Weird problem with fuses in my car amps

[TechBoyJK]

My amps

Alpine MRP-F450 70x4rms @ 4 ohm or 200x2 rms (bridged at 4 ohms per side)
Alpine MRP-M650 600x1rms

The mono amp has two 30amp fuses, and the 4channel has 2 20amp fuses. I have a 1000watt rms power kit from Lighting Audio, using 4gauge power wire as the main wire, which goes to a distrubution block, which splits off into dual 8 guage wires, that feed to a fuseblock with 2 60 amp fuses. Same with the ground, 4 guage wire, which runs to a distro block which then branches off to 2 8 guage grounds.. it all looks like high qualilty wire.

With the mono amp, I'm not blowing fuses, but eventually the amp will go into protect, and it will stay there until I replace the fuse. The fuse won't be blown, but I will see alot of "residue" on it.. I've tried various brands of fuses and its the same story.

it doesn't happen all the time, as I just went about 3 months w/o replacing the fuses, but it just happened again and I'm wondering "wtf"

anybody with more experience/knowledge care to chime in?

I'm starting to wonder if I don't have an adequate ground, because a few days ago I installed new components, and have since bridged my 4 channel amp causing it to draw more power. After about 10 minutes at high volume (no distortion) the amp is going into protect. It will come right back up if I turn down the volume.. If I let it cool for a few minutes, I can do it again for 10 minutes then it goes back into protect... Without letting it cool down, if I quickly pop in a new fuse (i shut the car down lol), it seems to go longer before shutting down again..

Could a bad ground cause these problems? Like the amps can't discharge heat through the ground well enough?

 

[spidey07]

Something is wrong (damaged speaker, something internal with the amp) or you are over driving the amps.

Running at that low an impedance can cause problems like you describe (over driving the amp). Speaker impedances aren't "flat". They vary with frequency. See if you can get an impedance map of your speakers to see how low they really drop.

It "could" be the ground. What are you grounding to?

 

[Unheard]

Ground was the first thing I was thinking. Also check your hot wire to make sure it isn't grounding out anywhere. I had a problem in my old truck that whenever someone would lean the passenger seat forward, fuses would pop. Turned out it was pinching my hotwire, and grounding out.

 

[amdhunter]

Could the amps be overheating? When my lil memphis amp overheats, it'll go into protect mode for about 30 min. Thankfully, it only happens on days > 90 degrees outside. Even then, in a years time it only protected itself 3x. I haven't even looked at the fuse in it yet.

 

[TechBoyJK]

Originally posted by: spidey07
Something is wrong (damaged speaker, something internal with the amp) or you are over driving the amps.

Running at that low an impedance can cause problems like you describe (over driving the amp). Speaker impedances aren't "flat". They vary with frequency. See if you can get an impedance map of your speakers to see how low they really drop.

It "could" be the ground. What are you grounding to?

Well, on the crossovers for the components that are hooked up to my amp, there was a +-2DB switch for the mid and tweet. I started out by having them both at +2db. Then the amp started shutting down. I'm guess what this does is lower the resistance for the speaker this is set for, causing more draw from the amp to increase the db.

But I've since switched it back to flat, and it still does it.. like i said, amp ran fine with no problems and never shut down until I bridged it, but its bridged in a way that the amp was designed for...

it is grounded to the car's frame... a good solid part too...

 

[TechBoyJK]

Originally posted by: amdhunter
Could the amps be overheating? When my lil memphis amp overheats, it'll go into protect mode for about 30 min. Thankfully, it only happens on days > 90 degrees outside. Even then, in a years time it only protected itself 3x. I haven't even looked at the fuse in it yet.

yea, the 4 channel amp is overheating.. i touched right after i shut it down and it was hot as hell, almost burned my finger.

im just wondering why its getting so hot. gain is set at nominal (0), impedences are correct, and it never got so hot until after i bridged it, but the amp is designed to be bridged....

it was warm the day it first went into protect, about 70 degrees out, but i tried it this morning when it was 50 and it still did it..

 

[spidey07]

you're over driving the amp. It can't handle your impedance and the volume you are asking for.

-edit-
Just looked at the specs of your 4-channel amp. Definately overdriving it.

 

[TechBoyJK]

Originally posted by: spidey07
you're over driving the amp. It can't handle your impedance and the volume you are asking for.

-edit-
Just looked at the specs of your 4-channel amp. Definately overdriving it.

well then should i bitch to Alpine? I bought it under the impression that it was rated at 200x2 at 4 ohms. And that is what I'm giving it. I could crank the amp to the same volume notch (70/80) and it wouldn't get hot at all... Now that its bridged and supposedly supposed to get almost double the power that way, I can't get it any louder than when it was non bridged cause it keeps shuttin down..

the othe alpine amp I have is rated at 400x1 at 4ohms and 600x1 at 2 ohms. Im doing 2 ohms on it, and it doesn't go into protect like the other one..

 

[spidey07]

You can call them. But most likely that's normal behavior, it's only got so much power.

The reason you can't get it any louder is because that's all the power the amp can give. When bridged it is much harder on the amp, hence increased heat. What you're basically doing is running out of power.

 

[Doodoo]

If your running the amp at 4 ohms bridged, it should not be overheating. How are your components wired? Could it be possible that somehow the components are wired in parallel...then you are bridging a 2 ohm load...so the amp really sees 1 ohm?

 

[TechBoyJK]

Originally posted by: Doodoo
If your running the amp at 4 ohms bridged, it should not be overheating. How are your components wired? Could it be possible that somehow the components are wired in parallel...then you are bridging a 2 ohm load...so the amp really sees 1 ohm?

yea, its rated for the setup Im giving it. I know its harder on the amp to bridge, but the amp is supposed to be built for that. my other amp, from the same line, just the mono block version, is running at 2 ohms and it doesn't over heat.

 

[Doodoo]

I would try and get a multimeter to see if its really at 2 ohms...it sounds like its at 1 ohm. Does it blow fuses if you keep the volume down or turn the gain down?

Edit: Just read that it doesn't blow fuses with the volume down. Sounds like an impedence issue.

 

[jtvang125]

Originally posted by: Doodoo
I would try and get a multimeter to see if its really at 2 ohms...it sounds like its at 1 ohm. Does it blow fuses if you keep the volume down or turn the gain down?

Edit: Just read that it doesn't blow fuses with the volume down. Sounds like an impedence issue.

The ideal resistance should be 4 ohms bridged. Most stereo and 4 channel amps cannot handle a 2 ohm load bridged. I'm thinking the resistance of the components are 2 ohms which is why it is causing the amp to get so hot and blow fuses.

 

[AlienCraft]

Originally posted by: TechBoyJK
My amps

Alpine MRP-F450 70x4rms @ 4 ohm or 200x2 rms (bridged at 4 ohms per side)
Alpine MRP-M650 600x1rms

The mono amp has two 30amp fuses, and the 4channel has 2 20amp fuses. I have a 1000watt rms power kit from Lighting Audio, using 4gauge power wire as the main wire, which goes to a distrubution block, which splits off into dual 8 guage wires, that feed to a fuseblock with 2 60 amp fuses. Same with the ground, 4 guage wire, which runs to a distro block which then branches off to 2 8 guage grounds.. it all looks like high qualilty wire.

With the mono amp, I'm not blowing fuses, but eventually the amp will go into protect, and it will stay there until I replace the fuse. The fuse won't be blown, but I will see alot of "residue" on it.. I've tried various brands of fuses and its the same story.

it doesn't happen all the time, as I just went about 3 months w/o replacing the fuses, but it just happened again and I'm wondering "wtf"

anybody with more experience/knowledge care to chime in?

I'm starting to wonder if I don't have an adequate ground, because a few days ago I installed new components, and have since bridged my 4 channel amp causing it to draw more power. After about 10 minutes at high volume (no distortion) the amp is going into protect. It will come right back up if I turn down the volume.. If I let it cool for a few minutes, I can do it again for 10 minutes then it goes back into protect... Without letting it cool down, if I quickly pop in a new fuse (i shut the car down lol), it seems to go longer before shutting down again..

Could a bad ground cause these problems? Like the amps can't discharge heat through the ground well enough?

Amps do not discharge heat through the ground, they do it through the heat sinks.
Put some fans across them and problems will probably go away.

Speaker impedance changes across the frequency range. IF your speakers are dipping below the amps rated impedance for too long a period, it will overheat, and blow fuses or output transistors, it's just a matter of time.

Oh yeah, as speaker coils heat up from this sort of "at the limits" usage, they draw more current as well. Further moving the 'Steady state' parameters off the ratings.

 

[TechBoyJK]

Originally posted by: jtvang125

Originally posted by: Doodoo
I would try and get a multimeter to see if its really at 2 ohms...it sounds like its at 1 ohm. Does it blow fuses if you keep the volume down or turn the gain down?

Edit: Just read that it doesn't blow fuses with the volume down. Sounds like an impedence issue.

The ideal resistance should be 4 ohms bridged. Most stereo and 4 channel amps cannot handle a 2 ohm load bridged. I'm thinking the resistance of the components are 2 ohms which is why it is causing the amp to get so hot and blow fuses.

components are 4 ohms, and the amp is setup at 4 ohms bridged.. its a 3way set with a passive crossover.. impedances are correct..

 

[spidey07]

Originally posted by: TechBoyJK
components are 4 ohms, and the amp is setup at 4 ohms bridged.. its a 3way set with a passive crossover.. impedances are correct..

Then you are simply turning the volume up too loud. The amp can't handle it.

Also watch your hearing. Listening at loud volumes WILL damage your ears. It did mine.

 

[AlienCraft]

Originally posted by: spidey07

Originally posted by: TechBoyJK
components are 4 ohms, and the amp is setup at 4 ohms bridged.. its a 3way set with a passive crossover.. impedances are correct..

Then you are simply turning the volume up too loud. The amp can't handle it.

Also watch your hearing. Listening at loud volumes WILL damage your ears. It did mine.

"....This one goes to eleven." </spinal tap>

 

[spidey07]

Originally posted by: AlienCraft

Originally posted by: spidey07

Originally posted by: TechBoyJK
components are 4 ohms, and the amp is setup at 4 ohms bridged.. its a 3way set with a passive crossover.. impedances are correct..

Then you are simply turning the volume up too loud. The amp can't handle it.

Also watch your hearing. Listening at loud volumes WILL damage your ears. It did mine.

"....This one goes to eleven." </spinal tap>

Yes, I know....just telling him to be careful.

Eitherway, that amp is not going to cut it for the volume levels he desires. That might be a good thing.

It's not a "weird" problem at all. It's totally normal. If you turn it up way too loud and your amps cut out - your amps can't cut it. He's YET to provide the speakers he's using and how they are wired. Bottome line, OP is turning it up too loud. If you amp is too hot to touch - you are doing something wrong.

 

[TechBoyJK]

http://www.hertzaudiovideo.com/Doc/pdf_hsk163.pdf

those are the speakers. its a 3way set that runs through a passive crossover, that then leads back to the amp..

3 speakers on the left and 3 on the right. (woofer, mid, tweet)

each set is 4 ohms. My amp is a 4 channel amp, that offers 200x2 at 4ohms stereo.

It is wired correctly. Gain is set to 0 (offers +-6)

 

[BATCH71]

If you are running 3 sets of 4 ohm stereo speakers in parallel to each channel bridged then you are not at 4 ohms, it would be 1ohm I believe and if that is the case then that would explain your overheating. I am assuming you are in parallel, If you are in series, then your speakers would be at ~10+ ohms and you would need to crank the hell out of the volume to hear them.

Get a JL Audio amp, it will handle your stuffs in spades

I put 2 in my Magnum and they kick ass!!


Dave

 

[Evadman]

If you follow the wiring diagram in that PDF then you are running at 1/2 ohm bridged, which is overdriving both amplifiers.

 

[TechBoyJK]

Originally posted by: Evadman
If you follow the wiring diagram in that PDF then you are running at 1/2 ohm bridged, which is overdriving both amplifiers.

the speakers individually may be 4 ohms, but the crossover is built in a way that makes the whole set run at 4.

 

[spidey07]

You have two PAIRs of speakers? Running on two channels?

My guess is you're at two ohms and you wired the speakers in parallel (2 ohms if you do). Wire them in series or get a better amp.

 

[TechBoyJK]

no, just one pair.. each side is rated 4 ohms at the crossover. i have bridged the amp from 4 channel to 2 channel stereo, which is 4 ohms per side.

 

[mrchan]

turn the gains all the way down and see if it still happens.

what HU do you have?