Amp overheating?

[MadMedwyn]

Hi, I'm running a Rockford Fosgate amplifier that's bridged to my subs. It seems to have an overheating issue. I have my gain turned completely down, only using the included bass knob to control the bass boost. The "Bass" setting on the stock HU is in the middle like it always has been, so this can't be an issue of simply overworking anything.

Anyway, I'll be playing some double-bass fairly loud and everything sounds great for about 10 minutes (I don't overshadow my music with bass either) and the bass will just cut off. I check my amp to find the "thermal" light turned on. And when I touched it, it felt like it could fry my hand off. I'm very concerned actually.

What disturbs me is that I'm not one of those kids that "bumps" to their music, with their gain wide-open and their bass boost all the way up 24 hours a day. So I can rule out user-error here. The shop said they will build me an air box for it with four fans to keep it cooler, but I'm surprised I need it. I know kids running twice the power I am in poor ventilation areas and they never overheat.

Is this a result of bridging my 2-channel amp? I think I've read before that 2-channel amps tend to heat up more when bridged. Is that true? Thanks for your input. (damn I probably should have bought a mono :ack: )

 

[WrenchGuy]

Don't use bass boost!

You are better off turning the gain up farther to match the preout voltage of the head unit.

http://www.icixsound.com/iv/view_video.php?viewkey=c13838ff95ccfa94cebd&page=&viewtype=&category=

Your gains being low is making the amp work harder to produce power.

 

[Polecat]

also, what is the gauge of power wire, to the amp? when you are hammering on the system, what is the voltage, AT the amp?

 

[JKmotorsports]

If your subs are svc 4 ohm and you have them paralled and bridged, then your problem lies there. If they are dvc 4ohm subs, then they need to be be wired 2 ohm and hooked up stereo at the amp or you can wire them 8 ohm and then bridge it at the amp.
Also, check your ground cable at the amp and the grounding point while the amp is playing at high volume to make sure you don't have any voltage loss.
And the gain on the amp needs to match the preout voltage of the source unit. Too low and you're just losing potential output. Too high, the signal becomes clipped and you can damage the amp and/or speakers.

 

[WrenchGuy]

My bad. I thought he had them on individual channels. Thats what I thought in the "Getting Subs" thread. I just seen bass boost and was like NOOOOOO!

 

[greengumby]

How would voltage loss cause an amp to overheat since the amp would not be receiving the correct amount of voltage, like a headlight or simular load the light would just go dim. Would it be possible that there is too much power going to the amp and there isnt enough resistance on the line to protect the load?

 

[WrenchGuy]

I think most of it is because he is higher on the boost knob than the gain is set for.

Its user error.

 

[MadMedwyn]

The subs are DVC 4-ohm and the amp runs a 4ohm load when bridged, like it is now. I looked this up on the woofer wiring wizard on rockfordfosgate.com. I have no idea how how exactly it's wired because I had it installed at a shop. All I know is that the amp appears bridged because one wire comes out of the left-most positive and the other wire comes out of the right-most negative.

I don't think this is a voltage loss issue. The needle stays right in the middle, occasionally demonstrating slight movements.

And I have no idea what my pre-out voltage is. I'm using the stock head unit and I'm running a line-out converter from my original Bose sub wiring. How am I supposed to get an accurate voltage out of that? I know aftermarket head units tell you what your voltage is but I have no idea here.

This is why I can't wait to ditch my bass boost remote, and get a new head unit with a "subwoofer" level controller. Thanks for your help. Looks like I'm going to throw out the RF remote because it's already loud as hell sometimes with the gain all the way down.

 

[WrenchGuy]

They should have them series paralleled I would think.

I can't figure out why you have those sub configurations for that little amp.

Set your gain at 3/4 volume.

Turn the gain down all the way. Turn the Radio up til all the speakers distort a little and back it off a little bit. Then at that volume setting turn your amp gain up til you hear the sub distort and back it off a little.

Do this with a familiar song.

Some amps just get hot also. Yes that hot too!

 

[MadMedwyn]

They should have them series paralleled I would think.

I can't figure out why you have those sub configurations for that little amp.

The subs only take 250W a piece. I didn't think I needed a bigger amp. I can't use this amp for anything else anyway because I'm not willing to spend the extra hundreds to get rid of my Bose sound. I've read reviews on these subs where people were using even smaller amps and they were still loving the sound. Even my local shop wanted to sell me two Diamond D1s which take the same power as the RFs i have now.

Anyway, I did what you said, and I'll tweak it some more. It hasn't cut off...yet.

 

[greengumby]

Hope it works out for yah

 

[WrenchGuy]

The subs only take 250W a piece. I didn't think I needed a bigger amp. I can't use this amp for anything else anyway because I'm not willing to spend the extra hundreds to get rid of my Bose sound. I've read reviews on these subs where people were using even smaller amps and they were still loving the sound. Even my local shop wanted to sell me two Diamond D1s which take the same power as the RFs i have now.

Anyway, I did what you said, and I'll tweak it some more. It hasn't cut off...yet.

I'm just saying a mono amp would have been better for those coil configurations. Also for subwoofers the mono's(class D) are more efficient.

You could also have the subs 2ohms by 2 on the amp. But then they're running stereo.

 

[MadMedwyn]

I'm just saying a mono amp would have been better for those coil configurations. Also for subwoofers the mono's(class D) are more efficient.

You could also have the subs 2ohms by 2 on the amp. But then they're running stereo.

Yeah I agree with you there. I probably should have gotten a p600.1 mono and two DVC 2ohm P2s instead of what I have now. Probably would have saved alot of trouble.

But too late I guess. I love the sound I'm getting right now and it's more than I can handle in some cases. I'm going to tweak the gain some more. I'll probably end up getting that air box made too just to be on the safe side. I think I'll be ok when it's all done.

 

[MadMedwyn]

Ok I gave it a good run for it's money today. The amp did cut off for about a second but I think that goes back to my voltage drop issue (I need a yellow-top). It could still burn your hand off though to the touch. I'm going to get an airbox made asap.