Question :
My Compact C9 has huge power but a lower Humm to her sound .
Tristar (probably due to less use ) slight smoother humm
MY C9 has so much suction but seen alot of use still works like new is the motor the same for cxl and c9 my Compact has the normal low pitch humm i know so well my Tristar
slightly smother is the motor the same for c9 cxl BOTH RUN WELL envirocare bag and both use cloth filter but c9 have since 2012.
