OK, Gunslingers, now you’re going to know I like to do things low-cost and half crazy, but I have one for you to try …

So, you want improved circulation AND silence for an amp that’s mostly ‘in a box?’ Don’t just create slits for entry and exhaust air … put a ‘chimney’ or two on the exit air flow.

Let’s say that the amp is in the lowest part of the cabinetry, sealed off from the rest of the gear, and that there are 3 or 4 feet of cabinetry above that. Create a thin-walled rectangle-shaped tube that runs up the back or sides of the cabinet for 3 or 4 feet through which air exits from the top of the section where the amp resides. Or use readily available pipe of a few inches in diameter, depending on your taste/style. Be sure the total cross section is 24 to 36 inches … as in one chimney 12 inches wide and 2 or 3 inches deep, or two pipes that are 4 to 6 inches in diameter.

This set up seems to do little at first. But once the air begins to warm, a slight updraft will be created which will encourage a greater air exchange than just a couple of ‘holes.’

Now, of course, a more ‘open air’ installation would be the easiest.

And if you going to use fans, I will post a suggestion later for an installation technique used in some professional installations.

Well, go ahead, lampoon the chimney idea!



[This message has been edited by bestbang4thebuck (edited May 01, 2003).]

Stack effect! Natural draft boiler- er, amp... That's a pretty slick idea, actually.

I can't wait for PC overclockers to get wind of it and start replacing case blowholes with cooling stacks.

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gonk -- Saloon Links | Pre/Pro Comparison Chart | 950 Review

[This message has been edited by gonk (edited April 30, 2003).]

Does anyone remember when the Mac was first out? They used to have heat issues also and the chimney thing was one of the cheapest things you could try and I'll be damned if it didn't work!
Just a little reminiscing!

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m-mmeyer
GO TWINS
My DVD's
"Pain heals, Chicks dig scars and glory is forever"

Two things about using ‘cooling fans:’

First, and this may be obvious to some people, but in my experience this is not obvious to all people: fans do not cool the air, they only increase circulation. If a fan creates a flow of air which causes heated air to exit and/or cooler air to enter, then the space through which the air flows will become less warm. If a fan merely moves air more vigorously around in a closed environment, like an enclosed cabinet, cooler and warmer air will be mixed together, but the average air temperature inside the closed space will not decrease.

Why do I say this is not obvious to all people? In one instance I was installing equipment in a small equipment room the size of a large closet. With the door shut, there would be no circulation to the outside. Inside would be equipment dissipating approximately 3000 watts of electricity as heat. When I presented this problem to the facilities person, the response was basically, “There were problems providing venting and cooling. We’ll just put a fan inside.” I have found other installations where this was actually done and people wondered why equipment kept burning up. Can anyone imagine putting two 1500-watt space heaters in a closet, with or without a fan, turning them on and closing the door? How far away are the fire engines and emergency crews?

My second point: the increased circulation of air also means more airborne particles and dust are drawn through your equipment. Personal computers have fans to force circulation and provide cooling. Has anyone looked inside a personal computer after a year or two of heavy use? Yikes! In professional installation training, for installations involving closed racks that have cooling fans, there is the cheap way and the better way. The cheap way is to put an exhaust fan at the top of the rack. Because the air pressure inside the rack is has been lowered, general room air enters the rack wherever it can, through both intentional venting and unintended gaps, carrying dust and dirt with it. The better way is to place the fans in the lower part of the rack, drawing cooling air inward ONLY THROUGH A GOOD FILTER. Warm air leaves the rack via intended venting at the top and through unintended gaps. Filtered air leaving the enclosed space does not introduce dust. If the filtering is done well, and maintained, the equipment does not overheat and the equipment does not become a dust collector. Good filtering also provides some muffling of any sound the fan(s) may make.

But, Gunslingers, don't go to overboard. Electronics designed to dissipate electrical energy as heat can get uncomfortably hot to touch and still be OK, although my general preference for consumer gear is the closer to room temperature, the better.

[This message has been edited by bestbang4thebuck (edited May 01, 2003).]

Middle Atlantic Products makes rack-mountable cooling fan panels. I believe there is a thermostatically-controlled model.

Don't laugh (or BARK), but there is actually a company whose sole mission is to provide cooling solutions for home theater type products.

http://www.activethermal.com/

But what do I know, I'm only a dog!

ARF, ARF says Iggy

BestBang, thanks for the interesting points.

The chimney concept certainly can work. The physics are sound - as anyone living in a house with one or more actual chimneys should know at first hand. But your concept does have some practical limitations, which make it impractical for my cabinet and probably for many other closed cabinets. (1) the chimneys must have a reasonably large cross-section (as you indicate in your post); most cabinets do not have enough additional space. (2) For an entirely passive approach such as this to work effectively, the main heat-producing components must be in sections that are pretty tightly sealed from the rest of the cabinet and have their own chimney. The resulting construction may become more of a plumbing project than a cabinetry project!

Regarding dust, well you're right of course. But with these quiet fans and their low cfm ratings, I prefer vacuuming the dust periodically, to reducing the air flow with an effective filter (which itself needs to be cleaned regularly).

Although it is true that equipment can get quite warm without damage, I believe purely on a logical basis (i.e. without any hard evidence) that keeping the equipment cooler tends to lengthen its life.

Last but not least: sealed cabinets. You may note that I referred in my original post to two fans: I have one at the top pulling air out and one at the bottom putting air in. I actually have a third, smaller fan which directly cools the tubes in my beloved McIntosh tube FM tuner, and which pre-dates the sealed cabinet. The tuner has a switched AC outlet which made it easy to have a small cooling fan that operates only when the tuner is on. Having said that, while a completely sealed space will indeed heat up, circulating the air can still have some cooling effect on actual equipment.

Zakman, unverified ratings must of course be treated with caution. We're in the same boat: neither of us has actually heard the other's fans. These RS fans are quieter than any computer cooling fans I've heard (but I haven't heard yours!), and I believe they move more air as well.

Iggy, ActiveThermal sells its products only through what in my own line of business I would call a VAR or value added reseller. In terms of home theater, it means that ActiveThermal sells only to companies that do custom installations.

I think we are all looking for something that presently does not exist. We have some sort of rack of Audio components that are enclosed to try and prevent dust and to give them some margin of safety. What we need is an AC 115v type of filtered fan that is low in audible noise. This seems like something that is needed by many enthusiasts and an opportunity for someone.

Check out my cabinet cooling Project


[This message has been edited by MeanGene (edited May 04, 2003).]