Tuning is part of playing guitar, whether you use a conventional tuner or automatic tuning. However, all tuning methods have a major limitation: They can tune only the open strings.
Frets are set to an even-tempered scale, which has inherent pitch errors. Furthermore, when you first pluck a string, it’s under more tension, so it starts sharp before it settles down to its final pitch—and even that “final” pitch can vary by several cents over the string’s decay. In live performance, these small tuning errors aren’t much of an issue. But in the studio, the guitar may be in a mix along with perfectly tuned instruments such as electronic keyboards. Although many pitch errors may be desirable for adding “character,” others might be problematic. Fortunately, there’s a solution.
Celemony’s Melodyne is associated with vocal-pitch correction, but it does much more. I’ve used Melodyne on bass, guitar, and ukulele, with both monophonic (single-note) and polyphonic (chords) playing. There are several Melodyne versions. Melodyne Editor ($499) and Melodyne Studio ($849) can edit polyphonic material, whereas Melodyne Assistant ($249) and Melodyne Essential ($99; also included with PreSonus Studio One, Cakewalk SONAR, and Acoustica Mixcraft 8 Pro Studio) handle only monophonic material.
Fig. 1—The “blobs” represent guitar notes.
Fig. 2—The pitch has been “flattened” so the notes don’t start sharp.
Figure 1 shows notes—represented by “blobs”—after being analyzed by Melodyne’s Polyphonic detection algorithm. You can move blobs up/down to change pitch, snap to a scale, or move left/right to change timing. You don’t have to correct to perfect pitch. You can quantize to within a certain percentage of perfection.
Note the red line within each note that shows pitch, and how each note starts a little sharp. Figure 2 shows the same notes after using Melodyne’s Pitch Modulation tool, which corrects for pitch changes, and even lets you “flatten” pitch variations within the note itself. Now, the note is not only right on pitch when plucked, but the decay has also been flattened to a more stable pitch. By overcompensating, you can even choose to exaggerate the instability, have the note start flat and rise up to pitch, or cut the note into pieces and process some pieces but leave others as is.
Traditionalists may object to correcting pitch, and I certainly don’t think you should apply this universally. Tuning variations and instabilities add interest to a vibrating guitar string, so I recommend fixing pitch only if it actually sounds wrong. But even if you use this technique rarely, you may find that the guitar part you thought you were going to have to do over doesn’t need anything more than a little digital magic.