[ jd303 ]

For various reasons, I haven't posted in quite a few weeks. There's a bunch of Jiras overdue, drafts sitting ready for me to clean up and publish, and videos and music I need to edit. Those still aren't going to get published this week, because I threw together something pretty handy with Claude this week.

KJZ (my guitar teacher) had a nifty "pentatonic shapes in A minor/C major" PDF file that was extremely handy for learning the pentatonic scales. He also has other ones out there with the diatonic modes, too. Now I know that the pentatonic is just the diatonic with a couple notes pulled out, but seeing it visually on the neck is extremely helpful. (Also, some of the diatonic are like right next to the pentatonic, so there's some nuance and exceptions there.)

I fed the PDF as an example of how I wanted this to work into Claude, and we got a nice artifact spit out. I had Claude add diatonic, and even throw in some of the blues notes. You can now visualize how all the scales overlap on different parts of the neck. If you want to get crazy, you can even see all the different modes on how they map over pentatonic. Pentatonic notes are red, diatonic are blue, and shared notes are purple.

My teacher and I use 3NPS, and it works best for us.

[ claude ]

Pick a pentatonic (any root, minor or major) and a diatonic mode (any root, any of the seven). The page draws the full neck, then the seven 3-notes-per-string shapes of that mode in order up the neck. Each shape gets paired with whichever pentatonic box shares the most frets with it.

In the shapes, the colors compare exact frets, not note names:

  • Purple is a fret both fingerings use.
  • Blue is in the 3NPS fingering only.
  • Red is in the pentatonic box only.
  • Amber is the blues note (the ♭5 for minor pentatonic, the ♭3 for major).

That fret-level comparison is where it gets interesting. In the same key, every pentatonic note is also in the mode, so by note name alone there's nothing red at all. On the neck it's a different story. In the A Aeolian shape at frets 5 to 10, the familiar box plays E on the B string at fret 5. The 3NPS fingering has already shifted up and grabs that same E on the G string at fret 9. Red shows you exactly where the two systems pull apart.

Switch to a mode that clashes and red means something else. Over A Mixolydian, the minor pentatonic's C has no home, and it sits right next to the mode's C♯. That ♭3 rubbing against a major 3 is the blues.

Each shape has five highlight buttons: Pentatonic, Blues, Diatonic (3NPS), Pent + Diatonic, and All. Hovering previews a layer, and clicking pins it. The mode presets float down the left side so you can switch modes from anywhere on the page.

It's one HTML file with no libraries and no build step. The fretboards are SVG drawn from the scale math, so every key and mode comes from the same code.

[ jd303 ]

It's live in the warez section and on the music tools page. If you play guitar, go click through the modes and watch the boxes shift around inside them. Lydian over A minor pentatonic is a good place to start getting weird.