This is one of the most common questions that I am asked by my pupils!
What is a scale?
A scale is the notes of a particular key arranged in sequence, starting from the tonic (also known as the root note, or key note) and leading up to the tonic one octave above. The main types of scales are major and minor scales. A major scale contains all of the notes of a major key. For example the one octave C major scale would contain the following notes, played in this order:
C D E F G A B C
A two octave scale would repeat the last seven notes one octave higher:
C D E F G A B C D E F G A B C
A three octave scale would add on the last seven notes one octave higher again, and so on.
What is an arpeggio?
An arpeggio is the notes of a particular chord arranged in sequence, starting from the tonic and leading up to the tonic one octave above. For example, a C major chord is made up of the notes C, E, G, so a one octave C major arpeggio would contain the following notes, played in this order:
C E G C
A two octave arpeggio would repeat the last three notes one octave higher:
C E G C E G C
A three octave arpeggio would add on the last three notes one octave higher again, and so on.
Arpeggios are particularly useful for chord progressions which step outside the key, or modulate (change key) frequently.
How do I use scales & arpeggios to improvise?
You match the scale to the key, and the arpeggio to the chord. Let’s look at a I VI II V chord progression in the key of C major:
|C |Am |Dm |G |
All of these chords are in the key of C major, so you could play the C major scale over any of the chords. If you wanted to use arpeggios, you would have to play the C major arpeggio over the C chord, the A minor arpeggio over the Am chord, the D minor arpeggio over the Dm chord, and the G major arpeggio over the G chord.
Try this, and you will see that you get a very different sound if you use the major scale as opposed to arpeggios. Often, just using one or the other can sound a bit dull. Try mixing them up a bit, to add variety. A more advanced approach would be to highlight particular chord tones (i.e. arpeggio notes) from the scale, depending on the chord that you are playing over.
Scales contain the notes of a key, arpeggios contain the notes of a chord. When improvising, match the scale to the key you are in, and the arpeggio to the chord you are playing over.
If you don’t know what a key is, you need to find out! The AB Guide To Music Theory is a great reference book for that kind of stuff. I’ll probably post a lesson on keys at some point, but in the meantime, feel free to contact me with any questions via my Facebook page.