In September, KEF released its new portable Bluetooth speaker, the Muo. There are a lot of players in the portable Bluetooth speaker market, so in order to rise up above the noise (so to speak) we took our time and engineered a product worthy of the KEF badge.

Stylistically based on our flagship Muon speaker, designed by renowned industrial designer Ross Lovegrove, Muo stands just 8” tall in its vertical position, but it punches far above its weight class when it comes to performance.

While Bluetooth speakers are convenient, they are often disappointing in terms of musicality. Either the highs are drab and lifeless, the mids are overpowering, or the bass is either non-existent or artificially prominent and over-bearing. In order to release a product we could be proud of and that represented our passion for musical accuracy, our engineers first had to overcome those obstacles that have left so many other products in its class wanting.


First: the Mono and Stereo 

The Muo, like other portable Bluetooth speakers in its class is a mono speaker that is designed for ultimate clarity and punch. In such a small package, stereo playback is simply not realistic (or enjoyable), but a second Muo can be added for a stereo Bluetooth system with the same soundstage and dispersion fifty years of KEF fans have come to expect.

A second Muo can be added in mono mode as well for when you are trying to fill up a larger space with sound but aren’t concerned about stereo playback. You can simply change the position of the units (vertical = stereo, horizontal = mono) to switch between modes.


Second: the Driver Configuration

If you put the Muo right up to your ear, you may notice that higher frequencies only come from the top (or right hand) driver. Rest assured, it’s supposed to work this way.

When two high frequency drives are in extremely close proximity to each other (in the Muo the center of the two active drivers are only 5 ¾” inches apart) the highs will tend to interfere with each other. This results in the muddy and weak high frequency response so common in other Bluetooth speakers. High frequency dispersion is also extremely narrow, meaning the sweet-spot is very narrow – the full sweetness of the highs are only heard in a narrow spot.

Two mechanical Uni-Q drivers comprise the active portion of the driver configuration, with the top (or right) driver producing the full range of sound and the bottom (or left) driver producing mid- and low-frequencies. Once you position the speaker a foot or more away from you, the highs will open up and you’ll instantly understand why it was designed this way.

The third driver is a passive radiator. Positioned between the two active drivers, the passive driver moves more air as a result of the sound energy inside the unit, resulting in a deeper and richer bass without the artificial equalization “bump” used by so many other speakers in its class.


Third: The Quality

Shrinking our Uni-Q technology down to fit in the Muo was an engineering achievement that we’re proud as a company to be able to pull off. I’m listening to Stan Getz and Joao Gilberto’s wonderful Girl From Ipanema as I type this paragraph after just listening to St. Paul and the Broken Bones’ Dixie Rothko and even though I’m a tad bit biased, there is no denying the musicality and sweet accuracy this little speaker produces.  

Both of these tunes were ripped from CDs and the Muo’s native aptX 4.0 codec allows the original files to shine. Bluetooth aptX is a near-CD streaming convention that processes the same sample rate as Red Book CD (44.1 kHz) and stores it in a slightly smaller sample word (24-bit for CD Red Book and 16-bit for apt-X).

This gives you the option of listening to your mp3 files in their native resolution as well as listening to your higher resolution files in near CD-quality. We’re not the only speaker company to do that, but when you add in our driver technology, you realize the benefit of what’s been done in the Muo.

I usually use a pair of X300A’s on my desk “for research” (at least that’s what I tell everyone), but I’ve got a pair of Muo paired in stereo mode setup just wide of my X300A’s and about 18” from my ears and I’m not missing a thing.


Fourth: The Battery

Out of the box, you should expect a couple hours of operation, but your best bet is to play with your new toy for a few minutes and then put it on the charger until the Muo is fully charged (the indicator will light green). This should take about 3 to four hours.

After a full charge, you can expect up to 12 hours use at a moderate volume at room temperature (as long as your room isn't non-air-conditioned and located in the tropics). The warmer the environment, and the louder you play your Muo, the shorter you can expect your battery charge to last.

Another thing to be aware of, as with all lithium-ion batteries that are charged while the unit is in use, power is divided between the operation of the unit and the charging circuit. This means that the louder you play your Muo during charging the longer it will take as the amplifiers will draw more power away from the charger. Theoretically with this type of battery, you could wind up in a situation where the battery never fully charges because it doesn’t receive enough power. So charge it up while you’re playing, but before you’re ready to head out with your Muo, leave it on the charger for a few hours without using it.


We take our music seriously, so when we decided to produce a portable Bluetooth speaker, we had to do it with the same precision and passion we put into all the rest of our products. Whether you’re using a single Muo on the beach or a pair setup in your house as a wireless Bluetooth stereo music system, we’re pretty sure you’ll agree that we got it right.

Jack Sharkey for KEF