Amp blowing fuses at high volume

[ST0NGE 10+ year member]

My amp, JBL Bpx500.1 is blowing the two 30a fuses in the amp when the volume is around 30, which according to my local audio shop, I can go up to about 35 before distortion.

The amp is pushing two 12" JBL Gt5-12's 4ohms svc each. And all the settings on the amp are right as they did it.

I have 4gauge wiring for power and ground and I believe both are good (power wire doesn't have any cuts or slits and my ground is solid)

I did the big3 a few months back w/ 4gauge but it didn't fix this problem or my headlight dimming, although I think I am getting better voltage.

I was thinking about adding a second battery, what do you guys think? Will this fix my amp blowing the fuses problem?

BTW, this is all in a 2000 MK4 Jetta with stock batt and alt

thanks!

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[jokers10 10+ year member]

I also have a MKIV Jetta, and I am running more power than you with a stock battery, and alternator, with the big 3 done in 1/0, and my power wire is also 1/0. My lights only dim at full tilt, but not by much, which tells me that you either need to work on your ground a bit, your amp is trying to do too much, or your amp is going bad.

Where did you ground your amp?

How did you set your gains?

Aren't Jettas the coolest?

 

[ST0NGE 10+ year member]

Ha yeah just the coolest lol.

I think I should ask where did you ground YOUR amp because I actually don't think mine is very good, haha.

I didn't set my gains, I had a local audio shop do that

 

[MisterDeadeye 10+ year member]

Can you get a picture of the speaker wire connections on the amp? Or can you at least look and see if the amp is being bridged?

There will be either four or two speaker wires connecting to the amp, which is it? (I'm talking about the wires that go from your amp to your sub box)

 

[ST0NGE 10+ year member]

Can you get a picture of the speaker wire connections on the amp? Or can you at least look and see if the amp is being bridged?
There will be either four or two speaker wires connecting to the amp, which is it? (I'm talking about the wires that go from your amp to your sub box)

Each subs wires come out of the box separate and then they meet at the amp and the two positive wires combine and the two negative wires combine, so they are running at 2 ohms

Many people say this amp can't do 2 ohms but I know it can, I did the research

 

[MisterDeadeye 10+ year member]

It looks like you made this same thread a few months ago: http://www.caraudio.com/forums/wiring-electrical-installation-help/525337-wiring-2-jbl-gt5-12s-jbl-bpx500-1-amp.html

I'm sorry to tell you, the problem is still the same. You can't run that amp at 2 ohm mono.

 

[ST0NGE 10+ year member]

JBL BPx500.1

That says there that it can do 2ohms.

And the guy who had it hooked up in his honda before me had no problems..hooked up the same way..hmmm

 

[IonRL205 10+ year member]

Just cause the shop told you how high you can go, does not mean it's true.

The manual says that amp is even 1 ohm stable, wiring at 2 ohms shouldn't be the problem. I'd check and make sure your gains are set correctly.

I dont think that amp has a protection circuit, so instead of going into protect when it clips, it just blows the fuses.

Switch should be set to bridge for 2 ohms.

 

[jokers10 10+ year member]

Mine is grounded at the seatbelt bolt. My 1/0 connector wouldn't fit through the seatbelt bolt, until I reamed it out. I then sanded the paint around that area, until I had bare metal. And then I tightened the crap out of it.

The manual says that amp can do 1 ohm mono. If it can do 1 ohm, it can do 2 ohm.

According to that page linked above, The amp isn't as efficiant at a 2 ohm mono load, meaning in order to make the same power, it has to draw more current. And that link says it draws more current than the fused rating. If it were me in the same situation, I would fix the ground like I did, and then start saving money for a new amp, or new subs to match the impedence load of your subs.

 

[MisterDeadeye 10+ year member]

JBL BPx500.1
That says there that it can do 2ohms.

And the guy who had it hooked up in his honda before me had no problems..hooked up the same way..hmmm

Most amps can be "run" at ohm loads for long enough to get a rating. That does not mean that they're stable to be run constantly at that load. If you want to fix your amp, hook up each sub to a different channel, and be done with it.

That guy's test even explicitly showed that the amp is very inefficient at 2 ohms mono, and was using much more current. You'd get the same amount of power running those subs on separate channels, and the amp would be much less costly on your electrical.

 

[jokers10 10+ year member]

I would also turn the gain down, so you are not spending money replacing fuses.

 

[ST0NGE 10+ year member]

Most amps can be "run" at ohm loads for long enough to get a rating. That does not mean that they're stable to be run constantly at that load. If you want to fix your amp, hook up each sub to a different channel, and be done with it.
That guy's test even explicitly showed that the amp is very inefficient at 2 ohms mono, and was using much more current. You'd get the same amount of power running those subs on separate channels, and the amp would be much less costly on your electrical.

Yeah I gotcha. I would get the same amount of power running them to the amp seperately? so they would be running in parallel correct?

 

[MisterDeadeye 10+ year member]

Yeah I gotcha. I would get the same amount of power running them to the amp seperately? so they would be running in parallel correct?

Well, that guy measured 634 x 1 at 2 ohms, and also measured 335 x 2 at 4 ohms, so you'd actually be getting more if you run them separately. Running them separately, they wouldn't be in series or parallel. They would just be wired. Take the pos and neg from one sub, and put them in channel one, and take the pos and neg from the other sub, and put them in channel two.

That way, you'll be giving ~335 to each sub, rather than ~312 to each sub. Your gain might have to be set lower or higher because of this, so you might want to go have a shop set it again.

To be safe, make sure the amp is not getting any power when you do this.

If you're still blowing fuses after that, then this was probably not the issue.

 

[ST0NGE 10+ year member]

Well, that guy measured 634 x 1 at 2 ohms, and also measured 335 x 2 at 4 ohms, so you'd actually be getting more if you run them separately. Running them separately, they wouldn't be in series or parallel. They would just be wired. Take the pos and neg from one sub, and put them in channel one, and take the pos and neg from the other sub, and put them in channel two.
That way, you'll be giving ~335 to each sub, rather than ~312 to each sub. Your gain might have to be set lower or higher because of this, so you might want to go have a shop set it again.

To be safe, make sure the amp is not getting any power when you do this.

If you're still blowing fuses after that, then this was probably not the issue.

Awesome thanks for that info. The reason I asked parallel is because on the back of the amp there is a setting for either 2ch/bridged or parallel. Do I want to hook It up like a 2 channel and put the switch to two channel?

 

[MisterDeadeye 10+ year member]

Yes.