The Lucasfilm THX standards successfully established important criteria for the total performance of movie theatre sound systems throughout the USA and the rest of the world. Turning their attention to the domestic stage, Lucasfilm produced a similar set of standards for home audio systems. Home THX certification was a guarantee that these very high standards had been met and that high quality reproduction of multi-channel film sound was guaranteed.

 

The THX specification comprised acoustically identical Left, Centre and Right front speakers with a significant and carefully specified amount of vertical directivity to reduce floor and ceiling reflections and improve speech intelligibility; dipole surround speakers to match the effect of multiple monopole surrounds in a theatre; and a high performance subwoofer with a pre-determined 80Hz crossover to the satellites. The KEF TDM home theatre system conformed to the THX Ultra specification where very good performance is required on music as well as home cinema signals.

 

The TDM23F front speaker used a symmetrical vertical array of two B169 racetrack bass drivers, two 76mm (3inch) midrange units and a 19mm (0.75 inch) tweeter to achieve the THX specified vertical directivity. The generous enclosure volume allowed excellent bass extension and seamless integration to the TDM45B subwoofer.

 

The horizontally orientated TDM23C centre speaker used a symmetrical vertical array of two 76mm (3inch) midrange units and a 19mm (0.75 inch) tweeter to achieve the required THX specified vertical directivity, flanked on either side by two B169 racetrack bass drivers. The generous enclosure volume allowed excellent bass extension and seamless integration to the TDM45B subwoofer.

 

TDM34DS quickly developed a reputation as one of the finest dipole surrounds in the world. Key to this was the controlled midrange/high frequency dispersion of the KEF Uni-Q array. The system produces a nice, broad null region around the listener and a gradual build up of mid/high frequency energy in the forward and backward directions. This means that there is very little ‘localization’ of sound at the speaker – the listener is enveloped in ambient surround information without it appearing to come from the speaker itself. This effect is further enhanced by the very low (250Hz) crossover frequency between the monopole woofer and the dipole mid/high frequency array.

 

Model 45B was the active subwoofer designed to match the satellite speakers in the TDM range. It utilised a 380mm (15”) long throw drive unit in a closed box, powered by a 300W amplifier. The operating mode was switch-able from THX to stereo to offer maximum flexibility to end-users.

 

Specification: TDM23F
System type: Three-way, wall/stand-mount
Enclosure type: Closed box
Dimensions (H x W x D): 715 x 316 x 180mm (28.1 x 12.5 x 7.1 inches)
Weight: 14.5kg (31.9 lbs)
Nominal impedance: 4 ohms
Power handling: 200W
Frequency response: 80Hz to 20kHz +/-3.0dB (-6dB at 65 Hz)
Sensitivity: 90dB at 1m for 2.83V
Maximum output: 114dB
Finishes: Black or White

 

System: SP3278
Drive units: 2 x B169 bass unit (SP1387), 2 x 76mm (3 inch) midrange unit (SP1404), 19mm (0.75 inch) tweeter (SP1403)
Crossover network: SP2278

 

System: SP3278
Drive units: 2 x B169 bass unit (SP1432), 2 x 76mm (3 inch) midrange unit (SP1404), 19mm (0.75 inch) tweeter (SP1403)
Crossover network: SP2313

 

Specification: TDM23C
System type: Three-way, wall/stand-mount
Enclosure type: Closed box
Dimensions (H x W x D): 256 x 715 x 180mm (10.1 x 28.1 x 7.1 inches)
Weight: 14kg (30.8 lbs)
Nominal impedance: 4 ohms
Power handling: 200W
Frequency response: 80Hz to 20kHz +/-3.0dB (-6dB at 65 Hz)
Sensitivity: 90dB at 1m for 2.83V
Maximum output: 114dB
Finishes: Black or White

 

System: SP3279
Drive units: 2 x B169 bass unit (SP1387), 2 x 76mm (3 inch) midrange unit (SP1404), 19mm (0.75 inch) tweeter (SP1403)
Crossover network: SP2279

 

System: SP3279
Drive units: 2 x B169 bass unit (SP1432), 2 x 76mm (3 inch) midrange unit (SP1404), 19mm (0.75 inch) tweeter (SP1403)
Crossover network: SP2312

 

Specification: TDM34DS
System type: Three-way, wall-mount
Enclosure type: Closed box
Dimensions (H x W x D): 295 x 419 x 196mm (11.6 x 16.5 x 7.7 inches)
Weight: 9.8kg (21.5 lbs)
Nominal impedance: 4 ohms
Power handling: 150W
Frequency response: 80Hz to 20kHz +/-3.0dB (-6dB at 65 Hz)
Sensitivity: 88dB at 1m for 2.83V
Maximum output: 112dB
Finishes: Black or White
System: SP3277
Drive units: B169 bass unit (SP1387), 2 x B160 midrange unit (SP1396), 2 x NT19 tweeter (SP1367)
Crossover network: SP2307

 

System: SP3277
Drive units: B169 bass unit (SP1432), 2 x B160 midrange unit (SP1396), 2 x NT19 tweeter (SP1367)
Crossover network: SP2307

 

Specification: TDM45B
System type: Active subwoofer
Enclosure type: closed box
Dimensions (H x W x D): 455 x 455 x 510mm (18.2 x 18.2 x 20.4 inches)
Weight: 28kg (62 lbs)
Drive Unit: 380mm (15”) long throw
Amplifier: 300W
Frequency response: 35Hz to 150Hz +/-3.0dB (-6dB at 28Hz)
Maximum output: 115dB
Finishes: Black Ash

 

System: SP3262
Drive units: 380mm (15 inch) bass unit (SP1390)
Amplifier: SP2274 (240V-EURO/UK), SP2271 (120V-US)

 

Download Reference Series Home Theatre Models TDM23F TDM23C TDM34DS TDM45B Brochure
Download Reference Series Home Theatre Models TDM23F TDM23C Installation Instructions
Download Reference Series Home Theatre Model TDM34DS Installation Instructions
Download Reference Series Home Theatre Model TDM45B Installation Instructions