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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
newbee
4,768 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. :-)
audiofeil
4,011 posts
 
Bmcleod offers very bad advice. Cooling fans should draw the air away from components, not blow air at them.

Good luck
inpepinnovations1e75
395 posts
 
Forced draft or induced draft, it doesn't matter, the tubes don't know whether the air is being 'pushed' at them or 'pulled' by them. Usually, however, one can get more air flow for the same size fan in a forced air setup, but the difference isn't much nor critical. I see only noise problems using a combination of forced and induced draft and no advantages.

Salut, Bob P.
audiofeil
4,011 posts
 
Hot air should be drawn away from tubes not cool air blown on them.

Thank you.
jamesk58 OP
73 posts
 
Well I just got the cabinet and set the equipment up. Everything is working great, but yes the underside of the shelf directly above the amp is hot as a skillet. Still thinking of getting some automotive heat tape for the underside of the shelf just to protect it and get the RS 4" fan to pull the air out of the lower part of the cabinet.

I had them drill three 3" holes spaced equally from top to bottom. I'm running cords/wires out of the top two and left the bottom one unused for the fan.

For now I think I'll plug the fan to the switched power strip I set up off the pre-amp so it will run as long as everything else is under power.
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