Kef Mu3 review: a successful audiophile test but very poor in features

Guillaume FourcadierAudio SpecialistJuly 13, 2021 at 3:130 p.m.© Guillaume Fourcadier for Clubic

A veritable institution in the world of Hifi, Kef is above all a dynamic brand that has taken up the challenge of standing out in the very competitive sector of True Wireless earphones. To do this, its Mu3 go all out, reminding us of the old glories of the very high end of the world of loudspeakers. A top of the range (230 euros) among the top of the range therefore. Will the brand's audiophile experience make the difference?

7Read the conclusionKef Mu3

Mu for Muon

Behind this potato form in a gray dress, we find the British designer Ross Lovergrove. This name is certainly not unknown to Kef lovers, since he is already responsible for the design of the High-End Kef Muon loudspeakers (the "no-limit in price"), two-meter-high metallic monsters for 115 kg on the scale, and 150,000 euros on the wallet.

Another universe therefore, but which Kef did not hesitate to invoke here, perhaps to bring himself luck.

The Muon, modest speakers for the price of a house © KEF

It is certainly necessary to hang on to this most particular design, which divided as soon as it was announced. The curved shape of the Kef Mu3 is not necessarily very current, but really stands out on the True-Wireless market. Above all, the product is much more pleasant once in hand than it is in the photo.

The manufacturing is nothing premium, since we remain on a plastic base only, but Kef knows his business well. The Mu3 are sufficiently dense, well assembled, and very little dirt. The certification is IPX5, a bit above the IPX4, which has almost become the standard for ANC headphones. Some competing products still do better, such as the Samsung Galaxy Buds Pro, certified IP67 (immersion resistance).

© Guillaume Fourcadier for Clubic

The box is just as strange, or original (depending on the point of view), and just as pleasant once in hand. Too bad not to have opted for a metal casing (like the Klipsch T5 II), which would have been perfectly in line with the Muon philosophy. This point would have been all the more logical since the Kef Mu3 are not compatible with induction charging. The first flaw in a small series of ergonomic simplifications.

If this charging box is serious, there are still some small squeaks, including the tray to rest the headphones. The hinge is quite thin, but rather solid. The only real complaint is the size, larger than average, which will not allow this case to fit in all pockets.

Very short and fairly wide cannula, with 4 sets of tips, for very acceptable comfort © Guillaume Fourcadier for Clubic

Without being the most comfortable earphones on the market, the Kef Mu3 are not too intrusive (short cannula even if quite wide), and retain an excellent hold if you put the right tips on. The port is done by inserting the headphones and making a quarter turn, like the Jabra 75T or the Sennheiser Momentum TW2.

Difficult to envisage a sports use, since no security is present, but the shape of the headphones is quite well optimized. Unless you have very small ears (the volume of the Mu3s is indeed not negligible), the headphones will be quite pleasant, even for long sessions of use.

Basic ergonomics, a little limiting

Like another audiophile brand, such as Earsonics with its Aero, Kef has chosen a product that is immediately functional and already very developed, without having to go through an application. A self-respecting choice, but which still seriously hinders the possibilities of such a product. Thus, you should not hope to adjust the power of the noise reduction, or the sound feedback, nor easily equalize the sound signature, or modify the commands linked to certain actions...

A functional count which is perhaps not definitive, Kef knowing his business quite well in terms of application (as the LS50 Wireless II showed). To be continued.

Ergonomics all in button © Guillaume Fourcadier for Clubic

As it stands, everything is based on the principle of Mu3 buttons, placed in a hollow at the back of each earpiece. The commands are asymmetrical, which makes it possible to slightly extend the possibilities of actions. In reading mode, it is possible to make a single click, a double click, yes a long press.

Purified functions therefore, but we have seen much worse, the essentials being saved and the whole thing being quite simple and intuitive. Nevertheless, some small gaps remain, such as the absence of return to the previous track. We can also underline a certain latency between the support and the triggering of the action, but this point remains quite random and just as much attributable to the telephone.

Decidedly not monsters of ergonomics, the Kef Mu3 do not integrate either an optical sensor, which would make it possible to trigger the pause or the reading once the headphones are removed and replaced in the ear.

Simple, but faultless connection

Like ergonomics, connectivity remains simple and efficient. No multipoint (connection to several devices in audio profile), but an almost perfect connection quality. Whether it's range or signal stability, we can't fault the Mu3s at all. In addition, the headphones can both work in mono mode.

© Guillaume Fourcadier for Clubic

Only strangeness, the absence of support for the AptX codec, probably to maintain optimal autonomy. Whether this codec is more efficient than SBC or AAC (this point is already debatable), there remains a fairly obvious marketing argument. Many will therefore be able to blame his absence.

Isolation ok, microphones to review

Kef goes up a notch in terms of insulation. Very dependent on the position of the earpiece and the tip used, it can already reach a good level in passive mode (ANC deactivated). The highs are very attenuated, as well as a small part of the mids.

With ANC, silence gains an additional level. Without being as fabulous as that of the Airpods Pro, the active noise reduction can be effective, but above all perfectly clean. There is no buzzing effect (related to a very slight phase shift) nor any hint of extraneous noise or hiss. The very purring frequencies are attenuated by 10 – 15 dB, and the isolation in the mediums can reach 20 dB in the best case (on fairly short windows). Kef is not likely to disturb the champions of the genre, but his general performance is largely acceptable - nothing more.

Not the smallest headphones, but not the bulkiest either © Guillaume Fourcadier for Clubic

The quality of the "Ambient" mode (sound feedback) is already much less convincing, partly because of the very high passive isolation. Here, the microphones try to catch up with the strongly attenuated highs, without succeeding. Without being catastrophic, the sound is very muffled, and the midrange frequencies are largely amplified, which does not allow the system to be really effective. A useful mode to stay a minimum alert, but quite disturbing.

The hands-free mode is… usable, but really no more. For a high-end product, the result is in line with what Sony offers on these WF-1000Xm3, that is to say quite mediocre. Even in a quiet environment, the voice is a bit choppy and slightly metallic. In a noisy environment, it is sometimes difficult to make a simple dialogue float. A function to be used sparingly.

The autonomy of the top of the basket

Announced at 9 a.m. with ANC, the autonomy is, on paper, quite fabulous. In practice, we did not always achieve such a performance, but the 8 hours – 8:30 hours are still reached (in AAC), which places the headphones above average.

Without ANC, the performance seems to oscillate a little more, but it is largely possible to reach 10 hours of use. The case, meanwhile, allows you to add a little less than two additional refills.

A technical and very airy sound, at the level of the best models

The Kef Mu3s are armed with an 8.2mm dynamic transducer “expertly tuned by Kef” in the words of the builder. The brand therefore probably did not develop this loudspeaker itself, but probably worked on specifications in collaboration with a manufacturer.

Nothing surprising, since this is the case for almost all brands, apart from a few giants or a few historical players, such as Sony or Sennheiser.

Measurement of the (compensated) frequency response of Kef Mu3. With a good insertion (green curve), the signature is already quite bassy but relatively balanced. A slight offset of the tips can cause the bass level to be lost fairly quickly (purple curve)

Kef thus does an excellent job, since by ear, a certain balance is established, while accentuating the bass and treble sufficiently to become quite “fun”.

The Mu3s aren't top-end killers, but Kef has tuned the transducers very cleverly. The bass is well highlighted, on a regular slope, not invading the mids. Several peaks in the treble allow you to maintain clarity without the sound becoming aggressive, and a small peak around 1 kHz – 2 kHz allows you to gain in separation of details, in aeration of the sound stage (this boost is a method well-known enough to amplify ventilation). The latter is among the most convincing of its kind, without becoming too artificial. The headphones do not have the technical richness of Samsung's Galaxy Buds, sold at the same price (230 euros), but compensate for this less precise side by being more relaxing.

Not as dynamic as a Sennheiser CX 400BT/Momentum TW 2 or the Sony WF1000Xm3, the Kefs show great versatility, and manage to remain energetic without ever being aggressive, all with an excellent level of detail. Those who don't like the relative acidity of the Sonys, but find the Sennheisers a little veiled, will largely find their account here. The Mu3s can be perceived as Klipsch T5 IIs, but with slightly rounder bass and more clarity. There is a certain balance here, while keeping a lot of potatoes.

© Guillaume Fourcadier for Clubic

The Kef Mu3 are extremely versatile and remain pleasant whatever the mix. Their very well thought-out sound signature allows them to largely find their place in the landscape, alongside the few best of their kind.

Kef Mu3: the opinion of Clubic

Effective on most points, well designed, very durable, the Kef Mu3 unfortunately give way to ergonomics. The lack of a dedicated application and advanced function limits the experience slightly.

Kef Mu3

7

Well-designed, durable and endowed with a most pleasant sound, the Kef retain some defects and, above all, are quite limited in terms of functions, in particular because of the absence of a dedicated application.

Most

The lessers

Manufacturing7

Ergonomics4

Insulation7

Autonomy9

Sound9

Manufacturing 7

Ergonomics 4

Insulation 7

Autonomy 9

Sound 9

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