Will,

I'm sorry, I made the obvious (to me) assumption that you would provide an inlet for the amprack.....you brought up the ideas of computer cases, so lets run with it....

So you go to mwave or newegg and buy a Antec 800 series case. What does it have....only two exhaust fans. Those inlet areas have filters on them for the dust. Now a computer case is a different monster because of all of the obstructions (AGP, PCI cards and the processor) all of these things impede flow....also a computer case is far from sealed.

So, you can still run just exhaust fans and be ok....you don't have to run inlet fans. Because of the obstructions, it's nice to run a side panel fan or front case fan....why, because of stagnation...you won't have much stagnant air in an amp rack.

 

the only way that the rack would be sealed is from the wood glue. there is no need to seal an amp rack. you can deaden vibration with matting.
that is what i'm trying to explain with the pull/push system. one draws air in/ one pushes out....to create a cross flow.

 

it will be enclosed (in a box style with plex on top) but i don't see why it would need to be sealed

 

Will, there are two types of cooling being experienced inside a sealed amp rack:

1. Passive conduction
2. Forced convection

The passive conduction is a product of heat transfering from the hot amplifier to the cool air in the rack....this will continue until the air in the rack reaches the same temperature as the amplifier....equilibrium.

Forced convection is a product of the cool inlet air being pushed across the heat sinks. Because of teh small size of the rack, and the low velocities, I doubt you will ever reach laminar flow across the heatsinks...this makes inlet fans unnecessary....there will be velocity losses across the amps due to head losses, but we are not talking about a wind tunnel here.

You don't want to just pull the hot air from the rack, you want to force it across the amps.

 

Let me clear up my nomeclature....by sealed, I mean the only big holes will be the inlet and outlet for the cooling system.

 

Let's think of it this way for a moment...take a shoe box...then cut a 80mm hole at one end, and an identical hole on the other end (cut them on the short vertical sides).

Then place an 80 MM 25 CFM fan as an exhaust fan at one end of the box...hook it up. What happens?

You flow 25 CFM through the box....constantly flowing that much air, as the shoe box (with the lid of course) always has the same volume of air in it.

Now, add a second fan as an intake fan...switch it on....what happens?

NOTHING....you are still flowing 25 CFM....there's also an argument to be made that due to the friction on the blades of the fan, you are now forcing hotter air into your amp rack...again minimal gains....but think about it for a minute...you ahve done NOTHING for air flow.

Now, cut a second set of holes on the shoe box...both 80mm, and put both fans on the exhaust side...now what

Double the air flow!!!

If the goal was to fill a bucket as fast as you could....would you want one hose or two?

 

see, now we are making sense. All i need in that design is an opening at one end to allow air in the one side. that is why i originally wanted two fans. like you said. i only need one probably. I am running a 700+ watt/2 channel soundstream amp for my subs (bridged to double wattage to speaker/lower ohm load) and a 600+watt/4 channel amp for my components (100 watt rms each channel). would I need 2 fans to cool?

 

Think of the scenerio that I already proposed with the shoe box....if there is no fan at the inlet, and there is nowhere else for air to come from, you will already have cross-flow.....physics says so.

 

What are the dimensions on the amp rack? What size fans?

Gotta have more information then that.

Again...if you want to double your fans and put inlets there...fine...go for it....but you are throwing your money in the garbage.

 

ok that shoebox example and clarification of the inlet hole in the box made more sense to me.