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5. Amplification & Power Handling
As with all professional loudspeaker systems, the power handling is a function of
voice coil thermal capacity. Care should be taken to avoid running the amplifier into
clip (clipping is the end result of overdriving any amplifier). Damage to the
loudspeaker will be sustained if the amplifier is driven into clip for any extended
period of time. Headroom of at least 3dB should be allowed. When evaluating an
amplifier, it is important to take into account its behaviour under low impedance load
conditions. A loudspeaker system is highly reactive and with transient signals it can
require more current than the nominal impedance would indicate.
Generally a higher power amplifier running free from distortion will do less damage to
the loudspeaker than a lower power amplifier continually clipping. It is also worth
remembering that a high powered amplifier running at less than 90% of output power
generally sounds a lot better than a lower power amplifier running at 100%. An
amplifier with insufficient drive capability will not allow the full performance of the
loudspeaker to be realised.
It is important when using different manufacturers' amplifiers in a single installation
that they have very closely matched gains, the variation should be less than +/-
0.5dB. This precaution is important to the overall system balance when only a single
active crossover is being used with multiple cabinets, it is therefore recommended
that the same amplifiers are used throughout.
6. Crossovers
The T40 has been designed to be used in conjunction with the Tannoy TX2 controller
for optimum performance, this provides specific crossover and equalisation functions
for the T12, i12, i15 & T40 combinations. If the TX2 controller is not being used a
24dB/octave active crossover will be required using 100Hz as the crossover point if
when used in conjunction with Tannoy T12, i12 or i15 loudspeakers.
7. Equalisation/Positioning
As with the T12 and i12 loudspeakers, the T40 is designed to need no equalisation or
correction to overcome system limitations. As a result, it will only need equalisation
to compensate for difficult acoustic environments.
Excess equalisation can reduce system headroom, and introduce phase distortion
resulting in greater problems than it cures. If equalisation is required then it should be
applied gently and smoothly. Violent equalisation will be detrimental to the overall
sound quality.
The frequency band over which a subwoofer operates is essentially omni-directional,
therefore efficiency of the T40 may be further enhanced if the unit is placed against a
wall, where the radiation in the forward plane will be doubled due to the addition of
the reflected rear directed energy, and a 3dB increase in sound pressure will occur. If
another boundary is introduced, say a floor, then the effective radiation space is
halved again, resulting in a further 3dB lift, and if placed in a corner, once again the
sound pressure level will increase by a further 3dB.
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