Precision and depth: KEF Q350 bookshelf speakers review

When coining the phrase ‘the best speakers’, there are plenty who will let out an involuntary sigh. After all, you'll only be truly won over if you hear them for yourself – something that KEF are clearly confident of with its KEF Q350 bookshelf speakers. Boasting big sound, these speakers contain the brand's Uni-Q driver array - an innovation that places the tweeter right at the centre of the bass/midrange cone. The result? Well, KEF claims that the unified sound field makes for a more natural, consistent and immersive listening experience.

Another bit of technobabble from high up on the spec sheet is the Computational Fluid Dynamics (CFD) port. Before you reach for your physics textbooks, this is the internal shape of the rear-facing bass port. It’s been designed – by people with giant craniums – to cut down on midrange frequencies leaking into the port for more bass clarity. All big claims, for sure. But do they add up? Resident audio expert Chris Duffill has rigged up the KEF Q350 bookshelf speakers for a lengthy test run.

KEF Q350: Design and build

Make no mistake, the KEF Q350s are larger than many bookshelf speakers, so it’s no surprise that they’re also reassuringly weighty. Lifting them from their packaging was no small feat, but I soon admired them gently placed on the floor. My first impressions were excellent. Not only is the walnut finish convincing it also feels quite hard-wearing. Although these do come in black or white, depending on what you prefer for your music room.

But it’s the beautifully designed and engineered cone with all that Uni-Q driver goodness behind it that really caught my eye. It’s telling that these speakers don’t come with clip-on fabric grills. Who would want to cover these artfully finished cones with black cloth?

At the rear, there’s a sizable rear bass port and standard speaker wire terminals. Looking at placement options, I did notice how deep these speakers are – they’re over 30cm from front to back. Knowing that the bass port needs a little functional room of its own, this is hardly an issue for me in a large-ish room, but if you’re stuck for space, keep this in mind – especially if you're putting these on an actual bookshelf.

KEF Q350: Setup

I mounted these on Atacama stands, weighed down with sand for stability and better isolation. There are no threaded stand mount holes or other attachment points on the Q350s, so Blu-Tac is your friend here. Yes, really. Not only does a fresh pack of the stuff form a solid bond over time, but it’s also removable without leaving any marks. A day after mounting mine like this, I did a tilt test to see how well it would fare – the speaker would have stayed on, even if the stand was almost pushed over. I did find that the lack of any features underneath made aligning the speaker with the top plate of each stand a little tricky. But masking tape and tape measure came to the rescue.

As for speaker wire, I attached gold-plated banana plugs to some  QED Performance Micro Speaker Cable. This is a good gauge of wire for this size of speaker. I hooked these up to my Marantz PM6007 amplifier – more than capable of providing the wattage and also a good match in terms of impedance. It's also a good match as a turntable for playing vinyl.

The sound

Ahead of my final review, I’d already spent several weeks having regular listening sessions – and that’s to allow a breaking-in period. In my speaker research, I’d heard from plenty of owners about the time the Q350s take to sound their best. As break-in periods go, 50 hours seemed to be the consensus. But did that turn out to be true?

Yes. In my experience, breaking a speaker in is absolutely essential – getting those cones worn in really does smooth out the harsh edge you get right out of the box. And that’s perfectly understandable – especially given the materials used on the cones here. At the start, I found the KEF Q350s to be powerful but a little of a blunt instrument. Even upper mids and highs would sound forced and too constrained.

Cut to a few weeks of persistent listening later, and they’ve warmed up very nicely indeed. I’m now getting the full-bodied bass balanced with warmer mids and well-defined – but far less clipped – highs. And, as for that high-tech bass port, I don't feel that the bass is getting muddled up with any errant midrange tones.

Analogue music test

I had a CD player hooked up to the Marantz. But the amp's excellent internal DAC matched my turntable so well that I switched over to records for the rest of my testing session. Using the Cambridge Audio Alva ST turntable I reviewed, I put the KEF Q350 speakers through their paces.

First up, something delicate to test the definition – James Horner’s orchestral soundtrack to Star Trek II: The Wrath of Khan. Choosing the softer, more pensive tracks like Enterprise Clears Moorings, the woodwind section really was an acoustic treat – and I found the stirring addition of the strings in that track did play to the Uni-Q driver’s strengths. Classical and orchestral music often falls foul of lesser speakers by becoming muddied in the midrange – but not here.

Second on my playlist was something with pop vocals and punch– David Bowie’s Let’s Dance. The title track did show off the KEF's strengths regarding the low end. When those bass drums kicked in, the Q350s drove it home.

What about those Uni-Q drivers?

Looking at the tech specs for a moment, I wanted to see if those Uni-Q drivers really did push out a more consistent, unified sound. I have to say that, in a room measuring around 18’ x 12’, I had no trouble listening from various seating positions. I never felt that the tweeters were becoming detached from the rest of the soundstage. So, that’s a win for the boffins at KEF.

The rest of my testing saw Judas Priest with Denim and Leather being let loose on the KEFs, as well as Guns N Roses. Sweet Child O’Mine was the standout here, as the track develops from a gentle soft-rock ballad into a real barnstormer. The KEFs managed to deliver all of the subtleties and vocal depth, driving the whole thing home with some serious bass and satisfying mid-guitar clarity at the end.

Any downsides?

For my money, a bookshelf speaker should really fit onto – well – a typical bookshelf. Although I’m not a fan of slotting speakers onto shelves, I can see plenty of rooms where this is the only option. If that’s you, measure up first – the Q350s are definitely on the large side.

And, on the subject of speaker placement, these speakers have a rear-ported bass reflex design. The bass is partially reflected from the rear, too close to any surface, and the bass can sound boomy and reverberated. KEF has the foresight to include foam plugs for the ports if you need to have them close to a wall. If you absolutely have to put these on a shelf or closer than 6” to the wall, bear in mind that you’ll be toning down the bass response somewhat. Personally, if thinking about a speaker for a shelf – for casual listening – I'd go for Bluetooth. Some Bluetooth speakers are excellent for bass – plus they are a more fitting option for tight spaces.

Verdict

KEF Q350 speakers benefit from being broken in. Once done, they deliver. All listening is subjective. But, having come from some larger Acoustic Research and vintage NAD speakers, these were definitely a step up in overall performance. For my money, they qualify as some of the best speakers for music at this price point.

I find the sound profile of these speakers to be well-defined and detailed in the midrange, yet with a natural warmth and a punchy bass once the volume was cranked up. And the initially overly broad high demands also softened over time, balancing with those lows and mids very well. All-in-all, my record collection has a new lease of life thanks to the KEF Q350 bookshelf speakers – they’ve reminded me what analogue listening is all about.

Chris Duffill is a Tech Product Writer for What's The Best and Yours. His background includes writing, editorial, marketing, design, video production and photography.

He specialises in home entertainment and audiovisual tech, including speakers, amplifiers, turntables, streaming media players, and TVs. He is also one of our resident experts in computing (PCs, tablets, smartphones, smartwatches), DSLR photography and all kinds of digital cameras. He also writes about retro gaming, game consoles and various electronic gadgets. If it plugs in, lights up or makes a noise, he’ll write about it.

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