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KEF KUBE 10b Subwoofer Review

KEF is a British company specializing in loudspeaker design and manufacture. The company started in 1961 under the direction of Raymond Cooke and Robert Pearch in Maidstone. Cooke was an ex BBC and later Wharfedale speaker designer. KEF now produces a range of products on a worldwide basis.

These include consumer speakers, studio monitors, subwoofers, and loudspeaker drivers. As well as speakers for iPods and headphones. The KEF KUBE 10b Subwoofer is just one of their extensive range of quality systems.

These days KEF is owned by GP Acoustics. They themselves are owned by the Hong Kong company Gold Peak Group. All design, research, acoustic engineering, and manufacture of their high-end products still takes place on their original site in Kent.

Being speaker design specialists, the subwoofer is a natural extension of their product range. But what exactly does the ‘sub’ do? You are about to find out in our in-depth KEF KUBE 10b Subwoofer Review…

The Subwoofer

The ‘Sub’ as it is often known, arrived as a consumer product in the 80s. It wasn’t that powerful or deep sounding and was actually initially installed in the wall.

However, that wasn’t the earliest use of a sub that we know about. That was on the Steely Dan album ‘Pretzel Logic’ in 1974. Likewise, another first for the great Charles Rainey and his ‘killer’ Precision bass.

Subwoofers at home…

It is a great addition to an audio or home cinema system. Decent subs will reproduce the lowest frequencies that are used, especially in movie soundtracks. They can be passive systems relying on an external amp. Or they can have an amp built-in.

There are quite a few to choose from at a variety of levels of quality. KEF are renowned for their high-end speaker systems.

So, let’s take a look to see if the KEF KUBE 10b Subwoofer is as spectacular as some of their other products…

KEF KUBE 10b Subwoofer
Our rating:4.6 out of 5 stars (4.6 / 5)


KEF may well hold one very important claim to fame. The in-house design and manufacture we have already mentioned. And this integrated approach to building speakers ensures they all follow an ideal or a vision. All singing from the same song sheet, you might say.

Committed to sound…

This is a mid-sized sub with, in some ways, a modest driver size. But it still manages to produce a powerful sound. Maybe Carole King was predicting it when she sang ‘I Feel the Earth Move.’

Significantly it also has a new system of bass frequency production. We will be taking a little look at that and what it does.

So let’s get a little closer to the KEF KUBE 10b Subwoofer and see if you can indeed feel the earth move.

The Build

Don’t get confused when you look at this cabinet. It is smart and chic with a certain upmarket elegance to it. In fact, elegance is a word that describes this sub well. All the more of a surprise then when you turn it on.

It will unleash a power that it doesn’t look capable of. The bottom end rumbles around you with ferocity. And it seems to do so without making any effort at all. You begin to realize you are in the presence of something very special.

Quick and accurate response…

It is a subwoofer without a ported design. In other words, it is a sealed unit. This means that the movement of the speaker is reduced to nothing. Whereas in a ported cabinet, the speaker moves freely.

The difference means that the sealed unit will give you a quicker and more accurate bass response. Many people prefer that tight bass sound.

This piece of elegance measures 14 by 14 by 15 inches and weighs 38 pounds. Inside is a 10-inch bass driver. It has a frequency response of 24 to 140Hz, plus or minus 3 dB. The variable low pass filter is 40Hz – 140Hz, and it has LFE or Low-Frequency Effects.

Built to boom…

Well-built and braced. The design and quality of the build ensure a well-rounded and clear sound. It has to be built that way. Anything less and this cabinet could not handle what you are going to throw through it.

But let’s pause, we ought to find something we don’t like if only for balance. The only thing we can find is that the speaker cover doesn’t come off. But then with a sub that looks like this, why would you want to remove it? So, no real negatives then.

The Sound

There are a lot of speakers these days that have a Class D amp built-in. The big plus point is that it has a higher level of efficiency than a Linear amp. And of course, it is much lighter in weight.

In the future, Class D amps will probably be the way things go with most products. But that is easier said than done. It is not easy to build a great Class D amp. However, it’s reasonable to say you need to know what you are doing.

Experts in audio…

Knowing what they’re doing is not something that worries KEF. The Class D amp that is built-in to this system is superlative and pushes out 300 watts. That is 300 ‘real’ watts, not the 300 that some others claim. The depth of the sound is staggering.

But that isn’t good enough for KEF and their design engineers. They worked to develop a system they call IBX. Otherwise known as ‘Intelligent Bass Extension.’ This extends the depth of the bass and allows the driver to show what it is capable of.

The IBX algorithm adds a bass sound that will more than surprise you. The earth is about to move.

Custom settings…

You can adjust the sound of the Kube using the controls for the crossovers, and the low pass filter, the phase, and the gain. These are on the rear of the cabinet. We will look at those separately.

The Kube also has some custom settings for EQ. These are pre-programmed and allow you to adjust the sound for the environment in which the sub is operating. These are for positions near a wall or on a corner, free-standing, and in-cabinet install.

The delivers a well-rounded sound and is very loud. A sound that has great depth and has depth right across the frequencies. In its range, it takes some beating.

The Controls

We have mentioned the controls, so let’s have a look at them. They are located on the back of the sub, are simple to operate, and control a number of functions. But they don’t go too far and become confusing.

The three DSP, Digital Signal Processing presets, we have already mentioned. They offer a set of EQ settings that are designed to let you maximize the sound potentials of the sub. These include matching the sound to the particular aspects of the room in which the sub is operating.

There is a range of line inputs and RCA phono sockets and phase selection. Plus, there is an automatic power-saving facility built-in. When the sub recognizes that there isn’t a signal, it will take on a standby mode. At this stage, the power on light at the back of the speaker will turn red.

Quality yet again…

There can be little doubt that KEF has produced another quality product. Not the top of their range, of course, but still a quality sub.

It is designed with one aim in mind. To give you the deepest bass sound for your movies and your music. And it does that at a price point that will not be exclusive. Let’s have a brief summary…

KEF KUBE 10b Subwoofer Review Pros and Cons


  • A well-made and elegant design.
  • A sealed unit design giving you a quick, accurate bass response.
  • Frequency response to 24Hz.
  • 300 watt Class D amp.
  • KEF’s IBX system to deepen the bass response.


  • The speaker cover is not removable.
  • Some may find it over their budget.

Also see: Arturia MicroFreak Review

Looking for Something Else?

We have your speaker needs covered for every angle. Take a look at our in-depth reviews of the Best Powered Speakers, the Best Wireless TV Speakers, the Best Floor Standing Speakers, and the Best Bookshelf Speakers Under $500 currently on the market.

Or how about the Best Sonos Speaker, the Loudest Portable Bluetooth Speakers, or the Best 7.1 Home Theater System you can buy in 2023.

KEF KUBE 10b Subwoofer Review Final Thoughts

This has to be one of the best subs around based on what it offers. KEF in the past has sometimes used slightly underpowered amps for their subs. Not the case here. This has plenty in the tank.

From its elegant design through its performance, it is of great value. And it is going to pin you back in your seat with its bass depth.

KEF KUBE 10b Subwoofer Review

Whether it be movies or music, this is going to do what you want. Prepare to Feel the Earth Move.

Until next time, may your bass be deep and your music be merry.

1 thought on “KEF KUBE 10b Subwoofer Review”

  1. I would be curious to hear your comments about B&Ws subwoofer that would be in the same catagory as the KEF KUBE 10b and how they might compare. Certainly it appears the KEFs might be more reasonably priced.

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