The Audio Track Mixer in Premiere allows us to control our sound in some very sophisticated ways. One of which is using Sends and Buses.
The reason this is important is that a Bus allows us to group similar audio – for example, all the male voices which are stored on different tracks – and apply a single audio filter – for example, an EQ or a Compressor/Limiter – to the entire group at once.
This simplifies audio mixing while giving us simplified control over our sound.
NOTE: A professional audio mixer will say: “Whoa! You may not want to do this in every case.” And they’d be right. But if deadlines are tight, your audio levels are all over the map and you don’t have the budget for a professional audio mix, this technique can bail you out.
Let me illustrate.
Here’s an example. I have male voices on A1 and A3 and female voices on A2. A1 is on-camera talking heads while A3 is the narrator.)
What I want to do is even out the levels for all the voices, then apply EQ settings to each groups to enhance their legibility.
While we can do this on a clip-by-clip basis, it is much easier to gather all the related tracks into a single bus, then apply filters to the bus to create the audio settings that we need. In this example, I’ll create a bus for the men’s voices and a second bus for the women.
It is always best to do your audio mix after your edit is complete. Then, in Premiere, choose Window > Audio Track Mixer to display the mixer. (There are two mixers in Premiere. This technique is designed for the Track Mixer.)
At first blush, the Track Mixer is extremely intimidating. However, the mixer is divided into separate vertical “channel strips” – one for each track in your sequence. All channel strips are identical. So, once you understand how one channel strip works, you understand all of them.
NOTE: In the Mixer, I renamed all six tracks by double-clicking the track name then changing the label to something that makes more sense.
CREATE A BUS
A “bus” allows you to gather multiple audio channels into a single audio channel. This allows us to simplify setting levels, adding effects or controlling output. Just as a city bus picks up people from all over the city and takes them to a common destination, an audio bus picks up audio from a variety of tracks and puts it all in one spot.
To create a bus, which Premiere calls a “Submix Track” go to Sequence > Add Tracks. Be sure to set both Video and Audio tracks to 0, so you don’t add unwanted tracks to your project.
I set the track to Mono because all my voices are mono. If I was feeding music or sound effects to this bus I would set it to Stereo. (Once you create a Submix, you can’t change it from Mono or Stereo. You’d need to delete that Submix and create a new one.)
When you click OK, a new Submix bus is added to the mixer (and your sequence). You don’t do anything with this in your sequence, all the work happens here in the Track Mixer.
NOTE: I repeated this process to create a second bus, then renamed the first bus “Male VO” and the second bus to “Female VO.”
ROUTE THE AUDIO
A bus collects whatever audio you feed to it into a single output. So, now, we need to route the audio from a specific track into the bus. In this example, I’m going to route audio from A1 and A3 to the Male VO bus. Then, route audio from A2 to the Female VO bus.
The easiest way to re-route audio from a track to a bus is to select the name of the bus from the popup menu under the word “Master.”
NOTE: By default, all audio tracks route directly to the Master channel for output. Also, by default, the Master channel is stereo. This routing must be changed to use submixes.
When we switch this routing to Male VO, the audio from Track 1 (Male OC) goes directly to the Male VO bus. The audio levels respect all keyframes applied to clips in the track, keyframes applied to the track, and/or the position of the fader in the track.
I’ve routed the first three tracks to the Male and Female buses. Notice that the pan controls have disappeared. Why? Because the bus was set to mono, which means that panning is no longer relevant for the source track, though we can still pan the bus track if we wish.
Although this is not necessary, I’ve also set the audio faders for all three tracks to 0 dB.
NOTE: A fast way to move a fader to the 0 dB position is to double-click it.
ADD AUDIO FILTERS
We now have our buses created and the audio routed. Next, we need to add audio filters to the two busses to smooth out levels and “sweeten” the voice.
To display the FX controls, click the small, right-pointing arrow at the top left corner of the Mixer to twirl it down and open.
The top section allows you to add up to five audio effects. The bottom section allows us to send audio from each track up to five different buses. For the sake of simplicity, in this example, we are only sending each channel to a single bus.
Click the small down arrow in the top section to display audio filters. Here, I’m applying the EQ filter, which allows me to increase or decrease specific frequencies to enhance a voice.
Here’s the filter, applied to the bus. I always start with the second slot, in case I want to add another effect later, I have slot 1 available.
NOTE: Yes, stacking order makes a difference. Audio filters process from the top to the bottom.
Next, I’ll add the Multiband Compressor filter to control levels.
This effect must always be in the bottom track, below all other effects.
To display the controls for an effect, double-click its name.
NOTE: Here’s an article on how to use the EQ filter.
And here’s an article on how to use the Multiband Compressor. Although written for Adobe Audition, the filter works exactly the same in Adobe Premiere.
All buses automatically output to the Master track, so you don’t need to change the routing on a submix track.
At this point, all your voice tracks are now shaped and controlled by these two buses. This means that as you adjust your effects, you are altering all your voice tracks by the same amount. Also, because you are reducing the number of filters applied to a mix, you are freeing up the CPU to concentrate on other tasks – like video playback.
The power of a bus is its ability to reduce the number of effects you need to apply, simplify your mix and provide more control over a multiplicity of tracks in the Timeline.
If you only have one or two tracks, you never need to use a bus. Applying filters directly to the track makes more sense. But, as your mixes get more complex, buses can help you keep them organized and under control.