![]() ![]() While we're talking in Amperes, it's worth remembering that electrical current is a dangerous animal a current of only 50 Milliamps (0.005 Amps) can be fatal, and our typical small rig above is using over a thousand times more current than this. Any system capable of delivering good bass power will need to draw a hefty current from the mains, and if, in the above example, we were to replace our typical small speakers with, say, a pair of Mackie SA1521s, the makers recommend that each speaker's mains supply is capable of providing seven Amps at 230 Volts! This is, of course, not a constant current requirement, but it does illustrate how important a good power source is for getting the best from your gear. Bear in mind that equipment may demand a much bigger supply current when it is first switched on, so don't be tempted to turn everything on from a single switched socket - you wouldn't want to do this anyway, for many other reasons, such as risking a huge pop through your speakers! Also consider that the power that you can safely run your system on may not be enough to realise its full performance capability. The table below gives a rough guide to the supply current likely to be required by a band with three backline amps and a vocal PA (based on UK voltage). ![]() A useful rule of thumb (if you don't have the manufacturer's stated figures) is to multiply the audio output power by 1.4 to get an idea of how much mains power would be needed, then divide by 230 to find out the current consumption. A typical full-range 'active' speaker with built-in amp modules, rated at 240 Watts audio output, would have a mains power rating somewhere around 350 Watts. If an amplifier were 100 percent efficient, you could, in theory, use all the mains power as audio output power, but this is not the case in practice, as some of the power used by the amplifier is dissipated as heat. One common mistake is assuming that audio output power is the same as the mains power required to operate the gear. It's much better to have a single power lead of the required length than two shorter ones joined together: less to go wrong!Ī professionally made distribution box with meters to indicate AC mains voltage and current. After all, that's what they're designed for! Try to avoid too many connections between this point and your equipment. If the total connected load of your system - including the backline equipment - is comfortably within the rating of a single or double 13-Amp socket, it's perfectly alright to connect it all from a single point. In a small venue that is only offering 13-Amp sockets of the normal domestic type, you can then work out how you need to wire up. As an example, a piece of equipment with a mains power rating of 100 Watts (not 100W of audio power) will draw a little under half an Amp. ![]() To convert Watts to Amps, divide the Wattage figure by 230 (mains voltage). It's generally best to work out the total current your gear will draw, adding up all the individual figures to find the total load you'll be connecting to the mains. The power rating may be expressed as a current (in Amps) or as a power figure in Watts. The power rating of each piece of gear should be stated on a panel fixed close to the mains connector, or where a fixed mains lead enters the equipment. Such gear might include a visiting disco, a lighting rig, or other event equipment - for example, fridges at summer events.Ī good first step, then, is working out what current your equipment will draw from the mains. What constitutes a suitable supply will depend, of course, on what you need to plug into it: if it's your own equipment you'll presumably know what supply capacity is required, but there may be other factors to consider if additional gear needs to be connected to the same supply. How much power will the average band's gear actually need? The only way to know for sure is to add up the power requirements of each individual item. When it comes to portable live-sound systems, this means firstly, using a suitable electrical supply secondly, using suitable equipment and, thirdly, connecting and using that equipment safely. Whatever you encounter, you'll need to know some basic rules. Whatever the size, complexity or cost of your live sound rig, one of the first - if not the first - question on your mind when you get to a venue will usually be "where do I plug it in?" Depending on the venue, the answer can vary from a wall-socket behind a plant pot to a dedicated and professionally-installed supply that is reserved for your exclusive use, fully tested and certificated, and for which (with any luck) you'll have brought an appropriate connector. Knowing how to properly handle the mains power we all need is also crucial to performance health. Staying safe on stage is more than a matter of simply making sure that willing hands are available before taking a dive. ![]()
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