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Lesson 4

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Modifying an RTPC with MIDI Controllers

While the vibrato effect is working, it feels like it’s a bit much to have it occur all of the time. When a musician plays a keyboard they will often use a physical control called a modulation wheel to modify the sound in a predetermined way, like adding vibrato. The movement of the modulation wheel is communicated with a special type of MIDI message called a continuous control number. There are many different control numbers available in the MIDI protocol, but the one generally used in conjunction with a modulation wheel is Continuous Control #1.

When the MIDI tracks you’re now working with were recorded, the keyboard player turned up the modulation wheel during the longer notes at the end of the phrases, presumably to create a vibrato. To recreate the intended effect. you can use that data to modify the LFO’s range property in real time, so that the vibrato only occurs for those notes where the modulation wheel was raised.

To the left of the Depth property value you see an RTPC symbol. Because it’s gray, this means that this property is not being controlled by an RTPC.

  1. Double-click the RTPC icon for the Depth property.

    The Vibrato Modulator Editor opens with the RTPC tab selected.

  2. For the Y Axis, choose Depth; for the X Axis, choose MIDI > CC 0-31 > CC#1:Modulation.

  3. An RTPC graph appears.

    Every continuous control message has a value assigned that ranges from 0-127. This is represented at the bottom of the RTPC graph. The default curve indicates that regardless of the modulation value, the LFO Depth will always be at 100%. You need to change this so that if the modulation value is low, the value of the Depth property will be too. By changing the shape of the curve, you can further modify the response so that the modulation value must be fairly high before the vibrato is noticeable.

  4. Drag the left control point all the way down to a value of 0 and play the track, then right-click anywhere on the curve and choose Exponential (Base 3).

    [Tip]

    You may need to move the RTPC cursor to the right in order to select the control point.

  5. Close the Modulator and Source Editor windows and listen to the Boss-A Music Segment. You can now hear that the vibrato only occurs at the end of some of the notes.

  6. Unpin the Transport Control and collapse the Boss-A Music Segment.

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