"It's a fantastic success to see them up and running," Mr Clayton said.
The competition was previously hosted in Rotorua in 1969, 1995 and 2003. Rotorua last competed in 2004.
The band used to be in the A Grade but players of that calibre are no longer in the band.
"To get to this stage you need at least four or five years as a learner and then you're looking at 10 years to get to the top," said Tauranga conductor Steve Thompson.
"But there's a lot of capable people between the two bands."
They got together yesterday for an extended practice, making the most of the public holiday. The two parts of the band practise separately and then meet up once a week as a whole.
"It will be a challenge but maybe this is the way bands will have to go these days," said Mr Thompson.
Mr McGregor said the competition had given the musicians new impetus. "A contest provides people with a focus. It's just like sport, we want to encourage people to want to do better without it consuming their life."
The championships run from July 8 to 14 at the Sir Howard Morrison Performing Arts Centre and include competitions for solos and groups on the first two days, then band performances. There are around 32 bands expected to perform, including two from Australia and one from the United States.
There will be a pre-contest concert for Rotorua Brass, details are yet to be finalised.