Learn How this room was tuned

The Uni-Q driver

Why the LS50 Wireless II plays its treble from the centre of its cone, and what absorbs the sound behind the tweeter.

KEF LS50 Wireless II Uni-Q, with MAT

In an ordinary two-way speaker the tweeter sits above or below the cone, so the high and low parts of a voice start from points a few centimetres apart, and how they combine shifts as you move around the room. KEF’s Uni-Q puts the at the centre of the . KEF says the two then share one acoustic centre, and the cone’s curved face guides the tweeter’s sound outwards, so the two blend in tone and in how widely they spread into the room. KEF’s way of putting it is that every seat is the best one in the house; here, with Dirac Live tuned across the whole sofa, that is the idea.

A driver pushes air both ways: as much sound comes off the back of the tweeter’s dome as off its front. Behind the dome, deep inside the driver, that sound has nowhere useful to go, and KEF says that left untreated, some of it reflects back to the dome and colours what you hear.

KEF’s fix is MAT, short for Metamaterial Absorption Technology, designed with the Acoustic Metamaterials Group: a material that absorbs sound through its shape rather than its substance. Behind the driver sits a plastic disc that looks like a maze, holding folded tubes in two layers, each tuned to a different pitch. A duct carries the tweeter’s rear sound through the middle of both magnets to the disc, where friction against the tube walls turns it into heat. The tweeter takes over from the cone at , and the absorber is designed down to , so it covers everything the tweeter plays. KEF’s white paper calls the result near-perfect absorption. MAT treats only the tweeter’s rear sound; the cone’s is left to the braced, damped cabinet.

Drivers
Absorber
Tweeter rear sound absorbed

KEF’s Uni-Q page, and its LS50 Meta and LS50 Wireless II white paper and product sheet (PDFs)

The Uni-Q driver from the front, to scale: the tweeter at the centre of the cone, with sound spreading out from one point.
The Uni-Q on these crimson LS50s, drawn to scale from photographs of them. The rings spread from the one point both drivers share.
  • The Uni-Q coming apart and going back together: the tweeter’s parts at the front, then the surround, the cone and the motor behind them. KEF’s animation shows a copper finish; on these crimson LS50s the cone and waveguide are grey. Video: KEF.

Uni-Q in three short films from KEF

  • Sit anywhere, hear every detail

    Both drivers play from one point, so the sound spreads evenly and the balance holds from one end of the sofa to the other. Dirac Live, measured across the whole sofa, takes it the rest of the way.

  • Cleaner, less distorted sound

    With the tweeter and the cone sounding from the same spot, the notes they share do not interfere with each other on the way to you.

  • Perfectly timed sound

    Every part of a note reaches you at the same moment instead of a little apart, and Dirac Live corrects the timing of the speakers, subwoofers and room together, as they play at the sofa.

Pressing play loads that film from YouTube, which then applies its own privacy terms; until you do, nothing on this page comes from YouTube. More on KEF’s Uni-Q page.