Symmetrical scales are one of the most powerful tools in a modern guitarist’s vocabulary — they open up sounds that sit just outside the major-scale world, and once you understand how they’re built you’ll find them far more approachable than their exotic reputation suggests. This session from the masterclass weekend digs into the theory and the fretboard application together, with the end goal always being music rather than mathematics.
What you’ll get out of this lesson
A clear definition of what makes a scale “symmetrical,” a look at the whole tone scale and both versions of the diminished scale, and practical guidance on how to visualise and use these sounds on the guitar.
Note: due to connectivity issues the original footage of this masterclass was heavily corrupted. The session will be reshot in the coming days.
What makes a scale symmetrical
A symmetrical scale has two defining characteristics. First, its interval pattern repeats before the octave — unlike a major scale, where the pattern of tones and semitones only starts again when you reach the next root note. Second, the scale has limited transpositions: if you move its notes to another starting point, you end up with the same set of notes as one of the other transpositions. The whole tone scale is the clearest example. Because it consists entirely of whole steps, the pattern restarts on every single note — which means the C whole tone scale and the D whole tone scale are exactly the same notes looked at from a different starting point. There are only two distinct whole tone scales in total.
The whole tone scale
The whole tone scale has six notes, all a whole step apart. Its symmetry means that any note in the scale could theoretically be the root. Practically speaking this gives the scale a floating, tonally ambiguous quality that suits dominant sounds with a raised fifth or raised eleventh. On the fretboard, the pattern is consistent across all strings (two frets between every note), which makes it relatively easy to visualise once you have the sound in your ear.
The two diminished scales
There are two diminished scales, and distinguishing between them is important because they serve very different harmonic functions.
The whole-half diminished scale (whole step, half step, alternating) is the true diminished scale — the one to use over a diminished chord. It contains the root, flat 3rd, flat 5th, and diminished 7th of the chord, plus a chromatic approach note a half step below each of those chord tones. That structure creates strong resolution pull back to each chord tone, which is exactly why it works over a diminished 7th chord.
The half-whole diminished scale (half step, whole step, alternating) is sometimes called the dominant diminished or double diminished scale. This is the one most players use over dominant 7th chords, and for good reason — it contains the root, 3rd, 5th, and flat 7th of the dominant chord, plus the flat 9th and sharp 9th as extensions. It creates an edgy, tense sound that resolves beautifully when the dominant resolves to its target chord.
“The diminished scale is actually the scale that starts whole half. Because this is the one that you’re going to want to play over diminished chords. If you look at this scale here, you can see I’ve got a root, a flat 3rd, a flat 5, and a 6, which is also the diminished 7th. That’s my diminished chord.”
Tritone and augmented scales
The session also touches on the tritone scale and the augmented scale — further members of the symmetrical family. These scales have even fewer transpositions (the augmented scale has only four distinct versions) and create their own distinctive colours. They are covered as additional options once the whole tone and diminished scales feel comfortable.
Taking it further
If you want to go deeper into the theory, searching for “modes of limited transposition” will lead you to a full mathematical account of all the symmetrical scales that exist and their properties. For practical purposes though, the whole tone and the two diminished scales cover the vast majority of musical situations where you’d reach for a symmetrical sound.
Your homework
This week, learn the half-whole diminished scale in one position and play it over a dominant 7th chord. Focus on hearing the flat 9th and sharp 9th as the most characterful notes in the scale. Even five minutes a day with this will begin to make the sound familiar, and once you can hear it you’ll start to notice it everywhere.