KEF Model105/3S

Commentary

This is a tall boy type speaker system developed with the latest know-how while inheriting the genealogy of the long-selling Model 105.

A TCC (Twin Coupled Cavity) system using two 20 cm cone type woofers is adopted to enhance the low-frequency reproduction capability.
This system employs a structure in which two woofers are mounted horizontally and vertically inside the enclosure. By twin-driving the woofers, natural deep bass sound is emitted instantaneously from a low-frequency port called an air diaphragm.
This structure looks similar to the bass reflex method, but the operation principle is different. In the bass reflex method, the resonance effect is used to increase the quantitative bass sensation, so it tends to be played back as sound after being delayed by one wavelength, or the bass expression tends to be wrapped around regardless of the musical tone. In the TCC system, the top and bottom horizontal woofers each have a sealed cavity, and an air diaphragm is arranged in an intermediate space between the woofers, so that the air layer acts as an effective load against the movement of the woofer and achieves high efficiency.
In addition, the magnets of the two woofers are connected to each other by a special rod. This not only serves as a four scan cell to prevent delayed resonance, which causes congestion, but also converts the force given by the two upper and lower magnetic circuits into acoustic energy.
This TCC system prevents the cancellation phenomenon that occurs when the phase of the unit and the duct are opposite to each other below the resonance frequency that occurs with the bass reflex system.

Two 16 cm cone type mid-bass woofers with polypropylene diaphragm are mounted for the mid-low range.

A coaxial unit UNI-Q driver composed of a 16 cm cone type unit and a 2.5 cm soft dome type tweeter is installed in the middle and high area.
The UNI-Q Driver is different from the coaxial unit which is unified only on the plane. In order to achieve a single sound in the depth direction, the structure in which the acoustic centers of two units, a tweeter and a driver, are completely overlapped is adopted.
In order to realize this UNI-Q structure, a new magnetic material, neodymium iron boron, which has 10 times the energy of ferrite, is used for the magnetic circuit of the tweeter, and the magnetic circuit of the miniaturized tweeter is superimposed inside the voice coil of the low frequency unit.

The unit layout is a vertical twin system with a UNI-Q driver installed in the center and a low-frequency unit mounted on the top and bottom, so that all sound sources coincide at the same point in space and a clear sound image is obtained over the entire frequency band.
The UNI-Q driver and Twin Drive midbus woofer are mounted with a 75 mm thick baffle block hollowed out. This baffle block is equipped with a high-compression chipboard MDF that is designed not to have a specific resonance frequency. Moreover, it is designed to be semi-floating from the enclosure to block unwanted vibrations from the enclosure, which adversely affect sound quality.
In addition, the back of each unit is separated by an aluminum diecast cover called a pot to prevent mutual interference.

KEF's unique Conjugate Load Matching (CLM) mechanism converts irregular and complex impedance into an infinitely flat resistance value over the audible frequency band, ensuring stable sound quality under all conditions.

The enclosure is made of 22 mm thick material, and the interior has a thorough vibration isolation structure that eliminates unnecessary resonance.
In addition, the exterior is finished with a beautiful walnut wood finish in which the wood grain is symmetrically matched by slicing a single veneer.

The pair characteristics of each unit are strictly controlled by a computer, and the L/R difference is kept within 0.5 dB.

In addition, a separate large input terminal is mounted for bi-amplifier drive.

The legs can be equipped with removable spikes and spike covers.

Model Rating

Method	4-Way, 5-Speaker, TCC System, Tall Boy Type
Units Used	For Ultra Low Band : 20 cm Cone Type x2 For low band : 16 cm cone x2 For Middle and High Areas : 16 cm Coaxial Type (16 cm Cone Type, 2.5 cm Dome Type)
Frequency characteristic	50 Hz ~ 20 kHz ± 2.5 dB (2m on axis)
Sound pressure level	93 dB (1m on the reference axis, 50 Hz to 20 kHz, anechoic room, at 2.83 Vrms pink noise input)
Impedance	4 Ω (± 2.5 dB, 50 Hz to 20 kHz)
Crossover frequency	160 Hz, 400 Hz, 2.8 kHz
Rated input	150W
Max Input	300W
External dimensions	Width 280x Height 1,104x Depth 405 mm
Weight	42kg