Exploring m7b5 on Minor 7s

It's no secret that I like m7b5 arpeggios. The other day I was trying to figure out all the options I use on a m7 chord, and came across what's almost a pattern but isn't. Nothing life-changing but some directions for further investigation.

NB: This post ended up as a bit of a "stream of consciousness" that I suppose at least illustrates my thought process when working out new ideas. It doesn't in any sense represent how I think when I'm actually playing music; you need to work on ideas like these until they come out without any kind of thought or calculation.

Here are the m7b5 arps I might use on a Cm7 chord to get a range of different flavours:

  • Cm7b5
  • Dm7b5
  • Ebm7b5
  • Fm7b5
  • Gm7b5
  • Abm7b5
  • Am7b5
  • Bm7b5

The "pattern" is that the roots spell out the notes of C Melodic Minor, except for the Ab; or they spell our C Harmonic Minor, except for the A. I think of them the first way because Abm7b5, the one built on the b6, has a special sound to me and I think of it as an exception.

Another way to think of this list of 8 options is to look at the 4 possibilities it doesn't contain, which are the for m7b5 arpeggios that contain the note E. I consider this note -- the major third -- a pretty strong flavour on a minor chord, so I like to treat it separately.

Here are some of the scales these superimpositions imply:

  • Cm7b5 (Dorian #4)
  • Dm7b5 (Aeolian)
  • Ebm7b5 (Dorian #4)
  • Fm7b5 (Melodic Minor)
  • Gm7b5 (Phrygian)
  • Abm7b5 (Harmonic Minor #4, aka Simhendramadhyamam)
  • Am7b5 (Dorian)
  • Bm7b5 (Melodic Minor)

You can probably see now why I treat Abm7b5 a bit differently. Those built on 1, 3 and 6 imply Dorian #4; those built on 4 and 7 imply Melodic Minor and those built on 2 and 5 impliy Major Scale modes. These are all pretty common sounds.

But Abm7b5 implies Simhendramadhyamam, sometimes called Hungarian Minor (although several scales get called that) or the Algerian scale (though it has nothing specifically to do with Algeria as far as I know). It's a mode of Double Harmonic, a scale I don't use often enough.

The key thing for me here is making these connections and then asking where they lead. For example, there's a very easy way to imply Simhendramadhyamam: on Cm7, play Bm6. This is exactly the same idea as playing Abm7b5 (all four notes match) but can be easier to "see". More useful perhaps are the two Maj7 arpeggios on the 5 and b6; this is already something I often play on Maj 7 tonality (e.g. DbMaj7 on CMaj7) so it's easy to transpose to this new setting. Or what about, more radically, the idea of alternating between b6Maj7 and b6m7b5?

By pure coincidence of names, this led me to another so-called Hungarian scale, the Hungarian Major or Nasikabhushani. This can be thought of as a blend of a dominant 7 and a diminished 7 built on the same root: 1 #2 3 #4 5 6 b7. On a Cm7 chord I might play this scale in five different places (each time, of course, avoiding the note E):

  • D Nasikabhushani
  • Eb Nasikabhushani
  • F Nasikabhushani
  • Ab Nasikabhushani
  • B Nasikabhushani

These root notes form the diminished 7 arpeggio built on the 7 of the Cm7 chord, plus the Eb. You could think of this as a pentatonic scale (which I call Diminished Add b2) or -- and here's what I prefer -- as the b6 minor triad + b6 diminished 7.

So here is how I want to think about this idea while I'm working on it: Visualize the b6 minor triad arpeggio and the b6dim7 arpeggio together. Any of those notes can be the root of a dominant 7 and a diminished 7 that together make the Nasikabhushani scale.

Sounds complicated! You can't think like this and play proper music at the same time. The sounds need to be internalised so they just come out when you "hear" them, and that takes a bit of time. But the reward is interesting, half-familiar-sounding lines with a distinctive flavour.