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Reversing fans |
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adambomb 
Old Croc 
Joined: 10 April 2006 Location: United Kingdom Status: Offline Points: 3220 |
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 Posted: 30 May 2007 at 1:40pm |
I would agree in the same frequency band, but I'm using the pair of EP2500 on Mid / Top and other amps for other bands, can't see a problem with that (apart from it all looking nice matching in the rack).
Would also have to agree with Norty, surface area and air flow is the important bit, can't see how the heatsinks would couple, as most are not directly connected to the chassie (outer case) of the amp.
maybe I should conduct some experiments with my EP2500s, fans normal / reversed, and see if the heatsinks vairy in temp at each end. Edited by adambomb - 30 May 2007 at 1:41pm |
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norty303
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Joined: 18 August 2004 Location: Eastbourne Status: Offline Points: 8806 |
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Posted: 30 May 2007 at 5:46pm |
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I believe that the EP and RMX heatsinks are bolted to the top plate, you'll see a screw in the middle which you have to remove to get the top off (iirc) and this is why the top gets very hot under heavy loads. this is also the reason why i wasn't so sure about having the amps next to each other, sure the base of the next amp up will transfer heat, but as the fan only cools the inside of the heatsink tunnel, it just means that the heat gets transferred into the insides of the amp above, with no fan to move the hot air out again
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My laser stuff: Frikkin Lasers
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4DPA
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Joined: 11 April 2007 Status: Offline Points: 1127 |
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Posted: 30 May 2007 at 10:56pm |
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Well I'm happy to be proven wrong...
It was something I was taught years ago and never really questioned as it made sense to me.. A test will have to be devised. |
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bs8901 compliant
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robertnisbet
Young Croc 
Joined: 27 December 2005 Location: Oxford, UK Status: Offline Points: 921 |
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Posted: 31 May 2007 at 4:56pm |
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Something I have seen from time to time is one fan reversed and the other left running as normal on a singl ampllifier. Supposedly this is an installation 'trick', used to ensure that even if something gets lent up against one side of the amp, front or back, there will still be a way for cool air in/warm air out.
Every amp I've ever acquired in this configuration has been changed back to factory standard and treated with some suspician for the first few gigs until it has proven itself to be reliable. |
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Robert Nisbet
www.robertnisbet.com Event Production Services |
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johnno
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Joined: 22 November 2006 Location: Australia Status: Offline Points: 162 |
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Posted: 07 June 2007 at 1:42am |
This installation trick probably goes back to the days of a single heatsink
and single power transformer, low power, by todays standards.
NOT a really good idea.
I've just finished repairing, actually, replacing an output module in each of
5 yamaha p4500's that had this mod done.
A while a go, a local audio tech had cleaned out the amps, he did quite a
good job, the amps had been running continously for 4 years at a pub,
you can imagine what the insides looked like.
He reversed one side of each amp, they lasted about 2 weeks.
What was'nt taken into account was the closet the rack is in.
Plenty of air in, but restricted on the way out.
Most of the pro audio amp designers put a lot thought into cooling, and
as Rog pointed out, it's not just the heatsinks that need airflow, but the
transformers, caps and other power supply components also need a bit
of cooling.
Have a look at the amps carefully, some are front to back, others back to
front, and others (crest v series, ARX etc have up to 4 fans (front and
back) blowing in, with the exhaust at the side & top.
I've always left a space between the amps, with a vented space at the
bottom and extra rack fans at the back to help the cooling.
/john
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a1161979
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Joined: 31 May 2007 Location: Australia Status: Offline Points: 1 |
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Posted: 23 June 2007 at 11:00am |
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What i have seen done is a panel mounted at the back of the amp rack with an opening at the bottom an one at the top. At the top opening are a couple of 240 volt 150mm fans that suck hot air out from the top (as hot air rises) mount the QSC's below the m2000. the hot air from the m2000 should be sucked upwards while your QSC's will have cool air rising from below...
 Make sure that you but a dust grill down the bottom of your rack though to stop dust from floors being sucked in. |
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johnno
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Joined: 22 November 2006 Location: Australia Status: Offline Points: 162 |
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Posted: 29 June 2007 at 7:07am |
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Just a quick update on the repaired yamy's, all went well for 3 nights, 2 amps had their power supplies fail, the other 3 are still going. Not worth fixing them, spare parts maybe. /john.
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4DPA wrote: