What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

H.H. Scott '59

KEF model 105

To get the best possible stereo image you need the best possible match between the loudspeakers. At KEF we produce matched sets of high , mid and low frequency units, using our unique computerised test facilities. Moreover our total system approach to the design of the enclosures and the electronic dividing networks, means that we can deliver model 105 in pairs that are nearer to the ideal "match" than any previous loudspeaker. KEF pioneered the use of computer digital analusis in loudspeaker design and you, the listener, can now hear the results: the most lifelike musical quality and the most astonishing stero perspective.
Model 105 is the newest additionto the wellknown Reference Series based on KEF's experience in the production of high-grade monitoring loudspeakers for sound and television broadcasting organisations. Its design is the result of a long-term development aimed primarily at avoiding the restrictions - particularly in stereo reproduction - imposed by the directional characteristics of conventional loudspeakers. Although the project involved some advanced mathematical theory, the design ojective was a very practical one, namely, that the high standard of sound quality and stereo realism to be achieved should not be confined to some preferred listening position, but should be maintained constant over a defined area large enough to accommodate a group of listeners. Judging by the outward appearance of Model 105, the most striking feature is the arrangement of the three drive units, two of which are mounted in a separate housing of somewhat unconventional shape. But this is only one aspect of a comprehensive development, in which drive units, filter networks, enclosures and spatial acoustic were all considered as part of an overall system-engineering plan.

KEF have combined subjective evaluation with objective standards. The result is Model 105: a loud speaker in a class of its own, which reproduces speech and music with the highest fidelity, even at realistic concert hall levels. Listen to a symphony on Model 105's and it's like having the orchestra in your room. Three fine drive units are used in Model 105, each matching perfectly the performance requirements of the system.
The low frequency unit is a 300 mm (12") driver with a massive magnet and high temperature motor assembly which easily accommodates the high power for which Model 105 is designed.
The 110 mm (5") mid range unit has an aluminium voice coil former, and a visco-elastic damped Bextrene diaphragm diaphragm supported by a special PVC edge suspension.
The high frequency unit is a 52 mm (2") radiator with a 38 mm (11/2") hemispherical Mylar plastic diaphragm and a damped roll surround. Each drive unit in the Model 105 has its own individual enclosure.

Model 105 Specifications

Dividing Network: 4th order Linkwitz-Riley band pass -6 dB at crossover points
Dividing Frequencies: 400 & 2,500 Hz
Nominal Impedance: 8 ohms
Programme Rating: 200 watts
Sensitivity: 86 dB spl for 1 watt (1m on axis-anechoic)
Maximum Continuous Sinusoidal Input:
35 Vrms 100 to 400 Hz
28 Vrms 400 to 2,500 Hz
11 Vrms 2,500 to 20,000 Hz
Maximum Output: 107 dB spl on programme peaks under typical listening conditions
Frequency Response: 30 to 25,000 Hz ±2 dB 38 Hz to 22 kHz at 2 m on measuring axis
Directional Characteristics:
Within ±1 dB of axial response up to 20,000 Hz (for ±5° vertical)
Within ±2 dB of axial response up to 13,000 Hz (for ±20° horizontal)
Amplifier Requirements: 40 watts minimum into 8 ohms
Fuses: Fitted to mid-frequency and high-frequency sections
Peak Level Indicator: Switchable to indicate power levels of 40, 50, 60, 100, 125, 150 and 200 watts
Dimensions: 965 x 415 x 455 mm, (38 x 16.3 x 17.9 in)
Weight Net: 36 kg (80lb)
Finish: Walnut

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