THE MIDI LFO

When you can’t do tempo sync in your DAW, do MIDI tempo sync

By Craig Anderton

Lots of effects parameters have tempo sync—like delay time, tremolo LFO rate, envelopes times, etc. But what if you want to sync, say, filter cutoff or resonance variations to tempo? Thanks to MIDI, it’s easy.

The key is to use a MIDI controller to control the parameter you want to sync, and fit the controller data to tempo. At least two programs, Cakewalk Sonar and Steinberg Cubase, let you “draw” periodic controller data whose period is quantized to tempo. If your DAW of choice doesn’t offer this option, then create a library of MIDI sequences with rhythmic controller values that you can paste in to MIDI tracks. Remember—because it’s MIDI, any controller shapes you create will work at any tempo.

Here’s how to create tempo-synched modulation in Cubase and Sonar.

STEINBERG CUBASE

With the Key Editor open, in a controller lane choose your controller (this example shows controller #7—main volume) and click on the Line tool’s drop-down menu. You’ll see options for Line, Parabola, Sine, Triangle, Square, and Paint. Suppose you want the volume controller to sync to tempo with a triangular wave, with one period of the waveform equal to a sixteenth note. Select Triangle from the Line menu, then choose the period with the Quantize drop-down menu—in the example in Fig. 1, 1/16 is selected (make sure Snap is selected as well).

Fig. 1: A MIDI "triangle LFO" set up in Cubase,

The Length parameter sets the amount of space between controllers, with 1/16th or 1/32nd note being a good compromise between resolution and data density. However, choosing coarser values can give cool “step-sequenced” effects, so don’t ignore that possibility! If you choose Quantize Link, then the control signal's resolution depends on the Zoom resolution.

Once everything is set up, draw as if you were drawing a line; drag the “line” up and down to set the waveform amplitude. The selected waveform will appear as the “line.”

To change the duty cycle with triangle and square waves, hold down Shift-Ctrl (Mac: Shift-Command) as you drag. While still holding down the mouse button and Shift-Ctrl/Cmnd, after defining the waveform’s length, drag right of left to change the duty cycle. There are other keyboard shortcut options; refer to the help for details.

CAKEWALK SONAR

Sonar allows for automated envelope drawing, including MIDI controller shapes. In Track View, open up an automation lane, and choose the envelope you want to create. Right-click on the toolbar's Draw tool, and from the context menu, choose the desired waveform (your choices are Freehand, Line, Sine, Triangle, Square, Saw, and Random—see Fig. 2). As with Cubase, the quantization value sets the waveform period.

Fig. 2: Another MIDI triangle LFO, this time in one of Sonar's automation lanes. Note the waveform's varying amplitude, which is based on how high the draw tool is from your initial click.

Click in the automation lane where you want the envelope to start, and also, to set its midpoint value. Drag up or from this point to set the amplitude, then drag left or right to set the envelope length. You don’t have to drag on a straight line; if you vary the height, you’ll vary the waveform amplitude, as shown in the screen shot.

Craig Anderton is Editor Emeritus of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.