Martin Audio Wavefront W8CT, Application Manual

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rails also ensure maximum performance under the real-world concert conditions of
less-than-optimum mains supplies and parallel cabinets.
See Section A1.6.1.
Most non-Martin power amplifiers’ 4 ohm performance figures are specified
assuming very well regulated bench supplies but fail to reach these specifications
under touring conditions. These amplifiers can be a totally false economy as they
cannot drive parallel cabinets without a very audible loss of headroom and quality.
Amplifier load tolerance
An efficient loudspeaker in live concert conditions can act as a surprisingly dynamic
and complex load. Most modern touring power amplifiers claim 2 ohm capabilities
but make sure your amplifier is also capable of driving reactive (ie inductive or
capacitive) loads without prematurely clipping or developing output stage crossover
distortion.
Mains safety!
A fully qualified technican should check mains safety and phase voltage before the
system is patched.
Power reserve
Power amplifier specifications are usually based on bench measurements made using
stable, high current mains supplies and well defined loads. Amplifiers sound best
when they have plenty of current in reserve for musical peaks.
1) Try to ensure that the mains supply stays within the amplifier manufacturer’s
specified range from no load to maximum load. An electrical technician
should check the mains supply vs demand using an accurate rms voltage
meter.
2) If unfamiliar generators are being used the electrical technician should check
the mains waveform (using a portable ’scope-meter) to make sure that it is
sinusoidal and not crawling with spikes or interference.
3) Avoid driving too many W8s in parallel. I would suggest no more than two
so that the amplifier’s 2
Ω
spec is kept in reserve for musical peaks.
4) Avoid using power amplifiers in bridged mode. Most commercial power
amplifiers are optimised for 2-channel operation. It is usually better to use the
appropriate amplifier in 2-channel mode than to use an inadequate amplifier in
bridged mode.
All material © 2007. Martin Audio Ltd. Subject to change without notice.