KEF model Carlton III typ SP3020, 1983-1985, made in England

Link: Brochure [PDF]

Marked: October 17, 1984 build and test 

Carlton III is a two-way floor standing loudspeaker of medium efficiency fitted with a passive bass radiator which extends the low-frequency response. The active drive units are of very high quality construction using special diaphragms for extremely low colouration. It is suitable for use with large amplifiers and will satisfy listeners who appreciate the most refined sound quality at realistic, live volume levels. For over twenty years KEF has pioneered the use of moulded plastics diaphragms in producing loudspeakers of consistent and refined performance. The drive units and the passive radiator employed in Carlton III are the outcome of this experience, aided by modern research methods and precise quality control at all stages of production. The configuration of drive units used in Carlton III closely resembles that used in the KEF Model 104218 which enjoyed world— wide success in the seventies. setting new standards for domestic loudspeakers. Great care has been taken in the design of the dividing network so that the crossover region, where both high and low-frequency louspeakers are in operation, does not suffer phasing effects which would confuse the stereo image. Carlton III will reproduce sharply-focused, solid stereo images with programmes of high technical quality. Mid—range reproduction is coherent and highly detailed. Cabinet work is finished in top quality simulated walnut laminate with brown knitted cloth grille which is acoustically transparent, but nevertheless obscures the drive units. With the grille removed, Carlton lII assumes an arresting high-tech appearance with smart front panel graphics in a blend of brown, tan, orange and cream. See overleaf for full technical description and data. DIGITAL RECORDINGS Carlton III is perfectly suitable to reproduce compact disc and other types of digital recording, with full dynamic range.

The basic design of Carlton III employs the latest developments in 200mm Bextrene cone drive units to cover the essential musical range up to 3kHz. KEF pioneered the use of Bextrene diaphragms in domestic high fidelity loudspeakers during the early sixties and have unrivalled experience in their manufacture and application. When correctly damped and terminated. Bextrene diaphragms are unequalled in performance, consistency and reliability. They are generally superior to most ofthe newer materials currently in vogue and notable for their very low colouration. An auxiliary bass radiator extends the low-frequency range flat down to 47Hz. The unique KEF series ‘C’ bass loading technique is also incorporated to further extend response down to below 30Hz whilst minimising the effects of subsonic signals due to records warps and other faults. The upper octaves are radiated by a 25mm impregnated cloth dome tweeter with an impeccably smooth frequency response and excellent directional characteristics. An important feature is the computer- designed “seamless” dividing network with fourth—order target functions centred on 3kI-Iz. Acoustic output is transferred smoothly from the low frequency driver to the high-frequency units without any audible phasing effects, even in directions well away from the main listening axis. Sensitivity of Carlton III is above average at 86dB/m/W — making no great demands on the amplifier. When fully driven with a 100W per channel amplifier 3 pair can produce peak sound pressure levels up to 106dB in an ordinary living room. There are no matching problems with Carlton III. Its impedance characteristic presents an easy load for any 8 ohm amplifier. Input connections are made to substantial 4mm binding posts that suit most low— loss super cables. Connection can also be made using 4mm banana plugs. 

Specifications:
System Type: Two-way, floor standing
Enclosure type: Closed box
Nominal Impedance: 8 ohms
Rated maximum power: 100W programme
Frequency response: 47-20,000Hz +/-2.5dB at 2m on design axis (-10dB at 29Hz and 30kHz)

Frequency range: 
47Hz to 20kHZ ± 2.5dB at 2m on reference axis
(-10dB at 45Hz and 30kHz)

Directional characteristics: 
within 2dB of response on reference axis
up to 20kHz for ± 5° vertically
up to 10kHz for ± 20° horizontally

Maximum output: 
106dB spl on programme peaks under typical listening conditions

Charactenstic sensitivity level: 86dB spl at lm on reference axis for pink noise input of 1W

Distortion: Measured at im on reference axis at mean spl of 90dB.
anechoic conditions
Second harmonic:
less than I% from 60Hz to 20kHz
Third harmonic: 
less than 1% from 150Hz to 20kHz
Enclosure type: 

• Mechanical reflex 
• Tuning frequency 28Hz 

Internal volume: 44 litres
Nominal impedance: 8 ohms
Maximum amplifier power: normal 100W, audiophile 150W
Minimum amplifier power: normal 10W
Maximum continuous sinusoidal input: 
20V rms from 20Hz to 2.5kHz reducing to 8V rms from 4kHz to 20kHz.
Sensitivity: 86dB at 1m for a pink noise input of 1W (anechoic conditions)
Maximum output: 106dB on programme peaks under typical listening conditions
Finishes: Simulated walnut veneer
Grille: Brown fabric
System: SP3020
Drive units:

• B200 bass unit (SP1075)
• BD139 passive radiator (SP1082)
• T33 tweeter (SP1074)
• Crossover: SP2026

Dimensions (W x H x D): 315 x 700 x 280mm (12.25 x 27.5 x 11 inches)
Weight: 12 kg (26.2 lb)

Normal use: programme with limited dynamic range. e.g. VHF transmissions, pre-recorded tape  cassettes, compressed pop records. etc. Conditions of use include loud listening levels with power amplifier often driven into clipping and tone controls or equaliser used to significantly boost low and high frequencies.

Audiophile use: reproduction of wide dynamic range recordings, e.g. direct cut discs. compact discs and digital tapes. Conditions of use include ‘flat‘ replay characteristics with only occasional overloading of power amplifier. 

This sketch indicates the limits of [he listening window, in the vertical plane. within which optimum tonal balance and stereophonic effects will be perceived.