I’d say that adding multiple sources is a bit trickier than that. The most obvious thing is that same frequencies will be reaching people from different distances and therefore with different delay times, which creates all kinds of phasing problems. When a venue is small, this is even worse because you get reflections from edge surfaces, standing waves etc. If it’s a bar it can get even more complicated because the room can have an odd shape, you may be in a corner or whatever - all the problems multiply.
So you need to know what you’re doing. Because yes, you’ll help those front rows, but will cause issues for others. In large venues, because mains are wide apart and higher up, the dead spot in front of the stage may be pretty large, too, so front fills help. But also, assuming those front fills don’t pump too much volume, their sound doesn’t interfere too much with areas further back where mains work properly.
Our sound guy was running around the room with a measurement mic on a stand and an iPad, running sweeps and all kinds of funky noises, and also listening to music in different places, with mains and those fills on a separate mixer bus, adjusting stuff on the mixing desk, until he was satisfied with sound in different spots. Sometimes he decided that fills don’t work and didn’t use them. It’s always a compromise and a balancing act.
It took him maybe 5-10 minutes before the sound check, but if I did it I’d probably spend weeks lol - I only understand in principle what to look for but never did it myself.
could have kept talking for ages, was great
