Jeff can correct me if I'm wrong, but I think what he was suggesting was using a 9v power supply even if the fan is 12v. I don't think it will hurt the fan at all and it will run a little slower and, therefore, quieter.
I think he is right, because we do it in our computer mods all the time. We step down the voltage from or 12v supply to 7 or 9 sometimes as low as 5 if the fan can take it. Also you can throw a rheostat in line and make it adjustable.
I just installed a fan for my Pioneer Elite 49. Got the parts from Radio Shack.
12VDC Adapt #2731773
You should use a short extension cord to seperate the converter from you amp or receiver. Also if you screw the fan directly to the shelf you might get some vibration & therefore some sound- this can be solved by installing some weather striping between the fan and the shelf. Good luck.
Parts express sells 2" CPU fans that are ultra quiet for less than $5. I think they require 9-12 V DC. If using a fan for one component I would suggest using one of these. If using it for a rack go with a bigger one like a 4" one.
I will soon have an amplifier that will reside in an audio cabinet. If I were to install a little computer fan on the back of the cabinet, would it be better to 1) Install the fan so that it blows incoming air into or across the amplifier case, or 2) Install the fan high up so that it exhausts warm air out the back of the cabinet?
Ron, I would think the later option would be better as installing the fan to blow air directly into the component would also blow in dust while exhausting warm air high up shouldn't suck dust into the component.
Some computers have component specific fans that blow directly onto a component. Many of the newer CPU's have a heat sink mounted directly to them and a dedicated fan, which blows onto the heat sink. Some video cards use this same method for cooling the video chip. Some computer cases have a fan that sucks air into the case, across the CPU and forces the warmer air out through vent slots or holes, while some case just exhaust air out the back or side of the case. When I built my computer last fall, I used a case that houses four fans. These are in addition to the component specific fans mentioned above. I only use three of the case fans though. One fan sucks air in from the front and blows it across my two hard drives. The other two exhaust warm air out the back of the case. And yes, it is noisier than your average computer, but I want to make sure it doesn't overheat and cause damage to any components.