C10, C20, C30, C40, C40D, C42, C60, C80

C10 (1985-88)
 
This tiny bookshelf speaker was the latest in the long and illustrious line that started with the famous Cresta system in the mid-1960s. Using a new B160 polypropylene coned bass/midrange driver to reduce colouration, the system was designed for wall or shelf mounting. The result was a diminutive little box that sounded much larger and louder than it looked.
 
C20 (1985-88)
 
Larger than the C10, and therefore able to use a 200mm bass/midrange unit, the C20 showed many similarities to its smaller brother, but with the greater cabinet volume allowing increased bass capability and higher sensitivity. The C20 was the classic bookshelf speaker in size, performance and price, and showed just how good the performance can be from a modest economical system.
 
C30 (1985-88)
 
The immediate successor to the famous Coda III, probably the most successful loudspeaker of its generation, the C30 had a lot to live up to. The formula was similar but the package had been significantly refined. The ‘flat’ balance of the Coda was retained, so this ‘large bookshelf’ speaker was best suited to open stand mounting. However, the new polypropylene coned 200mm bass/midrange unit had greater midrange sensitivity and improved bass damping, so shelf mounting was still a perfectly feasible option. C30 was broadly similar in size to the new C60 and Reference Model 103.2, and provided much of the performance of these more expensive stablemates in a simpler package.
 
C40 (1985-88)
 
The C40 was generous in both volume and drive unit. Bass was plentiful and extended, and the design was balanced to operate clear of room boundaries on open stands. The two new 200mm bass/midrange units used polypropylene cones. Operating as a 2½-way system, the lower driver was used only at the lowest frequencies, augmenting and extending bass output, substantially improving power handling capacity, and assisting bass damping. The system would go exceedingly loud, would handle plenty of power, and, with a generous bass delivery, was particularly suited to the cost- conscious rock listener.
 
C40D (1987)
 
The C40D was a derivative of the C40 with one of the two active bass drivers replaced with a passive radiator, producing a design similar to the Cara(1986).
 
C42 (1989)
 
The C42 was a system developed from the C40D.
 
C60 (1985-88)
 
The C60’s direct line of descent was from the highly regarded Caprice II, which in turn had much in common with the Reference Series Model 103.2. Where the similarly sized C30 gave sound basic engineering with the emphasis on cost-effectiveness, C60, at a higher price, provided much of the extra subtlety and refinement of the Reference Series. Already an inherently sensitive design, the C60 was further improved by inclusion of KEF’s innovative ‘conjugate load’ network, which allowed much more of the available power of the amplifier to be utilised.
 
C80 (1985-88)
 
Substantially the largest C-Series model, the slim, elegant, floor standing C80 was very much the Reference Model 104/2 for the cost conscious audiophile. The famous B139 provided exceptional bass quality and extension for the cabinet size and the new polypropylene-coned B160 allowed high sensitivity and power handling along with low colouration through the mid-band. The C80 was the second C-Series model to benefit from KEF’s ‘conjugate load’ crossover network design, originally developed for Model 104/2. The net effect on your hi-fi system of replacing a conventional 8 ohm speaker with one which presents a 4 ohm constant resistance is that you can double the sound power output of your existing amplifier without any increase in distortion.
 
Specification: C10
System Type: Two-way, bookshelf/stand-mount
Enclosure type: Closed box
Size: 300 x 205 x 172mm (11.8 x 8.1 x 6.8 inches)
Weight: 3.7kg (8.2 lb)
Nominal Impedance: 8ohms
Rated maximum power: 60 programme
Frequency response: 90Hz to 500Hz +/-3.0dB rising 3dB to 1kHz-20kHz +/-3dB (-6dB at 70Hz)
Sensitivity: 88dB for a pink noise input of 2.83V (under wall-mounted conditions)
Maximum output: 106dB on programme peaks under typical listening conditions
Finish: Simulated Walnut, Rosewood, Black Ash
System: SP3057
Drive units: B160 bass unit (SP1199), T33 tweeter (SP1089)
Crossover: SP2057
 
Specification: C20
System Type: Two-way, bookshelf/stand-mount
Enclosure type: Closed box
Size: 340 x 247 x 212mm (13.4 x 9.7 x 8.4 inches)
Weight: 6.5kg (12 lb)
Nominal Impedance: 8ohms
Rated maximum power: 100W programme
Frequency response: 72Hz to 400Hz +/-3.0dB rising 3dB to 800Hz-20kHz +/-3dB (-6dB at 58Hz)
Sensitivity: 90dB for a pink noise input of 2.83V (under wall-mounted conditions)
Maximum output: 110dB on programme peaks under typical listening conditions
Finish: Simulated Walnut, Rosewood, Black Ash
System: SP3053
Drive units: B200 bass unit (SP1200), T33 tweeter (SP1211)
Crossover: SP2053
 
Specification: C30
System Type: Two-way, stand-mount
Enclosure type: Closed box
Size: 503 x 247 x 212mm (19.8 x 9.7 x 8.4 inches)
Weight: 7.3kg (16.1 lb)
Nominal Impedance: 8ohms
Rated maximum power: 100W programme
Frequency response: 70Hz to 20kHz +/-3dB (-6dB at 60Hz)
Sensitivity: 90dB for a pink noise input of 2.83V
Maximum output: 110dB on programme peaks under typical listening conditions
Finish: Simulated Walnut, Rosewood, Black Ash
System: SP3058
Drive units: B200 bass unit (SP1206), T33 tweeter (SP1211)
Crossover: SP2058
 
Specification: C40
System Type: 2½-way, floor standing
Enclosure type: Closed box
Size: 650 x 247 x 262mm (25.6 x 9.7 x 10.3 inches)
Weight: 9.6kg (21.1 lb)
Nominal Impedance: 8ohms
Rated maximum power: 100W programme
Frequency response: 68Hz to 20kHz +/-3dB (-6dB at 58Hz)
Sensitivity: 91dB for a pink noise input of 2.83V
Maximum output: 111dB on programme peaks under typical listening conditions
Finish: Simulated Walnut, Rosewood, Black Ash
System: SP3054
Drive units: 2 x B200 bass unit (SP1205), T33 tweeter (SP1211)
Crossover: SP2054
 
Specification: C40D
System Type: Two-way, floor standing
Enclosure type: Passive radiator
Size: 850 x 265 x 315mm (33.5 x 10.4 x 12.4 inches)
Weight: 19.8kg (43.5 lb)
Nominal Impedance: 4ohms resistive
Rated maximum power: 300W programme (into 4 ohms)
Frequency response: 50Hz to 20kHz +/-3dB (-6dB at 38Hz)
Sensitivity: 87/89*dB for a pink noise input of 2.83V (*dependent on contour control)
Maximum output: 112dB on programme peaks under typical listening conditions
Finish: Walnut, Rosewood or Black Ash real wood veneers
System: SP3082
Drive units: B200 bass unit (SP1205), BD200 passive radiator (SP1223), T33 tweeter (SP1210)
Crossover: SP2107
 
Specification: C42
System Type: Two-way, floor standing
Enclosure type: Passive radiator
Size: 850 x 265 x 315mm (33.5 x 10.4 x 12.4 inches)
Weight: 19.8kg (43.5 lb)
Nominal Impedance: 4ohms resistive
Rated maximum power: 300W programme (into 4 ohms)
Frequency response: 50Hz to 20kHz +/-3dB (-6dB at 38Hz)
Sensitivity: 87/89*dB for a pink noise input of 2.83V (*dependent on contour control)
Maximum output: 112dB on programme peaks under typical listening conditions
Finish: Walnut, Rosewood or Black Ash real wood veneers
System: SP3104
Drive units: B200 bass unit (SP1205), BD200 passive radiator (SP1223), T33 tweeter (SP1210)
Crossover: SP2107
 
Specification: C60
System Type: Two-way, stand-mount
Enclosure type: Closed box
Size: 470 x 250 x 312mm (18.5 x 9.8 x 12.3 inches)
Weight: 12kg (26.4 lb)
Nominal Impedance: 4ohms resistive
Rated maximum power: 200W programme (into 4 ohms)
Frequency response: 66Hz to 20kHz +/-3dB (-6dB at 55Hz)
Sensitivity: 89dB for a pink noise input of 2.83V
Maximum output: 110dB on programme peaks under typical listening conditions
Finish: Walnut, Rosewood or Black Ash real wood veneers
System: SP3056
Drive units: B200 bass unit (SP1202),  T33 tweeter (SP1210)
Crossover: SP2056
 
Specification: C80
System Type: Three-way, floor standing
Enclosure type: Closed box
Size: 850 x 265 x 315mm (33.5 x 10.4 x 12.4 inches)
Weight: 19.8kg (43.5 lb)
Nominal Impedance: 4ohms resistive
Rated maximum power: 300W programme (into 4 ohms)
Frequency response: 50Hz to 20kHz +/-3dB (-6dB at 38Hz)
Sensitivity: 87/89*dB for a pink noise input of 2.83V (*dependent on contour control)
Maximum output: 112dB on programme peaks under typical listening conditions
Finish: Walnut, Rosewood or Black Ash real wood veneers
System: SP3055
Drive units: B139 bass unit (SP1212), B160 midrange unit (SP1203), T33 tweeter (SP1210)
Crossover: SP2055