Amplification & Power Handling; Power Selection (I8T Aw); Equalisation - Tannoy i8 AW User Manual

5. Amplification & Power Handlin
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 loudspe aker 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 of 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
the 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
compressor/limiter or active crossover is being used with multiple cabinets; it is
therefore recommended that the same amplifiers are used throughout.

6. Power Selection (i8T AW)

Determi ne the maximum power in watts needed at each speaker location. The i8 AW
transformer can be tapped at 60W, 30W, 15W, & 7.5W (70V line only) via the rotary
switch located on the metal plate at rear of the loudspeaker. When the relevant
tappings have been se lected add the individual wattages required at all speakers and
select an amplifier with a rating equal to or exceeding the total wattage required. All of
the transformer primaries should be connected in parallel to the output of this amplifier.
If for example, you select the 7.5- Watt transformer tap, it means that at full rated
amplifier output the speaker will receive the full 7.5 Watts. If the amplifier gain is
reduced each speaker will receive a proportional amount of power, maintaining the
overall syst em balance.
When calculating amplifier wattage requirements for a system, it is recommended that
a generous wattage safety margin (3dB of headroom) be left so that the system does
not have to operate continuously at its full rated output.

7. Equalisation

The i8 AW loudspeaker 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.
Over- equalisation can reduce system headroom, and int roduce phase distortion
resulting in greater problems than cures. If equalisation is required then it should be
applied gently and smoothly. The i8 AW loudspeaker is a point source, phase coherent
design and violent equalisation will be detrimental to the overall sound quality.
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