Installing high performance speakers in ceilings and walls is not always straightforward, and a problem sometimes encountered is the limited depth available within drywall structures to accommodate traditionally engineered speakers and back-boxes.
DALI is proud to introduce a solution: the PHANTOM K-60 LP. The K-60 LP, fully designed and engineered by DALI in Denmark, is a ceiling and wall speaker that uniquely combines class leading acoustic performance with extreme low profile dimensions, and no need for a back-box. In other words; The DALI K-60 LP is the best sounding ultra shallow CI speaker on the market today.
The PHANTOM K-60 LP headline depth dimension, from the inside surface of its front baffle to the extent of its back plate is only 36.5 mm (1.43 in), yet its acoustic performance and sound quality is comparable to, and in some respects outperforms, that of conventionally engineered ceiling and wall speakers of a similar size.
Re-thinking bass/midrange driver architecture
The K-60 LP bass/midrange driver architecture is a completely new development by DALI’s in-house engineering team and was inspired partly by the architecture used in the smaller drivers developed for the award winning DALI KATCH G2 wireless Bluetooth speaker.
Bass/midrange driver acoustics
A new bass/midrange architecture that offers reduced depth would of course be of little worth if the resulting driver’s performance were to be compromised, however that’s far from the case with the K-60 LP. The most obvious witness to its remarkable performance is the complex 3D form of its pressed and anodised aluminium diaphragm. The selection of aluminium for the diaphragm was necessary in order to achieve the stiffness and rigidity required considering the low profile driver architecture, but in addition to integrating curved and dome regions the diaphragm incorporates seven localised stiffening ribs to provide further rigidity. The stiffening ribs also provide a channel for the voice-coil lead-out wires (a small detail, but it actually results in slightly increased maximum diaphragm displacement) and their odd number was chosen to help suppress diaphragm resonant modes. As a direct result of its complex geometry, the K-60 LP bass/midrange diaphragm remains pistonic over much of its working range and consequently reaches a level of subjective performance all but unheard of in any similar installation driver, let alone one that offers such low profile dimensions.
Tweeter perfection
While the astonishing bass/midrange driver of the K-60 LP is its most notable technical highlight, its 25 mm soft dome tweeter is no less remarkable. The K-60 LP tweeter is directly derived from those used in DALI hi-fi models and offers much higher quality than would normally be found in similar installation speakers. In particular, and very unusually for a ceiling and wall speaker, the tweeter is fitted with a damped rear enclosure that serves to lower the fundamental resonance of the dome. The lower resonance enables the tweeter to operate further down the audio band and integrate more effectively with the bass/midrange driver at a relatively low 2 kHz crossover frequency.
The tweeter magnet system, again unusually for a ceiling and wall speaker, is a neodymium-iron-boron item. The magnet is designed with a central hole to provide an air passage to link the tweeter dome with its rear enclosure. NeFeB magnets are more expensive than the traditional ceramic alternative, however their low weight and compact size bring significant packaging benefits to a speaker such as the K-60 LP. The tweeter dome is encircled on the K-60 LP front panel by a short curved waveguide that provides dispersion control and radiation impedance matching. And the dome itself is an extremely fine and lightweight woven fabric item that’s able to respond almost instantaneously to reproduce the finest musical detail. It dovetails perfectly with the subjective qualities of the K-60 LP bass/midrange driver and expresses all the qualities that are to be expected from a DALI speaker.
No back-box necessary
A further important element of the K-60 LP’s low profile dimensions is that no back-box is necessary. Back-boxes potentially play multiple roles in ceiling and wall speaker installations: they define the air volume that the bass/midrange driver requires in order to meet its low frequency bandwidth specification, they can assist in reducing sound transmission to adjacent rooms, and occasionally they are required for fire safety compliance. If however, as in many installations, the second two back-box grounds are not relevant, a back-box can add installation complexity and consume precious installation depth.
So the K-60 LP is able to meet its low frequency bandwidth specifications with anything from no back-box at all, to one of 5 litres minimum internal volume. This however means that the low frequency characteristics of the K-60 LP bass/midrange driver had to be specifically engineered to work with a wide range of rear air-volume compliance. So the driver’s suspension compliances (suspension and surround) are fine-tuned to provide the restraining force that would otherwise be the responsibility of the backbox air volume. And the K-60 LP driver also, despite its low profile format, is still able to reproduce significant low frequency volume levels from its remarkable ±7 mm maximum diaphragm displacement.
