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power amp, rack, heat


a boy named sue

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What are the issues regarding rackmounting a power amp? My power amp has passive cooling via two huge heat sinks; one each channel forming the sides of the box a picture is here . These heat sinks are oversized when the amp is sitting out in the open but I'm not sure how hot they'll get when I put them in a rack, specifically a portable case. There will be a bit of a gap between the heat sinks and the walls of the case.

 

Any ideas? a better picture

A man is not usually called upon to have an opinion of his own talents at all; he can very well go on improving them to the best of his ability without deciding on his own precise niche in the temple of Fame. -- C.S.Lewis
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The heatsinks are designed to draw the heat that builds up inside the amp and then disappate thru the heatsink.

 

Most often , amps with large heatsinks , as the one pictured , do not have any forced fan cooling. Used often in High End Audiophile amplifiers for a much quietier noise floor.

 

They are not intended for closed rack mounting.

 

PJR

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Thanks guys.

 

I think I'll just put a handle on it (in the middle of the front) and carry it separately, its not very light anyway and if it takes up 5 spaces (1 below, 2 for it and 2 above) then that'll mean a large rack. I've seen lots of cooled racks but not portable ones. If I ever get enough gear to need a rack at home then I'll put it on a ventilated shelf with a fan above it.

A man is not usually called upon to have an opinion of his own talents at all; he can very well go on improving them to the best of his ability without deciding on his own precise niche in the temple of Fame. -- C.S.Lewis
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Yeah I use it for "giging" although we've only had a few gigs. I play through it at church every week. I built the amp from a kit because I thought it'd be fun and save a few dollars. Also I can use it in my living room if/when I get a real 'bass' power amp with stuff like a volume nob!

 

The power amp makes no noise with nothing plugged in (I don't have to turn it off during the sermon), I play through a very dodgy PA speaker which is not flat in response, also I'm only using a 9V mixer as a preamp (no eq) so I have trouble dialing in a tone. I just bought a Behringer EQ (15 band)(stereo), a compressor (stereo), and a DI/signal splitter to drive them. I plan to use different settings for each channel and play through the PA speaker and a 1x10" sub I have lying around in my living room! I should bite the bullet and buy a decent cab (or some decent drivers and build one). I'm going to build my own case for all the rack stuff out of ply.

 

In summary. Any power amp would not be the weakest link in the chain but I do feel good about being able to fix this one - cause I made it.

A man is not usually called upon to have an opinion of his own talents at all; he can very well go on improving them to the best of his ability without deciding on his own precise niche in the temple of Fame. -- C.S.Lewis
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I might be missing something here, but if you have the covers off the rack won't the heat sinks work as intended?

No , they won't.

It wouldn't be quite as bad as if you left the amp on , with the covers on.....but you'd still create an oven like atmosphere within the case that would surely make the amp run hotter than intended.

The heatsinks are individual fins designed to draw heat away from the inner components of the amplifier. With that in mind.....you'd definately compromise the cooling effects from the inner components.

 

PJR

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A couple of points.

 

1) The heat sinks are oversized so that they form the two sides of the amp...that much cooling isn't needed; they only get slightly warm.

 

2) I'm going to have 1 U space below, 2 U above and drill some holes in the top and sides (to correspond with where the MOSFETs join the heat sinks). The fins will pull air in when they're hot and push it out the top.

 

Thanks for all the feed back...I'll put in a fan too if things get warm!

 

btw here is the PA speaker I play through Robb.

A man is not usually called upon to have an opinion of his own talents at all; he can very well go on improving them to the best of his ability without deciding on his own precise niche in the temple of Fame. -- C.S.Lewis
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i think PJR is overstating the danger. a home hi-fi amp is designed to be fairly cool to the touch, even when being driven hard. or like you, overdesigned. that said, i think 1U below and 2U should be fine for a church gig. if it overheats (and doesn't explode), put a fan on it.

 

one question, though. why did you buy a compressor, EQ, and DI when you could just as easily have bought a preamp to do all of those? i mean, a behringer compressor and EQ is $250, and a DI is another $30 or so, which puts you in the range of a new BBE DI/preamp or a used preamp.

 

that speaker is funny, but i imagine you can get some sounds of it that work. not great, but workable.

 

robb.

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I could have bought a used preamp if I waited long enough. But I had this tax return money burning a hole in my pocket (my wife and I put tax return money in to discretionary spending on our budget). I really like the idea of a graphic EQ and the stereo stuff means I/we can use it as our PA latter on. I think the Australian market has Behringer stuff even cheaper (relatively) to the US market.

 

I wanted a high end pre-amp with 30 band EQ all tube signal path etc...

 

Anyway, from now on anything new is on the floor

 

Anyway, from now on anything new is on the floor

A man is not usually called upon to have an opinion of his own talents at all; he can very well go on improving them to the best of his ability without deciding on his own precise niche in the temple of Fame. -- C.S.Lewis
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