Help with rackmount amp

Douglas Hudson · From: Galena, Kansas, USA

Hey guys,
Here is the situation. I have a 4 space rack that has a tuner, profex, eq, and a stewart amp. Last sat. night when we finished playing I went to turn off the rack and the amp was very very warm. It did not give out during the show, (was running approx. 6 hours). My question is should I open up the rack by removing a unit to get better airflow to the amp for cooling, or any suggestions you have I would appreciate. This is my first with rack mount amp.
Thanks
Douglas Hudson

John Daugherty · From: Rolla, Missouri, USA

Doug, You probably need to provide a way for the heat to escape from the rack case. Your best solution would be to add two openings in the case. One for intake, one for exhaust. A small, quiet "muffin" fan would work good when mounted in one of the openings as an exhaust fan. (Stewart amps are great amps but do not have fans)
That amp WILL shut down when it gets too hot. Then you will have to wait for it to cool before it turns on again. I suggest you find a way to cool it before you have problems in the middle of a gig.
Just opening the back of the case does not work very good. The heat rises to the top of the case. A lot of that heat is conducted up through the amp chassis, making the amp hot when the heat sink is on the bottom of the rack case. (I have been there,done that)

Jay Fagerlie · From: Lotus, California, USA

A fan would really help out.
Make sure it is a DC fan, not an AC fan.
Mount it in the back and set it to blow air towards the front. The fan should have a little arrow showing direction... You'll probably want to aim it at the power amp.
Jay

Jack Stoner · From: Kansas City, MO

I have a 6" round speaker grille on each side of my rack. That provides, so far, adequate ventillation for the equipment. I haven't had to resort to a fan, even here in Florida.

One of the problem with the Stewart amps is, they rely on ambient air flow for ventillation and in that case it might be necessisary to add a fan.

I've got two power amps, a MosValve 500 and a Peavey DPC-1000, depending on which power amp is the "flavor of the month" will depend on how I mount it in the rack. The Peavey basically draws air from the bottom and I have an extra air vent at the bottom of one side so I make sure it's mounted on that side. The MosValve 500 draws air from the bottom, so I make sure it's mounted with it's bottom next to the 6" grille so it can suck in air.

Just a comment, I see equipment from major manufacturers that run very hot but they don't provide any means of ventillation or like the Stewart amps just rely on ambient air. However, many like to load up a rack and not allow for any air flow and "bake" the equipment. It will work for a while but ultimately the constant overheating will take it's toll on the equipment. Another no-no is the "bag" type racks as they are like putting a blanket over the equipment - no ventillation at all.

Jon Light · From: Saugerties, NY

As to your specific question, yes, I do believe that removing a unit (or moving into a 5 or 6 space rack) to open things up will improve things some.

Douglas Hudson · From: Galena, Kansas, USA

Thanks for all the great info guys. I will probably have to move out a unit and add a fan just for safety.
Douglas Hudson

Douglas Hudson · From: Galena, Kansas, USA

Hey John,

We were just in Rolla at z's place last weekend! Actually is in Doolittle but close enough LOL. We will be in your area again on the first weekend in August. The Smiths Brothers Band

James Cann · From: Phoenix, AZ

Hook Moore · From: South Charleston,West Virginia

Doug, I use a Stewart world 1.2 rack amp. Mine gets a little warm but never hot. I leave an empty rack space on either side of the amp covered with only a perforated rack filler strip. I also stand my rack up to allow for a chimney affect allowing the heat to escape. The main thing is to allow air circulation around the amp and you will have no problems.
Hook

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www.HookMoore.com

Jay Fagerlie · From: Lotus, California, USA

James,
AC fans generate noise. Where the brushes connect there are actually sparks that will be very audible. Ever hear alternator noise in a car stereo? Same thing.....
DC fans are brushless and can be powered by a little 9 volt adapter (wall wort)
I had a heating problem with my home theater system and set up a dc fan with a wall wort and it keeps it nice and cool.

Jay

David Spangler · From: Kerrville, TX USA

One of my racks is an SKB 4-space with rails front and back. In the back, I put 4 tall rubber feet and set it on its back on the floor. In the front, I have 3 devices and a 1U vent panel. This lets air enter between the floor and the edge of the case, warm air rises out through the vent panel and seems to prevent heat build-up. The Stewart PA1000 has never shut down. I like having the rack facing up beside me so I can see it well and reach the controls without turning around.

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David Spangler

Dave Grafe · From: Hudson River Valley NY

In regards to fans, not all AC fans generate sparks at the brushes and all DC fans do have brushes, in fact DC fans have gaps in the commutator that usually generate more sparks than the continuous commutators found in most AC fans. Worst of all are the "wall-wart" power supplies often generate more AC line noise than any motor. Either one can work quite well, but proper shielding and grounding is going to be indicated regardless of whether you use an AC fan or a DC one.

My point being, ALL fans are going to present a potential for line noise in addition to the acoustical whine of the motor and the noise of the air being moved.

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