2. amps-preamps
  3. 1170013775

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
inpepinnovations1e75
395 posts
 
Again, induced or forced draft doesn't change the amount of air cooling the tubes nor its quality. Even if the pressure is positive inside the cabinet, dust enters from the room in the air being blown in by the fan, unless one has a filter on the intake of the fan.
At any rate, the tube amplifier should not be placed inside a cabinet and if one must, it should be placed at the highest level so that its heat doesn't affect other components.
audiofeil
4,011 posts
 
Good planning Jamesk58. You're doing it correctly.

Have fun.
jamesk58 OP
73 posts
 
The amp needs to be on the bottom for low CG and overall stability. I also intend to get some heat tape to attach to the bottom of the immediate shelf above the amp. My Akai tape player is situated directly above. I don't believe I'll run into an issue with overheating the other componets, but do want to keep the amp at a reasonable temp.
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.
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