I always feel better when the fan is on, but it is not a must have. In the combo's it only really cool the outer three tubes, but it's better than purely roasting the tubes. To keep them quiet, I do my own refurb and apply a good amount of dielectric great to the fan magnets and housing. After that they are barely noticeable. On of the fans on my head sounded like a turbine jet engine until I did the rebuild. It's now something that you have to listen for to hear. If you want to upgrade, the new Mesa Globe fans are very quiet, but to maintain originality I still use the Howard Cyclohm's.