fuse problems

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=98777
Printed Date: April 27, 2024 at 1:41 PM

Topic: fuse problems

Posted By: 5kwatts
Subject: fuse problems
Date Posted: November 08, 2007 at 2:48 PM

prymid 2000watt amp with two 15 audiopipe subs, pioneer headunit......finally got the amp working but now that i have it bridged at 2ohms it keeps blowing the power cable fuse........it is because i have a 30amp fuse or could it be sumthing else??? maybe if i put a bigger fuse in it will it help??

Replies:

Posted By: collyn eastham
Date Posted: November 08, 2007 at 3:20 PM

1st. The fuse is inline with the battery to protect the vehicals wiring.

2nd. The fuse needs to be appropriate for the wiring size. The wire needs to be the correct gauge for the amp draw to the systems amps. If you are running that kind of power, you need 0ga. wire and a 200amp fuse. The fuse needs to be as close to the battery as possible.

3rd. Why are you using a 30 amp fuse? posted_image

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Collyn Eastham
a.k.a. 300MBQuart
08 HHR Panel

Posted By: coppellstereo
Date Posted: November 08, 2007 at 3:32 PM

Find the 'RMS' rating of that amplifier and let us know.
What is the model number of the speakers, and how do you have them wired?
DO NOT put in a bigger fuse until you figure out the problem!!!

What size power wire are you using?
Does the fuse pop as soon as you turn the amp on, after listening for a while, or .. when?

My thinking is that you have your woofers wired below the amps stable range or that you have a short in the power cable.

Give us the model numbers of the amp and woofers and we can tell you how best to get this working properly.

Posted By: haemphyst
Date Posted: November 08, 2007 at 4:10 PM

If you are bridged into a 2 ohm load, you are presenting a one ohm load PER CHANNEL to the amplifier. I know of NO Pyramid amp that'll run for very long with a one ohm load connected to it.

Also, if you are running a 30A fuse, yes, that's WAY too small. Even if the amp is 500watts, (probably a bit optimistic) 500WRMS/60%=833W 833W/14.4V=57A.

As long as your power wire is AT LEAST a #8, yes, you can upgrade that fuse to a 60 or 75A without issue. It's is there to protect the car anyway, NOT THE AMPLIFIER. If you are using a #8 wire from your battery, you COULD put a 100A in that wire, safely.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: techman93
Date Posted: November 08, 2007 at 9:22 PM

One problem is the brand of amp. Not typically known for quality or giving real wattage for output. Normally it is high and exaggerated. However for a 2000 watt amp 0 awg wire is better then 8awg. 4 - 2 awg may suffice.
What is the rms of the amp? What length from power source is amp located? These will determine the correct wire gauge.
If the amp is 600 watt rms at a distance of 16 ft then 4 awg would be ok. If it were 800 watt rms at the same distance you would need to step up size to 2 awg. Being it is Pyramid then it will be more like 300 watt rms x 2. So 4 awg will be more then sufficient.
If the amp is a four channel, do not run at 2 ohms, it will blow amp. These amps are not designed to run lower then 4 ohms bridged. Each channel can run 2 ohms but even still it says you can do it, I would doubt the amp would last that long. Save some cash and buy a better piece of equipment.

Posted By: 5kwatts
Date Posted: November 09, 2007 at 6:13 PM

audiopipe txx-ap15 15" dual 4 ohm subs pb779x pyrmid amp the fuse pops after i crank it up for about 5 mins and i noticed while in bridged mode my lights dim alot and it didn't do that befor it was bridged........the power wire im using is a 12awg i think

Posted By: DYohn
Date Posted: November 09, 2007 at 6:25 PM

You cannot safely bridge that amp into a 2-ohm load. In bridged mode it requires at least a 4-ohm load.

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Posted By: jeffchilcott
Date Posted: November 09, 2007 at 11:39 PM

5kwatts wrote:

audiopipe txx-ap15 15" dual 4 ohm subs pb779x pyrmid amp the fuse pops after i crank it up for about 5 mins and i noticed while in bridged mode my lights dim alot and it didn't do that befor it was bridged........the power wire im using is a 12awg i think

Lots of problems in that statement.

2 dual 4 ohm subs cannot be wired to a 2 ohm load, unless you are not running all the coils. Your amp even though its not 2000 Watts still needs 8 agu or larger power wire. 12 guage is likely to set you car on fire.

If you do not understand what you are doing, you might want to take it to a shop and have it installed correclt before you, break equipment, light the car on fire, or both.

With your subs you have the logical option of 2 ohm per sub, per channel. This would be your best and safest way to wire it. Again you still need to get a real amplifier kit.

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Posted By: fknfbm
Date Posted: November 10, 2007 at 12:12 AM

First off... Pyramid. I dont care if that amp takes up 6 cubic foot of space, its still not gonna draw 2000W . Easiest way to determine a fuse for the power cable is to add up all the fuses on your amp. That amp... what ? 2X20A =40A. You would be safe throwing in a 50A fuse on the power wire. In my years of installing I have always used this rule. Add the fuses of your amps max current draw and then add 10 more for safe keeping.

If you want to determine the "max" wattage that your ebay amp is "pushing" add the amperage of the built in fuses. Like I said earlier, 2X20A = 40... 40a by a maximum of 14.4 volts = 576. Substitute your amps built in fuses with the 40 accordingly.

Ohms law doesnt lie...

Posted By: techman93
Date Posted: November 10, 2007 at 12:20 AM

Pyramid PB779x amp manual
300w x 2 rms
if you have all coils of subs parallel, that would be a 1 ohm load mono, not good. you could run them parallel 2 ohms per channel or series parallel 4 ohm mono.
posted_image

2 ohms per channel.
posted_image

4 ohms mono.

Wire gauge of 12 doesn't make any sense. You need 6 - 4 awg definitely. A good fuse holder with 60 amp ANL or AGU fuse or at most 100 amp fuse. If you use thick wire on power, use same gauge on ground cable as well. Also make sure the ground you choose is a good solid ground. The best way to determine is meter the resistance from the negative side of battery and the ground point.

Posted By: 5kwatts
Date Posted: November 10, 2007 at 12:46 AM

ok i got it i had it wired for 1ohm mono with 2 subs...............but my amp came with two 45amp fuse's......would it be ok to throw in two 30s and put a 45 in the power cable??

Posted By: techman93
Date Posted: November 10, 2007 at 1:45 AM

Had you been reading posts on advice?
Take the two fuses and add. 45 amp fuse + 45 amp fuse = 90 amps total + 10 amps over = 100 amp fuse in an appropriate fuse type and fuse holder. (ANL fuse and fuse holder shown below) Also as noted before, change power and ground wire to appropriate size. Last of all, wire the subs differently. Here is a good site for speaker wire calculation. Speaker wire calculator
posted_image

Scosche 100 watt amp kit

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The wire I'm test'n isn't doin' what it's supposed to be doin'... I am so glad I printed that tech sheet, with the wrong info.
Do it right the first time... or I might have to fix it for ya

Posted By: DYohn
Date Posted: November 10, 2007 at 9:57 AM

5kwatts wrote:

ok i got it i had it wired for 1ohm mono with 2 subs...............but my amp came with two 45amp fuse's......would it be ok to throw in two 30s and put a 45 in the power cable??

Please read the replies you have already gotten. This is starting to feel like a troll thread and is headed for a lock.

Here's your bottom line:

NEVER change the size of fuse that comes installed in an amp
ALWAYS use large enough power and ground wire to support the current the amp is designed to draw
ALWAYS use a fuse large enough to protect the power wire (see the power and ground links to the left)
Your amp will be destroyed by a 1-ohm load. This is probably why it is blowing fuses.
With two 4-ohm DVC woofers, wire each one for 2-ohms (voice coils in parallel) and connect each woofer to its own channel of your amp (wire in stereo, not bridged)
If you do not understand this or you do not know how to do this, take your car and all your gear to the nearest car audio shop and seek help.

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Posted By: haemphyst
Date Posted: November 10, 2007 at 10:24 AM

watts...

1. Your amplifier DOESN'T make as much power as it claims to. Period.
2. You CAN'T run it bridged into 2 ohms. Period.
3. Even if number 1, above, is the case, your power wire is too small. YOU SHOULDN'T USE A #12 TO POWER AN AMPLIFIER. Period.
4. The underhood fuse is to protect the car, not the amplifier, and its capacity is based on the WIRE IT IS PROTECTING. IT HAS NOTHING TO DO WITH THE RATINGS OF THE FUSES IN THE AMPLIFIER. Put that notion out of your head RIGHT NOW. Period.

So. Those FACTS being laid out for you, here is what you MUST do:

1. Rewire the woofers for a safe load, 2 ohms or higher for stereo mode, and 4 ohms or higher for bridged mode.
2. Run a larger power wire, at LEAST number 8 from your battery to your amplifier.
3. Protect that wire with a fuse, based upon ITS size, using the following chart:

#8 - 100A
#6 - 120A
#4 - 150A
#2 - 225A
#0 - 350A

4. And finally, for PETE'S sake, PLEASE buy some good equipment.
5. Let someone who knows what they are doing install your gear, you're gonna lose a car, if you keep up like this.

You HAVE to understand (at least a little bit) what you are doing BEFORE you start playing with car amplifiers. They're high current devices, and require special installation considerations. PLEASE learn a bit about electronics before you burn your car to the ground!

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: haemphyst
Date Posted: November 10, 2007 at 10:26 AM

Wow... Great minds think alike, although I think you worded yours a little nicer, DYohn! posted_image

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: DYohn
Date Posted: November 10, 2007 at 10:31 AM

Thanks and Yep! Although I do wish I had included your line about burning the car to the ground, as sometimes that's all kids understand. That and "More BASS!"

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Posted By: tcss
Date Posted: November 10, 2007 at 1:01 PM

Don't you guys wish you were back in retail again? LOL

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There is no such thing as free installation!

Posted By: DYohn
Date Posted: November 10, 2007 at 1:12 PM

tcss]D wrote:

n't you guys wish you were back in retail again? LOL

I'd probably go broke in 6 months by talking kids out of buying high-margin garbage.

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Posted By: sarcomax
Date Posted: November 10, 2007 at 4:17 PM

I talked three people out of buying caps today...Fortunatly for my wallet, three other people listened to their friends over me and bought caps.

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Posted By: 5kwatts
Date Posted: November 10, 2007 at 9:05 PM

i finally got everything working in the blazer thanks for you help..........but now everytime the bass hits my speedo bounce's.......is this normal??

Posted By: DYohn
Date Posted: November 10, 2007 at 9:34 PM

Don't drive wearing speedos.

posted_image Sorry, couldn't resist. If your vehicle has a mechanical spedometer, yes, sound pressure can make it bounce.

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Posted By: 5kwatts
Date Posted: November 11, 2007 at 11:28 AM

lol thank you once again........its all working and slams like hell only thing i need now is dynamat cuz everything is rattling posted_image

Posted By: collyn eastham
Date Posted: November 12, 2007 at 7:08 AM

sarcomax wrote:

I talked three people out of buying caps today...Fortunatly for my wallet, three other people listened to their friends over me and bought caps.

I would have talked them all into a HO alternator and a better battery posted_image

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Collyn Eastham
a.k.a. 300MBQuart
08 HHR Panel

Posted By: supradude
Date Posted: November 12, 2007 at 2:06 PM

collyn eastham wrote:

I would have talked them all into a HO alternator and a better battery

Easier said than done. Once a person gets the "magical" cap on the brain it's like they've got to have it. I try to tell people, but if they insist, that's what they get.

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'85 Toy

Posted By: sarcomax
Date Posted: November 12, 2007 at 2:45 PM

We don't sell alternators or batteries. wait... do double "a"'s count?

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Posted By: haemphyst
Date Posted: November 12, 2007 at 8:42 PM

Except "AA's" are TECHNICALLY cells! posted_image

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."