Scales in thirds provide an excellent way to develop and refine your left-hand technique. Additionally, they will improve your fingerboard knowledge, shifting, and right-hand balance. 

Theory

What are thirds?

In music, a third is an interval spanning three notes of the scale. For example, in the C major scale, the interval from C to E is a major third, while the interval from E to G is a minor third. When we play scales in thirds, we are essentially skipping one note of the scale and playing the next, creating a harmonious and melodically rich sequence.

Thirds can be found throughout classical music and the classical guitar repertoire. Some notable example include Bach’s Cello Suite Prelude No.1,

Sixths and tenths

Thirds are building blocks of western harmony and this fact becomes even more evident when we look at sixths and tenths. If you take the two notes in the interval of a third and invert them you will have a sixth. The notes remain the same but because of the inversion the interval is further apart and creates a different sound.

Similarly if you take the upper note of a third and raise it up and octave you will have a tenth. Because of the distance between the two notes you have a clear separate of a lower and upper voice. This makes tenths ideal for bass and melody and you will find plenty of examples where tenths are present. Lagrima is perhaps the most famous example in the guitar repertoire.

Sight-reading and fingerboard knowledge

Because thirds, sixths, and tenths appear so commonly in the music we play, becoming familiar with how they appear on the score can greatly assist sight-reading.

Technique

Finger positioning

With two notes on adjacent strings you will find that scales in thirds challenges you to position your fingers with accuracy and consistency. Make sure to curl your left hand fingers and avoid collapsing them onto the adjacent string. If your fingers are not positioned correctly you will hear it because the upper note will be muted or it may buzz.

Efficient Movement

As you play through the scale maintain a relaxed hand that has the fingers hovering over the strings. Avoid fly-away fingers that move into the air when not being used or fingers that are tucked away into your hand.  By avoiding these inefficient movements you are making the playing easier and more accurate.

Left-Hand Preparation

Left-hand preparation is a core element of classical guitar technique, and these scales are fantastic opportunities to practice in preparation for repertoire. When you have one pair of notes being held down you need to consider where the next two notes are and prepare your fingers accordingly. If it is possible, you should move your fingers into position over the frets where they need to be. If that isn’t possible you need to get the available fingers at least moving in the direction of where they need to be.

Shifting

The shifting involved when playing scales in thirds is quite varied. Not only do you have to shift smoothly and quickly to achieve a legato connection but you will need to incorporate barre technique and all four fingers.

You will find that guide fingers can be very useful when shifting in thirds, although beware that they might cause some unwanted string noise on the bass strings.

The Right Hand

Unlike normal classical guitar scales we are going to repeat the right-hand fingers as we go through scales in thirds.

To start off with I recommend playing the notes at the same time. This will work on your finger independence and you can hear the legato connection as it forces you to move the fingers at the same time. If you practice them in split pairs you don’t have to get both fingers in place at the same time, and you should take advantage of this fact. What I mean by this is you should place the fingers sequentially, one at a time so that the movement of the left hand is smoother.

Legato

Listen for a legato (connected) transition between each pair of notes as we go through the scale. This means that you should take is slow, slow enough that you can see what the fingers are doing and refine their movements if need be. All of the previous points on technique will impact your legato and if you are finding that your playing is staccato (detached) then you will need to investigate what is getting in the way. 

Practice

Tempo

Because we have two notes at a time we will not be playing these scales at a fast tempo. Rather, it is more important to focus on good left hand movement and legato in these scales. A moderate tempo of eighth notes at 60 – 80 BPM is reccomended. Of course, if you would like to push your limits you can aim for a more virtuosic 120 BPM.

Splitting thirds (melodic thirds)

One useful variation of this scale is to play in melodic thirds, i.e. splitting the pairs of notes instead of playing them together. This approach will change your left and right hand movement and offer a different challenge when you practice.

Rhythms

Adding dotted rhythms can help to work on

Dynamics

Incorporating a crescendo/decrescendo dynamic into your scales can be an excellent way of practicing musical shaping and control of the scale. This dynamic swell can also help you achieve a legato approach.

Fingering

While I have provided fingering for you in this lesson it will be very helpful for you to devise your own fingerings for scales in thirds, sixths, and tenths. Not only will you need to consider how fingering impacts shifting and legato but you will also develop your fingerboard knowledge.