The Mixer

Submitted by Ben on Tue, 09/25/2007 - 15:14

Figure 9: Mixer strip

Mixer Strips

Ardour's mixer has a very efficient and well-built design. It's interface graphically represents the signal path of each track. Imagine the audio signal flowing downward from the input to the output, through the various widgets present in the mixer strip. Each track and bus has its own mixer strip.

Mixer strips appear by default in the order in which you create them. You can rearrange mixer strips by dragging their titles in the mixer window's track list, to the left of the mixer strips.

At the very top of each mixer strip are two buttons that hide and minimize the mixer strip, respectively. In between these two buttons is an area which clearly shows the track's colour. The button directly underneath shows the name of the track, and lets you rename, switch polarity, or assign a MIDI controller ID number.

Pre-fader Sends

Audio signals flow downwards from the input button to the pre-fader sends list. This is where sends, inserts and plugins are added (these will be discussed later). Directly below the pre-fader sends are the mute and solo buttons. Next, the signal goes through the fader.

The Fader

The fader is the primary level control for the selected track. You can adjust the fader bar with your mouse, or input a specific numerical amount in the small box directly above the fader. To the right of the fader is the meter, which will show you when your levels are peaking. The number above the meter tells you the maximum value that the track's level has reached. You can reset this counter by clicking on it. It's a good idea to keep levels below zero to prevent clipping and distortion. Below the fader, the small "M" button changes the automation mode on the selected track (more on that later).

Going down the mixer strip, the group and metering mode buttons are next. With the group button, you can assign tracks to groups to simplify editing operations on multiple tracks. The metering mode button toggles between post, pre and input modes. In post mode, the meter will display the level of the track's output, after being processed by the pre-fader sends, fader and post-fader sends. In pre mode, the meter will display the level of the track after the pre-fader sends, but before the fader. In input mode, the meter will show the level of the track's input, prior to pre-fader sends.

Post-fader Sends

After the fader comes the post-fader sends list. This one works just the same as the pre-fader sends list, only it affects the signal after it has passed through the fader. We'll get into specifics about how to use the pre- and post-fader sends lists later.


These panning controls are fairly simple to use. In a stereo track, the top controller pans the left channel, and the bottom controller pans the right channel. Mono tracks have just one controller, at the top. You can adjust the panning by dragging the green bar through the panner. The small triangular wedges at the top of each panner are bookmarks for left, right and centre panning; click on them to send the channel's panning to that location.

The link panning control button which looks like a double arrow (⇒) causes both the left and right channels to change simultaneously. Activate it and drag one of the panners back and forth to observe this effect. Now try changing the panning link direction with the arrow-shaped button to the right of the link panning control button.

The small "M" button operates in the same way as the one for the fader in controlling automation modes. We'll discuss automation more later.

Our signal's voyage through the mixer strip is soon to end. The output button controls the track's output and operates in a similar manner to the input button. Below the output button is the comments button, which you can click to leave helpful reminders on your track's comment sheet.

Signal Path Summary

Ardour's signal path is summarized in the figure below from the Ardour manual, designed by Sampo Savolainen.

Figure 10: Ardour 2.0 signal path diagram by Sampo Savolainen (click for full size).

Now that we are a bit more acquainted with the mixer, it's time to create a track.