A subwoofer is no longer a special speaker reserved only for audiophiles and music lovers. It is a part of the speaker sound system if you want a wholesome audio experience at home. The speaker is named subwoofer because of its specific task. The work of a subwoofer is to deliver low-pitched frequencies ranging from 20Hz to 100Hz. However, there are times when the subwoofer is not functioning properly and you’re wondering why does my subwoofer sound weak?
The subwoofer plays heavy bass notes to emphasize the booms, rumbles, thuds, and low notes that can otherwise not be entirely audible or sound muffled when played through regular speakers. The subwoofer delivers clear and punchy bass by amplifying the low frequency. It can elevate the room’s acoustics and create a theater-like setup at home.
However, all subwoofers are not the same. The size of the unit is not always a reflection of its capacity. And sometimes, the subwoofer doesn’t deliver what it should. The bass isn’t strong or emphatic enough. It sounds weak, low, and even non-existent.
That means there’s something wrong with the unit. There are various reasons for a subwoofer to sound weak. In this article, let’s learn more about subwoofers, why they produce weak sound, and how bass boost is possible through a few adjustments.
How Does a Subwoofer Work?
A subwoofer has a built-in amplifier that delivers better, cleaner, and stronger bass. Also, many subwoofers are powered (they need to be connected to a power source separately) for the built-in amplifier to do its job. The powered subwoofer is also known as an active subwoofer.
On the other hand, a passive subwoofer doesn’t need any external power supply. The subwoofer works using the power sent from the other speakers in the speakers set.
The Internal Design of a Subwoofer
- Voice coils
- Top plates
- Pole pieces
- Dust cap
- Diaphragm/ cone
- Frame/ basket
- Surround (made using rubber/ foam)
The voice coil and the magnets form the motor system of the subwoofer. When the subwoofer starts to play, the motor system gets hot. The subwoofer generates a lot of heat, which could overheat the adhesive on the cylinders. This, in turn, causes the wires to unwind, resulting in damage. An overworked amplifier also damages the subwoofers and the audio system.
A subwoofer’s cabinet/ enclosure type can also impact its sound quality . For example,
- A ported subwoofer has a port or a hole that helps amplify certain low frequencies without causing any damage to the unit.
- A sealed subwoofer has no such port/ hole. This gives a cleaner and tighter bass.
- The isobaric enclosure is where you set up two subwoofers in a single box. Each subwoofer has its enclosure. You can customize the subwoofers the way you want (cone to cone, magnet to magnet, etc.).
How to Test a Subwoofer Speaker?
Whether you have the best wireless TV speakers or the best karaoke speakers, you should regularly inspect the subwoofer. You need to observe if the subwoofer is delivering clean notes or if it sounds hazy/ fuzzy. Also, check the low-frequency range of the subwoofer because all models do not transmit the same frequencies. In such instances, the subwoofer will not play low-frequency sounds even if it is in perfect working condition.
If the subwoofer starts to produce distorted sounds, it’s an indication that you are pushing it beyond the limit. It happens when you increase the subwoofer’s volume to the maximum and play it loud. Reducing the volume should bring back clarity.
Leaving the subwoofer volume knob at maximum for long will result in a blown subwoofer. It can also damage the internal system. This can badly affect the subwoofer’s output, resulting in soft sound.
Play different kinds of audio tracks (music, movies, shows, etc.) to test the sound quality of the subwoofer. Adjust the volume settings to find the right spot where it’s clear and crisp. Don’t touch, push, or hit the subwoofer. These units are delicate and can stop working if there’s slight damage to the internal setup.
Another way to test a subwoofer and determine why does my subwoofer sound weak is to use a multimeter. You’ll easily know if the subwoofer is blown, malfunctioning, or in perfect working condition. (A subwoofer volume can be weak in a room with poor acoustics).
What is a Blown Subwoofer?
A blown subwoofer comprises damaged voice coils. This happens when the subwoofer receives too much power or clipped signal from the receiver/ input source. Even the best subwoofers can end up with blown coils.
For example, if a subwoofer starts to play distorted output, it’s a sign that the voice coils are almost damaged and will blow sooner or later. It could also be because of the source cable, so check if the cable is defective.
A subwoofer might end up with too much power if you haven’t checked its RMS (root mean square) wattage, which indicates its continuous power-handling capacity. When the subwoofer receives too much power continuously, it generates more heat, thus blowing away the voice coils.
A distorted signal makes the subwoofer soft and hazy on the low frequency. We increase the volume to combat this, sending too many distorted signals to the subwoofer and blowing up the voice coils.
Use a Multimeter to Test if the Subwoofer is Blown
- Unplug the subwoofer and remove all the input cables.
- Take the subwoofer out from the enclosure.
- Position the positive probe of the multimeter on the positive terminal of the voice coil.
- Do the same to the negative terminal.
- Turn on the multimeter to read the resistance.
- If the reading is steady and over 1 ohm, the voice coils are good and don’t have any problem.
- Zero resistance means the voice calls are damaged.
- Abrupt shifting in the reading means the coils are blown.
How to Tell if a Subwoofer Is Blown?
Knowing whether or not a subwoofer is blown will help you determine the actual reason for its lack of performance. There are three different ways to identify a blown subwoofer. One method is to use the multimeter (we’ve already seen the process in the previous section). Now, we’ll look at the other two methods to tell if the subwoofer is blown.
Test the Sound
Is the subwoofer even playing the sounds? Can you feel at least a slight thumping sensation when you get close to the unit? A perfectly working subwoofer will vibrate when delivering the output. That’s why we recommend placing the subwoofers on the floor or where they cannot fall.
If you do not hear any sound from the subwoofer, check the RCA cables and power cable. The sound weakens with bad cables. There may not be enough power supply. It can be necessarily dangerous to continue using damaged cables.
If you can hear some vague sounds (distorted, hazy, mushy, or weak), it’s a sign of coil damage and can blow any minute.
Test the Cone
Another way to test the subwoofer is to check the cone. Since the cone in the subwoofer is built to move, you can easily spot what’s wrong. You need to press your palms lightly on the surface of the cone to sense its movement. Don’t put too much pressure or push the cone. You only want to touch and feel its vibrations (or the lack of them). Here’s how you can evaluate and assess the cone:
- No movement in the cone is a sign of subwoofer damage.
- If the cone is wobbly and has irregular movement, it’s a sign of suspension system damage.
- If the cone is making scratchy sounds, it’s a sign of cone damage and you must remove it before it causes more harm to other parts
How to Fix a Blown Subwoofer?
Got the answer to the question why does my subwoofer sound weak but don’t know what to do next? Here’s what we recommend!
The first thing to do when you realize that the subwoofer is blown is to unplug all the cables and separate them from your speaker set. If warranty covers the unit, do not open it. Talk to the seller and ask for a replacement or repair (as per the warranty terms).
If it’s no longer covers warranty, you have a couple of options:
- Fix the blown subwoofer on your own
- Take it to an expert
We always recommend the second option unless you are the expert. However, if you still want to try and fix it, here’s what you need:
Items Required to Fix a Blown Subwoofer
- Soldering iron
- Putty knife
- Air compressor
Process to Follow
The process of fixing the subwoofer will depend on whether the damage is in the voice coils or cone. Either way, use the screwdriver to disassemble the unit from the enclosure. You should also remove the wires, so check the connectivity of each wire. Wrong connections will give the same result – a blown subwoofer.
Now carefully remove the surround without disturbing the edges of the frame. Next, take out the voice coil and the cone. Use the putty knife to cut the terminal wires. Gently place all the components separately aside.
Clean the area where you plan to place the voice coil. Dust and dirt can also lead to defective subwoofers. That’s where you use the air compressor. Then replace with a new voice coil. You’ll also need to replace the spider.
Spread the glue liberally onto the cone and fix it in the coil. Leave the subwoofer for a day to let the glue dry. Then apply more glue to the edges of the surround and attach it back in place. Wait for one more day for the glue to dry.
Reattach the wires as per your notes. You’ll need the soldering iron for this. If you have never used the instrument earlier, don’t try it directly on the speaker. Get someone with experience to solder the wires and complete assembling the subwoofer.
What Happens if a Subwoofer Is Unpowered?
An unpowered subwoofer is also called a passive subwoofer and doesn’t have an external power supply. It does require an external amplifier to deliver the bass notes. An unpowered subwoofer is built to prevent high crossover frequencies.
These models are lightweight, portable, simple, and easy to upgrade. However, the quality of an unpowered subwoofer depends on the quality of the amplifier it is connected to.
How to Fix a Subwoofer With No Sound?
To fix a subwoofer with no sound, you first need to identify the root cause. We’ve detailed the methods in the previous sections:
- Check the input cables and receiver
- Check the buttons on the unit and the remote control
- Do the three types of tests to identify the problem
- Follow the steps listed in the above section or call the manufacturer/ technician to fix the subwoofer
How to Get More Bass Out of Your Home Subwoofer?
Even with a supposedly bad subwoofer, you can create a worthy sound system that sounds good.
Place the subwoofer in the right position in the room: The corner of the room is a good choice to amplify bass. Place it between two main speakers at a distance to adjust the room acoustics.
Change the subwoofer’s crossover frequency by identifying its lowest range. Adjust the frequency settings for the subwoofer to hit harder.
Adjust the bass settings in the equalizer. There’s no one-solution-for-all here. For most subwoofers, you need to change the settings based on the type of input.
Start with the lowest volume and gradually increase it to the point where the subwoofer sounds the best. Volume control can help with bass boost.
Use quality cables for connections. Invest in a voltage protector to prevent fluctuating power supply. You can also bring in a second subwoofer for better bass management.
So, you’ve finally got the answer(s) to the question why does my subwoofer sound weak. There could be several reasons for the subwoofer to become weak and stop producing sound over time. The quality of the audio output depends on the model and how well you take care of the subwoofer.
Don’t disturb the subwoofer or touch it unless necessary. Dust it periodically and contact an experienced technician to test the subwoofer. With proper maintenance, the subwoofer will last for a long time.