2. amps-preamps
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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
 
So I just completed the install and the fan is just too freaking noisey! It hums along at something like 3100 rpms and you just can't stand it for more than 30 seconds. I powered it up prior by itself and it seemed fine but once installed in the cabinet you can hear it in the next room.

The electronics store person where I got some of the wiring and a little protectant grill talked me out of the reostat because he said it would be hit and miss to get the values right and may not adjust properly. But I can't leave it running full tilt all the time so I'm either going to toggle it for on/off sessions or find a reostat that works.

Geez, why isn't anything simple....
newbee
4,767 posts
 
FWIW, I bought a fan rheostat for a fan at Home Depot and hardwired it to the fan on a long enuf cord so the control was easily assessable to use and it works fine. What is causing all of the noise it the vibrations and its very hard to eliminate these without reducing the RPM's substantially. You can reduce the effect of the residual vibrations by the way you attach the fan to the cabinet. What I did was to glue some heavy medium soft pad of rubber on to the cabinet surface and then glued the fan to the rubber. You can't just screw something on using rubber as a gasket. The vibrations will pass right thru the screws to the cabinet. Between the rubber isolation and the rheostat you should get the fan down to inaudible.
jamesk58 OP
73 posts
 
Thanks Newbee. I will go for the rheostat to get the RPMs down and I like the rubber pad idea. Is that something also availible at HD?
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ssvlaunch
27 posts
 
I used two 12 volt fans that were recommended on a previous agon thread. They are way quieter than the ones I bought from Radio Shack first. I mounted them on the "gel" isolator that you can buy from the fan supplier. Once I got them mounted to something solid they are very quiet. It really doesn't take much airflow to keep things cool and since I am pressurizing the cabinet I do filter the intake air. Here is the link http://www.directron.com/sil.html
Good luck!
mijknarf
266 posts
 
I'm far from an expert, but I experienced your same frustration a while back when trying to put a fan on my rack. After doing what you did, I found a very quiet 12v fan here. This is a 12v DC fan meaning it needs a 12v DC power converter like the ones you use to charge your cell phone or run a calculator. I had a few of these laying around, so I used 6v converter. On a DC fan, the speed is varied by adjusting the voltage, so mine is running at half speed (6v vs. 12v). I had some spare urethane dampers that Herbie Audio Labs uses on his tube dampeners, I used these to isolate the fan from my mount. I can't tell if its on or off unless I put my ear right next to it. Even at half speed (~900 RPM) it moves plenty of air. It may be an option for you. E-mail me for more specifics if you wish. Good luck.
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