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Old 1st April 2007
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Question Amp blowing fuses

Probably one for stipud methinks. Twice today the 15amp inline fuse from the battery to the amp blew. It was on a bass heavy track on both occasions, does this mean the current draw is exceeding the fuse rating hence blowing or am i overcomplicating things. Is going to a 20amp fuse an option or is it a fire risk? I've looked at the amp manual and it doesn't state a fuse size but does say the max current draw for the amp is 85amps! Its a JBL GTO 75.4 if thats of any relevance.
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Old 1st April 2007
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What gauge wire are you running from the battery to the amp?

Where have you grounded?

Which fuse is blowing, the one near the battery, or one at or in the amplifier?

Do you use bass boost? How have you set your gains?

Pictures of your power distribution and amplifier settings will help.
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Old 1st April 2007
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Gauge? Not sure, the wiring kit was described as suitable for a 1200w application.

Amp is grounded under carpet of rear seat, its nice and tight and clean as a whistle.

Fuse is 8" from battery connection.

Bass boost in on via the head unit.






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Old 1st April 2007
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First of all... take wattage ratings printed on products with a grain (more like a 5 ton block) of salt, ESPECIALLY IN THE UK. For some reason they will write anything on products there in order to make a sale. Real wattage is rated by CEA standards, in "RMS" watts - aka continuous power. When a product says it puts out 1000 watts "MAX", but 500 "continuous/rms/etc", then that means the amp puts out 500. The 1000 watt number is just there to fool people who don't know better.

Check out this guide and look at the power cable calculator. For a wire to actually support 1200 actual watts over 20+ feet, it would have to be 2 or 0 gauge (see here for an example of that size).

From the looks of it, your wiring is 10 gauge (it is only a hair bigger than your speaker wire!), which means it would MAYBE be sufficient for your amplifier on a 4 foot run of wire, not the 20ft or so it takes to get to the back. I am guessing the 15 amp fuse came with the wire (signifying the maximum amperage that the wire can carry). In that case, no... I would definitely not recommend going with a bigger fuse. Doing so will far exceed the current capabilities of your wire, and will either cause the wire, amplifier or even CAR to burn up. I've seen it happen many times when people run too small of wire, so be careful.

According to your amp manual the amplifier you have is capable of drawing 85 amps at full tilt. This far exceeds the 15 amps your current wire is capable of carrying, and explains why the fuse keeps blowing. With this in mind, I would recommend you buy a 4 gauge wiring kit to replace your current one. A good 8 gauge would be absolute minimum, yet likely not a large improvement on your current wire.

As for your amplifier settings, there is some room for improvement.

I am assuming you are powering the amplifier with front bridged to your subwoofer, and rear to your 6x9's?

Front:
Bass boost: 0dB - all it does is add distortion, and make it very boomy. Every 3dB you add also makes your amplifier try to produce twice as much power. This will quickly shorten the life of it's transistors, especially if the requested power is greater than it's capabilities, which causes "clipping".

Crossover: LP - stands for low pass, which means it cuts off higher frequencies, allowing your subwoofer to play bass, rather than distorting on higher notes.

Freq: try to get this around 100Hz or so. Your dials aren't very helpful at displaying where this is, so my rule of thumb is to listen to something with very deep vocals, and ensure that no vocals are being produced through the subwoofer.

Input level: pick your bassiest song, and turn your stereo up as loud as you can tolerate. Turn this knob up until the bass stops getting louder, then turn it back down a hair. If you turn this too high, the amp will "clip", which can be heard as typical breakup distortion.

Rear:
Boost: 0dB
Crossover: HP - this time we cut out bass frequencies
Freq: Set it to 100Hz, or wherever you set your subwoofer crossover.
Input: adjust to taste - you do not want these to overpower your front stage, and make it sound like you are facing away from the stage. Try to create a live environment in your car!

That should just about cover it. I would recommend you skim through that guide I posted earlier, as it is very helpful for first time do-it-yourself installs. For further help you can check out the how to section of my forum, or just let me know
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Speaker wire is VERY heavy gauge so amp wire looks puny compared to it. I never did the wiring, i left it to a supposed expert who has wired it the same as the handbook suggested...rear to sub, front to 6x9's. I've noticed the book says set the sub to low pass, but mine is set to flat...could this be a problem?

What is mystifying me is why it has taken 2 years for a fuse to blow and then it goes twice in 10 minutes?

Would adjusting the "bass engine" settings of the Alpine head unit help?

Appreciate the help btw.
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Put in a 200w fuse
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Quote:
Originally Posted by Chris 9-5
Put in a 200w fuse
A cheap 200w fuse or an expensive one? Remember, you always get what you pay for.
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Quote:
Originally Posted by Kermit
A cheap 200w fuse or an expensive one? Remember, you always get what you pay for.
Would a fuse from an Aero blow faster

Man I bet a Viggen Aero fuse blows damned fast
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If i put a "Cayenne" badge on my 9-5 does that make it a Porsche?
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Old 1st April 2007
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Quote:
Originally Posted by Kermit
If i put a "Cayenne" badge on my 9-5 does that make it a Porsche?
Not if done by yourself - it has to be glued on by a dealer to make it a real Porsche.
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Quote:
Originally Posted by Kermit
Speaker wire is VERY heavy gauge so amp wire looks puny compared to it. I never did the wiring, i left it to a supposed expert who has wired it the same as the handbook suggested...rear to sub, front to 6x9's. I've noticed the book says set the sub to low pass, but mine is set to flat...could this be a problem?

What is mystifying me is why it has taken 2 years for a fuse to blow and then it goes twice in 10 minutes?

Would adjusting the "bass engine" settings of the Alpine head unit help?

Appreciate the help btw.
From looking at your speaker terminals it appeared that it was front powering the sub, but after checking the manual it looks like JBL does their terminals backwards, so it is indeed set up with the sub on the rear. Tune it like I said above, except switch around where I said front/rear (basically, tune the sub for LP, and the 6x9's for HP). It is definitely a HUGE no-no to have the sub playing flat. That will feed it everything from bass to midrange to treble, and greatly reduce it's efficiency.

In the alpine headunit, you want to keep bass boost at 0 as well. Other than that, you can tune to taste. Moral of the story is, if you want your bass louder, adjust the amp level, but do not use bass boost. If you want it louder beyond that, you need a bigger amplifier. Bass boost is the bane of my existence, and the cause of more melted amplifiers than I can count. If your amplifier has a remote level/gain control knob, I recommend getting one of these. That way you can set the level depending on the music you are listening to.

I am guessing the reason the fuses are starting to blow is that your first fuse was actually way higher than it's normal rating. Now that it has finally given out, you throw in a 15 amp fuse and it dies like it should. These types of fuses are notorious for being unreliable for feeding large amounts of power, so make sure that 4 gauge kit you buy also comes with a glass fuse and holder.

One final recommendation is to upgrade your front speakers. Power them off of your amplifier instead of the 6x9's -- leave them on your headunit power instead. I guarantee you this will sound about 5 million times better.
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  #12  
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Quote:
Originally Posted by stipud
I guarantee you this will sound about 5 million times better.
For the 5467 time, stop exagerating
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