Seriously, there’s nothing like a guitar. But there are also many ways keyboard players can add a guitaristic element to their music.
There are two main flavors of guitar playing, rhythm (chord-based) and lead (single note-based). Rhythm guitar is harder to emulate not just because it’s strummed, but because guitar voicings tend to be “wider” than piano voicings. Figure 1 shows where the notes from an E major chord on guitar would fall on a keyboard. The first step toward emulating guitar parts is to avoid playing keyboard voicings.
Furthermore, rhythm guitar often combines open strings that have a long decay with fretted strings, which have a shorter decay. And as the strings are strummed, they don’t all hit at the same time.
One option for a convincing rhythm guitar part is to forego the keyboard and use sound libraries or virtual instruments, such as Big Fish Audio/Vir2’s Acoustic Legends or the Strum Acoustic GS-1 plug-in from Applied Acoustic Systems. These map strums on the keyboard in such a way that with practice, you can create convincing acoustic rhythm guitar parts.
Lead guitar lends itself well to synthesis, because the gestures involved in creating a single-note solo—pitch bending, vibrato, and sometimes, rapid-fire licks—are part of a synth’s standard repertoire.
Pitch manipulation, either by a vibrato tailpiece or finger vibrato, is a guitar trademark. With synths, use the pitch wheel for bending: A mod wheel controlling LFO vibrato produces a periodic effect that isn’t at all guitar-like. When imitating tailpiece effects (like “dive bombs”), remember that these primarily bend pitch down, and can bend up over only a limited range (e.g., a half step).
Another common lead guitar effect is holding a note so that it sustains, during which time the timbre changes. Emulate this effect by changing a waveform’s duty cycle (e.g., change a square wave into more of a pulse wave) during the sustain. While this isn’t exactly how a guitar sounds, the effect can add interest.
Or, create a layer with a sine wave an octave or octave + fifth above the fundamental to simulate the “whine” that feedback produces. Tie this to the mod wheel (or a footpedal) so that increasing the mod wheel toward the tail end of a note’s sustain adds in the pseudo-feedback.
Aftertouch can also work to bring in feedback or add pitch bend, but satisfying results require good aftertouch resolution (it needs to be smooth, not “stair-stepped”).
Sometimes a guitar sound depends on effects (chorus, flanger, wah, etc.). In fact, the wah-wah sound is so associated with guitar that adding a good wah effect can help compensate if the guitar samples themselves aren’t that great. However, the main “effect” with guitars is an amp that creates distortion, along with a speaker cabinet (which is actually a very complex filter). Running your synth through a guitar amp is one possibility, but there are some great guitar amp simulator plug-ins such as Peavey’s ReValver Mk III, IK Multimedia Ampli- Tube, iZotope Trash (Figure 2), Native Instruments Guitar Rig, Waves GTR, etc.
Sure, you’ll get more authentic results with a Real Guitarist . . . but not always better results. Even though I play guitar, sometimes I break out a synth or sampler to do a “guitar” part because it has more of a synthetic vibe that happens to work well for a particular tune. Don’t you just love options?