I got some 200 mm fans, two intake two exhaust. I also got a temp controller. After I extended the back of the amp cabinet and completely sealed the enclosure the system is working very well. Temps remain @ 30C after the fans come on.
The fans are rifle bearings. 166 CFM / fan. I wanted to get quieter fans, but they were sleeve bearings and I wanted higher quality. I decided to put rheostats on each set of fans to quiet them down. I've got it dialed to come one at 32C and it cools down to 30C quickly. I would have liked to have them come on a bit earlier, but then they don't turn off at a temp I like them to when set to come on so low.
I hear the amp fans more than the cabinet fans. Even so, the noise in my room with PJ and amps on is 44 DBs. Not too bad.
Here's a link to the fan controller. It's used in HVAC, but works great for this purpose too. http://www.homedepot.com/p/Suncourt-...S100/100028788
My amps bring air in on one side, and blow it out the other side. I have been taking temp measurements on the air intake side, at the top of the cabinet. Is this the best spot to put a thermometer probe for a permanent thermometer display as well as dial in controller on/off temps?
Since I have speed control, would it make sense to turn the intake up a bit and the exhaust down? It seems to me this would 'pressurize' the cabinet with cool air a bit better before the exhaust sucks it out of the top.