KEF R50 Dolby Atmos-enabled Speaker Preview

If you haven’t been paying much attention to the A/V world lately, it’s fair to say the official unveiling of Dolby Atmos at CEDIA this year has attracted quite a bit of attention. What is this Atmos thing I speak of? In short, it is Dolby’s new object-oriented surround format which makes the jump from 2-dimensional 5.1 and 7.1 formats to 3-dimensional sound. For consumers looking to upgrade their systems in order to support this format, you have 2 options in terms of loudspeakers: you can either add in-ceiling speakers or Atmos-enabled speakers. Priced at $1,200/pair, the KEF R50’s are an example of the latter option, which fires a driver array towards your ceiling, which combined with Dolby’s proprietary DSP magic, creates a virtual height channel.

Design Overview

In many respects, the KEF R50 isn’t what we’d qualify as a groundbreaking loudspeaker. The driver array, a two-way concentric design, is taken directly from KEF’s pint-sized R100 bookshelf speakers, although the R50’s feature a sealed enclosure versus the vented box of the R100. The array is angled at 20 degrees, and features a 1” aluminum dome tweeter nested within a 5.25” aluminum mid/woofer. This arrangement has several benefits, chief for this application being controlled directivity. In contrast to some Atmos-enabled speakers which rely on a “lip” to control directivity at the cost of potentially introducing diffraction effects, the R50’s mid/woofer acts as a waveguide for the tweeter, constraining its dispersion pattern. Per Jack Oclee-Brown, KEF’s senior research engineer, the directivity control provided by the concentric arrangement was sufficient on its own to fit within Dolby’s spec for Elevation speakers. While KEF did experiment with a lip, they found that it introduced diffraction without offering any meaningful improvement.

A shot of the KEF R50 with the grill on.

Looking to the specifications, the R50s have a rated frequency response of 105Hz - 18.5kHz, +/- 3dB, which is adequate for an Atmos-enabled speaker. The system has a nominal impedance of 8 ohms (4.8 ohm minimum), and a rated sensitivity of 85dB with 2.83V at 1 meter, suggesting that these speakers will need a fair amount of amplification to reach “spirited” levels (say for simulating a low jet flyover).

Analysis and Summary

We believe that the two-way concentric driver array as seen in the R50 is an excellent choice for an Atmos Elevation speaker. Power handling and ultimately dynamic capability are generally improved over “full range driver” options, and with proper crossover design, cone breakup isn’t a concern. At the same time, we’d be curious to compare the R50 against the Atlantic Technology 44-DA, which also features a concentric driver array, but costs $500/pair. Unfortunately neither KEF nor Atlantic Technology were demoing their Atmos-enabled speakers at CEDIA 2014, so we’ll have to wait a little longer to get a full picture of how these ostensibly similar designs compare.

Unless otherwise indicated, this is a preview article for the featured product. A formal review may or may not follow in the future.