What Does a Subwoofer Do? [A Beginner-Friendly Guide]

Georgi Karaivanov
Georgi Karaivanov

Updated · Aug 12, 2022


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When it comes to sound systems, you’ve likely heard the word subwoofer before.

It’s a vital part of any speaker set, which enriches the sound and adds low frequencies. It can do wonders for your overall audio quality, especially if we’re talking music or films.

But here is the vital question:

What does a subwoofer do, exactly?

Here’s the deal:

What is a Subwoofer?

A subwoofer is a special loudspeaker designed to output low-frequency sounds like bass and sub-bass.

How low, exactly?

We are talking frequencies below 200 Hz, sometimes even down to the double-digits. These are tones that many other loudspeakers wouldn’t be able to produce on their own. That’s why subwoofers are sometimes necessary.

They aren’t meant to be used on their own. Instead, they complement the overall speaker setup to enrich the sound by adding extra bass. As such, they are often found in professional environments like stage concerts and cinemas.

But subwoofers aren’t only meant for the pros. Many home theater systems also come with dedicated subs.

What Does a Subwoofer Do?

So they’re just speakers that output low frequencies? No big deal, right?


Having a subwoofer vastly increases the sound quality and can open up the audio mix of an audio system. The difference is not obvious right away, but it’s night and day. 

Here are some of the most important applications:

  • Clarity of bass tones: The presence of a dedicated loudspeaker for bass means low frequencies are more pronounced.
  • Richer sound: Adding lower frequencies to the mix prevents the audio from sounding tinny. The overall mix is more balanced as the bass and sub-bass can be accurately reproduced.
  • No distortion: Subwoofers are designed to have as little distortion as possible. Regular loudspeakers may not be able to reproduce bass frequencies without crackling.
  • Reveals new sounds: By having a subwoofer speaker, you might start noticing brand new (to you) sounds. And that’s likely because your system couldn’t reproduce them.
  • Seamless blending: If your subwoofer draws too much attention to itself, you’re doing it wrong. A sub should never stand out, and should only complement your system in a way that doesn’t feel overbearing.
  • Smaller overall system: Having a subwoofer can actually lead to shrinking the size of your home theater. That’s because you won’t need extra loudspeakers to create large and spatial sound.

What Are the Different Types of Subs?

Believe it or not, there are actually different kinds of subwoofers. Each of them is meant for a slightly different purpose. Let’s go over them one by one and see why someone would prefer one over another.

What is an Active Subwoofer?

Active subwoofers are also known as powered subwoofers. Their main distinction is that they come with their own amplifier. It uses its own AC power and connects to the rest of the home theater system using a line output.

Most home theater systems use active subwoofers.

This is because they are easier to install than their passive counterparts and don’t require an external amplifier.

What is a Passive Subwoofer?

A passive subwoofer is one that does not have a built-in amplifier. Instead, it has to be powered by an external one. That amplifier needs to output enough power to be able to sustain the extremely low frequencies a subwoofer can reproduce.

The necessity for an external amplifier means more wires running around. But on the flip side, the actual speaker itself is more affordable.

So, two types: active and passive.

But there’s more.

If you ever go around shopping for subwoofers, you might stumble upon terms like ported or sealed cabinets. But what do all these mean?

Let’s get into all the different types of subs you might encounter.

Ported Subwoofer

In terms of subwoofers, a port is a hole in the actual cabinet of the speaker. The purpose of a port is to allow extra air to escape, resulting in a louder overall sound.

Some high-end home theater systems utilize ported subwoofers.

The extra volume they’re capable of mostly comes in handy in loud action movies. However, they also take up more space.

Sealed Cabinet Subwoofer

A sealed cabinet subwoofer is one that doesn’t have extra ports coming out of it. As a result, this means more subdued lower frequencies, unlike its ported counterpart. But that’s what makes them ideal for music.

Sealed cabinet subwoofer sizes tend to be much more compact than ported ones. They’re better for smaller spaces or if you’re going for a more minimalist approach with your sound system.

Down-Firing Subwoofer

Most subwoofers you will see are front-firing. This means their speaker is situated at the front of the cabinet, and it projects sound forward. This is so that if you’re sitting in front of the subwoofer, you get the most out of its audio.

But not all subwoofers are like that.

The so-called down-firing subwoofers have their speakers pointing downwards. This is better for setups with raised subwoofers and for achieving a more gravelly sound.

Passive Radiator Subwoofer

Passive radiator subwoofers take the idea of ports and take it to the next level. They work similarly to ported ones, but are more sophisticated, and have a much higher range of frequencies.

Passive radiators are not powered by an amplifier or electricity. They work off the air pressure inside of the cabinet. They can effectively simulate a woofer sound without any extra power or wires running around.

That being said, if loudness is your number one priority, ported subwoofers are still the way to go.

Horn-Loaded Subwoofer

Horn-loaded subwoofers are designed for loudness, first and foremost. They utilize a longhorn speaker which allows for louder volume, more efficiency, and better directionality. Sound leaks out a lot less from the sides or the back of the unit, meaning much greater precision.

Their cons, however, are that they are often large in size and much more expensive than other subwoofer types.

What is the Difference Between a Subwoofer and a Speaker?

Here is something which might seem surprising:

A subwoofer is actually a speaker. It is just a special, low-frequency speaker designed to output nothing but bass and sub-bass.

But you can’t just buy a subwoofer, place it in your living room, and call it a day.

That’s because they are intended to be paired with other speakers, never on their own. You should only ever think about buying a subwoofer if you already own a sound system. Many home theater systems already come with subwoofers bundled in.

So what are the advantages of owning a subwoofer?

  • Richer sound
  • More pronounced bass frequencies
  • More balanced mix
  • Louder overall volume

But of course, there are also disadvantages. Here is what you should consider before purchasing one:

  • They take up extra space
  • Some subwoofer types are very expensive
  • More wires running around

At the end of the day, a home stereo with a subwoofer will absolutely sound better than one without. But whether the advantages outweigh the possible disadvantages is up to you to decide.

Wrap Up

A subwoofer is a special speaker which outputs low-frequency sound, namely bass and sub-bass.

It is a unit that is usually paired with home theater systems and leads to a much richer sound. This is because the presence of a subwoofer accentuates the low-end, leading to a more balanced mix.

There are many different types of subwoofers.

From active and passive ones to ported subwoofers, front or down-firing ones, horn-loaded, or ones with passive radiators. The choices you have are vast.

Thinking about purchasing a subwoofer? 

If you are ready to deal with a bit of an extra setup and an additional cost, go for it.


Can you use a subwoofer as a speaker?

No. Subwoofers are only meant to output bass and cannot be used without a speaker setup.

How does a subwoofer work?

A subwoofer uses an amplifier to convert current into a low-frequency sound via vibration. The result is a much deeper sound than what most other regular speakers are capable of. Check out our What Does a Subwoofer Do section for a more detailed outline of how they function.

Are subwoofers worth it?

A subwoofer can definitely enhance your home theater’s overall sound. If you are willing to put up with extra wires and costs, they are absolutely worth it.

What makes a subwoofer good?

Loudness and power efficiency are important aspects. But also how much space they take up, how easy the setup is, and how affordable they are. Some subwoofer types would be better suited for certain setups instead of others.


Georgi Karaivanov

Georgi Karaivanov

My fascination with technology began from quite an early age thanks to computers and video games. Nowadays, I love anything related to music production and astronomy. Coincidentally (or is it?), both of those have a great deal to do with tech. Honestly, most of the stuff that can be accomplished with modern electronics kind of seems like magic to me. This is why I feel this strong need to constantly learn more about it and talk about it, almost to the detriment of others.

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