Then, on that new aux track, click on the “input” box of its
channel strip, and select the name of the bus(es) where you just routed the
individual tracks. All channels that you designate to be output through the
bus, rather than the main stereo output, will be routed through this aux channel
first, and then to the main output.

That aux channel can now
be treated like any audio track, with plug-ins, volume changes, panning changes,
etc. Adjustments made to the individual audio tracks will still have an effect,
but you can also affect all channels assigned to that bus together, applying
the same compressor or EQ to several different tracks of voices, or tweaking
the volumes of layers of tracks.
Yes, Master…

Try to always use a master
fader, it not only creates a quick way to see if your final mix levels are correct,
but also creates one more stage at which effects or automation can be applied.
An EQ or compressor inserted on the master fader can bring a mix together in
a way that individual track adjustments cannot.

If a sonic element has unique
problems, apply plug-ins to that track alone. A compressor on the master fader
will unpleasantly squish background sounds if one track gets too loud. Rumbles,
hisses or peaks are better dealt with on specific channels, or if shared by
several tracks, on a bus. A gentle gain-controlling compression and peak-limiting,
and overall EQ smoothing are best applied to the master fader.

With or without effects,
remember that all the tracks are interacting, sometimes the way to make an element
more prominent in the mix is to reduce the level of the other tracks, rather
than turning it up. Or as is routinely done in music mixes, make room for the
primary sound by EQing the background to clear out the frequency ranges that
compete.

And in the end, use your
ears to decide what’s right. Digital editing programs have the tremendous advantage
of providing visual feedback that can help make decisions, but in the end, it
doesn’t matter how lovely your automation curves are drawn, it matters how your
mix sounds.

 

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