NEW ORLEANS — Chuck Blamphin still remembers his first Jazz Fest in 1973 — “I was floored. I was hooked the minute I walked in,” he said. The next year, he returned, not as a audience member but as a stage manager — a role he’s held for 40 years.

That makes the 66-year-old the longest-tenured stage manager at the New Orleans Jazz and Heritage Festival, a group that has many longtime members.

On Friday, with a quiet, calm and methodical presence, Blamphin oversaw a three-piece band being switched out with a 13-piece band.

Already a few minutes past time for the first act to wrap up, Blamphin took hold of the microphone. “I hate this part,” he said, of having to gently remind the musicians it’s time to stop.

For the audience, it’s a time to chat, sit down and rest or make a run to the beer tent or bathrooms. But Blamphin called the 20-minute period of time in between acts “the Chinese fire drill part.”

Microphones are moved, instruments zipped carefully into cases, various pieces of electronics unplugged and plugged and monitors changed.

Then there’s the sound check, where people call out questions over the microphone in a language only people in the business understand.

A handwritten diagram on a note pad is shown around, laying out who and what goes where as the next musicians climb the narrow wooden steps carrying tubas, tambourines and trombones.

Blamphin carries around a roll of masking tape and clothespins, securing set lists to music stands.

“Each set change is a minor miracle,” Blamphin said.

It’s a concerted effort, and everyone knows their role, he said, describing his sound crew as one of the best at the festival.

The first day is wonderful, he said, with everyone relaxed and in good spirits. It’s also a day to work out the bugs.

“And there’s been a few bugs,” he said.

Blamphin’s second act was a few minutes behind schedule. The crowd filled in, looking up at the stage in eager anticipation beneath a sea of straw hats.

While he has moved around to various stages and all genres of music, Blamphin has long been a fixture at the Fais Do Do Stage.

“I meet incredible musicians,” he said. “And there’s no people more friendly than the Cajun/Zydeco bands.”

The stage is the perfect size, he said, with an audience close to the stage and full of typically older but lively dancers.

Blamphin said about 15 years ago, when he saw everyone else having so much fun, he took Zydeco dance lessons. He takes a break from work every now and then to put his feet to the grass and enjoy the music from the other side of the stage.

One of the hardest parts about working is when someone comes up to him and tells him how a band just “blew the roof at the Blues tent,” Blamphin said. “I have to live vicariously.”

Blamphin singled out the first day of the Jazz Fest following Hurricane Katrina as the most special in his four-decade career.

“It was a very emotional day,” he said. “You could see it in the people who worked and the enthusiasm of the performers and in a look of ‘thank goodness’ from the audience,’’ he said.

Many members of the corps of producers have been with Jazz Fest for more than 25 years, said Quint Davis, Jazz Fest’s longtime producer and director.

Davis calls it a “festival family.”

“We’ve all grown up together,” Davis said. “That’s one of the things that makes it work well.”

The festival staff has grown up along the musicians, Davis said, and “Chuck has seen it all.”

“Chuck is the right combination of a great professional and a great person,” Davis said. “He’s the perfect balance of learning the profession and the kind of person we want representing New Orleans to musicians and to the audience. He’s the ideal.”

Davis said that Blamphin also “hasn’t changed a whisker in 30 years — he’s got the same energy and the same glow.”

On Monday, Blamphin will go back to an entirely different world: Work at his desk job, before starting all over again Thursday.

While the work can be demanding, and never without new challenges, Blamphin said he is more fortunate than most people to have the opportunity to work at Jazz Fest and is appreciative of every single musical set that comes onto his stage.

“How many people get to do something like this?” he asked.

“They want me to stay ’til 50,” Blamphin said. “It’s going to be tough, but I’ll try.”