HELP! I have a song with a strong sixteenth note rhythm in 4/4 at 130BPM. But halfway through, the sixteenth notes stay the same tempo and switch to a triplet rhythm (alternating 1+ 2+ 3+ 4+ and 1 a2 a3 a4 a). How should I write that? Constant triplet brackets in 4/4? 12/16 time signature? A very uncomfortable 6/8?
your description of the change is not entirely clear, but if it's all groups of 3, i would say use 12/8. and if the value of time needs to change, use 'note equals note' notation. for example if you're using 12/8 and you need the new tempo to be dotted quarter = 130, then write quarter note = dotted quarter note, when the transition occurs. However, (and this was unclear to me from your description) if the old 16th note needs to become the new 8th note (in 12/8) then you can write sixteenth note equals eighth note. Or if you use 12/16 you don't need any conversion. it will also be assumed that it's grouped in 3s if you beam them that way