Firstly, I should declare an interest in KEF. As a youngster, I was enamoured of the brand, and always wanted a pair of KEF Concerto loudspeakers, an ambition never achieved (although I have since owned other KEF models). Financial interests aren't the only potential sources of bias in reviews.
Of course, things have come a very long way since the KEF Concerto. In particular, in recent times, KEF has been keen on coaxial drivers, with the tweeter mounted in the centre of a larger unit. KEF calls its system the "Uni-Q driver array", and that is what KEF has installed in its R700 floor standers.
The 25mm aluminium dome tweeter is responsible for frequencies of about 2900Hz, while the surrounding 125mm aluminium cone mid-range driver carries the load between 500Hz and 2900Hz. Below, 500Hz is delivered by two 165mm bass drivers, one mounted above the Uni-Q, one below.
Given the efforts that KEF has put into making each loudspeaker have a single-point source — a virtual one in the case of the bass — it's a pity that the speaker sits just a little too low for ear-level tweeters. These are just 800mm from the floor. On my couch, which is pretty standard, my ears were at the level of the top woofer, rather than the tweeter.
The enclosures are bass reflex loaded with two ports on each. Foam bungs are provided to insert if necessary to tame the bass for close wall placement. Rather heavy die-cast aluminium feet are provided, which screw onto the bottom of the speakers, providing greater side-to-side stability. Spikes screw into these, and can be adjusted from the top using a hex key.
The cabinets on the review speakers were finished in a gorgeous, piano-black gloss that would not have looked out of place on a Steinway. The cloth grilles are removable, and the speakers look even better with these off, with the drivers surrounded by brushed aluminium rings, contrasting nicely with the black of the enclosure.
One excellent thing about these loudspeakers is their ability to retain their composure as the volume control is advanced. The only apparent change in the sound was that it got louder — it did not get harsher. It did not get confused. The drums on "Those Damned Blue Collar Tweakers" from Primus' Sailing the Seas of Cheese kept spiking above the melodic elements of the sound, cleanly and controlled, even when the more complex instrumentation kicked in, increasing the effective average level. My SPL meter was showing an average level of 100dB SPL, and it sounded enormously loud, but it was still extremely clean and coherent.
A clue to the reason why the speakers could manage this performance came towards the end of the track as the bass guitarist slides a powerful note down to the bottom of its range. It was here that the low frequency limit of these speakers became evident.
They sounded fine, and most people wouldn't notice, but if you're used to hearing this track on speakers that go solidly all the way down to 20Hz, you will notice that the solid bass foundation at its lower reaches is first muted, and then largely disappears as the note descends.
My suspicion is that KEF has traded off extreme bass extension in favour of exceptional power handling in the normal bass range. And that's a sensible trade-off. Especially as you do get almost all of the musically significant bass.
There is more to stereo music than sheer rocking power, of course. On the Primus, there were suggestions of top-class imaging, so I put on the track "Nobody" from Ry Cooder's Jazz CD. The tonal balance of this track was about as perfect as you can get, with the male vocals delivered without any of the common "chestiness" so often created by loudspeakers, and with a truly startling naturalness. The vocals were beautifully located, including during the multi-part vocal sections, with the precise location of each able to be clearly identified.
KEF hasn't lost it over the years. With the R700 stereo loudspeakers, aside from the deepest bass reaches, you're getting AU$10,000 sound for half the price.