Why is my amp getting hot?

[JoshGuy 10+ year member]

So i have a somewhat old sherwood 250 x 2 amplifier hooked up to some older JL W3 D4 subs. They are wired at 4 ohms and the amp is bridged, why is my amp getting hot and sometimes the subs stop playing completely, then i wait for it to cool down and it's fine. Got any ideas why? And yes i know both are lower end and no i dont really want anything right now so no offers please=D

Sherwood A/B 250 x 2:

250 x 2 @ 4 ohms

500 x 2 @ 2 ohms

600 x 1 @ 4 ohms

JL W3 D4 are 300 rms @ 4 ohms

Click to read more...

 

[sacsking916 5,000+ posts]

Cause it's an a/b and its not as efficient I'm guessing.

 

[Kangaroux 5,000+ posts]

are your gains properly set? all bass boosts off? you might be pushing the amp too hard

 

[JoshGuy 10+ year member]

I can go check, ill let you know. I just turned it down to lower gains, should this fix it somewhat? And A/b and d class wouldnt really make a difference unless its a monoblock. That would help but im not too sure

 

[Kangaroux 5,000+ posts]

I can go check, ill let you know. I just turned it down to lower gains, should this fix it somewhat? And A/b and d class wouldnt really make a difference unless its a monoblock. That would help but im not too sure

not really, monoblocks are just meant for power on a single channel, that's their only difference. class D's are more efficient and don't heat up as much but in turn don't have quite the amount of SQ you can get with an A/B amp. i'm just thinking you're pushing that amp into clipping, and since it isn't very efficient to start with, is not creating a nice situation.

 

[JoshGuy 10+ year member]

im a noob whats clipping?

 

[Kangaroux 5,000+ posts]

im a noob whats clipping?

The sine wave on the left is an unclipped "healthy" signal. The sine wave on the right is clipped (the wave is cut off at the bottom and top).

basically, if you use bass boosts or push your amp past it's limits then it will begin to clip. clipping is bad for your subs because when your sub is playing a clipped sine wave, it will be extended out in one direction for a longer period of time and, since it's not moving, will generate heat. this extra heat can cause the glue around the voice coil of the sub to melt. once that happens you get coil rub and the coil only get's worse. at that point your sub is basically a paperweight unless you can get it repaired

 

[JoshGuy 10+ year member]

That graph helps a whole lot thank you. So what do you think my gains should be set at? Or what would you suggest, i know its not a perfect situation for these subs.

 

[supermaxx123 10+ year member]

I had a jl audio e4300 ad it heated all the time, and i was only powering components and a 6 1/2" sub. I never had a problem with it, it just liked being hot. My mb quart 4200, rated 25watts more per channel was power the same things, pushing them harder and never got nearly as hot as the jl. I'd say some amps are just weak.

 

[JoshGuy 10+ year member]

Thats what i figured, i need a new amp:/ dammit

 

[supermaxx123 10+ year member]

to be honest, 250x 2 is a lot of power for a 2 channel. that is if it's a true 250rms @ 4ohms. lower impedance draws more current and is less efficient. This might not help(as far as being louder) but try running the amp bridged @ 8ohms.

 

[JoshGuy 10+ year member]

Yeah it runs true, it's when sherwood was a good name i believe. It is a little under rated i think. But yeah running it at 8 ohms is definitely an option. still want to try and keep as much volume as i can though

 

[supermaxx123 10+ year member]

doesn't hurt to try and i will guarantee it will run cooler.

 

[JoshGuy 10+ year member]

sweet thanks man