KEF Q500 floorstanding loudspeaker review

The Q-line of the British manufacturer KEF is probably the most updated series of loudspeakers in the world, its rebuilding is regular and, as a rule, not just cosmetic. The Q-family was upgraded once again in 2010, with updates to both the design and construction of the speakers. The series now features 9 speakers in different models: three Q900/700/500 floorstanders, two Q300/100 shelf speakers, two Q600c/200c ‘centers’, a Q800ds dipole rear channel loudspeaker, and a Q400b active subwoofer.

There are more differences between the new Q Series and its predecessor, but one thing is certain – the Uni-Q coaxial driver has been at the heart of the speaker for generations. Since 1988, when KEF introduced its first coaxial midrange/high frequency driver, the new unit represents the 11th generation of such speakers infrequently used in the industry due to the sheer number of technical challenges involved in their development. KEF was never daunted by complexity, but rather by the sheer size of the drive units and the better phase-matching of the two co-axial units, together with improved control of the directivity of the loudspeaker in the high frequencies. This adds up to a lot: volume, intelligibility of the musical scene, and an expansive zone of good stereo effect instead of the “sweet spot” created by highly directional loudspeakers.

The new Uni-Q incorporates many technologies adapted from the top Reference and Blade designs: an enlarged 25mm dome tweeter with a ‘double’ diaphragm housed in the proprietary Tangerine Waveguide, a rear tweeter damping chamber. Technologies reduce tweeter distortion, improve sensitivity, and enhance directivity. The midrange driver is equipped with an aluminum diaphragm, a larger magnet system and a long, large voice coil made of aluminum wire with a diameter of 50 mm for power transmission. The elimination of resonances from the working band of the midrange driver is carried out with the help of two new technologies. One of them is called Cone Breakup Control: voice coil and diaphragm are connected by a special bond that remains rigid for the MF/LF vibrations, but resilient for the parasitic high frequency modes, which causes their attenuation, like car shock absorbers damping minor road bumps. The Z-Flex midrange diaphragm surround follows a similar pattern with its unusual radial ribbing that allows only low-frequency natural resonances outside the midrange bandwidth.

The Q-series bass drivers are completely new. Like the midrange drivers, they’re fitted with oversized 50mm voice coils and aluminum diaphragms. High-powered magnet motors have a central air duct to ventilate and reduce compression.

Optimized speaker drivers and ingenious cabinet construction make it possible to use simple 1st order filters in the Q-series, which bring minimal phase distortion to the sound.

An interesting feature of the upgraded Q-Series floorstanders and centers is the use of a kind of inverter cabinet design called the “passive radiator” which uses conventional drivers with diaphragms and suspensions instead of FI sockets, but without motors. Of course, the conventional phase-inverter is quite efficient and cheap, so it’s used everywhere. But the tubes in the chassis create a lot of problems: audible air turbulence, and resonance of the chassis and the port itself. More often than not, it is not even at the bottom of the speakers, but in the middle frequencies, which is much worse, because it is perfectly audible to the human ear. Passive radiators are much more expensive and heavy-duty than plastic or metal pipes, you mainly have to rely on listening experiments, but the above drawbacks do not have, thus expanding the working range in the bass area no worse than conventional port-phase-inverters.

The Q500 models are the “junior” in the line of Q-series floor-standing loudspeakers. The speakers come with the smaller of the two new 130mm diameter Uni-Q driver options. The same caliber have a bass driver and two passive radiators. The Q500’s enclosure is divided into two acoustically independent compartments: the coaxial module in the top compartment is loaded on its passive radiator, while the similarly loaded bass driver works in the bottom compartment. All the drivers point forward. The speaker cabinets have a strictly rectangular profile with a black painted front and wood grain “paper” surface made from real wood fibres. This pioneering approach is both ecological and practical because it replaces the veneer with a perfect reproduction of its grain and color. KEF’s Q-series comes in three finishes: black oak, cherry and walnut. The pedestal of the loudspeakers can be mounted on plastic feet with metal spikes. On the rear panel is the original plate with two pairs of universal gold-plated terminals, but without visible crosspieces. Actually, the jumpers are in place, only hidden inside the panel and “set” by turning two small knobs – a very sensible approach, because otherwise the jumpers are often lost.

53 900 Dollars.

Specifications

Type: floor standing, passive radiator

No. of Bands: 2.5

Speakers mm : HF – 25, MF – 130, LF – 130

Recommended power of the amplifier W : 15-130

Frequency range Hz : 40-40k

Crossover frequencies Hz : 2,5k

Magnetic shielding: no

Sensitivity dB : 87

Impedance Ohm : 8

Two-cable connection: yes