Scott,

If I recall, the T2 experienced the problem prior to the OS updates. The T4 never had the problem. When I talked to Yamaha many years ago about this problem they said it had something to do with the processor not being able to handle all the tasks at hand with the amount of available RAM memory. I believe the T2 OS updates addressed this by consolidating some of the OS tasks, thereby freeing up RAM for the vocal processor on/off function to perform a bit faster. The problem is most noticeable when you are in the middle of a word when you punch the harmony button. If the song is somewhat slow, such as Have You Heard by the Duprees, you can usually time the foot pedal depressions and avoid the problem--but not always. The delay is about 1/4 of a second, which is very noticeable.

Gary

Gary