is tuning is mavila temperament taken out to just 7 notes. With 7 notes it works well on a kalimba. My kalimba remained tuned to mavila for years actually. It's in 7edo at the moment but I kinda miss the way it was before. Mavila is a microtonal musical temperament with very flat fifths. If you stack 4 of these fifths on top of each other, you'll get a minor third instead of a major third. As you continue generating more pitches by stacking fifths, you'll eventually get an "anti-diatonic" scale where all the major chords become minor chords and vice versa.