This twin Loudspeaker system consist of a direct radiator low frequency unit mounted concentrically with a horn-loaded high frequency unit. The voice coils of both loudspeaker systems are fed through a specially designed cross-over network. The frequency response of both units is intrinsically level and the wide frequency response is not obtained by trick effects, such as cone break-up or diaphragm resonance. The desigh of the low frequency cone, which forms the final section of the high frequency horn, is such that even distribution of high frequencies is odtained over a wide angle and in order that the low frequency diaphragm shall move as a truepiston, the body thickness has been increased and the surround is specially treated to prevent the setting up of subsidiary resonances.
The high frequency unit is of particularly robust construction to ensure adequate power handling capacity and to enable it to take over from the L.F. unit at a sufficiently low frequency to avoid the latter's running into break-up troubles. The diaphragm is a light alloy pressing located to within very close limits on the backplate by means of a turned recess. An aluminium voice coil conductor is used in order to preserve the correct mass relationship and phase matching arrangement to ensure a level and extended high frequency response. The first section of the H.F. horn is formed from the center pole and is continued by the L.F. cone.
In the design of this loudspeaker, great care has been taken to ensure that the entire system is truly apperiodic which, together with its wide frequency range result in really outstanding reproduction.
This Loudspeaker unit isavailable in two forms - a 15" version, capable of handling up to 25 watts which is particularly useful for use with high quality Sound Reinforcement systems and 12" version capable of handling up to 15 watts, which finds itsmain application in high quality Phonograph and Radio reproducing systems. An example of a suitable Cabinet design for the latter application is shown above and takes the form of a corner mounting Bass Reflex Cabinet.
There is no doubt that where the input source is of sufficiently high quality, the Tannoy Dual Concentric Loudspeaker system is well in advance of any type of loudspeaker hithertto commercially available
TECHNICAL SPECIFICATION
12" Dual Concentric Loudspeaker
Frequency response: 25 - 20,000 Hz
H.F. Voice coil diameter: 2"
L.F. Voice coil diameter: 2"
H.F. Voice coil impedance: 14 ohms at 3000 Hz
L.F. Voice coil impedance: 18 ohms at 400 Hz
Flux density L.F. Gap: 10,000 gauss, B± L± 6-3 x 10¹⁴
Flux density H.F. Gap: 15,000 gauss, B± L± 1-1 x 10¹⁴
Power handling capacity: 15 watts
Impedence via crossover network: 18 ohms
Polar distribution: -3 dB at 10,000 Hz for 60⁰ inc. angle
Intermodulation produces: less than 2 %
Bass resonance: 35 Hz
Crossover frequency: 1,700 Hz
Overall Diameter of Frame: 12⅜ "
Overall Depth: 7½ "
Fixing Holes p.c.d.: 11¾ "
Weight: 10 lbs (Crossover network on separate chassis)
Finish: Black Anodised and Cadmium plate
15" Dual Concentric Loudspeaker
Frequency response: 23 - 20,000 Hz
H.F. Voice coil diameter: 2"
L.F. Voice coil diameter: 2"
H.F. Voice coil impedance: 12 ohms at 2000 Hz
L.F. Voice coil impedance: 12 ohms at 400 Hz
Flux density L.F. Gap: 12,000 gauss, B± L± 7-7 x 10¹⁴
Flux density H.F. Gap: 18,000 gauss, B± L± 1-39 x 10¹⁴
Power handling capacity: 25 watts peak
Impedence via crossover network: 15 ohms
Polar distribution: -4 dB at 10,000 Hz for 60⁰ inc. angle
Intermodulation produces: less than 2 %
Bass resonance: 40 Hz
Crossover frequency: 1,000 Hz
Overall Diameter of Frame: 15¼ "
Overall Depth: 9 "
Fixing Holes p.c.d.: 14½ "
Weight: 30 lbs (including Crossover)
Finish: Cadmium plate and stove enamel
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