Of the many landmark innovations KEF has pioneered, arguably the greatest of all is the Uni-Q point source driver array, with its outstanding acoustic clarity and off-axis dispersion. With over twenty years of continuous innovation and development the Uni-Q driver array achieves a level of sound quality over a broad area simply not achieved from conventional speakers. It is not easy to produce a convincing and realistic illusion of a live performance because the sound from a high quality loudspeaker does not come from a single source, or drive unit. Two or more units are required to faithfully reproduce the entire audio spectrum from the low bass produced by a concert organ or a cinema explosion, to the delicate nuances of the human voice in the midrange right up to the shimmering treble of cymbals. Most loudspeakers have the midrange and treble drive units mounted one above the other, so the sound is coming from two different places, causing audio 'confusion' and losing the chance of achieving a truly natural sound. With Uni-Q, the midrange and treble units are mounted at precisely the same point in space - allowing them to integrate perfectly and create the ideal sound field for the listener to experience a convincingly natural sound. It has been well known for many years in the audio industry that one of the ideal forms for a loudspeaker is the 'point source' - where all the sound is radiated from the same point in space. To do this, the drive units (for example, the bass and treble units in a two-way system) need to be mounted so that their acoustic centres are at the same place. The problem in achieving this was the sheer physical size of the treble unit, which prevented it from fitting in the centre of the bass unit. Various forms of co-axial units emerged where the tweeter was mounted either in front of or behind the acoustic centre of the bass unit but these have significant drawbacks. The key to the invention of Uni-Q was the arrival on the market of a new magnetic material called Neodymium-Iron-Boron, which has ten times the magnetic strength of a conventional ferrite magnet. This material allowed a high sensitivity treble unit to be made small enough to fit within the voice coil diameter of a typical bass unit and so be placed at the precise point where the acoustic sources are 'coincident'. With the acoustic centres at the same point in space the acoustic outputs of the bass and treble units are 'time-aligned' in all directions allowing the designer to achieve perfect integration between the units not just on one axis, as is the situation with vertically separated units, but in all directions. The first advantage of Uni-Q, therefore, is the lack of the vertical interference pattern of separated bass and treble units, which restricts the region of high quality sound output to only +/- 10 degrees above and below the principle axis. This same effect not only limits the vertical listening area but also produces a dip in the total energy output in the bass/treble crossover region, causing a distortion of the reverberant energy in the listening room. In Uni-Q systems this effect is completely eliminated. The second advantage of Uni-Q is what we call 'matched directivity'. With the treble unit mounted at the centre of the bass driver's cone, its directivity (the spread of sound away from the main axis) is governed by the angle of the cone, which also largely determines the directivity of the bass driver. So with the coincident mounting of the two units, the directivity of the treble unit is adjusted to be virtually the same as that of the bass driver. The listener is not, therefore, as limited to a central 'sweet-spot' as with conventional speakers. And, of course, the same is also happening in the vertical plane, so the reverberant energy in the listening room maintains an even balance, adding realistic ambience to the sound without introducing tonal colorations. The directivity is often referred to in engineering terms as the 'Q', and the 'Unifying' of the 'Q' gives rise to the name 'Uni-Q'. From a listener's perspective, the combination of the matched directivity and precise time alignment in all directions gives significantly improved stereo imaging over a wide listening area, the realism of which is enhanced by the even balance of the reverberant energy within the listening room.

A truly revolutionary tool in the KEF acoustic armoury, Metamaterial Absorption Technology (MAT) is a highly complex maze-like structure that eliminates unwanted sound from the rear of driver, resulting in a purer, more natural performance. Metamaterials are specially developed structures that use existing materials in such a way that they exhibit new properties. MAT’s tuned channels absorb 99% of the unwanted sound from the rear of driver, compared to around 60% absorption from loudspeakers using different approaches. A new technology as exciting as Metamaterial Absorption Technology requires a great platform from which to perform. Rest assured, new KEF speakers that benefit from Metamaterial Absorption Technology will be here soon. The performance benefits will blow you away. KEF always pushes the technological boundaries in its mission to create the best possible sound; MAT is the physical manifestation of that drive. The result of a joint development project with the Acoustic Metamaterials Group, MAT breaks completely new ground in loudspeaker design.

As music flows through the components of a speaker crossover, timing issues can occur. This blurs the music, losing the beat and covering up the details that define the performance. KEF’s unique Music Integrity Engine corrects these errors, bringing the beat back into step and restoring the important little details.

Shadow Flare is derived directly from the Reference Series. The tweeter no longer has line of sight of the cabinet edges, creating a ‘shadow region’ at the points where the potential for diffraction is highest. The result is vastly improved fine detail, particularly when it comes to the subtle nuances of plucked strings and other percussive sounds.

Other than the output from the drivers themselves and port output due to the tuning frequency, any secondary radiation from the loudspeaker is undesirable and will cause colouration. With the majority of loudspeaker enclosures, there are some frequencies where the enclosure walls move and radiate some sound. This wall motion may either be caused by air pressure in the enclosure or due to vibration transmission from the driver.KEF’s technique, called damped bracing, consists of strategically placed wooden braces that, instead of being rigidly coupled to the panels are joined via a lossy interface. The braces are placed where the panel movement would otherwise be greatest and the lossy layer, like normal damping pads, converts the energy into heat. Additional damped braces are situated at the back of each driver, which reduce the level of reactionary vibration transmitted from the driver to the cabinet. The reduction in sound output from the cabinet varies model by model, depending on the exact geometry, but is typically of the order of 20dB.

KEF's Selecta-Mount system gives you the freedom to place the loudspeakers wherever you want.The sound of a loudspeaker will vary according to where it is located relative to the boundaries of a room. When a loudspeaker is moved from a free space position to being mounted on a wall the sound at the listening position is significantly altered. Sound, which would otherwise diffract to the rear of the speaker, is immediately reflected forwards, causing interference with the direct output from the drivers.Wall mounting a loudspeaker produces the familiar 'comb filtering' effect - alternating constructive and destructive interference with the direct signal depending on the phase difference between direct and wall-reflected components. Below 200Hz output is increased up to maximum of just under 6dB. At around 400Hz the wall reflection is out of phase with the direct signal and a dip in response results. At around 650Hz the path length difference is equal to a full wavelength, so we see a peak in the response.Additional filter elements are included into the 'Selecta-mount' crossover network of the speaker to compensate for the response change when the speaker is wall mounted. The response lift from 80 to 200Hz is the main effect that is corrected in all 'Selecta-mount' systems In the Selecta-mount systems the wall filter is automatically engaged when the speaker is mounted onto its wall bracket. When fitted onto the regular stand the wall filter is bypassed. The customer is not required to do any switching.

The bass response from a loudspeaker is critically dependent on the internal cabinet volume. If you want good bass extension, to hear all those powerful low notes from organ fundamentals to life-like movie explosions, you need a physically large enclosure. It all comes from the basic physical laws that determine how a conventional bass drive unit interacts with the air inside the cabinet. ACE technology allows us to circumvent these basic restrictions and gain the freedom to adjust the 'effective' internal volume by filling the enclosure with activated carbon. ACE works by a process called adsorption - the highly porous carbon granules take in or give out air molecules in response to the change in air pressure caused by the inward and outward movement of the speaker cone. This flow of air molecules is always acting to reduce the internal pressure variations - making the enclosure appear to be much larger than it actually is. The more activated carbon we put into an enclosure the bigger the effective internal volume becomes - up to a point where losses start to dominate. Typically, we can double the internal volume whilst still maintaining a high quality bass roll-off characteristic. Using ACE to reduce the enclosure volume whilst maintaining the same bass response. The first public demonstration of ACE was based on the RDM monitor - the ACE loaded version maintained the same bass performance with 40% less volume. The volume increase can be utilised in two main ways: (1) reducing the size of a particular speaker while keeping the performance the same or (2) increasing the bass extension from a given speaker whilst keeping the size the same. In general, it's a bit of both as we will custom design the bass driver for each application and look for the best overall compromise. In sound quality terms ACE has some major advantages - principally that it allows us to design a speaker with the bass extension of a reflex system but with the superior transient response of a closed box. In addition to the measurable parameters, the sound quality of ACE enclosures is consistently well liked by audiophiles, with a precise and detailed bass reproduction.