Theory
There's something to peek at near the end of this week — the double thumb. Until now the thumb struck downward in one direction with a "thump." The double thumb strikes down, then snaps once more as it comes back up. Down-up, two notes from one motion. It's advanced, so today you only taste the principle — great if it works, fine if it doesn't. There's no need to rush at all.
The most common exercise is the octave. Strike open E (R) downward with the thumb (down), and as the thumb returns, hook and pluck the E at fret 2 on the D string (R an octave up) upward (up). Both notes come from one thumb. Unlike a finger pop, the thumb rides like a drumstick, up and down. The low down sounds like a kick, the octave up like a snare.
The knack is relaxing the thumb and rolling it lightly. On the way down, "thump" with the flesh of the tip; on the way up, hook the string slightly with the nail side for a "tick." As slow as BPM 50, watch only whether down and up come out evenly sized. A weak up is normal — today it's enough just to feel that this thing exists. There's no separate notation; just think of it as two thumb strokes.
Even on a 5-string, the octave is the same as on a 4-string. Keep the low B covered with the side of the thumb, and focus only on the octave two E's. Today the goal isn't mastery but experience. Tomorrow you finish this week's popping melody line, so take the double thumb as a relaxed taste. First mark the two E spots on the fretboard.
▶ 4-string. The lower open E (down), the upper E at fret 2 on the D string (up). Two octave spots.
▶ 5-string. The hand spots are the same as on a 4-string. Keep the low B deadened with the thumb.
See it
Today you just taste the double thumb. First warm the hand with the familiar thumb down, then roll the octave down-up. Each example comes in both a 4-string and a 5-string version.
First, the thumb down. Strike open E (R) downward in steady quarter notes to confirm the familiar down strike.
▶ BPM 60, 4-string. Four familiar downs. You'll add an "up" onto these.
▶ 5-string. The note is the same as on a 4-string. Keep the low B deadened with the thumb.
Now roll the octave down-up. The low E is the down, the high E is the up the thumb makes as it returns.
▶ BPM 60, 4-string. The low E is down, the high E is up. No notation for it, but both are one thumb.
▶ 5-string. The notes and spots are the same as on a 4-string. Keep the low B deadened with the thumb.
Today's practice
0–10 min · Warm-up Flow yesterday's double-stop lightly at BPM 60 to wake the hand. Today shake the thumb loose, letting all tension go.
10–20 min · Brain training As below, very slowly: measure 1 is down only, measure 2 is the octave down-up.
▶ BPM 50, 4-string. Measure 1 down, measure 2 down-up. It's fine if the up is a bit weak.
▶ 5-string. The notes and spots are the same as on a 4-string. Keep the low B covered with the side of the thumb.
20–40 min · Real play Roll the octave down-up slowly at BPM 60. If the up won't sound, drop the tempo further and practice just the thumb's return. Get the feel on the 4-string, then check it lightly on the 5-string too.
40–50 min · Record/feedback Record 30 seconds and listen for whether both down and up are audible. If not, a clear down alone is enough for today.
Done when: you can taste the principle of the double thumb — strike open E down, then make the octave E up as the thumb returns — at BPM 50.
Nudge the octave down-up just a little to BPM 70 and check that the shape survives even as the roll speeds up a touch.
▶ BPM 70, 4-string. Check that the down-up shape survives even as it speeds up a little. If not, go slow again.
▶ 5-string. The notes and spots are the same as on a 4-string. Always keep the low B deadened with the thumb.
- The up won't sound. If the returning thumb doesn't catch the string, no note comes out. Hook it slightly with the nail-side edge.
- The wrist is stiff. Tension makes rolling hard. Shake lightly with the thumb as the axis.
- The timing wobbles. Focusing on the up lets the down slip. Keep the beat with the down as your anchor.
- Neglecting low B (5-string). Absorbed in the octave, B rings easily. Always keep B covered with the side of the thumb.