Mine does kick up speed @ 50C. I've only had an SB 200, SB 220, Ameritron 811h & the KPA. None had the ramp up feature like the KPA. It's the quietest of all I've had even running on it's higher speed. When it's idling or resting vs. the the other amps...Forget abt it. They let you know they were on !!!!!!! K9IL