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
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?
Ag insider logo xs@2x
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.
bmcleod's avatar
bmcleod
57 posts
 
So the original link I posted was because the company specializes in low noise cooling solutions. But you still might salvage your installation with newbee's rheostat suggestion (or as I did in a another cabinet, 2 fans in series).

Another suggestion would be to make sure your mounting screw holes are slightly larger than the screws, and add rubber grommets under the screw head as well as a rubber washer between the fan and cabinet (cut out of old innertube). I've done all of this to reduce mechanical vibration into the cabinet which otherwise becomes a nice transducer. However, you'll still need to slow down the fans.
jamesk58 OP
73 posts
 
Thanks to both the latest posters. Yes, I do need to get the fan speed down and will look for a rheostat today. 3200 rpms is just too much. As I mentioned above, the fan seemed pretty quiet when I powered it up loose on a table- even at full speed.

Will also get some rubber grommets. I did slightly over size the holes so there is some movement around the long screws. Will probably need longer ones now that I'll add 2 more grommets to each side of the attachment.

If it's still too noisy I'll look for a better fan. This one is off the shelf from RS but appears to be well built. It is a ball bearing style so we'll see if I can get the noise down.
More to discover