Need help with stereo cabinet design.

If you're considering a built-in cabinet I'd suggest locating the fan in the attic to get the fan noise as far away from the equipment, and listening position, as possible. It can vent either directly to the attic or be ducted to the outside like a clothes dryer with a one-way flap. Although, if the latter you might get cold air blowback in cold weather even with the flap. Best choice of fans would be a squirrel-cage type, like the fan on home forced air furnaces; but smaller. The fan control can be located in the listening room for convenience. That type of fan is more efficient than a rotary blade fan and you can move a good quantity of air with a relatively small fan. The fan's CFM shoud guide you as to size.
Slatted wood shelving - perhaps maple for its resonance-draining properties - would facilitate air movement although these may need to be custom made.

For fans look at W. W Granger catalog, they have ones for every possible use. If it were me I would use something like the Star Sound rack that I use. It uses mainly open steel shelves with the components mounted on cones coupled by discs. Gives the best isolation I have has by far and you can build an enclosure with doors to hold it. There are other good racks available. I think this would give you better sound and the cost would probably be comparable to a custom built cabinet. With any custom cabinet , no matter the care taken, you never know how it will sound. Years ago Martin Colloms had a custom built cabinet made, even placing it on a large marble slab to add mass and so it could slide on carpet. It weighed several hundred pounds but was not a success despite his best efforts. If you use a rack you will at least know what you are going to get and many of them are very attractive.

jgialco is SOOOO right. Listen to him totally!

Just thread refrigerant tubing in the isolation draining sloted maple or I might add Myrtle shelves. Put the compressor far away in a different structure if you can. The compressor draws a bazillion amps so keep it well clear of the audio component's dedicated lines and have it on a 240 volt outlet of it's own. You will need a very quiet tuned port to evacuate the air evenly . a simple bulbous portable Oreck type house hold vacuum cleaner should be kept in the basement rember to get a very long special extension tube with splitters and nozzles for each compartment.

I would build a small closet between and behind the speakers. Use curved walls which are double-insulated. Insulate the ceiling and floor. Sliding glass door (heavy and double-insulated) on the front with heavy curtains attached to the front. Put 5 dedicated outlets inside, along with an adjustable fan and a vent hole to outside. Create a small hole on either bottom side to run your speaker cables, and pack them full of some thick cushioning material. Have an isolated ground for your dedicated outlets with an audio-grade grounding rod (one for analog, one for digital). Look into audio grade wiring (8 gauge). Consider adding an ExactPower PowerCore and Conditioner. Put a HRS rack inside the closet. Then there will be nothing further to do.

I'm sorry. There is one more consideration for isolating everything from the floor. The floor inside the closet should be built on their own floor joists that are separate from the room and the closet wall. An elastic skin can be used between the joist and the flooring.

Now you have ground, air, electrical, and component isolation.

Consider a thermal alarm inside, in case of fan failure. There may even be a way to set the fan on a variable speed thermostat.

Jgiacalo is correct, get the blower as far away as possible.

I built a closet for my equipment. I ran 2 blowers, one on each side wall. One blower brings conditioned air in from the hallway and the other to take the air out and to the attic. I ran 4' insolated flex duct from each blower and then reduced down to 2" PVC with a 2"T every 6 inches. The 6" spacing allows me to put the shelves where ever I want and still get air onto the shelf. Then I used armaflex with different diameter holes to control the air volume from each 2" hole of the pvc supply. The only place in the closet the air does not go is where my TT is, those holes are blocked off.

If you are going to use a blower to move air only in or out, you must make the unit loose so it can get the air from the room or send it into the room. If the structure is too tight you will not get any air. The air must have some place to go.

I used Russound ACT1 12 volt trigger to turn them on and off with my ARC REF3.

if you live in a cold climate, do not duct the run into the attic. Either run out through the attic and out the roof, or out the side of the house. You never want just plain warm air dumping into your attic.

Thanks for all the suggestions. It will definitely be a cabinet rather than a closet, given the room design and my desire to see the components when they are in use. I wonder if, when the cabinet is open, the heat will rise to the top, where it can be vented, or if much of it will escape out into the room. I like the idea of putting the fan in the attic, with a switch in the cabinet or using the 12 volt switch on the REF 3.

I live in Austin, TX, which has a very warm climate. My main reason for considering venting is concern regarding adding heat to the room. In the winter, or should I say on the cold days that we sometime have in winter, I'll obviously want to let the system add heat to the room.

I wonder how the power required to exhaust heated air compares to the added air conditioning work load due to non-exhausted heat.

As for isolation, I agree with the suggestion regarding separate joists. In that particular spot we're considering a small concrete pad for that purpose. I suppose we could bolt down a rack system to that pad and somehow add wood facing to the shelves to improve their aesthetics.

Thanks,

Chuck