64 Audio U12t

Professional in-ear monitor system with 12 balanced-armature drivers

In a nutshell

The U12t show that elaborate in-ear designs not only satisfy the demands of professionals on stage, but can also to be taken seriously by sound engineers and audiophiles. The high level of the design is not just for its own sake; rather, it results in the highest sound quality. This means that the price is significantly higher than that which you would pay for a mass-market product. Professional and audiophile demands are undoubtedly best served by the U12t, or the adapted A12t. I would reserve my assessment of this significant surcharge for the last few percentage points of sound performance and leave it up to the buyer to decide on their demands and their budget.


An established name in the field of professional in-ear technology 64 Audio is a US manufacturer with a team of 70 employees, offering a sound trusted by top studio producers like Michael Brauer.

Remarkably, the U12t has twelve precision balanced armature drivers per side. A considerable effort has gone into their design; it is particularly impressive since there are no sound conductors inside the casing that might unintentionally influence the sound. A passive crossover unit assigns four drivers to the bass range and six to the mid-range. Further BA drivers supply the mid-high range and the high frequencies directly into the sound port. The design is based on an ergonomically shaped black aluminium casing which is suitably robust for use on stage, and as well as looking attractive, it is absolutely perfect for the job. The sound port is fitted with one of six memory foam adapters.

The high quality twisted pairing cable uses a solid gold-plated 3.5mm right-angle plug on one side and a secure fit over the auricles on the other side. The cable is connected to the drivers via a plug connection, so it can be easily exchanged. The U12t come in a sturdy plastic transport case, which contains the headphones, a cleaning tool and a clip for cable attachment. Another impressive feature is the addition of two alternative apex damping modules (Air Pressure Exchange). In contrast to most in-ear systems, the U12t is not a completely closed system, which places greater stress on the eardrum due to the mass of air trapped in the ear canal. The damping modules, come in the form of small cylinders which can be inserted into the housing interchangeably, providing relief from pressure and thus reducing stress on the ear. You can choose between an external attenuation of 20 dB and a 15 dB version. The latter allows improved interaction between the artist, fellow musicians and the audience.

In Practice

Using these in-ears is absolutely straightforward due to the focus on pure reproduction: just plug in the cable and get started. The U12t is part of the Universal series, which addresses the needs of the most demanding hi-fi customers as well as stage musicians. They are comfortable to wear even over long periods and at the same time, safe enough for stage use, a quality which is achieved by the use of robust materials used and a high standard of workmanship. The manufacturer is undoubtedly drawing on years of feedback from musicians. The same model is also available in a custom-fit version (A12t), which is about the same price but is fitted directly to the owner’s ear by means of 3D ear impressions, thus reducing wearing discomfort. Colouring designs can also be varied to reduce visibility of the units. The universal version has does have its advantages, particularly when several musicians share a receiver, or if the equipment will be sold on after use.



With the A6t 64 Audio has added a sophisticated in-ear headphone to its product range, and we were thoroughly convinced by the sound. The doubled number of drivers is intended to provide even better sound quality and three-dimensionality.

Thanks to the manufacturer’s low impedance design, the U12t also operates virtually independently of the impedance of the headphone amplifier and delivers superb sound neutrality, excellent detail resolution, plenty of definition, clarity in the trebles as well as pressure at the necessary level for stage use. In direct comparison to the A6t, the system is a bit more powerful in all areas: the bass range is even more powerful, especially in the low bass, while the mids offer more focus and resolution and the high frequencies are a bit more open.


With the U12t you will enjoy a deep descending low bass that is resistant to overload even at high levels. But I especially enjoyed the bass range with its tight contours and the clearly comprehensible dynamics and tonality. There is no rumbling or personal volume control but they provide a really enjoyable listening experience.

With a total of seven BA drivers in the mid-range, the resolution is impressive: acoustic instruments and voices sound authentic and convince with those details that often get lost by cheaper products. These include the specific characteristics of certain voices, the emotionality of solo instruments such as violins or a grand piano, which are conveyed in an impressive way, as well as those small background noises that bring a recording to life. This quality includes dynamics which are directly reproduced: as in the jazz drums of Esbjörn Svensson Trio’s Strange Place for Snow, which are reproduced as naturally as possible.

The U12t is equally suitable for more complex production. It provides the ear with the opulent range of an electronic stage or allows a band to really rock out.

In the high-frequency range, these in-ears are brilliant at providing space and, in particular, increase the resolution of details, spatiality and location in the stereo panorama by mapping fast transients. The threshold of harshness is certainly reached, for example when listening to Britney Spears: Toxic, but it doesn’t overtake the listening experience. For an in-ear system, these give an extremely remarkable performance that can definitely compete with high-quality over-ear designs.

The stereo panorama is built up flawlessly and is stable, while spatial details – whether artificial or defined by surroundings – are revealed. The same applies to the reproduction of dynamics. The result is a sound image that, depending on the production, reliably distinguishes between intimacy and a large room; there is a wide range of pianissimo and fortissimo, ambient sound as well as warmth and compression. Musicians and producers make their decisions on this basis, while audiophile listeners can immerse themselves more deeply in the music.

4 years ago by Ulf Kaiser
  • Rating: 4.63
  • Sound
  • Handling
  • Price/Quality
  • Function

Technical specifications

  • Ear couplingIn-ear
  • Typeclosed
  • Transducer principle12 Balanced Armature drivers
  • Frequency response (headphones)10 - 20.000 Hz
  • Impedance10 ohms
  • Cable length120 cm

What's in the box

  • TrueFidelity foam eartips (S, M, L)
  • Silicone eartips (S, M, L)
  • m20 apex module
  • m15 apex module
  • Removable 1.2m premium cable
  • Cleaning Tools
  • Air dehumidifier
  • Shirt clip
  • Hardcase

Special features

  • Crossover: Integrated 4-way passive crossover
  • Isolation: -20 dB and -15 dB by supplied apex modules
  • Connection: 2 pin

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