Why do most 2 channel amps run hot when bridged?

chipper · 15th September 2010, 06:20 AM

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.

ratza · 15th September 2010, 06:54 AM

They run hot because each amp sees half the load and the current through the final stage doubles.

Perry Babin · 15th September 2010, 11:25 AM

The amp will produce the same heat with 2 ohm stereo as 4 ohm mono. To the amp, they're the same load.

chipper · 17th September 2010, 03:51 PM

Quote:

Originally Posted by Perry Babin

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?

macboy · 17th September 2010, 04:28 PM

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...

Perry Babin · 17th September 2010, 05:04 PM

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.

chipper · 17th September 2010, 07:45 PM

Quote:

Originally Posted by Perry Babin

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?

Perry Babin · 17th September 2010, 09:09 PM

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

ppia600 · 19th September 2010, 05:00 PM

Mounting the amp lower also helps, heat rises so don't hang it from under the deck like some people do.

15th September 2010, 06:20 AM	#1
chipper diyAudio Member Join Date: Oct 2008	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. __________________ Feel the PUNCH

15th September 2010, 06:54 AM	#2
ratza diyAudio Member Join Date: Dec 2007 Location: Sibiu, Romania	They run hot because each amp sees half the load and the current through the final stage doubles. __________________ Any solution is a compromise.

15th September 2010, 11:25 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The amp will produce the same heat with 2 ohm stereo as 4 ohm mono. To the amp, they're the same load. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

17th September 2010, 05:04 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	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. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

19th September 2010, 05:00 PM	#9
ppia600 diyAudio Member Join Date: Jun 2007 Location: Louis y ana	Mounting the amp lower also helps, heat rises so don't hang it from under the deck like some people do. __________________ Don't worry... you can always turn the gain down!


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17th September 2010, 04:28 PM	#5
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	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...

17th September 2010, 09:09 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	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 __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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