Live Sound Amp Positioning
Friday, February 19th, 2010The best position for your amplification is as close to your speakers as possible. The world seems to be moving to powered cabinets even in the concert world. This is the ideal as far as amp positioning is concerned. In a multiple amp active system it is best to have an amp rack close to each speaker stack.
There are losses in any wire. The longer the wire the greater the loss. Also the greater the current the greater the loss. Powering speakers requires high current, so shorter wires will deliver more of your available power to your speaker cabinets. In addition, speakers are low impedance devices. If your speakers are four ohm and the resistance in your speaker wire is one ohm twenty per cent of your available power will be absorbed within your speaker wire. The resistance of the wire includes both conductors, so if the wire were to measure a half ohm on one conductor the total resistance would be one ohm.
There is not as much signal loss in low level wiring for two reasons. Since the power formula uses the square of the current, low current levels do not incur as much penalty. In addition to that the impedance of the input that you are driving is much higher, so the relationship is different. Where one ohm of resistance in the wire driving a four ohm load would equal a twenty per cent loss if that same one ohm line resistance is driving a one thousand ohm load the loss would be only point one per cent.
Smaller PAs for bands working in clubs may not lend themselves to multiple amp racks. If you must run wires for longer distances it is important to use heavier gauge wire. The lower the gauge number the thicker the wire. For speakers it is important to use heavier gauge wire for high power or longer distances to get the best performance from your sound system.