cooling mono amps


I have two BATVK-55 mono block amps sitting in an Audiov Zirconia rack. They give off a lot of heat when the ac is not on. I read threads about pulling the air away from the tubes and have seen 5.25" fans on line, two configured in a 19" panel. I was wondering if one of those mounted at the back of the rack, one behind each mono block, will suffice? Should I include a thermostat? Is ther another quiet fan I should be looking at? I would appreciat your comments and suggestions. Thank you.
bgmyers
"They give off a lot of heat when the ac is not on"

Are you trying to cool the room or the amps?
You can also check the coolerguys.com site, they have nice cooling solutions for home theater/amps.
A possible CAVEAT regarding fans: Some years ago a letter to 'Audio Amateur' magazine warned that a C-J MV-45 owned by the writer had the strange habit of sounding very noticeably worse with the tube cover [solidly] in place, compared to simply removing the cage. It turned out that problem was not a mechanical or electromagnetic problem with the cage itself -- it was the quiet fan unit he'd installed causing an overall degradation in the sound (not just some identifiable noise).

Some years later I read something about these fans not always being what they seem due to the use of hidden current pulsing circuits aboard -- the implication being that your DC fan, for example, may not be so "DC" as it appears to be, or as represented in its promotional material. I don't know any more about this, but I'd be very interested to hear the real technical scoop on these devices. How closely did you guys compare? Just asking. If there was an assumption up front that the electrical operation of the fan is benign, could this belief itself have enough of a masking effect -- maybe just in the moment -- so that some small negative could have gotten overlooked. I'm not suggesting the thing wrecked your sound, of course... we all simply accommodate.
Larger diameter fans spinning slower are much more quiet then a smaller diameter fan spinning fast both moving the same amount of air.