Why Does My Subwoofer Sound Weak? (SOLVED)

Norvan Martin
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Before you decide to remove and replace a supposedly bad subwoofer because it has low volume problems, run through these quick steps to diagnose and fix the problem.

A powerful and thundering subwoofer is important for a good sound system. So, if your subwoofer sounds weak with low volume, it can really affect the quality of your experience. In this article, we will provide several fixes for your subwoofer if it’s struggling with low volume.

This is actually a common situation where the speakers are loud, but the sub is barely audible. Sometimes all you can hear is a low rumble. Please note that this is different from when your subwoofer is humming even with no input. So, let’s get to the fixes for your subwoofer low volume problem.

1. Check The Volume and Connection

Check The Volume

The first obvious thing to check is the sub’s volume and connections. This may seem like a no-brainer, but you should realize that many subs may have a volume control at the back that you may not even notice. Check the entire sub for a volume knob and adjust it.

Check Bass Knob

Also, sometimes the volume knob may not be working properly. Normally, you can feel it as you turn the knob.subwoofer bass knob

As you turn the knob, if there is no friction, it is probably not working properly and needs replacement.

Check Connections

Subwoofer connections are very important. If you are connecting your sub to an amplifier or receiver, you need to be careful with the connections. This is because you normally have many connection choices. Here is an example. If you are connecting your sub to a receiver, you may choose to:

  1. Connect the line out from the receiver to the line-in on the sub (stereo RCA)
  2. Split the LFE/Pre-Out of the sub

If you tried the second option, for example, that could be the problem because you could have an issue with a bad Pre-Out jack. In this case, it would be good if you had a second sub to test.receiver output to subwoofer

Here are some instructions for connecting subwoofers in special cases:

Connecting your subwoofer to an amp with no sub-out

Connecting passive subwoofers to two-channel stereos

So, if the sub’s volume is at the max level and the connection is good but you are still having the low sound problem, read on.

2. Check the Receiver

If you are connecting your subwoofer to a receiver, in many cases, the problem may not be with your subwoofer and may actually be an issue with the receiver.

Check If The Reciever Is Causing The Problem

A quick and easy way to test this is to switch out the subwoofer and if it doesn’t work, you know the issue is not with the sub.receiver sub issue

However, if you don’t have a second subwoofer, then you will have to do other troubleshooting steps.

An easier way to test is to connect the subwoofer to another source and if it works, you will know the issue is not with the sub. You can connect the sub to a media player or similar device.

If you have determined that the receiver is the actual culprit, more than likely the issue is somewhere in the receiver. It could also be faulty components but check the settings first. Here are some important receiver settings to look out for:

Set Speakers To Small

If your main speakers are set to LARGE, they will attempt to play the full range of frequencies, including all the bass.
 
This means the bass output for the sub could be interacting with the speaker’s output and that will cause problems. However, if you set the speakers to SMALL,  all bass will be directed to your sub.
set speakers size to smallFor example, in Realtek audio settings, if you have your left and right main channel speakers set to “Large”, the subwoofer will not work because it will not receive its bass frequencies.
 
In this case, Realtek will then send all your bass frequencies to just the left and right channel speakers. When you set the speakers to “Small”, then Realtek will send the bass to the subwoofer!

Set Sub Output and Volume Control

Regardless of which A/V receiver you have, it will likely have sub-output and volume controls. Set the Sub-output and Sub volume control settings to max.

Turn Off the Bass Enhancer

If your receiver has a bass-enhanced setting, turn it off as it can sometimes affect the bass quality.

Set Your Receiver To Stereo Mode

If your receiver has this mode, make sure you set it. This way, it will know it should run in at least 2.1 channel configuration. This means there are two main channels and a sub (the simplified form of surround sound). If you do not do this, some receivers will not send anything to the sub if it is in 2.0 channel mode.

Adjust Receiver Bass Settings (Bass Management)

  • Crossover Point: The crossover is the point of change between low frequencies which are sent to the subwoofer and the higher frequencies which are sent to the speakers. As far as the sub is concerned, it is the frequency at which your subwoofer starts playing bass. So what should your crossover settings be? You want your crossover to be set to where your speakers start to ‘roll off’. Let’s take an example. If your speakers can’t go below say 80Hz (check your speaker’s specs), then set your sub’s crossover to about 80. In fact,  80 Hz is normally recommended as the best crossover setting. This is because this is the generally accepted point at which it becomes difficult for humans to localize sounds.  Here are some general frequency ranges for different speakers so you can know where to set your sub’s crossover:

   On-wall or Tiny ‘satellite’ speakers:150-200 Hz.
   Small center, surround bookshelf: 100-120 Hz.
   Mid-size center, surround bookshelf: 80-100 Hz.
   Large center, surround, and bookshelf: 60-80 Hz.
   Very large center, surround bookshelf: 40-60 Hz.
   Tower speakers with 4”-6” woofers: 60 Hz.
   Tower speakers with 8”-10” woofers: 40 Hz or full range.receiver subwoofer bass management

  • Phase Switch: If your system’s phase is not set properly, it can cause problems like ‘out of phase’ issues of ‘phase cancellation’. What do we mean by phase? Well, an easy way to put is is that when both speaker channels are in phase, we hear the sound at the same amplitude level (loudness) at the same time in both ears. If you have a phase switch, switch it between 0 and 180 degrees and see if you hear a difference. We find about 120 to be a good phase setting.

Phase and Crossover Frequency on Your Subwoofer

  • LFELow Frequency Effect is a channel that produces low-frequency bass info not found on any of the other channels. You will normally find this setting in 5.1 or 7.1 discrete surround systems.
  • Reset The Receiver: If the receiver settings seem out of wack, then just reset the device and try again. In most cases, the manufacturer would have set the most suitable settings for normal play.

Check If The Receiver Is Faulty

The best way to check if the receiver is faulty is to test with another sub. Also, if other connected devices are experiencing similar issues, the receiver may be the problem.

In this case, you will need assistance from an audio technician. Don’t forget to check the cables as well. If the receiver is working, then the amp may be the problem.

2. Check The Amplifier

If your sub is connected to an amplifier, the issue could be caused by the amp. You can check the amplifier settings as well as electronic components to see if it’s a problem.

Typically, if your sub sounds fine at low volumes, but sounds weak when the volume is turned up, then the amplifier is often the issue. Firstly, you should verify the manufacturer’s recommendation on amplifier size vs subwoofer to make sure you’re providing enough power to the subwoofer.

Otherwise, focus on the issues below:

Check Amplifier Setting – Gain

Gain is the degree to which the amplifier will amplify (multiply) the sound. A higher gain will mean greater sound.amplifier gain settings

Start by playing a song, and turn the gain up until you can just start to hear it and start to fill in the bass.

Check Electronic Components

Here are some possible issues with the amplifier’s electronics:

  • Capacitors in the amplifier can deteriorate with age or heat.
  • Some amplifiers have the fuse on the board. Some fuses tend to be blown easily

An easy way to determine if the amp is the problem is to connect the amp to another device like a music player or DVD player (turn down the amp first).

Remember to check the cables as well. If the amp is working, then you may have a bad cable from the subwoofer.

3. Check Subwoofer Settings

Increase Subwoofeer Levels

Normally, if you would like louder or softer bass from your subwoofer, then the simple thing to do is to adjust the levels. This is different from the volume control of the rest of the system!  However, the method to do this varies depending on your model.

The most common way to do this is with the sub’s remote. Most sub-remotes have a button labeled WOOFER that can adjust the level from say -6 to +6.

Sometimes you can even go to +10. Adjust it to whatever the maximum is. If your remote does not have this setting, then it is best to check the manual.

Check Crossover and Phase

If the subwoofer levels are maxed out, then you need to check other settings. Here is what you need to check for:

Crossover and Phase: Some subwoofers allow you to set their crossover and phase as you can do with some receivers. The same rules apply (check the receiver setting above). Here is a summary:

  1. Find the roll-off frequency of your speakers (normally 80Hz) and set the crossover to that frequency.
  2. Turn the phase knob until the bass quality improves. Some subwoofers will have a phase switch that allows you to set the phase to 0 or 180. In most cases, this will be set to ‘0’ but it may need to be set to ‘180,’ or somewhere in-between like ‘120’.

Check Subwoofer Settings

Quite simply, set the AVR crossover sub at 120 and the speakers to 80.

Here is a full guide on how to set the phase and crossover frequency of your subwoofer.

4. Get A Better Cable

We already mentioned the importance of checking the cables when you check the receiver and amplifier. Double-check that all of your cable connections are tight and secure. If you find that they are defective or worn, be sure to replace them.subwoofer cable

You should also switch the power cable in the socket 180 degrees. This can be the problem with some simplifier subs.

5. Check The Subwoofer Power

If your subwoofer is not receiving enough power, that will likely cause it to sound weak. Often, this is due to low voltage or a weak amplifier. 

Ensure that you are using an amplifier that can output the power that the subwoofer requires. If you are using a weak, old, or compromised amplifier, then there is the potential for failure and sending clipped signals which could damage the sub.

6. Improper Polarization

In the quest to optimize your subwoofer’s performance, addressing polarity issues is crucial. A lot of people miss this, but it affects how strong your bass sounds.

The root of the problem lies in phase discrepancies, stemming from how the subwoofer’s driver moves in relation to the drivers of other speakers in your setup.

The trick to fix this is simple—just switch the subwoofer’s polarity. This makes sure it moves just like the other speakers, and it could boost the power and quality of your bass. Flipping the polarity might be what you need to kick your subwoofer into high gear and get it working smoothly with the rest of your sound system.

For more information on subwoofer polarity, check out our article on how to set the subwoofer phase. While subwoofer polarity and phase are not quite the same, switching the subwoofer phase is the easiest way to address this issue. 

7. Run YPAO

If you have a Yamaha speaker or a Yamaha sub, then you should make sure the Yamaha Parametric room Acoustic Optimizer (YPAO) is set properly.
Run YPAO for receiver
YPAO is an auto-calibration system that attempts to automatically adjust the settings for each of your speakers to help you get the cleanest and clearest sound possible. It does this based on the acoustics of the room your system is in.
 
Here is a quick way to do it:
1. Turn the subwoofer volume 1/4 up
2. Run YPAO
3. Turn all my speakers to “small” and then adjust the subwoofers to your liking.
 

FAQs

Does My Amplifier Size Matter? 

If your subwoofer sounds good at low playback levels, but the sound weakens when you increase the volume, this may mean only one thing. Your amplifier is small for your system and needs replacement with a larger one of more suitable ability. Depending on the size of your audio system, more than one amplifier may be necessary. The best configuration is one amplifier channel for each subwoofer.

Am I underpowering My Subwoofer?

In general, underpowering your subwoofer is not necessarily dangerous for it. However, not giving your sub enough power definitely will cause weak sound. Also, you have to be careful not to power up the sub with an overworked amplifier. An overworked amplifier sends out a clipped signal, which can seriously damage your subwoofer.

Can my Room Acoustic Help?

Specialists in the audio-video field indicate that room acoustics are of primary importance for every audio-video system. Professionals also highlight that most homemade studios have nasty standing-wave issues, which even the best subwoofers can not overcome. Poor acoustics can weaken the sound of your sub. So, make sure you have a good acoustic in your room before blaming your sub for the soft sound.

Why is my subwoofer volume still low?

When your subwoofer sounds weak, a more severe problem can be a motor fault. Once you make sure that the reason for the weak sound is not one of the above, verify whether the motor is still running correctly. The battery or the fuse may blow and cause issues with the motor. Such a defect would affect the sound quality.

How Do I Make My Subs Hit Harder?

To make your subwoofer hit harder, you can add filters and phase shifters. On the other hand, you can focus on adjusting your sub’s low pass filter or its phase dial. Other methods that you can use to make your sub hit harder are to change the voice coil or get a new enclosure that generates more bass. 

How Can I Improve Subwoofer Bass?

There are many ways to go about getting more bass out of your subwoofer. There are also ways to go about making your subwoofer louder even without an amplifier. Try them once you have fixed your subwoofer’s low-volume problem. By doing so, you will get maximum performance from your sub!
 

Conclusion

There may be many issues that are causing your subwoofer low volume problem. Start off by checking the volume controls and connections as well as the receiver and amplifier settings.

You should also check the sub’s settings and the conditions of your audio electronics. We hope you find the issue in your system causing your subwoofer low volume problem and get your sub booming again!

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin