# How hot is an amp supposed to run?



## kangking (Jul 30, 2015)

Just installed a brand new JBL 5ez amp in the car and it sounds great. Running a 4 channel JBL speaker setup with a JL w6v2 sub. After setting the gains and crossovers it has a lot more power than I need and sounds crystal clear. 

One issue though, after driving for an hour tonight with it on (2nd day of use) and it was so hot you can't leave your hand on it for over 5 seconds. Was playing it at vol level 18 (goes up to 40 on hu) gains were set properly @ vol 30 so it's not even close to maxing out. At vol 18 it still pounds to where I don't want to turn it up any higher. It hasn't shut off or gone into protect mode, still the amount of heat worries me. Heat is coming from the large heatsink on top of amp, but I noticed the whole amp was hot even by the dials. Reading some online reviews one reviewer on crutchfield said his amp does not get hot. Although one amazon reviewer said amp runs hot and after 6 months of his amp running hot it constantly went into protect and eventually shut down. Not sure if anyone else here has this amp so I can see if it can stand running hot every day.

Amp is properly wired with oxygen free copper 4awg power cable and grounded to the frame of the car, under the car. With the ground wire 0 gauge was used (installer says it does not make a difference if ground is larger gauge than power). 

Sub was tested and showed about 2.3ohms on the multimeter and is a 2ohm sub (compatible for this amp). Speakers shouldn't be an issue. I would think heat would be coming from sub channel. Sub beats really hard.

Amp is mounted to top of sub with about 3 inches of clearence under the trunk when the trunk is closed? Could it possibly not have enough ventalation? Installer said this is not an issue. Still would like some ideas before he looks at it, maybe there's something I can do right now.

Here's some photo's of the install if this makes any difference. 1st pic is when we first hooked it up, 2nd is of ground wire mounted to bottom of vehicle on frame, 3rd and 4th are of the reviews I referenced


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## kyheng (Jan 31, 2007)

Is normal since you are running lower impedance.


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## Weigel21 (Sep 8, 2014)

May be running a "little" warmer than it could be, but if it's not going into protect, then I wouldn't worry "too much".

Given how hot it's been lately and how close the amplifier is located to the trunk lid, which I'm sure is still fairly warm on the bottom side, the amps probably not running any warmer than another 5EZ in the same location. 

However, your grounding point doesn't look to be as sufficient as it could be. This could be causing the amplifier to working a little harder and generate more heat.


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## quickaudi07 (May 19, 2010)

My Mosconi amps get so hot, and they have build in fan's and still get hot as ****, My sub duty amp which is Audison, gets so hot, im sure you could boil eggs on it... 

think about it, you have 5 ch of amp in this small package, it puts out lots of heat for internal parts, if you want to be safe, put some small spacers under the amp, and rase it a little and put a small fan so it has a air flow.... 

If the amp would have been over driven or overheating than it would have shut down on you long time ago  You will be fine.

Amps could run up to 85*C which is hot as hell!


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## etroze (Dec 24, 2013)

Chances are you have 2ohm JBL speakers as well so that kind of load over the entire amp, yes I would expect it to run warm. Is it something to worry about? I don't think so as every JBL amp I had wired into a 2ohm load got warm.


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## Victor_inox (Apr 27, 2012)

It`s normal, leave it be.


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## cajunner (Apr 13, 2007)

recheck your speakers for any faulty parts in the crossovers and coils that measure too low.

the 2 ohm sub that measures 2.3 ohms is a potential short since it's not registering what it should, which is lower than nominal on the DMM, like 1.8 ohms.

get a different sub combo that goes to 2 ohms and try it for an hour and measure your temps on the heat sink if you can.

also look more closely at how you are setting up the amp because if you have it so loud that 18 is sufficient then 30 is too high and I would guess you have a malfunction on your DMM testing routine, if not the DMM itself.

but probably human error, eh..


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## jtaudioacc (Apr 6, 2010)

if you could put your hand on it for 5 seconds, that's nothing. lol


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## LaserSVT (Feb 1, 2009)

What I thought was hot others have assured me is not. My JLs would run 125* unless I was really jamming and they would hit 150*. My Mosconis run 120* and really jamming for a couple hours and they will hit 150* seats down and 180* seats up (no ac vent hitting them) which is why I keep the sets down unless there is someone in the back.
The Sinfoni Amplitude, that damn thing runs hot no mater if its whispering at you or screaming. Always stays around 150*.


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## cajunner (Apr 13, 2007)

I remember reading about how the BBQ RF amps, the DSM series, were said to run hot and I have to imagine it's the circuit that causes that to happen.

Like, a running bias that makes the amp draw 1.5 amps or more at idle, will push enough heat into the sinks that it would stay above a certain temperature once it stabilized.

But those hot-running amps are almost always the ones people like the best for sound quality.

so there is a direct relationship between steady state amp temps and expected sound quality.

it makes sense if the components used in the hot amp are better quality, and can handle a higher temp range.

and it makes sense that a company would set their bias to decrease efficiency at low power levels, if it made an appreciable difference in sound quality.

so, as a matter of logic, or following this train, amps that run hot should sound better, and amps that run hot should also be expected to run hot and not as cool as most other designs where the amp manufacturer puts his circuit at the most efficient, with idle draws of less than .6 amps.


Because I believe that the idle temp is what makes the temp floor, or base level of operation and bias setting is what influences idle temp, and that running an amp hard so that it goes above 150F when playing loudly and 125F at idle, is probably hotter than most people would like using a system of "hand holding" as a measurement ruler.

But 150F is not bad if the amp is able to run hard and not go too much higher, which is not easy to do if you've got 150F temps in your trunk in the middle of the summer day on a dark colored car.

I agree that there is a discrepancy between "amp cool" and "hand cool" but I still like to know that I am going to enjoy the amp for a long time, even if I can't keep my hand on it after jamming for an hour.

I think that's where most of us are, and I would want to know why a class D amp is running hot if the consensus is that model of amp runs cool, even in some applications.

Some class D circuits hardly need a heat sink and others are dissipating a lot of heat, but the parallel or correlation between high idle bias and sound quality, I don't believe, carry over from the class AB qualifications. 

zzzest an opinion, but if a class D amp is getting hot just sitting there, somebody screwed up on it.


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## Victor_inox (Apr 27, 2012)

If it was that simple........

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## Victor_inox (Apr 27, 2012)

Amp can always be designed with better heat dissipation in mind.mostly to please people who don't feel comfortable around 120F hardware.

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## Victor_inox (Apr 27, 2012)

Because there is absolutely no reason to lower that temp otherwise

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## Victor_inox (Apr 27, 2012)

I love my tube space heaters,it's like staring on fire.

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## Vmax911 (Jun 1, 2012)

That's why I preheat my amps for ultimate SQ!


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## Alrojoca (Oct 5, 2012)

From what I remember Amps get usually as hot or hotter than the outside temperature even being on without playing music.

The smaller they are the hotter they may get.

And when not turned on, after a cold night and you check them, they are way colder than the outside temperature. And sometimes may have some moisture than you can see and feel on your hand, It is all relative to the outside temperature conditions.


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## nineball76 (Mar 13, 2010)

Don't trust the "touch" test. 110 is a hot tub, 115 can scald you. 175 is normal thermal limits of an amp, which will fry an egg. We cook steaks around 160-170. Just to give comparison.


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## Victor_inox (Apr 27, 2012)

nineball76 said:


> Don't trust the "touch" test. 110 is a hot tub, 115 can scald you. 175 is normal thermal limits of an amp, which will fry an egg. We cook steaks around 160-170. Just to give comparison.


Good reference points, agreed 100%


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## jpswanberg (Jan 14, 2009)

I use my Manley Labs amps as space heaters in the winter .... JPS


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## kangking (Jul 30, 2015)

Appreciate all the replys to this!!! Now I don't feel so worried about my amp frying on me!!! Install was done properly and the sound is great in my car. Hopefully it lasts a long time!!!!


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## EmptyKim (Jun 17, 2010)

nineball76 said:


> Don't trust the "touch" test. 110 is a hot tub, 115 can scald you. 175 is normal thermal limits of an amp, which will fry an egg. We cook steaks around 160-170. Just to give comparison.


Hope you don't cook your steaks to 160-170...


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## nineball76 (Mar 13, 2010)

EmptyKim said:


> Hope you don't cook your steaks to 160-170...



Restaurants require food to be cooked to 165, even pizza places

Edit: chicken needs to be 165. It's beside the point I was making. 175 degrees for amp to reach thermal is still beyond anything you'd want to touch.


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## kangking (Jul 30, 2015)

Just a small update to this thread. 

Reset the amp today, turned the gains wayyy down. Now I can use the whole volume scale 1-40. When the amp was running hot I was only turning radio up to 20-22 before audible distortion occurs, even though I set it according to the JBL guide.

The amp is a JBL 5ez amp. The reason I bought it is because of (price #1, got a hellova deal on it) lol, and easy gain setting. It comes with an included test tone cd, you turn head unit to ~75% volume and play test tone cd. Then you turn gain dials until they all turn green, then your gain is set. (supposedly)

Problem with this is, test tone cd must be really low in volume because playing any music you can't get up past 22 without distortion. Today I said, f the jbl test tone cd and just set it by ear. Turned up radio to about 30-32 and just messed around with crossovers and gains some more. Before I was doing it on the head unit, but it didn't sound quite right: head unit high passes my speakers too high (wont go below 50hz). Set crossovers on speakers at 40hz (lowest amp can go) (anything higher than that sounded too bright) and lo passed sub at 40 (since speakers are at 40). Then I set the amp gains for a good 10-15 minutes doing careful checking for balance. Got it sounding really good. Volume goes up to about 35 before audible distortion occurs (which is ok with me since I'm sure the head unit distorts around that volume too)

I think amp should run cooler now, or will this make any difference?


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## quickaudi07 (May 19, 2010)

Victor_inox said:


> I love my tube space heaters,it's like staring on fire.
> 
> Sent from my SAMSUNG-SM-G925A using Tapatalk


The way you going Vic, they will  

J/k,,, i'm sure they are tested many times before putting in to production!


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## Victor_inox (Apr 27, 2012)

quickaudi07 said:


> The way you going Vic, they will
> 
> J/k,,, i'm sure they are tested many times before putting in to production!


What way is that?


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## quickaudi07 (May 19, 2010)

Victor_inox said:


> What way is that?


You were talking looking at your tube amps, they look like heaters  i was referring it to that. even thought hey look like they will set on fire, i'm sure they wont... and you have been testing everything to make sure they are 100% in working order thats all. sorry wasn't clear enough


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## Victor_inox (Apr 27, 2012)

quickaudi07 said:


> You were talking looking at your tube amps, they look like heaters  i was referring it to that. even thought hey look like they will set on fire, i'm sure they wont... and you have been testing everything to make sure they are 100% in working order thats all. sorry wasn't clear enough


To fully understand what I mean you`ll have to get yourself a nice tube amp and try for yourself.


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## rxonmymind (Sep 7, 2010)

Vmax911 said:


> That's why I preheat my amps for ultimate SQ!


That's too funny.Thread fight!...." I can hear the difference in sound when my amps are warmed up"


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## quickaudi07 (May 19, 2010)

rxonmymind said:


> That's too funny.Thread fight!...." I can hear the difference in sound when my amps are warmed up"


Me too all 3 of them have fans inside. Sounds like a jet plane when music is turned to mute mode 

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