KC62

Reviewer: Srajan Ebaen
Financial interests: click here
Main system: Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Audirvana 3, Qobuz, Tidal, Denafrips Terminator+ clock-synced to Soundaware D300Ref SD transport/USB reclocker; Preamp: Vinnie Rossi L2 Signature with WE VT52/300B or Elrog 50/300B; Power amps: LinnenberG Liszt monos; Headamps: Questyle CMA-800r monos; Phones: HifiMan Susvara; Loudspeakers: Audio Physic Codex; Cube Audio Nenuphar; Aurai Audio M1 [on loan]; Cables: Complete loom of Allnic Audio ZL; Power delivery: Vibex Granada/Alhambra on all source components, Vibex One 11R on amps, LessLoss C-MARC Entropic cords between wall and conditioners; Equipment rack: Artesanía Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands; Sundry accessories: Acoustic System resonators, LessLoss Firewall for loudspeakers, Furutech NCF Signal Boosters; Room: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room so no wall behind the listening chairs
2nd system: Source: Soundaware D100Pro SD transport; DAC/pre: Denafrips Terminator or COS Engineering D1; Amplifier: Bakoon AMP-13R or Crayon CFA-1.2; Loudspeakers: Acelec Model 1 w. Franck Tchang magnesium super tweeters, sound|kaos Vox 3awf, Zu Submission subwoofer; Power delivery: Furutech GTO 2D NCF; Equipment rack: Hifistay Mythology Transform X-Frame [on extended loan];  Sundry accessories: Audioquest Fog Lifters; Furutech NFC Clear Lines; Room: ~4x6m
Desktop system: Source: HP Z230 work station Win7/64; USB bridge: Audiobyte Hydra X+; Headamp: Kinki Studio Vision THR-1; Phones: Audeze LCD-XC on Forza Audio Lab cable; Powered speakers: Fram Audio Midi 120
Upstairs headfi system: Source: Soundaware A280 SD transport; Integrated amplifiers: Schiit Jotunheim R or Bakoon AMP-13R; Phones: Raal-Requisite SR1a, Audeze LCD-2, Final Sonorous X & D8000, HifiMan HE-1000
2-channel video system: Source: Oppo BDP-105; DAC: Kinki Studio; Preamp: Wyred4Sound STP-SE II; Power amp: Pass Labs XA-30.8; Loudspeakers: German Physiks HRS-120; Room: ~6x4m
Review component retail: €1'500

Unicorn sighting? Only if you misspell it. KEF's Uni-Core array is very real. It's a patented solution to move two force-cancelling woofers into 1/3rd closer proximity by sharing one motor system with concentrically sleeved voice coils. The first model to exploit this invention is today's KC62, a black or white micro subwoofer which combines two 6.5" force-canceling woofers with 1kW of class D power inside an extruded 14kg aluminium chassis of ultra-compact 246 x 256 x 248mm proportions. There are five DSP presets: room, wall, corner, cabinet and apartment. With them we input automatic boundary gain compensation. The same DSP also includes a smart limiter to avoid overdrive should our inner headbanger emerge.

Next come 105dB max SPL and a shocking -3dB/11Hz reach claim. Compare that to the recently reviewed ModalAkustik MusikBass. That began its 6dB/oct. acoustic roll-off at 35Hz to be -6dB at 18Hz despite 2 x 12" woofers. That's because its so-called RiPol loading, whilst categorically avoiding room pressurization effects by operating as a velocity converter instead, also caused serious out-of-phase cancelling from dipole radiation.

With KEF's 180°-radiating pressure generator type, the RCA-based 4th-order 24dB/oct. low-pass filter is 40-140Hz variable. LFE signal already filtered in an AV receiver or pre/pro bypasses it. A matching high pass on RCA outputs can alternately daisy-chain another subwoofer. Speaker level inputs via push connector are provided as well. The KC62 is the Brit's first model to exploit their new Uni-Core array. Its drive units use another company exclusive called P-Flex aka origami surround. Scroll back for the lead image to see its internal geometry. As Fostex and Purifi do with their own suspensions, it exploits pleats to better resist the acoustic pressure in the cabinet without decreasing sensitivity like traditional half-roll surrounds. Finally there's a 3rd KEF innovation by way of a patent-pending real-time motion feedback accomplished without a sensor. That reduces distortion for tighter signal tracking by monitoring the voice-coil current. Philips had early sensor-based motion feedback decades back and various so-called servo subwoofers including Velodyne's applied their own take. KEF call theirs Smart Distortion Control Technology.

These three innovations follow KEF's earlier meta material as a type Medieval labyrinth-shaped diffuser which absorbs 90% of rear radiation when mounted behind a tweeter. Someone at the company's R&D lab must be drinking hyper-caffeinated brain juice. Innovation stimulates evolution. Those who insist that nothing new happens in hifi should keep an eye out for KEF. Their team clearly aren't content to rest on their laurels and of late have bowed a number of inventions which promise to advance the state of our audio arts.