The other day I was helping a DJ friend tune up his new self powered speakers and ran into a real issue trying to explain how everything goes together. As someone who deals with complex multi-part audio systems on a daily basis and has a good understanding of gain structure, there was a bit of a disconnect when talking to someone who plugs in a powered mixer and goes.
The first issue was understanding the difference between the speaker outs and line level outs on his powered mixer. It didn't help that the one time he had encountered powered speakers in the wild was at a church where they were feeding their boxes from the speaker outs! (No wonder you could barely crack the master open before horrific distortion started.) It was late and I was having a hard time trying to explain the differences and come up with examples. So instead I switched tactics and just showed him a fool proof way to plug his system in.
A powered speaker is a complete sound system in a box. There's usually a rudimentary mixer on the back panel allowing you to plug in one or two things, some even have a mic pre. Then there's a master volume which is the key here. If you know what setting on that knob is unity gain you can just set it there and your system should operate smoothly. Someone used to a powered mixer can just use the master knob like they always did to set the level in the room and as long as they keep the red lights off the amps in the powered speakers won't distort.
Finding unity can be kind of a trick though. It's a fairly safe bet that powered speakers on the market today are operating at +4 and not -10 so they should be able to handle the higher levels coming at them from pro audio gear. (I'm sure someone can contradict me on that and give an example of one that's -10, that's what the comment section is for, hit me up.) But only a few makers actually mark unity gain with a "0". I've seen them that mark the maximum setting with a +6 but have no indication as to where unity falls below that. I've also seen the dreaded 1 to 10 scale. In that instance unity could fall anywhere between about 7 and 10. You either have to look it up (which we weren't able to do at the time) or take a wild guess and watch for clip lights.
Whatever you think of them, powered speakers are becoming a major factor in audio systems today. With their increasing capabilities and falling prices they're going to turn up more and more. Like any piece of gear, there will be people out there using them that don't understand them and therefore aren't getting the best out of them. Here's hoping a little knowledge will trickle in and help people bring better audio along with their new, highly portable, micro sound systems.
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