What is a Subwoofer?

5 mins read
Listeners of all kinds swear by subwoofers, from music connoisseurs to home cinema movie buffs. However, for a budding audiophile at the very start of their sonic journey, this particular addition to your speaker setup likely comes with a lot of questions - what exactly is a subwoofer, how does it work, and do you need one? 

In this guide, we'll demystify these fascinating pieces of audio technology, delving into the amazing components that power them and covering the unique innovations that elevate KEF's subwoofers above the rest.​​​​​

What Does a Subwoofer Do?

Do you ever listen to a piece of music that’s nearly perfect - but not quite? Something is missing that you simply can’t put your finger on. Or perhaps you’ll be gaming, and the adrenaline-pumping drama of a level just isn’t there. The roars of the beast you’re battling simply don’t have the expected impact. Well, what’s missing is bass. The low frequencies add a satisfying rumble in your chest. That’s where a subwoofer comes in - reproducing the lowest frequencies in a piece of audio, usually down to 20Hz, but often even lower into the infrasonic frequencies.
 
See our complete guide to subwoofers to uncover the different subwoofer types available as well as tips and tricks for subwoofer placement and more. 

Collection of all KEF Subwoofers

How Subwoofers Work

A subwoofer is a speaker too, so the principles of operation are the same. An alternating current (audio signal) flowing through the voice coil produces an alternating magnetic field that opposes the permanent magnetic of the motor system. This generates an alternating force on the voice coil, which causes it, along with the rest of the moving assembly - cone, surround and suspension, to move backward and forwards.  This generates pressure differences in the ambient air around the speakers, which we eventually perceive as sound.  The only difference is the scale of the operation, particularly the volume of air subwoofer drivers need to move. 

To produce a high sound pressure level (SPL) at low frequencies, a speaker driver needs to move a large volume of air. This can either be achieved by having a large radiating area and/or large displacement capabilities. The design of a good subwoofer relies on the balance of the two. We have a range of technologies that help us minimise the compromises in achieving this balance and deliver excellent performance as a result. 

    Why Add a Subwoofer to Your Audio Setup

    A subwoofer isn’t necessary - particularly if you have powerful speakers like our LS60 Wireless that are capable of full range output on their own. However, if you love hearing the boom of bass in your music or feeling the drama on a screen reflected in the quaking of your floorboards, a subwoofer will give you what you need. Additionally, even for a full range system, adding in a subwoofer or two to take over the taxing task of reproducing the lowest frequencies, leaves the main speakers with an easier task of producing the rest of the frequency range with improved clarity and lower distortion.

    See our guide explaining how a subwoofer enhances your audio experience to fully unpack the benefits of this exceptional piece of audio technology. 

    How Are Subwoofers Drivers Made?

    Each subwoofer driver contains several integral components, each with its vital role in delivering phenomenal bass. 

    • The chassis is the mainframe, holding all the components together whilst providing a platform to mount the subwoofer driver in the cabinet. 
    • The cone, or diaphragm, is connected to the voice coil and is responsible for moving the air around it when it moves back and forth in response to the voice coil force.
      • The spider is a flexible component anchoring the voice coil assembly to the chassis, controlling the cone’s movement and keeping the voice coil centred within the magnetic gap. 
        • The voice coil is wound around a cylinder called a bobbin and works with the magnet to move the cone when the alternating current passes through it. 
          • Voice coil windings are terminated in external lead outs that are connected to the driver terminals. 
            • The motor system consists of a permanent magnet surrounded by steel parts. These components together form a permanent magnetic circuit within which the voice coil is suspended in an annular gap in the top steel plate. 

              KEF Subwoofer Technology

              At KEF, we’ve taken the genius of the subwoofer and brought it to groundbreaking new levels with our unique, patented subwoofer technology. 

              We know how integral the cone's movement is to driving that high-fidelity bass. That’s why we created P-Flex Surround, specially engineered to resist the acoustic pressure in the cabinet, allowing more precise movement and being flexible enough to allow for easy and unhindered movement of the cone. Our cones are made of hybrid paper and aluminium, lightweight for fast response and rigid for durability.

              The incomparable DSP - or digital signal processing -  of a KEF subwoofer is all down to the magic of our Music Integrity Engine. These clever algorithms keep every component of your subwoofer working together in perfect harmony, including iBX Intelligent Bass Extension for depth and Smart Distortion Control Technology for clean sound. Moreover, the Music Integrity Engine allows for up to five dedicated room EQ settings for perfect integration.

              Our subwoofers, with innovative space-saving designs, never take up more room than necessary. Thanks to Uni-Core, back-to-back drivers are combined into a single motor system, so you won’t have to sacrifice space for bass. 

              Complete your KEF speaker setup with a subwoofer today. Then, once you’ve secured your perfect subwoofer, our guide to integrating your subwoofer and speakers will help you to create superbly synchronised sound. 

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