F# 6/9 — 4-Voice Polysynth

F# 6/9 is built from F# – G# – A# – C# – D#. On the 4-Voice Polysynth those tones land as real keys, and every chart below names the tone under each one — root position first, then the shapes that earn their place: inversions, the open spread, the 1-3-7 shell.

The 4-Voice Polysynth allots 4 voices across its 49 keys (C2–C6): enough for most qualities, but the extended colors make the reducer earn its keep — each chart shows the arithmetic.

Under this keyboard's own voice architecture the engine reports: dropped: 5th — kept: root, 9th, 3rd, 6th.