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13 Reasons Why Bass Fades When Volume is Turned Up

Car audio systems can be quite complex, and their problems are most often difficult to root out. When you’ve got a system with this many wires and settings, it’s surprisingly easy for things to go wrong.

In the course of setting up and testing a ton of car audio system over the years, we’ve encountered plenty of issues ourselves. Fortunately, we’ve learned a lot along the way.

In this guide, we’ll walk you through the main reasons why your subwoofer bass is fading when volume is turned up, and the possible solutions fix it.

13 Reasons Subwoofer Bass Fades When Turning Up Volume

#1: Incorrect Gain Setting

Is gain the same as volume? This is a question that we get asked all the time. It’s no wonder why so many people screw it up.

It’s really easy to confuse the “gain” and “volume”. This is because when the gain is turned up, the volume increases and vice versa. However, the gain control is not for adjusting volume. It simply adjusts the amount of signal coming from your receiver into the amplifier.

In fact, the main purpose of your amp gain control is to match the output voltage of the source unit to the input circuit of the amplifier (how much it amplifies a signal) so that the signal isn’t severely clipped and distorted.

It goes without saying that properly setting the gain on your amplifier is key to getting great sound in your car.

The gain control determines how far you have to increase the volume on your headunit for the amplifier to reach full power.

So, if you set it too low, then you’re essentially choking back on what the amp is there to do in the first place. In other words, your amplifier will not be able to reach its full power, which could allow the headunit to clip which in turn will result in a distorted signal being delivered to your speakers. This is especially true with low voltage OEM headunits (lower than 2.5 Volts – typically factory units).

If you have your gain set too high, the amplifier will easily reach its full power at a lower volume control setting from the head unit. This will drive the amplifier clipping, and therefore distortion will be introduced into the sound.

To sum it up, the key here is to find the right balancing point for your system to minimize amplifier clipping.

#2: Amplifier Clipping (square wave)

Amp clipping goes hand in hand with incorrect gain setting. An amplifier is said to be clipping when it’s overdriven and attempts to deliver an output voltage or current beyond its maximum capability.

Driving an amplifier into clipping may cause it to output power in excess of its power rating or supply voltage.

Since the supply voltage defines the absolute maximum peak output voltage from the amp, the signal (the tops and bottoms of the sine wave) will be clipped or ‘cut off’ if the input sensitivity is set too high.

It’s called clipping because the highest and deepest points of the sine signal wave — the troughs and peaks – are removed, leading to a distorted signal that resembles a square wave.

Excessive clipping can make your amp overheat in no time, which in turn causes the amp to go into protect mode, making your bass fade or gets softer when volume is turned up.

Furthermore, when the audio signal is severely clipped, not only does the sound quality take a massive hit, but the speakers are at risk of being damaged.

Severely clipped audio signal causes the sub to move somewhat erratically. It makes the voice coils of a speaker pop into a position and sizzle. It’s doing it with almost twice the power of the speaker’s maximum capacity, which could damage the speaker if it lasts longer.

Clipping is mostly caused by incorrect gain setting – specifically when the gain is set too high – but it can also be caused by a number of things including but not limited to:

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

#3: Low voltage

There’s no denying that when it comes to car audio, more power means more sound and vice versa.

So, when you upgrade your stock car audio system, it’s important to consider the extra power requirements that come along with a beefed-up sound system. Otherwise, you may experience voltage drop, which could make your subwoofer bass go down when volume level is turned up.

Voltage drop happens either because your car’s stock electrical system can no longer keep up with the increased demand for electrical current, or because too much current is being pulled through small gauge wires, too long wires, or both.

I mean think about it, subwoofer amps require a whole lot of juice to perform properly. Thankfully, most cars produce more of that than they need, which is how your car can keep its battery charged even if you have many other accessories running at the same time.

The bad news is that your alternator isn’t an infinite source of power. There comes a point where the alternator isn’t quite keeping up with demand, and that point is often the installation of a power hungry amplifier such as a dedicated subwoofer amp.

So, essentially when your electrical system can no longer take the load demand, your subwoofer amplifier doesn’t get the voltage it needs to operate making your bass fade to a point where it’s hard to even tell you have a sub — or, worse, completely cut out until the electrical system can catch back up.

A severe voltage drop can also make your amplifier go into protect mode.

A car amplifier might also overheat easily under low voltage conditions because in order to try and produce the same power at the lower voltage, it draws more current – more current means more heat.

So, if your stock electrical system can no longer handle your beefed-up sound system, you need to consider upgrading it in order to maintain a stable power supply.

To test if voltage drop is the reason why your bass fades, use a multimeter to check your voltage at the amplifier while it’s playing. If the voltage on your amp is dipping below 12 volts when it starts to fade, then there’s your answer.

#4: Insufficient Wire Gauge 

There’s no denying that the wires you use to install your amplifier are just as, if not more important than the amplifier itself.

I mean, think about, in order to get the most out of your amplifier, its power and ground wires need to be thick enough to accommodate the demand for electrical current. Otherwise, the amplifier won’t operate efficiently or put out its rated power.

The thing is that when you turn the volume up on the head unit, the amplifier will be grasping for more power in order to reproduce those low bass notes, but when it can’t draw any more from the electrical system – either because you’re using conductors (wires) which are too small in diameter, too long, or both – the amplifier may keep blowing the fuse,  experience thermal shutdown, or drop into protect mode to prevent serious damage, making the subwoofer give out.

To avoid this, and in order to ensure proper current flow, make sure your wiring kit is matched up to the amp (or vice-versa).

As a general recommendation, follow the guidelines below as a quick reference in determining 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

#5: Sub(s)/Speakers Out of Phase

If you hang around with car audio enthusiasts or if you frequent any of the popular car audio forums there is a good chance you’ve heard this term before.

You wouldn’t believe how many people have their speakers wired “out of phase”. Essentially, when your speakers or subs are out of phase, this simply means that their wiring is incorrect which can cause them to move in different directions, thus you will not be hearing the sound waves correctly.

Conversely, when your speakers are in phase, they’re in sync and move at the same time in the same direction, providing you with the best sound possible.

When speakers are in phase:

  • All frequencies that the speakers are capable of reproducing are represented well.
  • Imaging is optimal.
  • Sound stage is wide – most importantly – deep.

When speakers are out of phase:

  • The frequencies cancel some and boost others, muddying the imaging.
  • Bass sounds muddy and muffled.
  • Sound stage is just not right.

Technically speaking, a speaker that’s wired out phase has it its negative (-) terminal connected to the positive terminal of the amplifier, and its positive (+) terminal connected to the negative (-) terminal of the amplifier.

While being “out of phase” may seem like a small issue, it really does mess up the sound quality of a stereo system. This is especially true when your subwoofer(s) is wired out of phase with the rest of your speakers.

In fact, the loss of bass is one of the most common symptoms of a subwoofer that’s wired “Out of Phase”. So make sure your subs are wired correctly. This is especially true when you have an enclosure with two subwoofers.

I mean, when two subs are mounted in the same box with both woofers facing the same direction and one of them is wired out of phase, the subwoofer that’s wired out of phase moves the opposite way. This means that when one subwoofer cone is moving forwards (compression) the other will be moving backwards (rarefaction). Think of it this way: one sub is pushing while the other is pulling. This causes big bass cancellation.

All in all, make sure your subs and speakers are wired in phase. And most importantly, make sure your subwoofer(s) is wired in phase (same polarities) with the rest of your speakers.

#6: Bad Ground

When installing a new amplifier in your car, the ground wire is a crucial component that will either make or break your sound system.

A bad ground can cause all sorts of problems that you can think of starting with lack of punchy bass, all the way up to sub amp damage. For this reason, it should be one of the very first things to check when your stereo system starts to act up.

Symptoms of a bad ground include but not limited to:

  • Clipping
  • Lack of punchy bass output
  • Amp going into protect mode
  • Amp restarting or cutting in and out
  • Whining or popping or any audible noise that’s not normal
  • Burning or fire
  • …etc.

So, to make sure your amp ground isn’t the reason why your subwoofer is fading, trace the ground wire to where it’s attached to the chassis, and inspect it thoroughly for any visible damage in the form of kinks, tear, or cuts in the insulation. Any wire with the smallest damage must be fixed or replaced.

P.S : Ground wire for the amplifier should be the same size as the power wire.

 

Also make sure the ground connection isn’t loose, corroded, or rusted. If it is, clean it and tighten it firmly — use a lock washer, a star washer, extra screws, and any other technique that will keep this connection tight, clean, and most importantly electrically conducting.

It goes without saying that the best location to have your amp grounded is to the vehicle’s chassis or the sub frame, and the grounding point should be as near to the amplifier’s location as possible – preferably within eighteen inches of the amp’s location.

The grounding point should also be sanded down and scraped clean of any paint or primer, so that the connection is bare metal to bare metal.

#7: Bad RCA Cable

If you’ve ruled out all the potential causes we listed here so far, but your subwoofer bass is still fading, there could be a problem with your RCA cables.

So, make sure all the RCA cables are in good shape, and that they haven’t become loose or have a lot of wiggle room at the amp.

You might also need to open up the amplifier (be careful, this could void your warranty) and check if the RCA joints aren’t cracked or defective (barely making contact). This is because sometimes the RCAs seem to fit snug but the problem is inside the case.

P.S: It’s highly unlikely for an RCA input jack solder connection to crack loose from the PCB.

 

#8: Weak Subwoofer Amp (underpowered subwoofer)

Obviously, bass frequencies are much harder to amplify than the rest of the spectrum of sound — that’s why there are so many beefy subwoofer amplifiers out there dedicated solely to reproducing bass.

So, if you have a weak amplifier and you’re pushing it past its comfortable operating range, potential current for bass runs up against the power supply’s limits. In other words, the amplifier is running out of juice making the rest of the sound – that don’t require as much current – continues to go up in level and kind of overpower bass frequencies.

If that’s the case with your system, then you might want to invest in a dedicated subwoofer amplifier or to upgrade your amplifier to a more powerful one.

#9: Subwoofer in Wrong Enclosure

You shouldn’t expect much from a subwoofer that’s mounted in a bad enclosure. A subwoofer box that’s not well-designed and well-tuned won’t be anything to write home about.

Every subwoofer has an ideal set of box dimensions. So, make sure your subwoofer is mounted in the right enclosure.

You also need to make sure the box is fully sealed and has no air leak. This is because any leak in the box – no smaller how it is – will significantly hurt your sub’s output and accuracy.

Air leaks usually happen when silicon wasn’t used around all of the edges and corners when assembling the box, resulting in your subwoofer sounding bad especially at high volumes.

Generally speaking, the best way to fully seal your subwoofer box and make it airtight is to use a Polyurethane adhesive sealant. This could be any wood based glue that will expand when its dried up sealing up all the air leaks.

P.S: Don’t mount your subwoofer into the enclosure without allowing the sealant to cure for at least 24 hours. This is because the fumes that these sealants release are known to cause damage on driver surrounds, and also weaken the adhesives used in speaker assembly.

 

#10: Overdriven Subwoofer

Overpowering a subwoofer occurs when the power handling ratings of the subwoofer are exceeded and the subwoofer receives a signal that far exceeds its operating range.

For example, if your subwoofer is being pushed by 50% more power than rated, it’ll start sounding less and less “good” and more and more “bad” until its motor structure is so sloppy and starts to make noises that aren’t part of the signal.

When you give your subwoofer too much power, not only does it sound bad and distorted, but it can also damage your sub, especially if you do it for an extended period of time.

Obviously, the amount of power going to the sub is directly related to the volume control. So, when a subwoofer is overdriven by a large margin, it’ll easily hit its max wattage at 1/3 volume or a bit higher, making the rest of the sound overpower bass frequencies.

This the reason why it’s crucial to match the subwoofer/s as closely to the output of the power amplifier as possible – you can go over or under the sub’s power handling rating by about 15% or so without it being problematic.

#11: Blown Subwoofer

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

One of the easiest ways to tell if a subwoofer is blown or not is by checking its voice coils using a multimeter.

So, set your multimeter to ohm or resistance and touch the subwoofer terminals with the multimeter leads. Each subwoofer has its own specific ohms reading. If your subwoofer is functioning properly, the ohm reading on the multimeter should be what the sub was rated at (more or less). If the multimeter shows a reading that’s far below what the sub is rated for or if the reading fluctuates wildly, then there’s your answer.

#12: Loose Connections 

Last but no least, make sure all your connections are tight and sure. Sometimes, a loose speaker wire can prevent current from reaching the sub’s motor structure, making the subwoofer cut out or worse not produce any sound at all.

#13: Headunit

If everything seems to be good, make sure yo go through all the audio settings in your headunit – you never know if someone has accidentally adjusted down your subwoofer output, or any other setting that controls bass output.

For example, some Ford vehicles have a feature in their OEM headunits called “Occupancy Mode”. If you set it to “All seats”, everything sounds normal. However, if it’s set to “Driver”, the bass starts fading the higher the volume.

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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