Subwoofer Not Working But Amp Has Power [SOLVED]

Norvan Martin
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Whether you are dealing with your home stereo or a car, amplifiers, and subwoofers can greatly enhance the sound quality and your experience by adding more power and bass. However, you may find yourself with the common yet annoying problem where the amp has power and turns on, but the subwoofer does not work. 

In this article, we will fix this issue – your speakers or sub stopped working but the amp has power. 

This issue is often due to a variety of reasons, including incorrectly set volume, loose cables, wiring issues, a blown fuse, incorrect inputs or cabling, or the sub or speakers themselves may be at fault. The most common issue is wiring. 

Just because the power light is on doesn’t mean that the amp is in good condition. We have seen amps blow but still light up.

If you suspect that you are having a wiring issue, check out this article on how to connect a subwoofer to an amplifier

Otherwise, read on for more fixes. 

What Should I Check First?

The best way to troubleshoot is to unplug the fuse under the hood, disconnect the amp, and find a replacement amp to swap in and test. 

  1. Initial Checks:
    • Ensure all relevant devices are powered.
    • If there’s no sound from the subwoofer, the issue could stem from any device in the setup, or the subwoofer could be blown. Here is a quick guide on how to check if your subwoofer is blown
  2. Amplifier Power Check:
    • Confirm if the amplifier is powered.
    • If it’s not, turn it ON.
  3. Amplifier Light Indicators: If the amp switch is ON but the power lights are OFF:
  4. Signal Light Indications: If the amp is powered, the switch is ON, and the signal lights are lit, the problem could be the subwoofer.
  5. Subwoofer Power Cable Check: Ensure the power cables from the sub are correctly connected to the socket.
  6. Subwoofer Switch Check: If the main power switch is ON but the subwoofer isn’t working:
    • Ensure the power switch on the subwoofer itself is ON.
  7. Wiring and Connection:
    • If all the wiring appears correct and the subwoofer still doesn’t produce sound, proceed with further troubleshooting. 

If all the wiring is okay and the subwoofer is still not producing sound, then read on for additional troubleshooting. 

Subwoofer Still Not Working, What Do I Do?

For many music lovers without any experience with troubleshooting subwoofer and amplifier problems, the first option is to call in a technician.

However, if you have experienced such challenges before, there is no need to panic.

In fact, before calling for a technician, there are several DIY fixes you can try to bring your stereo back to life. 

DIY Fixes For Subwoofer Not Working But Amp Has Power

Some of the Do It Yourself trials you can easily try to correct this problem have been discussed below:

1. Check The Volume, Gain, and Bass Knob

  1. Volume, Gain, and Bass Knob Check
    • After powering the amplifier and subwoofer, inspect the volume knobs for both the amp and the subwoofer. If set low, adjust them appropriately.
    • Understand the role of the gain:
      • Helps match bass levels between the subwoofer and main speakers.
      • Adjusts output levels.
      • Though different from volume control, it influences sound in a similar manner.
    • Review the bass knob. If it’s a replacement knob, ensure compatibility since not all bass knobs work with every amp.
  2. Common Oversights
    • The simplest issues are often overlooked:
      • If experiencing problems, checking the volume should be a priority.
      • It’s a common misconception that non-working subs or amps indicate significant issues.
      • Always verify the volume setting before jumping to conclusions.
  3. Muting Issues
    • It’s possible the subwoofer might be muted.
      • Press the mute button multiple times to toggle and possibly unmute the subwoofer.
    • Once unmuted:
      • Adjust the volume.
      • Listen for sound from the subwoofer.
      • Check and adjust the amplifier’s volume similarly.
  4. If Problems Persist
    • If the above DIY solutions don’t resolve the issue, remain calm.
    • Move to the next troubleshooting step, which involves checking and fixing the inputs.

2. Check The Inputs

Inputs are the next big culprits that are more likely to cause a loss of signal in your audio setup.

For instance, if your amp is working properly but the subwoofer cannot produce any sound, there could be a problem with the input. Here is a guide on how to connect a sub to an amplifier subwoofer line inputs

First, check and ensure that the input cables are tightly plugged in. Check the head units too. Also, ensure that any loose cables are correctly fixed. 

If the input cable is already well fixed, unplug it. Once you have removed it from the head unit, inspect it for breakages, cuts, or any open sections. After ascertaining that the cable is in good condition, connect it back. 

With the cable back in place, switch the units ON – both the amplifier and subwoofer. You should then check if the inputs are now working properly by turning on the system and trying to adjust the volume again.

If this fails to solve the problem, consider changing the cables. However, before changing your input cables, ensure they are the cause of the problem. Otherwise, consider other potential causes such as poor wiring. 

3. Check The Wiring 

Other than the inputs, faulty wiring is another factor that can cause subwoofers to fail even if amps are powered.

The types of wires connected to a subwoofer are power and speaker wires. If the system is in your car, the wiring will be under the dashboard, and any disruption affecting the wiring won’t allow the subwoofer to work. Therefore, if nothing else resolves the issue, check the wiring. 

4. Check The Subwoofer Fuse

In some cases, the issue could be the subwoofer fuse. Usually, the fuse blows when there’s a power surge. This happens to break the circuit and safeguard the subwoofer from significant damage. 

Because the wiring can sometimes be more complicated, especially for different subwoofer units, consider engaging an experienced sound technician to investigate the issue. 

5. Check The Speakers 

The amp has power, but the sub is still not working? Even after ruling out all the other problems, it’s time to check the speakers.  subwoofer fuse

It’s common for speaker wires to become loose, especially when the subwoofer overheats. However, the speakers themselves can also be damaged.

If the speakers are inoperative due to damage, fixing the other devices or the wiring system won’t resolve the issue. 

If you suspect your speakers are damaged, the best approach is to find a suitable replacement.

Begin by checking the speaker power level and that of the subwoofer, along with other speaker ratings such as impedance.

This is essential because you’ll want to replace your speakers with new ones that have similar specifications to match the requirements of your home receiver. 

Other Troubleshooting Options

  1. Check that the sub is enabled in the settings: Select Settings, then Speaker, followed by Speaker SP, and confirm that the speaker pattern ends in .1 or .2. If the pattern ends in .0, the sub won’t work.
  2. Check that the subwoofer LED indicator light on the A/V receiver is on. Sometimes, the low-frequency effect (LFE) signal fails to reach the subwoofer depending on the source of audio. The LFE indicator lights when the signal is present. Note that many TV channels broadcast in 2-channel audio and may not send this signal. The sound field setting should therefore be turned to A.F.D. AUTO or a different sound field. If you have a Sony receiver, a simulated LFE signal may be sent to the sub. The SW indicator then lights up.
  3. Confirm that the power cord of the subwoofer is properly plugged into an active AC port. Remember the subwoofer will not switch on if the AC outlet is faulty or not active. If the power cord is missing or your sub does not have one, then the sub is passive. You may need to purchase an active subwoofer or just continue with the troubleshooting. 
  4. If you have an active subwoofer, check and set the volume on the back to its middle position.
  5. Your subwoofer may have a cut-off frequency adjustment. If that is the case, turn it to the maximum position. This will allow it to pass all the low frequencies to the sub. 
  6. Also, if the sub has a standby function, check it and switch it off.
  7. Join one end of the audio input cable to the audio input connector and gently tap on the center of the opposite end of the audio cable with your finger. Ensure the subwoofer is properly powered, is switched on, and volume adjusted properly. You should hear some thumping sound when you tap the other end of the audio cable. If the sound fails to come out, the subwoofer may be experiencing a service issue and you may need to call your audio technician.
  8. Wire the other end of the subwoofer cable to the audio output port of the amplifier. This is usually at the back of the receiver. Besides, some amp models will have two outputs capable of connecting and driving two subs at the same time. 
  9. If the speakers are set to large, no sound passes to the subwoofer when you select a music sound field setting. You can troubleshoot this by checking the A/V receiver menu and ensuring that none of the speakers are set to large. 

Subwoofer Turns On But No Sound

So, what if my subwoofer turns on but there is no sound? Here is a quick troubleshooting process:

  1. Ensure that the amplifier is plugged in and turned on.
  2. Check the input of the amplifier. Ensure that the amp’s input is connected to the head unit and check the RCA cables.
  3. Check your amplifier power because your amp might turn on even without receiving the required operating voltage. In this case, the amp will be on, but the sub will not produce any sound. Many amps power on at 6-10 volts but need at least 12 to 14 volts.
  4. Ensure the subwoofer has not been muted or the volume is not too low.
  5. Ensure the amplifier settings and the subwoofer are properly configured. For example, certain subwoofer settings may disable the subwoofer.
  6. Replace the subwoofer connecting cable.
  7. Check to see if the subwoofer is short-circuited. Short-circuiting is one of the most common subwoofer problems. This is normally due to any metal causing the positive and negative terminals to come into contact. 

To learn more, check out our guide on troubleshooting an amp that has power but there is no sound from the speakers or subwoofer

Conclusion

When your amp is powered but the subwoofer can’t deliver any sound, always begin by checking the volume level. However, if the volume is not the problem, check if the inputs are connected properly.

Again, if the inputs have no issue, check the wiring followed by the speakers. You can fix the problems with simple DIY procedures to ensure the subwoofer produces sound, and you can enjoy cool music 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