For the past 18 months I have used 2 Radio Shack 120v fans in my system (12w each) running in parralel off of a fan controller. I have had no problems with it, and it makes no noise that I can hear.
The “speed controller for 115V fans” came from Edmund Scientific’s (
http://www.scientificsonline.com). Part #D30347-60 (US$4.95) in their latest paper catalog (C029D) page 62. I could not find it at their internet site.
This controller is about 1.5” (37mm) square. A nice safety feature is the second pot (trimmer pot) which allows you to set the lowest speed the fan will operate at.
I have no idea what the max load is that you can put on the controller. The voltage regulator (or what ever it is called, it has an aluminum tab with a hole on it for heat sink mounting) has two numbers on it 8T24A, and H2581. My electronics knowledge is close to nothing. Maybe one of the electronics experts can tell us what kind of load it can handle. The controller also has a diode and a couple of capacitors.
All the catalog says is “Keep those fans under control! Components protected from dust by clear plastic case. 120VAC, 60Hz.”