Daniel J SaitQ. What do you feel are the key features that differentiate the Ci200RR-THX from other in-ceiling units on the marketplace?
Dr. Jack Oclee-Brown: The Ci200RR-THX is based around our latest Uni-Q driver technology. The Uni-Q uses a tweeter placed at the acoustic centre of the bass/midrange driver. Using this configuration we can make both the acoustic centre and the dispersion of the tweeter and woofer appear the same. The result is that once you add a crossover, it is almost impossible to tell that the sound is coming from two drivers. Normal systems suffer from interference because of the two separated drivers.
For a ceiling speaker this is particularly important because of the orientation of the speaker. For use in a home theatre, the Ci200RR-THX should be placed in the ceiling as close to the point above the front edge of the screen as possible, because of the wide off axis response, it will sound like the audio is coming from the screen. While this is true for all KEF Uni-Q speakers, with the Ci200RR-THX, special attention has been paid so that this is effective even in the largest theatre rooms.
Q. The ‘sweet spot’ of listening with the Ci200RR-THX is billed as very wide– how has this been managed?
A. With a traditional loudspeaker the sound becomes very directional at the crossover between the tweeter and the woofer. With a Uni-Q this problem is eliminated. In addition, the Ci200RR-THX utilises a large 1.5in tweeter with one of our most recent ‘tangerine’ waveguide designs which helps to keep the dispersion of the treble very wide. Overall the dispersion is more consistent than a traditional loudspeaker, which means that you get good sound over a wider coverage area.
Q. What challenges were there in attaining THX ULTRA2 certification?
A. One of the most challenging parts of the ULTRA2 certification is the output level requirement. THX specifies a high maximum output level that can be quite tricky to achieve. In the Ci200RR-THX the large tweeter and the large voice coil on the woofer help us to hit this specification. Both of these features are also critical in achieving low levels of dynamic compression.
Q. Why is THX ULTRA2 Certification important for KEF?
A. KEF spent significant engineering and monetary resources, to design and build a speaker capable of being used as a LCR in very large theatre rooms – where the viewing distance could be greater than 4 meters and the cubic volume could be over 85m3 (3000ft3). This also required more expense on a larger motor structure (magnet) than is found in the typical in-ceiling speaker. Being one of the few in-ceiling speakers to achieve THX ULTRA2 Certification reinforces this point, and gives the end-user comfort in knowing their theatre will exceed expectations.
Q. How easy is the speaker to install?
A. The Ci200RR-THX uses KEF’s UTB (Ultra-Thin Bezel) and magnetic grille. So all you see around the grille is a very thin white bezel edge that can be painted to match the ceiling colour. Once the hole has been cut and the wire run to the location, installation of the speaker takes less than two minutes. All it takes is tightening four dog-leg mounting screws and then the grille magnetically snaps into place.
Q. Can an in-ceiling speaker ever be as good as free-stander?
A. The latest in-ceiling loudspeakers are extremely good and can offer performance that is, in many cases, as good as equivalently priced floor-standing loudspeakers. Acoustically there are advantages in both types of design. For example, with a floor-standing loudspeaker it is normally the case that the physical position will be better, most likely it will be placed directly in-front of the listener.
On the other hand, an in-wall or in-ceiling mounting results in a better acoustic loading for the driver. However, the installation is absolutely critical to getting the best performance from a wall mounted loudspeaker. It is important that the walls and ceilings are built as sturdily as possible to avoid vibration, and that the rear cavities behind the loudspeakers are well proportioned and filled with acoustical damping material. For ideal bass response with the Ci200RR-THX, we recommend a rear volume of 20 litres or more, but it can be used in cavities as small as 10 litres.