So, what is an aux bus? I’d like to parse out the two terms individually for greater clarity. Luckily, it’s going to be much simpler than parsing long German words like “bezirksschornsteinfegermeister,” which kind of translates to “head district chimney sweep” (30 letters long and by no way the longest in the language).
A “bus” is most often defined as an audio sub-group that sums (combines) assigned audio sources into a single dedicated channel and fader—like your stereo mix bus that combines the outputs of all tracks. For example, you might want to combine (bus) all your rhythm guitars together onto one stereo channel for greater control.
The term “aux” describes another audio path that is auxiliary to the main path. Most of the time, these are aux sends and returns used for effects or a new track with audio sources that have been already bussed there for sub-mixing.
Having more collective options outside of individual tracks can really make your mixes feel and sound cohesive.”
The lines between “aux” and “bus” are further blurred because DAW programs treat this function differently. For example, in LUNA (Universal Audio’s DAW), you create a new “bus” (shift + cmd + N) which instantiates a new channel to which you will route the outputs of any desired tracks. Using the same key commands (shift + cmd + N) in Pro Tools, does the same function, but this time you’re creating an “aux input.” Other DAWs have different ways and names to achieve the same result as well. Be sure to read the help guides for your DAW on this subject.
Now, I want to focus on the efficiency of combining tracks that can benefit from being processed via a single channel (an aux send) or by being summed together for ease of mixing. There are two widely used ways to do this. Let me show you how.
Fig. 1
Effects Bus via Aux Send: One way to cut down on CPU-hungry plug-ins and make your tracks feel more unified is to create an aux send and place a particular type of effect on it. Let’s use reverb for example. In Fig.1, I’ve created a reverb bus where I can route various tracks in the mix. It could be a piano, snare drum, lead guitar solo, and the main vocal.
Fig. 2
All of these tracks’ outputs are routed to the reverb bus, and I can control the amount of reverb (either pre or post fader) by the send level within each individual track. Notice how my send levels are different for every track, and they are pre-fader [Fig.2]. In this situation, I am deciding how much signal is sent to the reverb for each track.
Fig. 3
Effects Bus: Another way of using a bus is to group multiple tracks to be processed together—background vocals and horn sections are great for this. In this case, you can create a new bus, route the chosen tracks to it [Fig.3], and apply effects that are more tailored to gluing the individual tracks into one larger, consistent sound by using a common EQ, compression, and anything else you deem worthy.
Fig. 4
When I do this with background vocals (BGVs), I typically use more compression and thin out the bottom end of the grouped singers so my main vocal will still sound rich and full-bodied. As a bonus, you can also place an aux send on this bus [Fig.4], route that output to our reverb bus as well, and adjust its level accordingly.
It’s not uncommon for me to set up four to five stereo busses on a typical mix (three different reverbs, an interesting delay or two). I may not use them all, but having more collective options outside of individual tracks can really make your mixes feel and sound cohesive.
If you have questions or suggestions, you can reach me at recordingdojo@premierguitar.com. Until next time, namaste.
Diving right in, what is a VCA? Think of it as a glorified volume-only control that uses voltage to adjust the amount of a signal’s/track’s volume when routed to its output.
Say you want to easily adjust the overall volume of your drum tracks within your mix. Perhaps you have several drum-loop tracks, drum machine soft synths with MIDI sequence tracks, and a full drum kit with multiple mics spread over multiple tracks (you know, a typical session). Or you might want to combine (sum) four individual rhythm-guitar track outputs into one VCA and be able to control the overall volume of all four from one channel. You can create a single VCA channel for all the drum tracks, another VCA for the rhythm-guitar parts, and then assign the outputs of those grouped tracks to their dedicated VCAs. Now, you can globally tweak the overall volume of all your drum tracks and all your rhythm guitars in your mix without changing the routing, plug-in levels, or effects sends, or the panning of any other tracks or groups.
The benefits of using VCAs really emerge after a mix has come together. For example, you might need to make an “all guitars up” version of the mix, or a “drums down 2 dB” version, etc. You may even want to automate volume rides in certain sections of a song—particular licks and fills, or even solos. You can also do this with vocals, background vocals, synths, etc.
Following the hypothetical example above, I’m going to show you how to create a VCA within Pro Tools and assign it to tracks of your choosing. Remember, every DAW has its own idiosyncratic way of creating and setting up a VCA channel, so be sure to consult your help section and/or read your instruction manual. Key commands may differ, but the process is essentially the same.
Fig. 1
Fig. 2
First, group (Cmd+G) all the tracks you want to be assigned to a VCA and name that group. I’ve named my group “DRUMS” [Fig.1]. Now, I’m going to create a VCA. Cmd+Shift+N, select VCA, and name it. I’ve named this “DRUMS” as well [Fig.2].
Fig. 3
Notice the new VCA channel and how there are no options for FX inserts, EQ, or panning [Fig. 3]? That’s exactly what we want, and it’s proof that we’ve set it up correctly.
Fig. 4
Finally, I’m going to assign my drums into a single VCA by clicking on the “no group” button and selecting “DRUMS” from the dropdown list [Fig.4]. That’s it!
Now you can rinse and repeat as many times as you like for as many instrument groups as you like. This is where VCAs really shine and can help you fine-tune specific volume relationships of instruments (and groups therein) within the fluid environment of a mix.
If you’re new to using VCAs, allow me to offer some suggestions that will help you get the most out of employing them. I use VCAs after I’ve shed proverbial blood, sweat, and tears obsessing over all aspects of the mix. Only after I feel like I’ve worked out a solid approach to EQ, compression, effects, parallel processing, outboard gear, aux busses, and all automation do I start using VCAs. On a self-judged scale of 0 to 10, my mix should be hitting about a 9. Then, I’ll typically fold all drum tracks into a single VCA, all bass (synth, stringed, etc.), all electric guitars (minus the solos), all synths and keys, all background vocals, and then group the lead vocal(s) and instrument solo(s) if appropriate. In this case, I have six VCAs to control the entire mix from a high level, and I can automate gain (volume) rides as needed to get that extra bit of focus and excitement out of the mix.
Next month, I’ll be guiding you through how to use aux busses to make your mixes better at an earlier stage.
Blessings and keep rockin’! Namaste.