What Are Subwoofers?

What Are Subwoofers

Have you ever noticed how some homes or venues have such deep rich audio, be it music or a movie? Sometimes you can literally feel the sound. In other places, the audio just sounds flat, dull, and lifeless. This is very often to do with the subwoofer or the lack of one. This often neglected or misunderstood speaker is essential for a deep quality sound. We take a look at the question – what are subwoofers?

Subwoofers Explained

Often referred to simply as subs or bass speakers, a subwoofer is designed to deliver enhanced audio at low frequencies. These are your base and sub-base frequencies. While the average loudspeaker tries to deliver all frequencies they fall short on the low frequencies. Even the so-called full-range speakers do not deliver the full bass experience that can be gained from a subwoofer. 

Why You Need a Subwoofer

Most standard speakers or audio systems are not able to deliver the true audio format as it is meant to be heard. Without a subwoofer, the system will not reach the lower frequencies and the sound will be incomplete. It will lack depth and impact. 

To get the original sound as it was recorded and intended to be heard a subwoofer is essential. This applies to music and movie soundtracks. To achieve the full range of frequencies for a full and complete sound you need a subwoofer. 

It is more relevant to certain styles of music such as bass-heavy rap, rock, or EDM (electronic dance music). The frequencies produced by instruments such as kick drums, pipe organs, and bass guitars will all be enhanced and improved. Action movies and even the spoken word will sound better. 

A quality subwoofer will enhance any audio. The result is a powerful, rich,  three-dimensional sound that you can hear as well as feel. 

What Is The Frequency Range of a Subwoofer

As we have explained, subwoofers are responsible for delivering the lower frequencies, typically sub-bass, and bass. The average home subwoofers have a frequency range of  20–200 Hz. Professional rigs will have subwoofers that operate under 100 Hz.  THX-certified systems deliver audio below 80 Hz. 

Subs do not work in isolation. They compliment the sound produced by the loudspeakers. They work with the woofer, the mid-range speakers, and the tweeters to create a vivid complete sound. 

The Evolution of a Subwoofer

While they were used professionally before, home or consumer subwoofers only came to the market in the 1960s. Cinema and movie developments in the 1970s increased their popularity. The audio cassette and later the CD or compact disk helped to drive the demand for subwoofers. 

This prompted producers of both music and movies to add more bass to their work. Those without subwoofers miss a lot of what is produced and lose the full effect of the audio. 

Now, most commercial venues, quality home audio systems, and decent car audios systems incorporate subwoofers. 

Subwoofer Size

Many are concerned that subwoofers are large and take up a lot of space. The early or traditional subwoofers consisted of a large box with a driver and did indeed take up a lot of space. Many are still relatively large but you can get more compact subwoofers these days. 

New designs incorporate a dual driver and an amplifier that is more efficient. This when done correctly, can give you quality low range or bass sounds without the need for a bulky subwoofer. 

Subwoofer Construction

A subwoofer is typically made up of a wooden or plastic box containing the driver and woofer. Some contain multiple drivers. Many subwoofers have a built-in amplifier. 

Subwoofer Designs 

There is a range of subwoofer designs. They are determined by the interaction between the cabinet and the driver. 

Here are the main options:

Sealed Subwoofers 

Also known as air-suspension or acoustic-suspension, these are the most common or traditional subwoofer designs. They are constructed from a sealed structure or box with a  single hole containing the woofer or driver. They generally have an integrated amplifier in the rear although some are external. 

The woofer is front-facing or positioned towards the ground (a down-firing subwoofer). The driver causes the air in the box to compress and decompress as the box keeps it contained. This gives it power and helps to deliver the low frequencies. 

Ported Subwoofers

These subwoofers sometimes referred to as bass-reflex subwoofers, contain a port that is tuned to transfer bass and power. The quality models are most effective. Less well-designed models are not that effective at delivering quality distortion-free sound. They can achieve a higher output than traditional subwoofers.  

Passive Radiator 

This design uses a passive radiator as a port. 

Ported vs. Sealed Subwoofer

For those with a bit more experience with subwoofers, many might ask what is better, a ported or a sealed subwoofer. To better understand the difference and determine which is best for you, here is the low down. 

Sealed Subwoofers

As you would imagine from the name these are in a sealed speaker box. These tend to be more compact and easier to position. There is much debate over which option is better but many argue that a sealed subwoofer delivers a more accurate sound and better frequency response. For this reason, for intricate music, they are arguably the better option.  

They are ideal for smaller rooms. Most audiophiles agree that they are better for music although a quality sealed subwoofer is still great for soundtracks and TV. 

Ported Subwoofers

The subwoofers have one or possibly more vents or ports. This allows air to escape. They generally deliver a more powerful bass that is deep and rich. The addition of the vent means that the speaker is generally larger. This makes positioning it more of a challenge. You would need a relatively large room or space if you are using a ported subwoofer. 

They deliver greater dynamic impact as well as and good bass extension. Provided you have the space they are ideal for movie soundtracks although the good ones perform equally well with music. 

So the question still remains, which is better? If you have a large room, want deep powerful bass, and volume, then ported is probably the better option. For smaller spaces and crisp accurate audio, a sealed subwoofer might be a better bet. The main aspect you should worry about is quality. The best subwoofers, be they sealed or ported, should meet your requirements. 

Where to Position the Subwoofer

This is a question that puzzles many home users. High-end systems should probably be set up by experts. The average sound system or home theater system that incorporates a subwoofer can be set up quite easily. Much will depend on the specific environment.

Each room or space has unique characteristics and acoustics so there is no definitive answer. Perfect positioning is unlikely to make a significant difference and a bit of trial and error might be the best way to find the ideal spot for your sub. 

In certain rooms, one might need to position two subwoofers. It really comes down to the size and layout of the space. Most rooms will be fine with a single quality subwoofer but some may need an additional unit. 

What size subwoofer do I need?

Yes, size matters. In the early days, subwoofers were massive heavy speakers. While they are still relatively large, advances in technology allow for much smaller subwoofers that still deliver impressive and powerful bass. 

In general terms, the larger the surface area of the subwoofer, the more air it can displace and the louder it will be. So if a rich and powerful bass is what you are after, lean towards the larger options. 

As with the discussion above there are pros and cons to size. Larger subwoofers will produce a more powerful sound with more volume and depth. Smaller subwoofers might not have the power but will be more accurate in their low-range delivery. 

The most popular and versatile subwoofers are 10 or 12-inch. For more accuracy, look at 6.5 to 8-inch subs. If you really want to rumble with major bass 15 to 18-inch subs will deliver but do not expect them to be as accurate or responsive as the smaller options. 

Once again, the quality of the speakers as well as the box is more important than the size.

Final Thoughts

If you want to take your home or car audio to the next level a decent subwoofer is essential. It will give your sound the depth and kick that it needs to be complete. Those deep bass notes can not be heard without a subwoofer. 

Fortunately, you do not need to spend a fortune to get a good subwoofer. Just be sure to include it in your system. That will allow you to enjoy the full range of frequencies for a rich and complete sound. 

This article was last updated on September 8, 2021 .

By Charl Jooste

Writing full time from home, Charl enjoys modern technology and advanced gadgets but still has a soft spot for quality reliable appliances. He is passionate about durability and quality going to great lengths to find the very best ideas and leading products to share with readers.