Carlton (1967-69)

The Carlton, released in 1967, was born out of KEF’s considerable experience in the design and manufacture of broadcast monitor systems for professional sound, film and television studios.
 
Tests indicated that the most critical range in a loudspeaker extended from 250 to 4000Hz, where the ear can detect very small changes level as well as quite small amounts of colouration. Key to this new system, therefore, was the M65 midrange unit, a highly sophisticated design based on a 2.5 inch hemispherical diaphragm made initially of aluminium and later changed to ‘Acoustilene’ (plastiflex doped bextrene). Driven at its outer edge by a 2.5” diameter voice coil working in a powerful magnetic field, the unit was highly sensitive, and some idea of its construction can be gained from the weight of the magnet structure, which was 6.5 lbs. The rear of the diaphragm was loaded by a 33” long pipe, damped with a density-tapered plug of long fibre wool. To ensure adequate power handling the voice coil former was made of aluminium with heavy copper wire encapsulated in resin.
 
The smooth transparency of this new mid-range unit was at once apparent. Alliance with the new T27 tweeter extended the range right up to 30kHz without directional effects and provided fatigue free reproduction of a standard far beyond that of any other loudspeaker of the time.
 
The woofer used to complete the system was an updated version of the well-known B1814 with its massive rectangular flat-fronted diaphragm of aluminium-skinned polystyrene, working in a highly damped and rigidly-braced, enclosed cabinet.
 
Fussy styling was deemed inappropriate with such a large enclosure, the simple design relying on first class cabinet work and carefully selected veneers of Teak, Rosewood (Palisander) or Walnut with a bronze grille.
 
Specification: Carlton
System type: Three-way, floor standing
Enclosure type: Closed box
Size: 36 x 17 x 14 inches (915 x 432 x 356 mm)
Weight: 85 lb (38.6 kg)
Input Impedance: 4-8 ohms
Maximum input power: 25W rms, 50W peak
System resonance: 45Hz
Frequency range: 20-30,000Hz
Input connections: Bulgin P.74 plug.
System: A6048
Drive units: B1814 bass unit (A6179), M65 Midrange unit (A6432), T27 tweeter (A6430)
Crossover: A6407