I've seen this asked but never answered, so I thought I'd give it one last try: Does anyone know of any venues for authentic trad music (not tourist "shows") in Dublin where young teens can attend? It appears most pubs have music after 10, when kids aren't allowed. We're looking for a venue for weeknight music. thanks!
Just how young is the "young teen"? If they look mature enough and are with an adult, there might not be any question raised.
No, there is no way she'll pass for 18.
Your best bet might be the Trad Music Pub Crawl mentioned in Rick's book. My wife and I went on it and enjoyed it. There are several similar tours you'll see advertized at the hotels. I realize it is a "tourist show" but they do talk about the music and play traditional songs. If you want to give a shot at getting her in, try the Brazen Head. It has its fair share of tourists but that's what you'll find in most of Dublin (and Ireland for that matter).
The pub at the Harding Hotel had sessions that I "think" started at 6:00 but it was probably only on the week-ends. I know it was certainly no later than 8:00. You might contact them to find out for certain.
Dublin pubs and bars want to keep their liquor license just like American bars. If your child is not able to pass for 18, it's really unlikely she will get in the door after hours. Even in the small Irish village where my relatives live, the pubs have started to crack down and check IDs & the kids have to go. Unless it's a tourist show, I have yet to run across any trad sessions happening during a weekday (most are on Saturday or Sunday afternoon and then the rest take place later in the evenings when the kids can't be there). And if you plan to go to Temple Bar in Dublin, you will get nothing "authentic". It's definitely music for the tourist masses over there.
Dublin is different than the rest of Ireland. Most towns trad sessions end early, 9 pm, and kids are fine. You may want to check out some towns that are reachable from Dublin and ask there. The best trad sessions aren't really advertised online. I usually look around for an announcement taped up at bus stops or outdoor bulletin boards - or ask a local where I can find a session.