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Review: KEF Q Series speakers (Q350, Q650c and Q750)

KEF Q series
KEF renews its KEF Q series - and that is quite important. The affordable Q-speakers are, after all, among the most popular models by the British at Maidstone.

KEF renews its KEF Q series – and that is quite important. The affordable Q-speakers are, after all, among the most popular models by the British at Maidstone. Better sound and a lower price may mean that the success will only increase. We look at it in this review.

The KEF Q-series loudspeakers for your home theater

With a brand like KEF, a loudspeaker range like the Q Series is more than just a little underexposed. What do you want, the British company has a lot of striking models in its range. The ultimate design speaker that is the Muon, the graceful Blade speakers, the spectacular sounding Reference series, the groundbreaking LS50 Wireless … there is a lot in the spotlight at KEF. Compared to all the foregoing, the Q series may be a bit boring. However, these are the speakers that average consumers may purchase, because they are affordable and can be used more universally. Put a set of Muons in your living room! That only works if you live in a castle or spacious villa.

This spring the Q series was renewed again. It is something typical of KEF that holds on to its historical names for its models, because we are now ready for the eighth generation of the Qs. The very first Q dates back to 1991 – 26 years ago! As a consumer you get a lot of choice if you choose the Q Series, because the range includes three floorstanders, two bookshelf speakers and a center. Only a series like Monitor Audio’s new Silver family will be out with even more members. A lot of choice is a good thing, we think, because that way you can select a speaker of the right size for your living room. Too big is not good, just as too small. This is certainly important for the stereo channels or left-right in a surround setup.

The wide range of speakers and the presence of the center speaker already indicates that the Q Series is intended for home cinema enthusiasts and for people who prefer stereo playback. We therefore look at both scenarios on the basis of the 5.0 set-up that KEF gave us. We received a set of Q750s (the middle floor stands, 649 euro each), a pair of Q350s (the largest bookshelf speakers, 279 euro each) and the Q650c (549 euro).

What’s new?

Those who say ‘KEF’ say ‘Uni-Q’. Uni-Q is the beating heart of almost every better KEF speaker and there are good reasons for this (see below). The coaxial drivers are also present at the Q Series, although it does have a different finishing level than the KEF premium speakers. But still, for the eighth generation Uni-Q on the Q-series has improved slightly, mainly by applying better attenuation at the tweeter.

What is striking about the bookshelf speakers (Q150 and Q350) is that the Uni-Q driver is now placed in the middle, where it was previously located in the upper half of the Q100 and Q300. That was necessary because those two smaller speakers at the front had a bass output under the Uni-Q driver. With the renewed bookshelf speakers the port has moved to the back. The result is speakers that are a lot tighter eyes, beautiful even, but slightly more sensitive to placement. On the other hand, a bass port on the back is better in terms of sound because there is less chance of ‘pollution’ from the middle due to unwanted frequencies that escape via a bass exit at the front.

KEF also did some minor interventions on the floorstanders and center speaker, which could potentially have a major impact. For example, the Uni-Q driver is mounted in a separate subdivision that decouples the loudspeaker better than before from the internal air movements caused by the woofers. Also important are new crossovers. In short, the adjustments that have been made seem to be mainly at the level of detail. That is not surprising, of course, if you are already on the eighth iteration of a loudspeaker family. It also does not mean that these ‘small’ adjustments can not have any major consequences.

Perhaps the best news to the new generation is that the price points have dropped quite a bit. Where the KEF Q600c (the previous center speaker) cost 649 euros, the recommended price of the Q650c is 549 euros. The Q300 bookshelf speaker was 349 euros each, that is 279 euros for the Q350. We note similar price decreases for each model. Especially when building a surround setup, that reduction is nicely included.

Tight finish

A sleek design has always been a hallmark of the Q Series, but with the new generation that goes even further. They are available in black and white, each time in a matt wood veneer. The walnut edition of the previous generation seems to have been deleted. The woofers and the Uni-Q driver are also matte, making the Q Series speakers look very contemporary. KEF did well, because in terms of form the Q Series is quite conventional. It is a rectangle, with no curves. The corners and edges are very sharp and seamlessly finished (which is more difficult). In front of the drivers there is not one screw to be detected, which together with that matte color makes these speakers more special that you would expect at this price point. On the weight you also feel that you do not have to deal with budget speakers here. They are pretty solid.

The Q750 we visited came with spikes and a foot in two parts that you can optionally mount. Always a good idea, because the speakers also get a better stability and fewer vibrations are passed to the floor. One notable innovation is that the Q Series speakers are no longer supplied with a loudspeaker grille. No, this is no longer in the box and must be bought separately. According to KEF, rosters are being used less and less – and indeed, the tight look of the Q speakers deserves that the drivers are just visible. The loudspeaker grilles can be purchased separately. For some people that is an extra cost, but the new Q Series is slightly cheaper than its predecessor.

Technical construction

The two bookshelf models (Q150 and Q350) are two-way designs with a bass reflex, while the center speaker and three floorstanders are all 2½-way. What does that mean? The Uni-Q driver is by definition already two-way, because it is a coaxial driver. This means that the tweeter in the center of the midrange driver is acoustically disconnected. This is immediately noticeable with the Uni-Q driver, because there is a kind of star for the aluminum tweeter. It does look a bit like an open-cut orange. This waveguide improves the appearance of high frequencies and casually gives the Q Series speakers a more unique appearance.

The great advantage of a coaxial driver is that it is a point source – a large part of the frequency range seems to come from one point, making the sound more coherent. Especially with large loudspeakers, there is a risk of a lack of phase coherence because they consist of different drivers that are mounted under each other. Music and film sound is therefore divided into frequencies over different drivers that are not entirely in the same place. A complex sound such as a piano touch thus comes at you from different starting points, while in reality it would come from one place. Only with a really bad loudspeaker you have a lot of problems with that, but even with a good one, a slight lack of coherence can make music less tight and smooth. In the case of surround, phase incoherence leads to a less accurate placement of effects. One advantage of surround is that with better AV receivers possible phase problems can be solved by a more sophisticated measuring system.

Depending on the model, the Q Series speakers are equipped with a Uni-Q driver of 130 mm (Q150 and Q550), 165 mm (Q350, Q650c and Q750) or 200 mm with the hefty Q950. The tweeter in the center of the coaxial driver is always the same 25 mm dome tweeter, except for the Q950 that gets a larger model. The top model is not only a bit more extensive than the rest, but is also slightly higher specified.

In a surround setup, we are particularly interested in the center. It is simply a crucial part if you really want to enjoy a good surround experience. The first impression we get from the Q650c with its centrally mounted Uni-Q driver is positive. The speaker is a bit bigger and heavier, a good sign. A center speaker needs to reproduce voices in particular, and that requires a certain high-bass reproduction, more than is sometimes suspected. After all, male voices can dive as low as 100 kHz.

Placement of the Q Series loudspeakers

As mentioned, the bookshelf speakers from the Q Series are equipped with a bass output at the back. With these two speakers you have to think about the placement. If you are forced to place them close to or against a wall or in a cupboard, you may have to weaken the layer. This may be necessary even after a calibration by the AV receiver, depending on how advanced your receiver is. We tested the Q Series for surround with two receivers: the Sony STR-DN1080 and the Arcam AVR390. The latter has a very good chamber measurement based on Dirac on board, which results in a clearly better result. However, the STR-DN1080 is price-wise more in the class of the Q Series.

The other Q Series speakers are all closed at the back, so they are slightly less sensitive to placement. The Uni-Q driver shows its strength here again, because another advantage of this coaxial driver is that the sound stays in balance in a larger area. The sweet spot is not super small. Turning on the speakers remains a good idea, but we would recommend that these KEFs do not do it that much. This way the whole bank can enjoy a good sound, not just that one person in the middle.

A center speaker is best placed under a TV or behind an acoustically transparent screen. The Q650c is, however, a pretty deep thing, so you have to provide good support. A bookshelf will not work, so perhaps a stand for this speaker is the best choice. In any case, the Q350 and Q750 that we have tested are not the smallest speakers either. Especially the Q350 is a larger bookshelf speaker, especially if you use it purely as a surround channel. In a smaller living room you might already have enough with the Q150. For our test we do not use a subwoofer from KEF – although the brand certainly has creditable subs in the range. The necessary support in the layer is provided by a Teufel T4000.

What does it sound like?

For our viewing test, we get ‘Pacific Rim’ up again. It is even more fun to pay homage to kaiju films and animated titles like Evangelion, also in preparation for the second part. If everything goes well, it will reach us in early 2018. One thing turns out to be right: you do not have to be in that one place to get a good surrounder experience. The Q650c center speaker also immediately stands out. This is not the film filled with sophisticated dialogues, but there is a lot of calling while giant robots are dealing with extraterrestrial giants. The Q650c excels at those moments, because both the placement and the display of voices is really good. You notice the added value of the Uni-Q driver when you pay attention to the center speaker and the surround channels. When pilot pilot Raleigh Becket returns to the military and enters the large underground Jaeger base, Marshall Stacker Pentecost (a stern-looking Idris Elba) gets the necessary explanation about an ultimate offensive on the kaijus. The conversation takes place in a large room where hundreds of technicians tinker with giant robots and other jaegerpilots keep their workouts. That spaciousness conveys the Q’s well, with all the possible sounds of welders and other workmen around you, while the conversation comes through the center – and all this neatly integrated into the large sound image.

The first impression we got when viewing Pacific Rim (and then a number of other films, such as ‘Arrival’ on Ultra HD Blu-ray) is also confirmed when we go through a series of demo fragments of the 2016 DTS demo disc. This is part of our fixed test methodology, in which we deal relatively quickly with films from striking surround tracks (such as ‘F & F 7’, ‘Kingsman’ and ‘Hitman’). The Q Series are speakers that are interesting for surround, especially if you like a truly pronounced surround image. It is also a great asset in gaming, we notice when we dive into the world of ‘Horizon: Zero Dawn’ on the PlayStation 4 Pro. The pinpoint accuracy or accuracy provided by the Uni-Q drivers allows us to quickly determine the position of upcoming Watcher robots. Games also often have continuous soundtracks that are more in the background, depth that the Q750s can deliver.

The Q Series speakers are a bit less bombastic in the low because of their somewhat more neutral character, without sounding thin. For music that’s fine and maybe even a big trump, but with movies you might want to turn on a subwoofer.

However, notice for the KEF experts that the Q Series is still somewhat more commercially tuned than the higher series, such as the Reference. That is why we also write that they do not sound thin – there is indeed a thicker bass foundation present but that does not dominate.

Conclusion

The KEF Q Series consists of speakers that are very modern and sound. KEF always strives for a view that is as natural as possible, and that is what the Q-speakers do. They are more neutral and universal compared to a whole number of others. The downside to this is that you may have to be more willing to fine-tune on receiver side, for example if you like to receive action movies with lots of bass. A better receiver will also make them shine much more. You may therefore call these speakers rather sophisticated than spectacular. In that sense they also form a better basis for a surround setup than more colored speakers, because they better tolerate finetuning. For example, if we compare them with the much cheaper Dali Spektor speakers that we have tested for this in a surround setup, then those Spektors out of the box offer a big wow factor – but the Q Series speakers are those that are more accurate and coherent. You will appreciate that with films, games and music.

Cons

  • Grille is not included
  • Bookshelf speakers are location-sensitive
  • Q350 is overkill for surround channels

Pros

  • Tight, solid finish
  • Uni-Q driver provides a natural sound
  • Nice price drop
  • Wide appearance ensures good off-axis performance

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