The Catalyst Nightclub is the largest club in Santa Cruz. The main room is 5000+ square feet and can hold 800+ people. Due to the size of the room, mainly larger bands play here. Local bands sometimes open shows. The acoustics in this room are usually pretty good, but it seems to depend on who is doing the sound on a given night.
There is also an atrium area with a large slanting plexiglass roof/ceiling reaching over 30 feet from the floor where they have live and recorded music, but the acoustics in the atrium don't do any justice to the music.
Drinks are somewhat expensive and the bouncers can be heavy-handed, especially at punk and metal shows.
The Catalyst, founded by Randall Kane in the 1970s, was originally located approximately where Bookshop Santa Cruz is today, with an entry on Front Street. It moved to the current location in 1976. It is (or used to be) decorated with avant garde sculpture and paintings by local artists. For many years it was considered the primary heterosexual 'pick-up' bar in town and had a revolving cast of colorful characters.