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10 Reasons Why Your Sub Is Cutting Out at High Volumes

When bass cuts out at high volume, the problem is usually in the amplifier. However, depending exactly on how your subwoofer is ceasing to function, you could also have a wiring problem, an electrical problem, or even a problem with your subwoofer or subwoofer wires.

To get to the bottom of things and fix this, you’ll need to check out each potential issue, perform any available fixes, and then check to see if the subwoofer is working correctly.

Here are the most common issues which may cause your bass to cut out:

10 Reasons a Subwoofer Is Cutting Out at High Volumes

There’s no really definitive way to tell you what’s wrong with your system without taking a look at it or at least without having all the necessary information about it. But we can offer you some insight on what could be the problem. So, let’s get to it.

1. Bad ground

A bad ground is one of the most common cause of amplifier problems. It can cause headlights to dim, amplifiers to burn, ground loop noise (engine whine), speakers to short and a host of other issues. For this reason, it should be the very first thing to check when something is wrong with your stereo system.

Basically, what grounding does is that it completes the electrical circuit powering your amplifier. So, if you’re dealing with poor wiring and grounding, your amplifier may keep cutting out, may not work very well, or it may fail to turn on. Not only that, but improper grounding can also lead to damage of the amplifier and other components.

To rule out improper grounding being the reason why your sub is cutting out, you need to trace the ground wire to where it’s attached to the chassis, and inspect it for any damage.

Most people usually just test for a continuity on the ground wire. However, you can check voltage all day long with a multimeter and everything would seem okay. This is because multimeters are extremely sensitive, and sometimes all you need is one or two strands of wire connecting to give you a good voltage reading. But when push comes to shove and a bigger load is put on the circuit, there might not be good enough connection to handle your load, making your amp and subwoofer give up the ghost.

Having said that, if the ground wire is in good shape, check the connection point. The latter must be part of the metal chassis or subframe, preferably within eighteen inches of the amplifier’s location. It must also be paint free. So, make sure it’s sanded down to bare metal.

Furthermore, ensure the ground connection isn’t loose or corroded. If it is, clean it and tighten it – use extra screws, a lock washer, a star washer, and any other technique that’ll hold this connection tight and secure, and most importantly electrically conducting, – because otherwise, the amplifier will no be able to operate efficiently.

Last but not least, in order to assure proper and smooth current flow, make sure the gauge of the ground wire matches the gauge of the power wire.

2. Amp in protect mode

Amplifier protect mode is essentially just a shutdown state that car amplifiers can go into for a wide variety of reasons. When an amplifier is in protect mode, its protect mode LED will turn on, or it’s power LED will turn to red or orange.

Knowing what caused the protection circuit to engage can help determine how to fix it. Did the amp fail to operate as soon as you turned it on? Did it happen after blasting for an extended period of time (may be thermal overload and it needs to cool)? Did it cut out after you hit a speed bump or drive over rough terrain (a wire connection may have come loose)?

Some of the most common causes of an amp going into protect mode include:

  • Improper installation of the amp
  • The amp has overheated for some reason (clipping, impedance mismatch, bad amp mount…etc)
  • Shorted out or loose speaker wires
  • Bad ground
  • Blown speaker
  • Incorrect gain setting
  • Internal amp failure
  • …etc.

The purpose of “protect mode” is to prevent serious damage to the amp or other components in the system. So, while dealing with an amp in protect mode may be really annoying, it might actually save you from a much bigger hassle down the line.

With all of that in mind, when your subwoofer suddenly stops operating, check your amp. If it’s in protect mode, there’s a good chance that’s the root cause of the problem, and you need to fix it as soon as possible.

Fixing whatever is causing the protection circuit to engage is a great way of hitting two birds with one stone: having a good operational amplifier while ensuring the subwoofer is able to perform as it has been designed to.

3. Amp overload

Amp overloading occurs because of impedance mismatch. Impedance – measured in ohm and uses the Omega symbol (Ω) for shorthand – refers to the load a speaker places on an amplifier. In other words, it’s the amount of electrical resistance, or load, a speaker offers to the current supplied by an amplifier. The lower the impedance, the higher the load on the amp (and the harder it has to work).

With that in mind, when an amplifier is presented with a very low impedance that’s beyond what it can handle, it’ll try to keep up with that load by drawing more current than its power supply is designed to deliver. What happens then is that it heats up quickly due to the extra power it’s trying to push out. Once it overheats, the protection circuit kicks in and shuts the amp down to prevent serious damage.

One of the most common impedance mismatch we come across more often is hooking 2Ω speaker up to a 4Ω amplifier or wiring four 4Ω speakers in parallel and end up with a 1Ω load, then bridging a 4Ω amp to that load.

An overloaded amplifier might keep running for a short period of time and then turn off, or it might keep running at low volume, but shuts off immediately as soon as the volume goes up.

With all of the being said, make sure your amplifier can handle whatever load it’s presented with.

4. Voltage problem – Too much current draw

Voltage drop is another strong causal factor of subwoofer is giving when you crank it up. This is especially true if it happens often when bass hits.

Amplifiers are power hungry and crave electrical current. Luckily for us, most car’s stock electrical system can produce more of that than they need, which is how your vehicle can keep its battery charged even with all the other electrical accessories turned on.

The downside, however, is that your alternator isn’t an infinite source of power. There comes a point where it can no longer keep up with the increased demand for electrical current, and that point is often when you upgrade your amplifier to a more powerful one or when you install a dedicated subwoofer amp.

The more connections and wiring a vehicle has, the more vulnerable the electrical system is to voltage drop.

So, when you have a big subwoofer or multiple subs, and a powerful amplifier, plus all the other electrical accessories, you put a lot of strain on the electrical system.

Amps by nature are known for drawing too much voltage from the system, and when your electrical system can no longer keep up with supplying the required amount of current, the amplifier doesn’t get the voltage it needs to operate and shuts off or drops into protect mode until the electrical system can catch back up.

That said, when your stock electrical system can’t handle all the aftermarket goodies, you need to consider upgrading it in order to maintain a stable supply of power.

To make sure the voltage drop is the culprit, you’ll need to use a multimeter to check your voltage at the amplifier while it’s playing. If the voltage is dipping below 12 volts, then there’s your answer.

5. Amp overheating

If your subwoofer gave up after playing for an extended period of time, there’s a good chance your amplifier may have just overheated.

Amp overheating or thermal overload can be caused by a wide variety of reasons including but not limited to:

  • Poor build quality
  • Bad ground
  • Improper mounting – Lack of air flow
  • Clipping
  • Blown/grounded speaker
  • Gain/punch bass control settings too high
  • Impedance mismatch
  • …etc.

Most car amplifiers are designed to shut down and go into protect mode if they get too hot, which can prevent a more permanent failure.

Lack of airflow is one of the most common cause of overheating. However, regardless of what’s causing your amp to overheat, thermal overload isn’t something you want to let linger. Your amp or other components could sustain serious damage.

That said, to keep your amplifier from overheating, make sure it’s properly mounted, and, most importantly, that it’s not overdriven.

6. Amp clipping

Clipping goes hand in hand with thermal overload. It’s a form of distortion that happens when an amplifier is overdriven, that is, when it is pushed to amplify a signal beyond its power capacity. Once the amp has reached its maximum output, it becomes impossible for it to further amplify the incoming signal without compromising its form.

Technically speaking, what happens is that the sine output signal loses its highest and deepest points — the troughs and peaks – leading to a distorted signal.

Generally speaking, when an amplifier is clipping, it’s because the gain is not properly set or the volume is too high. However, clipping can also be caused by:

  • Bad ground
  • Inadequate wire gauge
  • The need for a bigger alternator
  • Over-equalization of the source signal
  • …etc.

If your amplifier is clipping, it’s of utmost importance to properly adjust the gain setting on your amp, and ensure the top RMS output of your amp is no higher than your sub’s top RMS rating.

Excessive clipping can make your amp overheat fast, which in turn causes its protection circuit to engage, making your bass cut out.

7. Wiring problem

It goes without saying that the wires you use to install a car amplifier are just as, if not more important than the amplifier itself. This is because for a car amplifier to operate efficiently, it needs its power and ground wires to be thick enough to accommodate the amplifier’s demand for electrical current. Otherwise, the amp won’t run efficiently or put out its rated power.

The thing is that when bass hits hard, the amp will be grasping for more power, but when it can’t draw any more from the electrical system, it may experience thermal shutdown, blow the fuse, or drop into protect mode to prevent serious damage, making the subwoofer give out.

That said, to ensure proper current flow, invest in good amp wiring that’s not too thin or made of low quality materials.

As a general recommendation, use the chart below as a quick reference to determine the appropriate wire gauge for your amplifier.

Wire Gauge SizeTotal Amplifier RMS Wattage
0/1 AWG1000+ Watts
4 AWG400-1000 Watts
8 AWG200-400 Watts
10 AWG100-200 Watts

8. Incorrect gain setting

Most inexperienced guys confuse the “gain” and “volume”. This is because when you turn the gain up, the volume increases and likewise when you turn it down the volume goes down as well. However, the “gain” control is not a volume control knob. Confusing, right?

Amplifier gain refers to the input sensitivity adjustment necessary to match an amplifier’s input to the receiver’s output.

In technical terms, the purpose of your amp gain control is to level match the head unit’s output voltage (around 0.5V) to the gain structure of the amplifier (how much it amplifies a signal) so that the signal isn’t severely clipped and distorted.

Amplifier gain must be used moderately. Let’s repeat that in other words. Do not turn your amplifier’s gain all the way up – that’s inviting clipping and noise problems.

9. Shorted sub(s) wires

If bass cuts out while driving, the culprit is most likely a subwoofer wire that’s been damaged, or loose and is touching metal causing the subwoofer to short out.

This can also be caused by a short circuit at the terminals on the subwoofer preventing the electrical current and signal from reaching the subwoofer.

That said, make sure you visually inspect all the wires that connect your sub(s) to the amplifier. Look for any damage in the form of crimping, kinks, tear, or cuts in the insulation. Any wire with the lightest damage must be fixed or replaced.

If the wires are in good shape, ensure all of the connections haven’t come loose to the point where they can create a short.

You can also use a multimeter to check for continuity between one end of each wire at the subwoofer and the other end at the amplifier. If there’s no continuity between the two ends of the wire, that means one thing: there is a short or break in the wire. On the other hand, if there’s continuity to ground, then you’re dealing with a shorted wire.

10. Blown subwoofer

If everything checks out okay, and you’ve ruled out all the potential causes mentioned above, you’re probably dealing with a blown subwoofer.

Generally speaking, it’s easy to tell if a subwoofer is blown or not. However, It should be noted that there are varying degrees of damage of the subwoofer. For instance, a completely blown subwoofer out will not make any sound at all. Whereas, a partially blown subwoofer will sound weak and lack a lot of detail, but when you crank it up the amplifier “sees” a condition that makes its protection circuit kick in.

A subwoofer with a bad spot in its coils, for instance, will make the amplifier read a strange ohm load and cut out.

To check whether a subwoofer is blown or not, use a multimeter, set it to measure resistance ohms (Ω), and hook its leads to the subwoofer’s positive and negative terminals to determine whether there’s any electrical resistance in the coil circuit.

Any reading above 1.0 ohms indicates that the voice coils are not blown. Readings below 1.0 ohms, or readings that fluctuates wildly are a strong indication that your coils are blown.

Final Thoughts

At the end, we can all agree that distortion is the enemy – it destroys speakers, subs, and eardrums.

So, if you’ve been driving the amp/sub with distortion for an extended period of time, you will eventually cause the amplifier to become weak or, the sub to burn a coil out.

In other words, if your setup worked just fine for a year or so, that only means it took a year for the distortion to cause irreversible damage… everything works fine until it doesn’t work fine anymore, right?

Last but not least, if you’ve upgraded your system but left the head unit in place for whatever reason, it could be the reason why your sub is constantly giving out. Most stock head units are fitted with some sort of “limiters” in them so that people don’t blow the stock speakers.

On that note, if you’re using a line output converter, and your amp stays on but you don’t get any signal, check the line out converter. It could be culprit.

Alex Brown

Hey There, my name is Alex Brown, I'm an LA-based sound engineer with over 10 years experience installing, troubleshooting, and repairing commercial, automotive, and household sound equipment. I've installed highly competitive car audio systems, and everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I enjoy creating solutions and simplifying everyday needs. I also love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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