Acoustic and Unplugged Arranging

Definition

An acoustic or unplugged arrangement reinterprets a song with acoustic instruments (acoustic guitars, piano, upright bass, hand percussion, strings, voices), with little or no electronics. The term spread with the MTV Unplugged series (from 1989): among the most famous episodes are Eric Clapton (1992, with the slow acoustic version of Layla) and Nirvana (recorded in November 1993, released in 1994 as MTV Unplugged in New York).

What changes compared to the original

Role of the voice: more exposed, more intimate; the lyrics become the protagonist.
Tempo: often slower (−5/−20 BPM) or with a different feel (straight to shuffle, 4/4 to 6/8).
Harmony: an opportunity for reharmonization (chords with sevenths, sus, add9, moving basses).
Dynamics: from true pianissimo to forte, without heavy compression; the build comes from the performance.
Rhythm: drums are replaced by cajón, brushes, shaker, hand claps, percussion on the body of the guitar.

Typical instrumentations

Voice and guitar or voice and piano: the minimum; the piano or guitar must cover bass, harmony and rhythm.
Acoustic trio: guitar, upright bass (or acoustic bass), cajón.
Acoustic band: 2 guitars (one with a capo high up), piano, upright bass, percussion, vocals.
With string quartet: pads and countermelodies, very effective in choruses.

Arranging techniques

Transferring elements: identify the main hook (synth riff, bass line, drop) and give it to an acoustic instrument (arpeggiated guitar, piano, cello, whistle, choir).
Two complementary guitars: one in first position with open chords, the other with a capo at the 5th–7th fret or in Nashville tuning; pan L/R.
Bass: upright bass or the piano's left hand; on solo guitar, alternating bass with the thumb.
Percussion: cajón with a low hit (center, around 60–100 Hz) on beats 1 and 3, a high hit (edge, slap) on 2 and 4; shaker in eighth or sixteenth notes.
Backing vocals: 2–3 part harmonies on the choruses (see Pop Choral Arranging); “ooh”s replace pads.
New intro and outro: an arpeggio, an a cappella phrase, the chorus slowed down.

Example: from an EDM track to an acoustic version in A minor

Original: drop with synth lead and 808, Am–F–C–G progression at 128 BPM.

Acoustic version at 92 BPM:

Verse: arpeggiated guitar (Am–Fmaj7–C–G, i–VImaj7–III–VII), voice.
Pre: the cajón comes in and a cello in long notes (A2–F2–C3–G2).
Chorus: strummed guitar, second guitar with capo, backing vocals in thirds.
Drop hook: played by the cello or the piano with the melody doubled at the octave.
Bridge: just voice and piano, then a full final chorus.

Recording and mixing

Acoustic guitar: small-diaphragm microphone aimed at the 12th fret from 15–30 cm, possibly a second microphone near the sound hole or a stereo pair.
Room noise and finger noise are part of the sound: don't clean up too much.
EQ: HP at 80–100 Hz on the guitar if there is an upright bass, watch 200–300 Hz (boominess) and 2–5 kHz (strumming).
Natural reverb (room or short hall, 1.2–1.8 s) to unite the instruments as in a real space.
Light compression (2–4 dB) to preserve dynamics.

Common mistakes

Copying the original note for note with acoustic instruments: it loses its meaning without the production.
Too many guitars in the same register.
Unchanged tempo when the original song was designed for the dance floor.

Practice exercise

Choose an electronic track of your own. Rewrite it for voice, two guitars, upright bass and cajón: lower the tempo by at least 15 BPM, reharmonize the chorus with at least two new chords, transfer the instrumental hook to an acoustic instrument and prepare a 4-bar a cappella bridge.

Links

Arranging for Guitar, Piano Accompaniment Patterns, Reharmonization, String Arranging in Pop, Pop Choral Arranging.