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Cooling fans for tube amp

Just read a thread from 2005 about rack cooling fans. I'm having a custom built wood cabinet made with casters for my stack that includes an Audio Research D-90 that can get very warm after an hour or so.

Any new recommendations on what fan to use and how to set-up? Most computer fans don't have standard wall plug connectors.

I was thinking about a 4" diameter fan that will plug into my "Switched" power output off the SP-12 pre amp so it goes on auto whenever I power up. Should it "push" or "pull" the air? Mount on the back of the cabinet with a cut-out for airflow?

I may just run a power strip off the pre-amp's switched output to power one to two fans plus the subwoofer so they all only run when I power up the pre-amp and amp.

Also thinking of putting heat resistant tape/insulation on the underside of the wooden shelf directly above the amp.

Sound OK?

Or something better work w/o a major engineering project?
jamesk58
jamesk58 OP
73 posts
 
Thanks guys. I did check out a RS fan that was recommended by other users and I should be able to install w/o too much effort.

My biggest question that Undertow answered was the push or pull issue and he obviously said to pull the air out of the cabinet instead of pushing it back over the amp.

I could get really involved and install a thermostat so it only comes on when it gets too hot and then shuts off after cooling down, but for now I think I'll just go with the pre-amp switch and let it run when the system is under power regardless.
bmcleod's avatar
bmcleod
57 posts
 
The best option is to get two fans, one pulls air in from the bottom, the second pushes air out through the top - or from side to side, across the equipment. If you are going to get the 110 fans I would consider the rheostat idea to slow them down (noise), or wire them in series which would cut their speed in half.
russe41
95 posts
 
I like 24v DC fans, then usually run them at 12v.
Very quit Alternative.
jamesk58 OP
73 posts
 
Bmcleod or Russe41, would you run two 24v DC fans in series causing them to then run at 12v? or how would that work?

I will have three shelves in the cabinet with the amp on the bottom. What would be the best positioning for two fans? Originally I was thinking of one fan pulling air out of the back just behind the amp since that's the big heater. Not sure I could get circulation from top to bottom because of the shelves blocking air flow.

Possibly two fans pulling from the back- one high one low?
newbee
4,767 posts
 
Jamesk58, a couple of observations. 1) If you're cooling a cabinet with tubes you do not need or necessarily want direct air directly over the tubes and 2) don't move any more air than you need to to keep the cabinet interior at room temp.

If your cabinet has openings on the bottom, and top(where your fan should be), you will be surprised about how little air you must, and can, move by one exhaust fan to maintain room temps in the cabinet, even if you should keep doors closed. Thats why I recommended 110v w/rheostat. Use a thermometer to measure air temp and adjust the speed up and down 'til you have it at room temp. Easy to do. Keep it simple as possible. :-)
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