The guitar is the hardest rhythm instrument to fake. A drummer hits things; a bassist mostly plays one note at a time. A guitarist plays six strings at once, with a strumming hand that moves down and up across them, and a fretting hand constrained by where the notes are on the neck. All of that is audible.
The problem with single-note samples
Load a guitar into a sampler and play a chord on a keyboard and every note starts at exactly the same moment, at the same velocity, as if six people each plucked one string in perfect unison. Nobody strums like that.
A real strum:
- Spreads in time. A downstroke hits the low strings first and the high strings last - 10 to 40 milliseconds across the chord, depending on speed and force. An upstroke goes the other way.
- Varies in level. Downstrokes are usually stronger. Upstrokes often catch only the top three or four strings.
- Uses guitar voicings. The notes in a guitar chord are spread out in a way that comes from the fretboard, not from a keyboard player's hand.
You can program all of this by hand - offset every note, vary every velocity, voice every chord like a guitarist - and for a short part it is worth it. For a whole song, use tools built for the job.
Strumming engines and phrase libraries
- Strum-scripted libraries - Native Instruments' Session Guitarist series and others - let you hold a chord with one hand and play a strumming pattern with the other, or choose from patterns built into the instrument. The engine handles the voicing, the spread and the down-up motion.
- Phrase-based libraries play back recorded performances that follow the chords you give them. The feel is a real guitarist's; the trade-off is less control over the exact notes.
- Loops and audio phrases are recordings you chop and arrange. Different again - the territory of sampling and chopping, covered in the Hip Hop Pro module.
The difference matters. A phrase library performs like a guitarist responding to your chords; a loop is a fixed recording you are editing.
Voicings
How a chord is spread across the strings changes its character.
- Open chords in the first few frets ring out with open strings - the sound of acoustic strumming, folk, country, singer-songwriter pop.
- Barre chords move one shape up the neck. Fuller and more controllable, and they can be choked short for a tighter sound.
- Power chords - just root and fifth (and octave) - are the core of rock and punk. With distortion, they sound huge; without, thin.
- Triads on the top strings - three-note chords high on the neck - are the funk and disco sound. Small, bright, and they leave the low end to the bass.
- Extended chords - sevenths, ninths, elevenths - for soul, jazz, neo-soul and R&B.
If you program by hand, voice chords the way they sit on a guitar: the lowest note is rarely more than an octave and a half below the highest, and adjacent notes often skip a scale step.
Styles and textures
- Fingerstyle - plucking individual strings with the fingers. Intimate, clear, arpeggiated.
- Pick - a plectrum, brighter and with more attack. Used for strumming, single lines and fast picking.
- Clean electric - funk scratch, indie arpeggios, jangly pop.
- Overdriven and distorted - rock, metal, grunge. Distortion compresses and sustains, so parts can be simpler.
- Pickups. Single-coil pickups (Stratocaster, Telecaster) are bright and glassy - the funk and country sound. Humbuckers (Les Paul, SG) are thicker and darker, with less hum - the rock sound. The neck pickup is warmer; the bridge pickup brighter and more cutting.
Guitar in pop, rock and dance music
- Pop often uses the guitar as rhythmic texture: a muted 16th-note pattern, a clean arpeggio, or an acoustic strum that sits under the vocal.
- Rock builds on power chords and riffs, often doubled - the same part played twice and panned left and right for width.
- Dance music uses funk-style guitar: short, muted 16ths in the style of Nile Rodgers, or a looped disco lick. Here the guitar is almost a percussion instrument.
Strumming patterns and progressions
A strumming pattern is a rhythm played on the chord. The hand moves down on the beat and up on the off-beat continuously; what changes is which movements actually hit the strings.
A common pop-rock pattern in 8th notes: down, down-up, up-down-up - beat one down, beat two down and up, the and-of-three up, beat four down and up. Missing a strum while the hand keeps moving is what makes a pattern sound natural.
Pair patterns with progressions that suit the instrument. Guitar-friendly keys - E, A, D, G, C - let open strings ring and make parts more realistic.
Depth and dynamics
- Vary the intensity. Lighter strumming in verses, harder in choruses.
- Use mutes and dead strums. Percussive muted strums between chords are part of the rhythm.
- Double the part. Record or program two versions with small differences and pan them apart. Two identical copies will not work - you will hear one sound in the middle.
- Leave space. Stop the guitar for a bar, or drop to a single chord per bar in a verse. Absence is a dynamic.
Do this now
- Program a four-chord progression on a single-note guitar patch with all notes starting together. Listen.
- Now offset each note of every downstroke so the lowest string starts first, roughly 5 ms between strings, and reverse that for upstrokes. Vary the velocities.
- Load a strum-scripted or phrase-based guitar and play the same progression. Compare the three.
- Write a muted 16th-note funk part using triads on the top strings, panned slightly off centre, over a simple four-on-the-floor beat.