Does a Subwoofer Need an Amp?

Does a Subwoofer Need an Amp

A subwoofer is an integral part of any quality sound setup. If you want more “boom” from your music or want to feel machine gunfire and blasts in your bones while gaming or watching action movies, a subwoofer will get you there. Is it a good idea to power the subwoofer with an amplifier?

When wondering if a subwoofer needs an amp, look first at the subtype. If you own a premium powered subwoofer or are thinking of getting one, you may not need an external amplifier, unless you want to push the output to extreme levels. A passive subwoofer, however, can’t work without an amp.

The rest of the article will take a closer look at why subwoofers need an amp, the difference between passive and powered subwoofers, how to connect a subwoofer to an amplifier, and more. There’s also a section on the best amplifiers you should consider right now.

As an affiliate, I may collect a share of sales or other compensation from the links on this page.

Why Do Subwoofers Need an Amp?

Subwoofers are designed to reproduce low-frequency sounds. This takes a lot of power. In designs where the subwoofer came as a part of a larger sound system, it will be properly optimized to work with the rest of the setup without showing any distortions as a result of inadequate power.

With a standalone subwoofer, on the other hand, there is always the danger that it will be too powerful for the sound system’s receiver and the rest of the setup. Once this is the case, the subwoofer will not be able to deliver deep and clear bass without sounding labored.

The types of subwoofers that need an external amp to work are known as passive subwoofers, while those that can function without an amp are known as powered or active subwoofers.

What Are Passive Subwoofers?

Passive subwoofers are variants that can’t work on their own without being powered by an external amplifier. They are basically loudspeakers designed to produce low-frequency sound. Such subwoofers need the right amount of power to reproduce bass effects, and this can only be produced by the right type of amplifier.

With the wrong type of amplifier, the subwoofer will struggle to sustain bass, and you can see it having an effect on your power supply (dimming lights are the most common sign). The level of power you need from the subwoofer will come down to the specifications of your subwoofer, the size of the room, and how much bass you need.

Passive subwoofers are most common in custom sound installations as most people will rather not go through the hassle of the extra connection required. If you are an audiophile, however, you’ll probably want the flexibility that comes with having a passive subwoofer and a matching amplifier.

What Are Powered or Active Subwoofers?

Powered subwoofers are self-contained units that have the speaker and amplifier in one enclosure. They are designed in such a way that the subwoofer has all the power it needs by keeping the amplifier/speaker configuration perfectly aligned.

Powered or active subwoofers are practical options because you’ll only need a single connection from your home theater’s sound processor or receiver. This may also be known as the LFE or subwoofer pre-amp output. The connection will go from this output to the matching input on the powered subwoofer.

With this setup, the receiver’s amplifier doesn’t have to expend power on the subwoofer. Instead, it can then focus on powering the tweeters and other speakers in the setup easily,

Passive or Powered: Which Subwoofer Should You Choose?

Most people choose powered subwoofers because they come with built-in amplifiers and don’t need help from another receiver or amplifier to work. This ensures they are easy to use in combination with the average home-theatre receiver.

All home theatre receivers come with pre-amp line outputs. This can be one or two lines, but the bottom line is they are designed to connect to a powered subwoofer straight from the box.

If you choose a passive subwoofer, however, you need to consider the fact that the right amplifier for the subwoofer might end up costing more than the subwoofer itself. Is that an investment you can justify? As an average user, it is more cost-effective for you to just go with a powered or active subwoofer.

Also, you should know that the powering option for a subwoofer isn’t the sole determinant of the sound quality. It can have an impact, but if the subwoofer isn’t properly designed to deliver the sound quality you are looking for in the first place, it won’t matter if it is passive or active.

What Is Subwoofer and Amplifier Matching?

As you’ve seen above, you’ll need to match an amplifier to your subwoofer if you have a passive sub or if you think an amp can improve the sound from your powered subwoofer. To do this, you have to start by looking at the specifications for your subwoofer.

The impedance, listed in Ohms, is the first specification you should look out for. It is the number that shows much load a subwoofer will transfer to an amplifier. Amplifiers put out power based on the load attached, so you need to ensure the numbers match up adequately.

Once you’ve found the impedance, the next thing to watch for is the power output, which is listed as watts root-mean-square (RMS). For your subwoofer, the watts RMS is a measure of how much power you can realistically expect the sub to handle without any distortions or getting damaged. The RMS on the amplifier is a measure of how much power the amp can deliver.

After you’ve figured out the watts RMS and impedance on your subwoofer, it is time to choose the amplifier that will match it. For the best results, you should choose an amplifier that can deliver 75-150% of your subwoofer’s watts RMS. You should also ensure that the amp can work in line with your subwoofer’s impedance.

Do you have an amplifier already and want to find a subwoofer that can connect to it? Here’s what you should do:

  • Find out your amp’s power output at different impedance values (remember it’s in watts RMS).
  • Divide the power output by the number of subwoofers you are looking to buy so you can find the right RMS value to go with.
  • The watts RMS on your new subwoofer should be 75-150% of your amp’s value.
  • Check to see that the impedance on the sub matches what is allowed on your amp.

How Do You Connect a Subwoofer to an Amplifier?

connect subwoofer and amplifier

To connect your passive subwoofer to an amplifier, you’ll need an RCA cable (Amazon link). You’ll need speaker wires if you want to add some speakers as well. Once you have these sorted, you can follow the steps below.

Think About the Location of the Subwoofer

The first thing you should do during this process is to find an optimal location for your subwoofer. Since it is delivering low-frequency sounds mostly, it won’t need as much directional push as a speaker would.

However, since the process will involve cables and wires, you need to find a position that will allow you to hide the connection properly. Keeping it close to your other devices and the TV screen is always a good idea.

Connect the Subwoofer to the Amplifier

To get started, turn off the subwoofer and the amplifier and disconnect them from the power source. Once all turned off, connect both of them with the RCA cables. Simply connect the subwoofer output to the amplifier input. In some cases, the jack on the amplifier will be clearly labeled as “subwoofer output.” Your subwoofer is ready to go at this point.

Once done, you can turn on your amplifier and subwoofer and test your connection.

If you are adding speakers to the mix, you’ll need to connect them properly to the back of the amplifier. You’ll find the speaker outputs clearly labeled. Insert the bare end of the speaker wires into each of the outputs, paying attention to ensure you are connecting left and right speakers into the matching ports.

Top Powered Subwoofers to Consider Today

Have you decided to go with a powered subwoofer? Here’s a look at some of the top options you should consider today.

Electro-Voice ZXA1

Electro-Voice ZXA1SUB 12" Compact Powered Subwoofer

The Electro-Voice ZXA1 is a portable subwoofer weighing around 46 lbs (20Kg). It is designed for most small to medium living rooms. With its compact profile, you can choose to hang it or leave it on the floor. You’ll be surprised by its weight, especially after you’ve seen its solid build.

With the built-in 100 Hz high-pass filter, the ZXA1 will ensure your speakers don’t have to process low-frequency sound. This will enhance the overall efficiency of your sound setup. It’s a 12-inch subwoofer but can do the job of a 15-inch one effortlessly.

Most users of this powered subwoofer agree that it does an excellent job. Some of the positive reviews about it have come from sound technicians and musicians who have used the subwoofer in venues that are most likely larger than your living room. So, you need to be sure you have the right space for this.

Polk Audio PSW505 12-Inch

Polk Audio PSW505 12" Powered Subwoofer - Deep Bass Impact & Distortion-Free Sound | Up to 460 Watts | Easy Integration with Home Theater SystemsThe Polk Audio PSW505 12-Inch subwoofer is a powerful option from one of the most trusted brands in the audio world today. With the PSW505, you are getting a home subwoofer that will deliver deep, dynamic, and chest-thumping bass. It provides 460 watts dynamic and 300 watts continuous power. The frequency range is 23-160 Hz.

Other top features include a low-pass crossover, phase switch, and volume control. With the slot load venting on this subwoofer, you don’t have to worry about noise while in use, or distortion. To ensure users are contributing their quota towards saving the planet, PSW505 is designed to power down automatically if it’s not in use for 15 minutes.

Yamaha DXS12mkII

Yamaha DXS12 MKII Powered Subwoofer

Yamaha is a name you can trust when buying any music-related hardware. The work they did on the Yamaha DXS12mkII is yet another example of their commitment to delivering quality products and value for money. It comes with an 800W (continuous) power amp, powering the 12-inch driver with a 2.5-inch voice coil.

The DXS12mkII comes with built-in D-XSUB processing, which ensures you get a bit more thump with your low-frequency sounds. There’s also a selectable crossover point, which includes 80 Hz, 100 Hz, and 120 Hz.

While other subwoofers are designed to enhance the bass frequencies, Yamaha focused on making the bass heard instead. It’s no surprise, therefore, that many users love its sonic fidelity. The reliability and build quality are important talking points.

Behringer Eurolive B1200D-PRO

BEHRINGER EUROLIVE B1200D-PRO

If you are on a budget, the Behringer Eurolive B1200D-PRO is an option you should consider. This is a pole-mountable subwoofer that comes with a switchable +6 dB bass boost. It also features a selectable frequency range of 4 Hz-90Hz and a selectable hi-pass filtered output between 70 Hz to 150 Hz. Using it with your other speakers is easy.

Most users agree it is good value for money, but you should weigh your options if you’d like to enjoy a lot of electronic dance music (EDM). It can sound underpowered for some of them.

Top Passive Subwoofers to Consider Today

If you’d rather go with a passive subwoofer paired with an amplifier, here are some top options you can consider.

Bose B1 Bass Module

The Bose B1 Bass Module is a subwoofer that is designed to act as the bass foil for all Bose L1 systems. It’s made up of two 5.25-inch woofers that prioritize clarity in the bass delivered instead of too much thump. It comes with the Speakon connectors, which work well with the Bose L1 system.

Whether you are looking for a subwoofer that can blend into your home system or one you can also take outdoors, the Bose B1 Bass Module can deliver value for money.

Yamaha SW218V

The Yamaha SW218V is a subwoofer you can count on to deliver some of the best low-frequency sounds you’ll ever hear. It comes with two 18-inch woofers backed by 1200 watts power. The subwoofer also comes with aluminum frame drivers to ensure good heat dissipation and lighter weight.

Other important features include a carpet covering, steel corners, heavy-duty steel grille, and SpeakON connectors. All of these combine to make the loud and punchy Yamaha SW218V one of the best passive subwoofers in the market. Even when at high volumes, you can expect clear and crisp bass sound from kick drums, bass guitars, train rumblings, bomb blasts, etc.

JBL PRX418S

The JBL PRX418S is another powerful 18-inch passive subwoofer designed for easy setup and durability. It comes with an 18″ LF driver and a powerful 3200W Peak power rating, which means that it can handle all range of low-frequency sounds thrown at it effortlessly.

Bass sounds from EDM, hip hop, and metal rock are delivered cleanly, and you’ll feel every single punch. The subwoofer also comes in a highly reliable build, which means it can be used anywhere and not just indoors.

Top Amplifiers to Pair With Passive Subwoofers

If you’ve chosen to go with a passive subwoofer, here are some of the best amplifiers you can pair with it.

Blue Octave Home B1000S

This is one of the best options you should consider if you are looking for an amplifier for your in-wall subwoofer. It’s another option you can count on to deliver 200 watts output with an output impedance of 4-8 ohm. You’ll also find LFE and RCA inputs, as well as subvolume and crossover control knobs. You have all you need to squeeze out the best sound possible from your subwoofer.

Acoustic Audio WS1005

This amplifier is a sturdy option that supplies power at 200 watts. It also comes with a built-in crossover network and an output impedance of 4-8 ohm. The crossover and sub volume control knobs provide you with the flexibility you need.

Dayton Audio SA230

This is a high-quality subwoofer amplifier that you can trust to help your subwoofer to deliver clean and robust sound with its 18 dB/octave low pass filter. It comes with an adjustable phase and crossover, as well as low level, high level, and LFE inputs. Its steel chassis ensures you won’t have to worry about durability.

Theater Solutions SA200 Subwoofer Amplifier

This is another high-quality amp for your in-wall passive subwoofer. It delivers 200 watts of peak power output and impedance of 4 to 8 ohm. The frequency response provided is 50 to 200 Hz.

OSD Audio SMP250

With its low-frequency crossover, this is another quality amplifier you should consider for your passive subwoofer. With the option to choose between 75 and 250 watts output, you can choose the amp size you need to power your subwoofer. The amp also comes with a built-in variable high-cut filter. With its low pass crossover and phase adjustment features, you can tweak the bass signal.

Conclusion

A subwoofer most definitely needs an amp if it is a passive type. It won’t be able to function without one. An active or powered subwoofer, on the other hand, will always come with a commensurate built-in amplifier, but you can use an external amplifier to improve the outputs further if you think it is necessary for the sound quality you are trying to achieve.

When pairing a subwoofer with an amplifier, don’t forget to pay attention to the impedance and watts root-mean-square ratings.

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