Theory Of the Month

Half whole diminished scales are a piece of cake thanks to Nik Preston

Half whole diminished scales are a piece of cake thanks to Nik Preston

This month’s study is designed to help us get inside the sound of the half whole (HW) diminished scale over dominant chords, while using a very simple motif. Don’t be alarmed, this is an awful lot simpler to play than the notation opposite might make you believe!

We often use intervallic exercises to help familiarise ourselves with new scales or modes. As usual for these situations, it’s really worthwhile to practise all of the intervals that occur within the scale we’re working on. Due to the octatonic (eight-note) construction of the diminished scale, we have one more interval to practise than we would were we working with conventional seven-note, Major and minor scale harmony.

The first example features a motif predominantly comprised of tritones (steps of three whole tones), but it could have equally been any interval found within the scale. The chord sequence is essentially a short form (or double time feel) blues in the key of B flat; throughout the study we are using the HW scale built on the root of the relevant chord – Bb, Eb or F (or I, IV, V in the key of Bb).

Due to the symmetry inherent in diminished scales, there are actually only three such scales in western harmony in terms of pitch. For example, our Bb HW scale comprises exactly the same pitches as the Db, E and G HW scales. Eb is the same as Gb, while A, C and F are the same as Ab, B and D. In short, by using a study of allowable diminished scales over a blues, we have managed to practise every diminished scale there is. Handy, eh?

This study also conveniently doubles as a useful string-crossing exercise; you’ll note that Example 2 is exactly the same as Example 1, except that it’s been transposed up an octave. You’ll need a bass with 23 frets to play it in this key, but it’s there for reference (and maybe hardcore sightreading practice!) regardless of the range of your specific instrument.

This study is designed to help us become more familiar with the fretboard, build our knowledge of diminished harmony and improve our listening skills. As with all studies, the final goal is to develop our skills to the point where we feel confident to then go on and create. Practise it at a speed that lets you think about the intervals you are playing – not necessarily as fast as you can physically perform it. At least at first…!

Example 1 Example 2