Why do most 2 channel amps run hot when bridged? - diyAudio
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Old 15th September 2010, 06:20 AM   #1
chipper is offline chipper  United States
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Default Why do most 2 channel amps run hot when bridged?

Why does this happen with *most* two channel amplifiers? I have a Punch 150 run it bridged to a 400 single voice coil sub it's 4-ohms. So I don't know why it gets hot. But this is not the case. I'd like some information on these type of things. Oh yeah it starts to get hot after maybe around 10 - 15 minutes of listening time. I'm not one who blasts it constatly, just to get some bass going on.
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Old 15th September 2010, 06:54 AM   #2
ratza is offline ratza  Romania
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They run hot because each amp sees half the load and the current through the final stage doubles.
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Old 15th September 2010, 11:25 AM   #3
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The amp will produce the same heat with 2 ohm stereo as 4 ohm mono. To the amp, they're the same load.
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Old 17th September 2010, 03:51 PM   #4
chipper is offline chipper  United States
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Quote:
Originally Posted by Perry Babin View Post
The amp will produce the same heat with 2 ohm stereo as 4 ohm mono. To the amp, they're the same load.
Can heat cause a amp to fail? And if so what goes first? Power supply or outputs?
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Old 17th September 2010, 04:28 PM   #5
macboy is offline macboy  Canada
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Heat = Bad
For electronics of virtually any kind it is really that simple.
If the amp is getting excessively hot (can't keep a finger on it for at least 5 seconds) then consider using forced air cooling. Conveniently, PC case fans run off of 12 V DC...
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Old 17th September 2010, 05:04 PM   #6
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The power semiconductors used in amps are derated (can handle less stress) as the temperature increases.

The design of the amp and the type of signal determine which fails first.
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Old 17th September 2010, 07:45 PM   #7
chipper is offline chipper  United States
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Quote:
Originally Posted by Perry Babin View Post
The power semiconductors used in amps are derated (can handle less stress) as the temperature increases.

The design of the amp and the type of signal determine which fails first.
It's a Punch 150 (first series) runs kinda hot even at 4-ohms mono I don't know about the gains? But it sounds awesome. Is there anything I can do to keep the temperature down? I don't want it to burn up even in hot sunny days my amp is hot even thought i wasn't using it. Should I install a fan or something?
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Old 17th September 2010, 09:09 PM   #8
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Yes. A fan would make it more reliable. Mount the fan as is shown near the bottom of the following page:

Modified Punch 45

You can make a simple fan controller like the one the following page. Click on item #8 at the top of the page if this doesn't bring you directly to it.

Basic Switching Power Supply Design Tutorial
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Old 19th September 2010, 05:00 PM   #9
ppia600 is offline ppia600  United States
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Mounting the amp lower also helps, heat rises so don't hang it from under the deck like some people do.
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