"We're seeing a very high standard indeed from the bands and solo/duos."
The 30 acts will be further narrowed down by a panel of judges from the music industry, and on July 31 there will be an announcement of the final nine acts to compete in the grand final in Auckland on September 11.
The 21 acts not in the final selection will become contenders for the people's choice award, with the winner of the popular vote also competing in the national final.