Global tracks are a new addition to Logic 7. Global tracks provide a way to inspect and change certain song properties, including markers, time and key signatures, chords for MIDI Regions, and most importantly for our purpose here, tempo.
Global tracks are available in the Arrange window, as well as in the Matrix, Score, and Hyper editors.
Exploring Tempo Alternatives
When working with Apple Loops, the Global Tempo track proves invaluable. Using the Tempo track, you can automate tempo changes over time. But even better, from the Tempo track you have direct access to nine tempo alternatives. Because Apple Loops automatically adjust the tempo to match the song, these tempo alternatives let you experiment with different tempos, and then quickly apply the one that works best for the song.
From the Arrange window's local menu bar, choose View > Global Track Components > Tempo. The Global Tempo track appears directly under the Bar Ruler. Currently, there is a horizontal tempo line all the way through it. Directly above the line on the left side is the number 126, the song's current tempo.
You don't want to lose this original tempo, so let's experiment with a tempo alternative.
From the Global Tempo track's Tempo Alternative menu, choose 2. The tempo line changes to 120 bpm.
Press the spacebar to start playback.
Make sure the Arrow tool is selected.
With the Arrow tool, grab the tempo line and drag it up slowly to 130 bpm. (Don't drag quickly or you'll make drastic tempo changes.) When you release the mouse button, the tempo changes to 130 bpm. At any point, you can choose 1 from the Tempo Alternative menu to switch back to 126 bpm. For now, however, stay in tempo alternative 2.
Press the spacebar to stop the song playback.
Automating Tempo Changes
Using the Global Tempo track you can actually automate changing tempos over time by clicking new nodes into the tempo line.
Using the Arrow tool, double-click just above the tempo line at 9 1 1 1. A new node is created, and the tempo increases at bar 9. Clicking in new tempo nodes is not the most exact method of changing tempo. For more precision, use the following trick to open a text box into which you can type the desired tempo.
To delete a tempo node, click to select it, and then press the Delete key.
At bar 17, press Cmd-Option-Ctrl and double-click. A text box appears.
Type 122 into the text box, and press Return.
A new node is inserted and the tempo line changes to 122 bpm.
Play the song and listen to the tempo changes.
When you've heard the changes, stop playback.
Creating Tempo Curves
Currently, the tempo changes are sudden and dramatic. If a more subtle change is what you're after, you can create a continuous transition between tempos (a tempo curve) that slowly changes the tempo over time.
Before you create a tempo curve, you should select a Tempo Resolution setting. It will determine the number of tempo changes performed during the tempo curve: When the tempo resolution is set to 1/16, there will be four tempo changes per quarter note (16 tempo changes per bar); 1/4 will generate one tempo change per beat (four tempo changes per bar).
A different tempo resolution can be defined for each node in the Global Tempo track. With this in mind, select the tempo line you will turn into a curve, and set its tempo resolution before creating the tempo curve.
Select the horizontal tempo line between 130 and 140.
The line turns white to indicate it is selected.
From the Global Tempo track's Tempo Resolution menu, choose 1/32. Position the Arrow tool over the node on the right edge of the selected tempo line (directly under 140).
Drag the node to the left. A tempo curve is created.
Play the song and listen to the tempo change.
The tempo changes smoothly from 130 bpm to 140 bpm. Cool, but not terribly musical. Let's switch back to tempo alternative 1.
From the Tempo Alternative menu, choose 1. The song reverts to 126 bpm. Currently, the Global Tempo track occupies a lot of space at the top of the Arrange area. Let's hide the Tempo track to get it out of the way.
From the Arrange window's local menus, choose View > Global Tracks. The Global Tempo track is hidden.