Listen to jam-band guitarists like Warren Haynes, Derek Trucks, Trey Anastasio and Jimmy Herring and you'll immediately notice that their rhythm parts are just as inventive as their solos.
These guitarists make the most out of single-chord vamps, often played for minutes on end, by using different modes and inversions, chromaticism and a wide variety of rhythms. Though this harmonic approach dates back to late-Fifties modal jazz, it first surfaced in rock with Cream, the Grateful Dead, Santana, the Allman Brothers, Frank Zappa and George Clinton's P-Funk.
All deserve props for pioneering the jam-band format, a style that's since blossomed to include elements of funk, jazz, blues, bluegrass, rock and psychedelia.
In this lesson, we’ll examine these players' key chord moves to show you 12 different ways to approach playing a one-chord vamp.
Grooving On Triads
When jam-band guitarists improvise rhythm parts over static harmony - one chord, like G (G-B-D), for eight bars or more - they might use inversions of G, as well as other diatonic triads.
The G major scale (G-A-B-C-D-E F#), which includes C (C-E-G) and D (D-F#-A) triads, is a common choice for negotiating an unchanging, G-major-based harmony. These two chords are used in alternation with G in FIGURES 1A–B and in a more musical fashion in FIGURE 2, similar to the triad substitutions employed by Anastasio and Trucks.
Don't limit yourself to the G major scale, though. Any scale containing the notes G, B and D can be used here - the G Mixolydian mode (G-A-B-C-D-E-F), for instance. With that mode as a basis, triad pairs like F (F-A-C) and G, and Dm (D-F-A) and Em (E-G-B) [FIGURES 3A–B], can interact freely.
Check out the hip Allman-like vamp in FIGURE 4.
The A Dorian mode (A-B-C-D-E-F#-G) is often used over an unchanging Am chord. FIGURES 5A–B illustrate C, G, D (D-F#-A), Am (A C-E) and Bm (B-D-F#) triad groups within A Dorian.
FIGURE 6 incorporates C and D triads and a 4th-finger double stop (bar l, beat 3) in a passage vaguely reminiscent of Carlos Santana’s rhythm work.
Double-Stops and Modal Applications
Two-note chord partials also work well in improvised rhythm parts. In FIGURE 7, the G major scale is harmonized in 3rds on strings 3 and 2. Try the same pattern in G Lydian (G-A-B-C# D-E-F#), G Mixolydian, G Lydian Dominant (G-A-B-C#-D-E-F) and G Phrygian Dominant (G-Ah-B-C-D-Eb-F).
FIGURE 8 intermingles 3rds with single-note lines.
Inspired by Jerry Garcia, FIGURE 9 contains Mixolydian-based 6ths, scattered across different string sets and inflected with funky slides and rhythmic scratches.
Note the chromatic movement at the beginning of bar 2, FIGURE 10, which is also Mixolydian in character, incorporates 3rds and 6ths, thumb-fretted notes and chromatically descending 3rds on strings 2 and 3 (beats 3–4 of bar 2).
At an Oysterhead show, Trey Anastasio, Les Claypool and company might launch into a reggae groove similar to FIGURE 11A - two bars each of Am and G#m, repeated indefinitely. This creates an interesting dilemma: How do you improvise rhythm parts over a progression of unrelated chords without simply strumming triads?
One solution is to play double-stops built from minor pentatonic scales. Check out FIGURE 11B, which features 3rds and 4ths within A minor pentatonic over the Am chord. Continue the figure by moving everything down one fret to play G# minor pentatonic over G#m.
Freeform Modal Jams
If you're the only chord-playing instrument in your band and your bassist drones a single note, like E (implying neither major nor minor), try experimenting with mode mixture, freely borrowing triads from parallel (sharing the same tonic) modes.
As seen in FIGURE 12, this creates the effect of teetering between E major, E Aeolian and other modes - E Phrygian (E-F-G-A-B C-D), E Lydian (E-F#-G#-A#-B-C#-D#) and so on. For more of this sort of accompaniment, check out the jam-band musings of jazz/fusion maestro John Scofield on Überjam.