I’ll post a portion below - it was a fairly long and wide ranging chat. First let me set it up (this will get wonky). I fed Claude a screenshot of the Key Editor of some bars that I’d written. It was in C Phrygian but also had an extra F# added to the scale so there was a cluster of minor 2nds F-F#-G which added a bunch of ambiguity in the 4th/5th neighborhood. Initially there was some confusion on what was happening due to Cubase’s ‘habit’ of misspelling sharps & flats. This is from right after that got sorted out.
A few things worth noting about this specific 8-note scale:
It’s Phrygian with a chromatic 4th/#4 pocket The F–F#–G cluster is the only place in the scale with consecutive half-steps. Everywhere else the scale still moves in its normal Phrygian intervals (half-whole-whole-whole-half-whole-whole from C). So harmonically/melodically, you have one “hot spot” of chromatic tension around the 4th–5th, and the rest of the scale stays clean and modal. That matches what you found in the synth line — F# consistently resolving up to G — it’s functionally acting like a chromatic approach tone to scale degree 5, not a wholesale mode shift.
The bass’s F#–C tritone reading still holds Even with the enharmonic correction, F# and C are still a tritone apart, so that oscillation in the bass (bars 11–12) is real and still worth noting as a distinct device from the synth’s stepwise F#→G resolution.
Naming-wise This isn’t a “named” traditional mode (it’s not Phrygian dominant, not double harmonic, not a standard bebop scale) — it’s simplest just to describe it as Phrygian with a chromatic passing/neighbor tone between 4 and 5. That’s a very normal, controlled way to inject tension without abandoning the mode’s identity, which fits the “one hot note” character you’re actually hearing rather than the denser polymodal picture I described before.
A bit later
What the added F# does to this pattern
Without F#, the F–G dyad is a plain major 2nd — the “calmest” interval in the set. By inserting F#, you split that gap into two minor 2nds (F–F# and F#–G) instead of one major 2nd. So you’ve added a third “hot spot” to the mode, turning the one previously mild region into the most chromatically dense one. That’s consistent with what you’re hearing in the synth part — it’s not random alternation, it’s Phrygian’s natural m2/M2 shift plus an extra compressed cluster right at 4/#4/5.
The effect
Secundal dyads built this way give you a sound that’s dissonant but modally dissonant rather than chromatically dissonant — the ear tracks it as “colorful mode” rather than “atonal cluster,” because the pitches are still constrained to (mostly) your 8-note set. That’s a very Bartók/Messiaen-adjacent technique, and it also translates well to electronica — secundal clusters are common in ambient/IDM writing for exactly this reason: tension without needing functional resolution.
Is the synth voicing strictly adjacent scale-tone dyads throughout, or does it sometimes skip to a 3rd/4th and only use the 2nds as color at cadence points?
Much, much later (we’d also briefly discussed Monk earlier, so that’s not a random mention).
Bars 13–14: genuine stacked secundal harmony
This is the more striking passage. You’ve got Db3, Eb3, Ab3 (G#3), and Bb3 all sustained simultaneously for real duration — not passing tones, actual overlapping held notes. Stack those up: Db–Eb (M2) and Ab–Bb (M2), a perfect 4th apart from each other. That’s a quartal-secundal hybrid voicing — two major-2nd dyads stacked a 4th apart — which is a genuinely more sophisticated harmonic gesture than bars 10-11. This isn’t “chord + added 2nd,” it’s a real cluster-of-clusters, and it’s the moment in the part that would sound most identifiably “jazz harmony” rather than “modal melody with color tones.”
So you’ve actually got a progression in harmonic density across the phrase: looser, single-note-against-drone dissonance in 10-11, tightening into a genuinely stacked secundal chord by 13-14, then presumably loosening back out toward 15-16. That arc — tension accumulating into a real cluster rather than being uniform throughout — is probably a big part of why it reads as purposeful rather than random. Monk does this too: he doesn’t hold the same dissonance level the whole tune, he escalates into the “wrong note” moments and lets them stand out.
imo imo imo
