There are a lot of electric components inside your vehicle, including the amplifier. These components can easily get damaged in case of a sudden power surge since they are designed to handle only a limited amount of power.
To prevent this, we have different fuses installed. A fuse only allows a certain amount of current to pass through and melts apart (or you can say ‘blows’) if the current exceeds that threshold.
Replacing a blown fuse is much easier and cheaper than buying a new car component. Hence, it’s a no-brainer to use them wherever you can.
But if you’ve got a blown fuse you should check for its cause before replacing it. Not doing so will cause even the new fuse to blow, almost immediately.
Why Does My Amp Keep Blowing Fuses
Below we’ll discuss some of the common reasons why fuses blow.
1. Impedance Mismatch
An amplifier is designed to handle a certain load. But if speakers put a load too heavy on the amp, it’ll be forced to draw more current from the battery than what it was designed for.
This can cause the amp to overheat to either go into protection mode or damage its internal fuse. This is why you should carefully match the impedances of your speakers/subs and the amp when installing the latter.
2. Wrong Power Cable Gauge
The wire we choose for our power cable comes in different types based on their thickness aka. gauge. The wire gauge you go for will depend on your amp’s current draw and the length of the wire you’ll need.
It’s important to choose the correct gauge wire for your amp because it will run hotter, shut down, or have a shorter lifespan otherwise.
3. Bad Grounding
Along with the power cable, there’s another wire that you’ll need to connect when installing an amplifier: Ground wire.
Properly grounding this wire is important because you’ll get a blown fuse otherwise. Other symptoms of bad grounding include burning smell inside your vehicle, amp turning on and off repeatedly, clipping, etc.
When making a ground connection, make sure that the wire touches the bare metal surface of your vehicle (without any paint) and that the connection is stable and tight.
For more info, you can watch the video below:
4. Wrong Fuse Size
Fuses come with different sizes based on their ability to allow a specific amount/value of current to pass through. If you put a fuse with size too smaller than that value, it’ll blow frequently. On the other hand, if you pair a larger size fuse with the amp, it’ll not blow during power surge and will fail to protect the amp.
Amplifiers usually come with a specification called ‘fuse rating‘. This rating indicates the correct fuse size for that amp.
But if this rating is not present on your amp’s specs sheet, you can find the suitable fuse size by yourself using this formula: I=P/V.
In simple terms, you’ll have to divide your amp’s current draw by your system voltage to get the right fuse size.
5. Speaker Issue
If the amp blows fuse right when you turn the volume up, it can be due to speaker wiring or the speaker itself. To check the latter, you’ll have to physically inspect the speaker and see whether it’s blown or not.
If it’s blown, then the voice coil and cone area should be damaged. And you’ll have to replace both in order to fix the speaker. We’ve already written a separate post about fixing a blown speaker. You can check out out for more info in this regard.
6. Amp Gain
The gain is the measurement by which an amplifier can boost a signal.
Having the right amount of gain is important because you’ll get sound distortion or clipping otherwise. The clipping, in turn, causes the amp to go overheat and blow the fuse.
Most people think the gain and volume are the same. That’s why they set the former to the highest level.
Setting up the gain too high causes the amplifier to draw more current from the system, which results in the fuse blowing.
That’s why you should re-adjust the amp gain by matching your amplifier’s input to the head unit’s output to see if the issue resolves.
7. Shorted Power Wire Between Amp and Battery
Even when you have placed a fuse between the battery terminal and amplifier, the portion between the battery and fuse holder is still unprotected. It means that this portion can touch the vehicle’s body to create a short-circuit and cause the fuse to blow.
So, visually inspect that portion to see if it’s shorted and replace it if it is. To prevent this from happening again in the future, use zip ties around the cable.
8. Faulty Amp
If you have tried all the steps but the fuse is still blowing, then maybe there’s an issue with the amplifier itself. Maybe its power supply or transistors are damaged for some unknown reason. Since repairing an amp is beyond the scope of this post, you should seek professional help for this.
It’s equally possible that you have a poor-quality amp in the first place – especially if you’ve picked it up a cheap unit from Ali Express.
Frequently Asked Questions
How do you fix an amp that keeps blowing fuses?
The first solution should be replacing the blown fuse. But if the new one is also getting blown, then it indicates a deeper problem such as impedance mismatch, poor amp grounding, faulty amp, etc.
Will an amp turn on with a blown fuse?
No, it won’t. A blown fuse would not allow an amp to turn on again (unless you replace the fuse) as the circuit is open.
Is it OK to replace a 15-amp fuse with a 20-amp fuse?
Yes, you can but it’s not recommended. Choosing a fuse with higher-amperage will allow a higher amount of current to pass to the amp. This excessive current can be harmful for the amp and can damage it.
Do fuses affect sound quality?
No, the fuses don’t sound the sound quality of your car audio in any way.