Will the cabinet have an open back? An open back and enough space above your components may be sufficient. A fan may make enough noise to be noticeable.
FWIW I have my tubed amps on the bottom shelf of a cabinet. When used the doors in front of the amp is open. In the back of the cabinet I cut openings to accomodate two 120v fans wired in series. In that fashion they move lots of air, each fan at a lower speed. The fans draw the air over the amps and push it out the rear, The noise level is very low and not intrusive at all. After operating all day in about 6 cubic feet of space the amps are 'cool', relatively of course. You can get these fans at an electronics store for about $20 each plus some wire and a switch.
Zargon, I do use 5" 120v fans - they move a lor of air with less noise and vibration (only) when you use two in series. I've never used 5" 12v fans but I'd imaging the result would be similar. I got into the 120v models because I originally used just one and put it on a rheostat made for a fan (which was just a PITA - it didn't get enuf air movement when it was dialed down enuf to work quietly). The thing I wouldn't recommend is the smaller 12v computer fans. Not much air, lots of noise.
Many years ago I had my components in a tight open face, closed back and sides, shelved cabinet. I cut two holes in the 1/4" rear plywood and installed nearly silent small computer fans, switched to a power bar. At first use, I found a very slight vibration noise was being transferred to the plywood. I added 3/4" reinforcing bracing to the exterior of the plywood which stopped the vibration.
The cabinet was pushed close to the rear wall and collected dust. Within a year I was to changing out the fans because of wear which caused noise.
IMMHO any design with fans should include easy accessibility for cleaning and replacement.
Thanks for the replies. I had not really thought about ease of access to the fan(s).
As to the A/C question, do you think it's a good idea, in terms of energy savings, to vent the heat out? Have any other hot climate audiogoners gone this route? The heat would be vented out of the room, into either the attic or out the side of the house.
I live in the Central Valley in California - that may qualify for hot climate unless you live near Pheonix. :-)
I would find the addition of a venting system to the house more limiting than beneficial. Of course you could do it much the same as you would vent a dryer in the laundry room, not a big deal, but you wouldn't be able to move the location of the amp or cabinet much. You would still need the fan(s) and to accomodate the tubing from the cabinet to the wall you'd probably have to all for additional distance for the connecting tube. Oh, also consider, that the closer the fan(s) are to the amps the more efficient thier cooling action will be.
FWIW - I'd keep it as simple as possible and easily reversible.
This is an easier way to do it and requires minimum hassle:
The fans are Vantec 80mm square "Stealth" computer case fans (they also come in 60mm, 92mm and 120mm sizes) They are 12V but I run them in parallel from a 9V RadioShack wall wart for silent operation. Unlike most fans of this type, these feature roller bearings for extra quiet operation and believe me, they DO make a difference http://www.vantecusa.com/front/product/chg_page/35/-1
This method allows easy access for cleaning and replacement, and allows the "cooling" to follow the equipment, should your component layout change in the future.
PS: I live in Tucson, just a couple degrees less than Phoenix (usually ;-)
Hi Miles, for what it's worth, and not to bum you out:
I forgot to mention that by using low voltage direct current fans (12V DC) one avoids inadvertantly producing 60Hz AC hum in nearby interconnects or sensitive circuits. The other issue is that if a 120VAC fan is too noisy, it's hard to slow it down except by putting it in series with heat-producing resistors -- which is what Audio Research used to do in their early fan-cooled amplifiers.
I used to think the 120VAC case fans must have better performance compared to the "wimpy" 12VDC versions, but just for the hell of it, I compared the specs for the $12 Vantec Stealth 120mm size fan to the $50 Home Theater PQ fan you mentioned, and lo and behold, the 12 volt DC version has higher CFM airflow and lower dB noise level than the 120 volt AC version, frankly I was quite surprised.
Nsgarch, Out of curiosity, I looked up the fans you mentioned. The site sez that they have an automatic temp control function that is not only a turn on/off but actually controls the fan speed. Interesting and sounds great! But, there is no mention about how the automatic function is dialed in, something that would seem to me to be important, especially if the fans are placed some distance from the heat source.
Are you aware of how this works in actual use?
Newbee - leaving no turn un-stoned, I called Vantec on that issue and it was explained that many newer computer motherboards have built-in heat sensors so that the case fans can be turned on/off or their speed adjusted according to the conditions inside the computer enclosure.
I decided (rightly or wrongly) that implementing that capability in my little DIY audio application was probably going to be more trouble than it would be worth - so I put the whole thing out of my mind ;-)
But if you want to pursue it further and find a simple way to implement that feature, PLEASE share it with us!
Then the heat control is actually external to the fan - now that makes sense to me.
No, I really have no interest in implementing that 'feature'. Actually, to the contrary, for me simple is better. I do have a tad of residualy noise in my set up (I can only hear it when the music is off, sort of just like another environmental noise) but being an anal audiophile I may give these a try.
Newbee, that's also my approach (keep it simple.) But like I said, I did check with Vantec first. For one thing, I felt the fans were really more powerful than I needed them to be (although still very quiet) so after I spoke with Vantec, I decided to (simply) use a 9V instead of a 12V power supply, and that was that ;-)
Electronics that runs cooler lasts longer. You can use active cooling like fans and Airconditioning for your house. OR you can use passive techniques, like a chimmeny to draw air thru.
You can create problems with either technique. With fans, you can have dead spots with little or no air circulation...blow a fan at a piece of vented gear and you may interfere with the natural upward convection of warm air. Passive cooling needs good design and space. It may be possible, for example to cool power tubes with the addition of a smoke stack around the tube. Vented at the bottom, it will draw in cool air and accelerate it up as it warms.
I am currently designing an isolation space for my components. It will feature forced air cooling with input filter. Dedicated vents and a scheme of vibration isolation. The top will have my bigscreen TV, since I am unable to afford, either space or money, more than a single system.
On my worktable, i have a CPU fan, designed for 12vdc which runs fine off a 9v battery and is almost silent. That another poster uses similar is heartening and I may be on the right track. A large, maybe 120mm fan will move enough air, running on 9v. The rat-shack solution may work, even with multiple fans.
Many years ago, I built a fan cooler for my Carver Cube. It 'plugged' onto the back of the amp an drew air thru it. While very noisy, you couldn't tell, since played loud enough to NEED the fan, you could hear the music down the block.
Magfan, just remember that you should not be blowing air AT the component, especially tubes (for exactly the reasons you pointed out -- creating hot spots, unequal coverage, etc.) **Unless of course there's just no other way (but there usually is ;-)
The best use of component cooling fan(s) is to use them to assist/reinforce the natural convection created by the component without fans. I probably should have mentioned that with regard to the picture I linked above.
Similarly, in a room, or cabinet full of components, it's best to have an exhaust fan/or ducted fan at the top or ceiling, with filtered inlet grills at the bottom, or near the floor. In this situation (whole room/cabinet cooling), there are a number of companies that make purpose-built hardware such as http://www.middleatlantic.com
** The one exception I know is Audio Research, which still mounts fans on the bottom of their amps, which then blow air UP over the tubes. A sort of "forced convection".
Instead of a custom rack, you could use a Salamander Design Archtype rack that is open all around, to let your entire system breath, also making it eaiser to dust. A 5.0 is about 39'' tall 23'' w 16'' d. Has 5 shelves, an can have a stacking kit to add more to it. I keep my tube preamp in it and my tube amp on the side on top of a 2.0 I would not put the amp on the bottom, or all of your components would get heat. On top may work if it is not too heavy, or you don't have a turntable on top. I had a Cary V12R in a 15 x 12 room that ran very hot and used it as a heater in the winter, so it would make a difference on your AC bill. I now have a much cooler running Cary CAD 120s and it'll raise the temp. in the room, but not as much. Keep all of your components cool and as dust free as possible, and enjoy your system. Another thing cool about these racks is that they completely adjustable, so you can have the right amount of clearance for taller components.