Yamaha RY9 Owner's Manual page 48

ASSIGNING A BACKING - You can assign any of the 200 backing
accompaniments to play with a User pattern. (For details, see page 34.)
EXCEEDING THE MAXIMUM NOTE POLYPHONY - The RY9 has 28-note
polyphony, which means the maximum number of notes that can sound at
one time is 28. Depending on the pattern you have created, several drum
beats may fall on a specific location where many bass and chord notes
exist. Any drum beats that would exceed the 28-note capacity will be
"truncated", or cut off, or will not play.
Turning the power off while Pattern Record Mode is active, or while the pattern Copy or Clear
function is being executed, may cause the irretrievable loss of all User data.
Depending on the amount of data you have recorded, it may not be possible to fully record all the
available user patterns.
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