When the number of speakers is large over long cable runs, it is recommended that a distributed (70.7V/100V) system be used. For distributed line, the cable need not have a large cross sectional area as for low impedance, resulting in savings in cable cost. All speakers are placed in parallel with the output of the amplifier, allowing easy installation. Please refer to section 5.2 for installation guidelines. The wattage tappings can be individually adjusted, giving more flexibility within an installation.
4. Amplification and Power Selection (Low Impedance Mode)
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. Headroom of at least 3 dB 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, 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 they have very closely matched gains, the variation should be less than
When running low impedance loudspeakers in parallel, care must be taken not to allow the impedance to drop too low, as damage may be sustained by the amplifier. Most low impedance amplifiers will be able to handle loads of 2Ω to 8Ω. This means that when using a 4Ω amplifier, 2 × i7 Contour may be connected in parallel per input, although care should be taken as impedance varies with frequency and at some frequencies the impedance will drop to below 8Ω. For examples simple series/parallel combinations, please see Figures 4b, 4c and 4d.
Figure 4b: Simple parallel connection: 4Ω. | Figure 4c: Simple series |
| connection: 16Ω. |
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