Do not allow the fan to blow directly onto the tubes as this will cause microcracks. Place the fan's exhaust away from the amp, which will allow the cool air to be "drawn" into the amp, thus enhancing the natural cooling convection effect to take place.
Looking for Silent Fan Cooling f my ARC Tube AMP
I have my ARC tube amp in a corner. I like to stick a fan behind it . The one from radio shack worked great but made a little noise. Any suggestions . Thanks to all !