KEF Q750 Review
Big Sound at a Small Price: KEF launches the eighth generation of the Q Series and brings fresh wind into the entry-level models with modern design and innovative technology.
Klaus Laumann
Clear lines, right angles, and a matte finish in white or black make the Q750 appear timeless and simple in its own way. Nevertheless, it confidently puts itself on display: The chassis are meant to be visible; a front grille is only optionally available. For this, the diaphragms are color-matched to the cabinet.
Good things take time. Especially when it’s not just about a single speaker but an entire model series, and even more so when it’s the most successful model series in the entire portfolio. As a manufacturer, you should be able to score with innovations in the new edition. If you also see yourself as a pioneer in terms of sound, like KEF, this claim certainly doesn’t get any smaller.
That might be one of the reasons why the now eighth edition of the Q Series, first introduced in 1991, took so long to arrive. The English had already pushed the seventh edition from 2010 to the technical limit. New simulation methods and development insights from the first Blade generation resulted in a tremendous technological leap that explains the long life cycle of the model series at that time.
Clear lines, right angles, and a matte finish in white or black make the Q750 appear timeless and simple in its own way. Nevertheless, it confidently puts itself on display: The chassis are meant to be visible; a front grille is only optionally available. For this, the diaphragms are color-matched to the cabinet.
The Legacy of the Lineage
The entire DNA of the Q Series is also found in the current new edition. The central element, which already distinguished the speakers of the first generation, is KEF’s Uni-Q transducer. The letter “Q” stands in English for the directivity index, a measure that indicates how directional a speaker radiates sound. Normally, it increases with rising frequency, meaning that speakers bundle more strongly toward higher frequencies. The designation Uni-Q, on the other hand, stands for a uniform, that is, constant directivity index, both in horizontal and vertical directions. Such a uniform radiation pattern is achieved through the extraordinary driver arrangement, where a tweeter dome sits at the center of a cone driver, exactly where the dust cap would normally be. Already in the first generation, KEF relied on such a dual driver, which also gave the Q Series its name. The system has been continuously refined over decades and is found in various versions in almost all speaker models from KEF.
A new edition of the Q Series without a revision of the Uni-Q driver would therefore be almost unthinkable. However, there still seems to be sufficient potential for optimization: The tube that closes the tweeter at the back is now no longer cylindrical but tapers conically towards the rear. This is intended to improve sound transmission to the dome, which according to the manufacturer reduces harshness in the lower treble range.
Active and Passive
Active and passive at the same time: KEF uses a 2.5-way principle with a closed cabinet and two passive radiators on all floor-standing speakers of the new Q Series, which support an active driver. Speakers with a small volume can thus be tuned lower than with a bass reflex port.
With the floor-standing speakers, such as the tested Q750, KEF remains true to its line in other aspects as well. The English see the box as a 2.5-way bass-reflex design, where the resonance support in the bass is not realized with a reflex port but with the help of two passive radiators. A design principle that was applied in a similar form already in the very first series with the KEF Q60.
Active and passive at the same time: KEF uses a 2.5-way principle with a closed cabinet and two passive radiators on all floor-standing speakers of the new Q Series, which support an active driver. Speakers with a small volume can thus be tuned lower than with a bass reflex port.
Here too, they fine-tuned the details and were able to achieve improvements in both types of drivers, active and passive. The newly designed surrounds are said to allow greater excursions, reducing distortion at higher levels. According to KEF, the behavior of the active woofer in the crossover region could also be significantly improved through changes to the drive and centering, which should especially benefit the midrange reproduction.
Clear Lines, Right Angles, Exposed Drivers
Not only in technology but also in appearance, they stuck to the tried and true. The cabinet is primarily functionally designed; the clear lines and right angles give the box a timeless appearance and maximize volume. Spike outriggers ensure a secure stand but also a certain lightness. The rather sober appearance is underlined by a matte surface in the trend colors black or white. By the way, a front grille with magnetic attachment is now only optionally available; KEF prefers to showcase the drivers in the new Q Series. The diaphragms and the logo on the top edge of the box are therefore color-coordinated with the surface. This looks very coherent and noble; of course, you cannot expect handcrafted quality in this price range. In such speakers, it is not the optics but the sound quality that takes center stage. According to experience, KEF has a lot to offer in this regard, especially in the Q Series, which particularly benefits from technical advances in the higher-quality model series.
The Uni-Q driver has been the trademark of the Q Series from the very beginning. In the Q750, the dual driver with an external diameter of 16.5 cm covers the entire frequency range; the crossover to the internal tweeter dome is at 2.5 kHz. With such an arrangement, the sound over all frequencies comes from the same origin, minimizing time differences between the drivers.
In the listening test, the Q750 initially appeared gentle. “Automaton,” the new album by Jamiroquai, it played homogeneously, cleanly, and confidently, which was really no easy task with the rich synthesizer sound. The beats popped out from below with temperament and contour; impressive was the clean timing and a somewhat warmer palette of timbres. Only the last spark of treble energy didn’t quite ignite. Maybe this somewhat deliberate approach didn’t suit such energetic music? That’s how it was! With Anton Rubinstein’s ballet music from “The Demon”, the KEF could play out its true strength and thrilled with a fantastic, 3D photorealistic imaging as well as naturalness and a completely effortless layered sound. It gave the opera hall an impressive width and depth and such a spatial and enveloping sound image as one only knows from the best surround recordings.
And even Katie Melua’s “Lucy in the Sky” came with a three-dimensional clarity and a cozy atmosphere, so much so that the testers lingered in awe before this yet affordable box and listened for a long time. KEF thus had good reasons to let the new Q Series mature longer: You don’t make such a quality leap every day.
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