THE OFFBEAT LOUNGERoots Organisation · Graz · reggae & jazz, dub & ska

A seventh chord has four notes: root, 3rd, 5th and 7th – with four horns, each one takes a note. The 3rd and the 7th carry the colour of the chord, so jazz arrangers call them guide tones. In a band the bass usually plays the root – so the root is the first note the horns can leave out (a rootless voicing), and the 5th is next. Whatever you leave out, don’t double another note instead: give that horn a tension, a 9th, 11th or 13th that fits the chord (on a dominant seventh chord also ♭9, ♯9, ♯11 or ♭13). That keeps four different notes – and gives the voicing its crunch.

Here: maj7 → 9, ♯11, 13 · m7 → 9, 11 · 7 → 9, ♭9, ♯9, ♯11, 13, ♭13.

From chord to chord every horn moves as little as possible – it keeps its note or moves by a step. In a ii–V–I the 7th of one chord falls a half step to the 3rd of the next (C → B, F → E). Big leaps inside one horn only when you really want them.

Trumpet and tenor sax are B♭ instruments, the alto sax is in E♭. A written C sounds as B♭ on the trumpet (a major 2nd lower), as B♭ an octave and a major 2nd lower on the tenor (a major 9th), and as E♭ on the alto (a major 6th lower). The trombone reads in concert pitch, usually in bass clef. The staff above shows the sound; next to every horn you see what the player reads.

Trumpet E3 – B♭5 · alto sax D♭3 – A♭5 · tenor sax A♭2 – E♭5 · trombone E2 – F5. Good players go higher; the very top and the very bottom are hard work, so arrangers mostly stay inside.