I have been playing whistle in various sorts of groups for forty years
and NEVER had a feedback problem.This includes Generation,Clark,Tony
Dixon,Shaw and Chieftain whistles with Shure SM Mics and Cheapo Tie
Tack mics.And I will not play a whistle that does not work on at least the first note in the third octave.I know this is not very helpful if YOU are getting feedback problems,but look first at the
settings for your mic.