Turning chords into full accompaniments is often a real stumbling block for new guitarists. The alternating thumb technique is a quick way to build a sound.
To develop the technique here, you will need to be able to play some chords on the guitar: this is designed for people just starting out but not absolute beginners.
Listening to a great finger-style guitarist can be quite a perplexing experience! Somehow, on one guitar, they appear to be playing bass lines, melodies, and counter-melodies and it all seems to be happening with their right hand. For those still getting to grips with learning where to put their fingers to play a chord, the complexities of what’s happening, on the other hand, can almost be dispiriting.
Examples of this can be seen with Ralph McTell, playing a ragtime piece:
Also, Richard Thompson on “Vincent Black Lightening”:
In both cases there are some very complex, high-level techniques being employed and the Thompson piece involves an alternative tuning. However, both performances make use of a relatively simple technique: the alternating thumb.
Basic Finger-Style Guitar
With the left hand (for right-handed players!) form a D chord. 2-3-2-0-X-X
With the right hand, place the thumb and first three fingers on the four strings that are to be sounded (i.e., the high E, B, G and D strings). Sound the D string with the thumb, then pluck the other three strings at once. Either all four strings can be sounded together (a down stroke with the thumb and pluck with the three fingers, simultaneously), or the thumb can be sounded first (the root note) followed by the other three strings together.
Here, the thumb is sounded on the beat and the other three strings on the offbeat. While you can master this technique through guitar classes in New York, NY, it is also possible to experiment with plucking the strings individually and forming a finger-picking pattern.
Choose the second option: thumb on the beat, other three fingers on the offbeat. Repeat it several times: thumb, pluck; thumb, pluck; thumb, pluck. Now, comes the exciting part! At the moment the thumb is playing D as the root note.
An A also sounds good with a D chord. To play an A as a root note, use the thumb to sound the fifth string (the A string) followed by the same pluck as before. Alternate between the two and quickly a “country” effect is created. The effect can be varied by plucking the strings individually instead of together, thereby producing simple arpeggios.
The two chords where alternating thumb technique is as simple as that are D and A (0-2-2-2-0-X). In both cases, this country effect is produced by taking the thumb straight from the open string root note, to the open string below it, in the case of A, from the A string to the E string.
Things get a little trickier elsewhere on the instrument. To produce the same effect with a conventional C chord involves a little more movement with the left hand. Form a C chord (0-1-0-2-3-X) and sound the A string, playing a low C. Pluck again as before (which three strings can be chosen through trial and error, but the highest three work quite well). The second note here ought to be a G. Some people play C with the bass G already in the chord (0-1-0-2-3-3) in which case the thumb style is the same as before.
Alternatively (and this works well in some cases, the finger that is currently forming the C note on the A string can move down a string, on the same fret, to produce a G. Practice doing this several times. You can see the same technique used in the verse of this song:
It is also perhaps most famously used on Paul Simon’s “The Boxer”:
It will be noted that Paul Simon is playing the second version of the C chord, thereby not needing to move his third finger.
Difficult Alternating Thumb Technique
In fact, Ralph McTell used that very same technique on the rag-time piece (only moving the third finger is his case). The difference, apart from the speed of the chord changes, is that McTell is alternating the thumb both up and down. The first few chords he plays on that tune (actually with a capo on the second fret, so that is in D) are: C, E and A. On the C chord, as well as alternating from the root note C down to a G, he also sounds an E note with his thumb.
So, with the C chord on, his thumb is going from the A string (playing a C), to the D string (playing an E) then down to the sixth string (to play a G) back to that D string again, all before moving to the E chord. On the E chord, he alternates between two E notes, one the root E on the sixth string, the other on D string again. And even on the A chord, that same E note on the D string comes between the “country” alternating thumb between the A and the E (fifth and sixth strings). Obviously, in the case of Ralph McTell’s ragtime piece, there is more going on above the alternating thumb than a pure three-string pluck.
What the new guitarist has to do when introducing alternating thumb patterns to accompaniments is to learn which notes work and which don’t. It is also important to avoid overdoing it!
Once this technique is combined with small bass runs and hammer-on and pull-off techniques, some really good effects can be produced.