In this tutorial, you will learn the various Track Types in Pro Tools. Track Types are one of the key elements in understanding how Pro Tools works, how it translates the concept of a hardware mixing console into a virtual mixing environment. I will demonstrate that with easy to understand signal flow diagrams.
Different Signals - Different Flows
In the tutorial "Audio Clips vs. MIDI Clips', I already pointed out that in music production you have to deal with two types of signals, Audio signals and MIDI signals. This is especially important to look out for when it comes to the different Track Types and their individual signal flows.
What Do You Control, Audio Or MIDI?
Many onscreen controls or indicators in Pro Tools that are related to the signal flow or signal processing (mostly in the Mix Window) can "belong" to an Audio signal or MIDI signal. That means, you will alter either an audio signal or a MIDI signal, which, of course, is a big difference.
Here are a few examples:
- Fader ➊, Pan ➋, Mute & Solo ➌: Those common controls on a channel strip might affect an audio signal or a MIDI signal depending on the Track Type.
- Meter: Usually, a meter displays a level of an audio signal ➍. However, even if it looks the same with the same color coded segments, it could indicate MIDI Velocity values ➎.
- Channel Strip: A channel strip, the replica of an audio mixing console, is something that controls audio signals. However, there are "imposters" in Pro Tools' Mix Window that only control MIDI signals (MIDI Tracks ➐), or even more confusing, control audio and MIDI signals (Instrument Tracks ➏).
- Duplicate Controls: The Instrument Track, for example, has two Mute Buttons ➑, one for the audio signal and one for the MIDI signal, so you better know which one is which.
Clip Type ➤ Track Type
The next diagram shows the relationship between the Track Types and the type of Clip (Audio Clip or MIDI Clip), which determines if you are feeding an audio signal (blue) or a MIDI signal (green) into the Channel Strip.
- Audio Clips: You can feed an Audio Clip ➊ (which represents a pre-recorded audio file) to the Channel Strip, so its audio signal (the sound) can be altered by using all the controls on a Channel Strip ➋. For example, you can apply an EQ, compress it, or add some reverb, or any kind of effect to make it sound more interesting. Or, just set the right level and pan position.
- MIDI Clips: MIDI Clips ➌ are different. They only contain raw MIDI data, which are "instructions" on what and how to play your music. That MIDI data is routed to a MIDI Track ➍. Although it looks like a standard Channel Strip, its controls are MIDI controls that affect the MIDI data (MIDI Volume, MIDI Pan) and not any audio signal. Like a written score that needs an orchestra or a performer, MIDI Clips also need someone to "make it sound". That's why the Track output can be routed to a MIDI Sound Module ➎ (internal or external). Its audio output ➏ can then be sent back to one of the Audio Channel Strips ➐ in the Mix Window to be processed as an audio signal. Please note, that an Instrument Track is a special "two in one" Channel Strip that has controls for the audio signal and MIDI signal.
Now let's have a look at the signal flow diagrams of the five main Track Types in Pro Tools and see how they differ regarding the signal flow and their available components. I mark all the audio elements blue and the MIDI elements green. I discuss the topic about the routing (Input, Output, Sends) in a separate tutorial.
This is the basic signal flow of an Audio Track:
- Audio Clips ➊: The specialty about the Audio Track is that it is the only Track Type that lets you record audio signals on its Track Lane (Audio Clips). Those Audio Clips function as an additional input source during playback.
- Bus Input ➋: Please note that instead of routing an input signal from your audio interface (Input Busses = interface), you can route any signal from an Auxiliary Bus ("bus") to the Audio Track. That lets you record a signal of a different Track (Instrument Track or Aux Track) by routing it to a specific Auxiliary Bus on those Tracks and using that Auxiliary Bus as the input on an Audio Track.
- Metering: Also, pay attention to the Track Level Meter, which has an additional function. Instead of showing the Pre Fader or Post Metering, during recording, it shows the level at the Track's input ➌ before any Inserts.
Aux Input Track
This Track has the same components as the Audio Track with the exception that you cannot record audio on it, only pass audio through it.
- External Audio Sources: You can use the Aux Input Track as the audio input ➍ of External MIDI Sound Modules or any other audio source.
- Internal MIDI Sound Module: Loading an Instrument Plugin on the first Insert Slot ➎ of the Aux Input turns it into a MIDI Sound Module that can receive MIDI signals from any MIDI Track or Instrument Track in your Pro Tools Session.
- Audio Submix: A common use for Aux Input Tracks is to use it for "submixes". Route the output of multiple Audio Tracks (i.e. all backing vocals or all drum tracks) to a specific Auxiliary Bus and use that Auxiliary Bus as the input source ➍ on an Aux Input Track and process them as an audio group.
The MIDI Track carries only MIDI signals.
- MIDI only: As indicated by the green color, the signal on the MIDI Track is a MIDI signal, there is no audio signal running through that Channel Strip.
- Record MIDI: You can select a MIDI Input ➐ (from the available external MIDI controllers) to record that MIDI signal as MIDI Clips ➑ on the Track Lane. Use the MIDI Fader, MIDI Pan, and the MIDI Mute ➒, and route that MIDI signal to any MIDI destination (i.e. an external MIDI Sound Module) or an Instrument Plugin loaded on any Track in your Pro Tools Session.
- Meter: The Level Meter on this Track might look like an audio signal meter ➓, but it is not. Please have a closer look at the numbers of the scale, which shows values from 0 to 127. They indicate the individual velocity value of the MIDI Notes that are played on that MIDI Track.
As I mentioned already, the Instrument Track is a very special "two in one" Track, It can carry audio signals and MIDI signals:
- MIDI & Audio: The Instrument Track has two signal flows in one, audio signal (blue) and MIDI signal (green). You can utilize both signals or only one, depending on how you want to use it.
- Internal MIDI Sound Module: The audio signal flow and its available components are the same as the Aux Input. You can use one of the inputs ➊ (Input Busses or Auxiliary Busses), but most likely, you would load an Instrument Plugin on the first Insert Slot ➋ to receive the MIDI signal ➌ that you recorded on that same Track.
- Record MIDI: The MIDI signal path is like a built-in MIDI Track. You can select a MIDI Input ➍ (from the available external MIDI controllers) to record that MIDI signal as MIDI Clips ➎ on the Track Lane. Use the MIDI Fader, MIDI Pan, and the MIDI Mute ➏, and route that MIDI signal to any MIDI destination, but most likely to the Instrument Plugin ➋, loaded on the Insert of that Track.
Master Fader Track
The Master Fader is very different from the other audio-based Tracks, so please make sure you understand the "implications". I cover the concept in more details in a separate tutorial about the Output Window. Here is just a brief overview.
- No Input: First, the Channel Strip doesn't have an Input Path Selector, only an Output Path Selector ➊. However, that Output Path Selector has a different functionality.
- Output Assignment (not Routing): Think of the Master Fader Track as a component that you can "insert into" ➋ (assign to) any available bus ➌ before it reaches its final destination. This could be any of the available Output Busses (representing the output channels of your audio interface) or any of the Auxiliary Busses (internal busses). That has the advantage that you can control the signal level on that bus and also add some effects to the bus by adding any Effects Plugins to any of the four Inserts on the Master Fader.
- Inserts: The Inserts are placed after the Fader (Post-Fader). I repeat, the Inserts are placed after the Volume Fader ➍ ! This is somewhat odd, because that means you cannot use any compression plugins or limiting on the Master Fader, because the Volume Fader (i.e. during a fade out) affects the input signal of the compressor (threshold), and therefore, negatively affects how the compressor is supposed to work.
- Meters: The Track Level Meters are always post-fader ➎. The setting for Pre-Fader Metering (Options ➤ Pre-Fader Metering) has no affect on this.
Graphically Enhanced Manuals
I hope you found this tutorial helpful. If you are interested in learning more about Pro Tools, check out my book “Pro Tools | First 12 - How it Works” or any other title in my "Graphically Enhanced Manuals (GEM)" series. All the books are available as PDFs from my website, printed books on Amazon, and interactive multi-touch iBooks on Apple’s iBooks Store.
Thanks for your time and interest,