Axiom Home Page Forums General Discussion Technical Questions Cooling Fan

Interesting post Bigjohn. My onkyo runs hot as well. My old Onkyo that I had for just under 10 years ran hot as well. In fact the friend I sold it too has it in a small cabinet and had it melted the feet of his dvd player that was placed on top of it. (house cleaner closed the cabinet while listening to music and cleaning the house, the cabinet went thermonuclear).

I have considered the fan idea but worry that the noise would be pronounced although probably no more than my dvd player making noise while spinning the little discs. Definitely let us know how it goes if you install the fan.

I have run my newer 601 for hours and hours and it does get pretty scary hot but so did the old one and its still kicking after a decade of heat.

The only problem in my case was I NEEDED the fan. My HK630 was running hot enough to constantly kick in the automatic shutdown circuitry when the room was warm and depending on how load I was playing it. This is most likely because I am running the M80's.

So until I use separates for the M80's, I'll be sticking with the fan.

The way to keeping fans quiet it to run them lower than their specified voltage. I run 3 DC fans, all are 12Volt fans. I run them at 5 volts, they run plenty fast enough to move the air, and they are very quiet.

Heat greatly reduces the life of electronics, so even of your amp is not switching off, you may still want a fan, it's always better to run cool.

My Denon runs hotter than my monos. How do you limit fan speed on your fans?

Yeah, I'd like to know too. It would probably reduce the noise of my fan too even though its not much. Problem is the fan really runs faster than you need it to cool the receiver down. Slowing it to half speed would be ideal.

To slow the fan speed down, just reduce the input voltage. It won't harm the fan, if it's a DC fan. I use a power supply that has multpile outputs. 5V, 12V, 24V. You can get a power supply like this at Radio Hack, or partsexpress.com

If the fan is a 24V fan, run it at 12V, if it's a 12V fan run it at 5V.

Like This?

A variable power supply would definitely give you more control and with enough current allow you to run a chain of fans at lower than normal speeds. Ideally you would want the largest DC fan you can get and run it below its rated voltage. The larger fan running at a lowe speed will typically produce less noise than several smaller fans. More importantly is that you will have fewer fans on your equipment. As an example, you can look at Mouser Electronics (http://www.mouser.com/catalog/622/1316.pdf) where you would choose the largest fan with the lowest operating RPM.

It is true that heat breaks down semiconductors. Capacitors also do not like heat. I had to repair a friends NAD cd player that had burnt out semiconductors. The replaced parts also ran hot. That was about four years ago and the unit is still in operation.

A fan is a good idea. Period.

Thanks for the tip! I'm probably going to have to put in at least one fan behind the 525 once i get the doors on my entertainment center, any time in the next 20 years or so...

I guess I should also point out that fans do have an inlet effect. You do not want to put the fan directly over the unit unless you have a hole cut in your cover grill. The expression used in the HVAC industry is "The world doesn't suck, it blows". By this it means that fans operate more efficiently by blowing through a restriction rather than drawing through it. Fans need a bit of space at their inlet to operate most efficiently (and more quietly).

As another example, some computer cases draw and blow through the case for a more efficient cooling operation.

The best install would require further raising the unit to install a fan underneath, have it blow up through the unit (obviously to take advantage of natural convection).