The KM1 loudspeaker system was developed for the BBC in response to a need for a high level monitoring loudspeaker to be used in pop studios. Prototypes were installed at the BBC’s Maida Vale studios in the spring of 1982 and proved highly satisfactory for all types of music.

 

Many high output loudspeakers in use at the time suffered from frequency response distortion, deliberately introduced to make them sound more efficient than they actually were. Such tricks sound unnatural on classical music and speech and give a false impression of sound balance. The KEF KM1 had no such drawback and could therefore be used to balance a symphony orchestra just as well as a pop group.

 

Considerable resource was devoted to reducing the effects of thermal compression in the drive units with extensive heat sinking and the use of an oversized magnet to maximise the sensitivity of the T52 tweeter. The system was fully active and included adjustment for bass cut-off and damping and well as bass/midrange balance.

 

Specification: Model KM1
System Type: Three-way, stand-mount
Size: 763 x 1315 x 665mm (30 x 51.75 x 26.25 inches)
Weight: 140kg (308 lb)
Internal Amplifers: 4 x 100W (bass), 2 x 350W (midrange), 1 x 400W (treble)
Frequency response : 38-23,000Hz +/-2dB at 2m on design axis (-6dB at 34 and 25kHz)
Maximum output: 120dB at 1m (anechoic conditions)
System: SP3010
Drive units: 4 x B300 bass unit (SP1196), 2 x B110 midrange unit (SP1186), T52 tweeter (SP1187)
Active crossover boards: SP2036, 2037, 2038.
System: SP3081 KM1P (1987-88)
Drive units: 4 x B300 bass unit (SP1196), 2 x B110 midrange unit (SP1186), T52 tweeter (SP1187)
Active crossover boards: SP2036, 2037, 2111