I got interested in playing guitar in my early teens. The few lessons I took did little, but wearing out LPs taught me almost everything. This led to duos and trios performing at open mics around Houston, and later to quartets and quintets doing club gigs. My early bands usually owned a small basic “PA” [public address] system, which we rehearsed with and hauled to and from shows. We’d hire a sound person, or the club would have a house system and sound person.
At shows the sound quality was often unsatisfactory [to me, at least]. As I grilled sound engineers about the prevalent feedback, I learned how the systems worked, how to drive them, and how to mitigate problems. Soon I started “running sound” for pubs and/or bands. Once I became adept at the mixing board, my musician’s ear made me an in-demand soundman all over town.
DIY Sound at a bar/club
Some bars have a DIY house system: The band plugs two or three vocal mics into the onstage powered mixer — which drives a pair of house speakers plus two or more stage monitor wedges — and Bob’s your uncle. The larger venue usually has the budget for a pro-quality sound system and staff to operate same.
Sizing up the room
When I enter a room in which nothing much is happening, I hear “room tone.” I also like to call this the “acoustic signature” of the space. You hear it too, but my experience prompts me to take close notice. Every space [even outdoors] has an ambient character that results from position, dimensions, materials, angles, contents, people, and other stuff. This character affects the tonal quality of speech, music, and sound reinforcing.
Clubs
Pubs and small clubs have the advantage of intimacy between performing artist and audience. They often have a sonic disadvantage when hosting a loud rock act, because the small dimensions cramp and reflect the complex sound waves in a manner that is harsh to ours ears. We can “turn it up” only so much before we “overdrive” the room acoustics. Adding human bodies always helps to reduce unpleasant reflections and absorb harsh high and middle frequencies.
Large venues
Almost every small, medium, and large music venue — hall — has decent acoustics and a house sound system and sound person(s). I find that mixing in such spaces is usually easier than in pubs or stadiums, because the inherent audio problems are fewer.
Stadiums
Stadium concerts require large sound systems to project the mix to thousands of ears in a vast interior space. It is very difficult to supply full coverage to faraway listeners without injuring those closer to the stage and/or the mains (house speakers). Speaker placement is crucial, and numerous small speaker arrays work better than two massive left and right stacks.
Another stadium issue is low-end reflection (boominess). My preferred solution to this irritant is to be less greedy about bringing up then bass instruments.
Outdoors
Outdoor concerts require large sound systems to project the mix. The acoustics are almost always friendlier than with indoor situations. Weather is your variable.