# Jazz lite
> Interactive page: [`jazz.html`](jazz.html)
Three notes can carry a seventh chord: the **root**, the **3rd** (major or minor), and the **7th** (major or flat). That is a *shell voicing* — enough harmony to walk a **ii–V–I** without a six-string grip. v2 opens jazz; the dictionary still holds method-book sevenths, not a full extension chart.
Pair with [Play along](songs.md) (progressions, titles only) · [Chord dictionary](dictionary.md) · [Scales](scales.md) · [Ear](/tools/ear-training.html).
On the HTML page, Play becomes Stop on the same button. Tempo follows the metronome. TAB is high e on top — [Foundations · TAB](foundations.md).
**Sources (two-check):** Berklee guitar-lab shells (root + guide tones 3 and 7 on the A and D string sets) · Hal Leonard Jazz Guitar Method (ii–V–I as the first jazz cadence; swing eighths as a triplet with the first two tied). No copied heads or riffs.
## Shell voicings
Low to high, two useful orders: **R–3–7** (3rd then 7th) and **R–7–3** (7th then 3rd). Same three pitch classes; the 3 and 7 swap which string they sit on. Mute the unused strings.
**String sets:** *A set* = A, D, G (root on the A string). *D set* = D, G, B (root on the D string). R–7–3 often skips one inner string so the guide tones stay inside a four-fret box. Slide the whole grip; the letter follows the root.
## A-string set — C shells
Root C on the A string, fret 3. R–3–7 stays on A–D–G. R–7–3 skips D and puts 7 and 3 on G and B.
### R–3–7
```
e|-----------------
B|-----------------
G|-4---3---3------- B / Bb / Bb
D|-2---1---2------- E / Eb / E
A|-3---3---3------- C
E|-----------------
```
Cmaj7 = C E B · Cm7 = C E♭ B♭ · C7 = C E B♭. Only the 3rd and 7th move. That is the whole colour change.
### R–7–3
```
e|-----------------
B|-5---4---5------- E / Eb / E
G|-4---3---3------- B / Bb / Bb
D|----------------- skip
A|-3---3---3------- C
E|-----------------
```
Same letters, 7th below the 3rd. Use this when the next chord’s guide tones want to move by a fret or two on G and B.
## D-string set — G shells
Root G on the D string, fret 5. Friendlier box than C on this set (C is the same shapes twelve frets higher, or five frets up from G). R–3–7 on D–G–B; R–7–3 skips G and puts 7 and 3 on B and high e.
### R–3–7
```
e|-----------------
B|-7---6---6------- F# / F / F
G|-4---3---4------- B / Bb / B
D|-5---5---5------- G
A|-----------------
E|-----------------
```
### R–7–3
```
e|-7---6---7------- B / Bb / B
B|-7---6---6------- F# / F / F
G|----------------- skip
D|-5---5---5------- G
A|-----------------
E|-----------------
```
## ii–V–I
The jazz cadence: minor 7 on scale degree 2, dominant 7 on 5, major 7 on 1. In **C** that is Dm7–G7–Cmaj7. In **G**, Am7–D7–Gmaj7. One bar each on ii and V, two bars on I — a four-bar loop.
The room dictionary has open **G7**, **Am7**, and **D7**. It does not have Dm7, Cmaj7, or Gmaj7. Where a seventh shape exists, the HTML loop *strums* it. Where it is missing, you hear a shell (root + 3rd + 7th as fretted notes) — not a fake dictionary entry.
| Key | ii | V | I | How the model sounds |
|-----|----|---|---|----------------------|
| C | Dm7 (shell) | G7 (strum) | Cmaj7 (shell) | A-set shells + dictionary G7 |
| G | Am7 (strum) | D7 (strum) | Gmaj7 (D-set shell) | Am7 + D7 strums; I is the Gmaj7 shell |
Famous-title harmony (no melody): many standards sit on this cadence. Map a loop on [Play along](songs.md) if you want campfire letters in the same keys. Scale work for Mixolydian / Dorian colour: [Scales](scales.md) and [Modes](modes.md).
## Swing feel & muted comping
Straight eighths split the beat in half. **Swing** eighths split it as a triplet: the first two parts tied, then the last part. Count *1-trip-let 2-trip-let*; play on *1* and *let*. At slow tempos the long–short gap is obvious; as you go faster it tightens. The metronome still clicks quarters — you place the second note late, not the click.
Comping (accompanying) often leaves beat 1 open and *chucks* on 2 and 4 — muted eighths, not a full ring. That is a seed, not a transcribed chart.
```
e|-----------------
B|-----------------
G|-x---x---x---x--- muted swing eighths
D|-----------------
A|-----------------
E|----------------- 1 2 3 4
```
Hold a C7 or G7 shell in the left hand while the right hand mutes. Compare straight muted eighths on [Exercises · palm mute](exercises.md).
## Dominant 7 → altered colour
A plain dominant is R–3–5–♭7. Jazz players often add *colour tones* a half step above the root: the **flat 9** (♭9) and the **sharp 9** (#9). On G7 that is A♭ and A♯/B♭ — two fretted notes, not a new dictionary chord. Play them as extras after the shell, then resolve to C. Generic colour, not a quoted lick.
```
e|-----------------
B|-----------------
G|-4---1---3------- B (3) · Ab (b9) · Bb (#9)
D|-5--------------- G (root) stays
A|-----------------
E|-----------------
```
The 3rd (B) still says “this is major-third dominant.” The extra notes are paint. Resolve the colour into Cmaj7 (B and B♭ both want to move). Ear check: [Ear](/tools/ear-training.html).
## Three tracks
- **Beginner** — Own Cmaj7 R–3–7. Play the arpeggio walk slow. Listen to G7 from the dictionary. Do not rush the ii–V–I loop.
- **Intermediate** — Add R–7–3 and the G D-set shells. Loop ii–V–I in C with the metronome near 60. Chuck on 2 and 4.
- **Advanced** — Both keys. Swing eighths even. Add ♭9/#9 on G7, then land on Cmaj7. Name 3 and 7 out loud while you play.