My very first rock concert was Black Sabbath, in 1972 or 1973. I wasn't really a big fan -- I might (but might not) have owned one album (8-track?) -- but I knew they were "cool" and so pestered my dad about letting me go. I was 14 or 15, and he wouldn't let me go alone, so (bless his heart) he went to the show with me. The opening band was Black Oak Arkansas.
I don't remember a lot of details, but I do remember that it was louder than anything I had ever experienced in my life, or since. I distinctly remember the uncomfortable feeling of my breastbone rattling in my chest. When they finally played the one song that I actually knew well (Sweet Leaf), the song was almost over before I was able to recognize it. I just couldn't hear notes or melodies -- it was just a wall of noise. I also have a distinct memory of the moment of terror I felt when the guy sitting next to my dad offered him a joint. (It actually turned out fine: He just politely said no thanks -- or at least that's what his lips looked like he was saying.) And I remember how amused we both were watching the lead singer jumping around the stage like a maniac, while the bass player stood like a statue. Frankly, I can't say I really enjoyed the show very much, except for those 45 seconds or so of Sweet Leaf. But it was pretty cool to be able to go to school and tell people I'd seen Black Sabbath.
There's an important footnote to the story: When my dad agreed to take me to the show, it was only as part of a bargain: I had to agree to go with him, the next week, back to the same venue to see Lionel Hampton and his jazz band. I wasn't really into jazz at the time, and I didn't think it was "cool," but I have to admit that I enjoyed that show a lot more. I remember the horn section marching up and down the aisles, playing When the Saints Go Marching In, with Lionel leading the way playing on the backs of people's chairs with a pair of drumsticks.
I never did get into Sabbath after that, although I don't think that show was necessarily the reason. It's probably a good thing, as I might have been deaf before I got to college....