A mode is a type of scale that is particularly useful for improvising or composing bass lines over chords or chord progressions. The first thing to understand with modes is that they are derived from the major scale. Each mode relates to a particular scale tone chord and can be applied over that chord. The names of the seven modes and their relationship to the major scale as well as the relevant matching chords are shown here.
The Ionian mode is another name for the major scale. This is best illustrated by looking at the basic C major scale. It is also important to consider the order of the tones (T) and semitones (S).
T - T - S - T - T - T - S
The Dorian mode is constructed by starting and finishing on the second note of the major scale. This is shown in example 248, which begins with the second note of the C major scale (D) and finishes one octave higher. The tone and semitone order is therefore displaced one step.
T - S - T - T - T - S - T
The Phrygian mode is constructed by starting and finishing on the third note of the major scale, the note E in the given example. The tone and semitone order is once again displaced by one step.
S - T - T - T - S - T - T
The Lydian mode is constructed by starting and finishing on the fourth note of the major scale – in this case: F. The tone and semitone order is once again displaced by one step.
T - T - T - S - T - T - S
The Mixolydian mode is constructed by starting and finishing on the fifth note of the major scale – in this case: G. The tone and semitone order is once again displaced by one step.
T - T - S - T - T - S - T
The Aeolian mode is constructed by starting and finishing on the sixth note of the major scale – in this case: A. This mode is the same as the natural minor scale. The tone and semitone order is once again displaced by one step.
T - S - T - T - S - T - T
The Locrian mode is constructed by starting and finishing on the seventh note of the major scale – in this case: B. The tone and semitone order is once again displaced by one step.
S - T - T - S - T - T - T