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overpowered models - with suitably set controller limiters - without risking uncontrolled power bursts. The
MA series power amplifiers’ regulated power rails also ensure maximum performance under the real-world
concert conditions of less-than-optimum mains supplies and low impedance loads.
Amplifier load tolerance
An efficient subwoofer system 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
Most power amplifier specifications are 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
percussive peaks and sustained bass notes.
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 supply vs demand using an accurate 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 WLXs in parallel. I would suggest no more than two (giving 4 ohms) so that
the power amplifier’s 2 Ohm 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.
Gain and level settings
Gain switches
If you are lucky enough to have amplifiers with user gain switches, set them all to identical positions. A
voltage gain of 32dB will match the default controller presets and will provide a good balance of system
headroom and noise (assuming professional audio equipment is in use FOH).
Level controls
The front panel level controls should be turned down (fully counter clockwise) until FOH-to-Amp rack lines
All material © 2007. Martin Audio Ltd. Subject to change without notice.