A lot of things in the Top End swell up over the wet season — rivers, cane toads, even pianos.

Yes, pianos, according to fly-in fly-out piano tuner Martin Tucker.

Mr Tucker has been visiting Darwin every year for the past 10 years, tuning and tweaking the Top End's baby grands and uprights in a never-ending battle with the wet.

Martin Tucker says the pianos in Darwin that are played regularly are in the best shape. ( 105.7 ABC Darwin: Mike Kermode )

He told 105.7 ABC Darwin that pianos "like" humidity levels that hover between 30 and 50 per cent, which means the wet season average of around 80 per cent can cause them some grief.

The steel strings can begin to rust and fabric wrappings become weighed down.

"The felt swells up with the moisture in the air and that changes the sound.

"It's a bit like having a paperback book that you leave outside — if you leave it long enough over the wet season, the whole book swells up.

"And if that's the hammer that hits the string on a piano, if that swells up it just doesn't sound very nice."

Flying north for the winter

Mr Tucker said his time tuning instruments in the Top End started around a decade ago when he flew up from Hobart to visit a friend.

"They had a piano and being a piano tuner they said: 'Can you bring up your tools?'

"And then the neighbour said: 'Can you do ours as well?'

Martin Tucker tunes by ear and says there are now around 80 he services regularly around Darwin. ( 105.7 ABC Darwin: Mike Kermode )

Word spread and the trips became regular.

"Every year I would get to Easter time in Tasmania, get quite cold, book a ticket up to Darwin and arrive here probably late May just as the dry was kicking in."

Mr Tucker said there were around 80 pianos across Darwin and a bit beyond which he tuned, semi-regularly, by ear — the old-fashioned way.

"I'm a musician so that's just how I do it.

"The ear is the finest thing."

A steak on a cattle station in exchange

Most of Mr Tucker's clients are within bike riding distance in the northern suburbs of Darwin.

He said there was a piano at a croc cruise business on the Adelaide River that he had travelled to tune, and he liked to do at least one trip to Batchelor each year so he could go for a swim in nearby waterfalls.

He has also tuned a piano in "very bad" condition for some pastoralists near Alice Springs.

"It took me all day to fix," he said.

"But they had a cattle station and I got a steak for lunch — I was happy with that."

Like many dedicated experts, Mr Tucker is something of a purist and insists that all his clients really should get their pianos tuned at least once a year.

He has even had to tell some that theirs was too far gone and needed to be replaced.

"[There] comes a time, sometimes I tell my clients, 'this is the last time I'm tuning this piano, if you're serious about your piano you need to upgrade and get a new one'," he said.

"And what happens, a year, two years later, they ring me: 'Martin, we really like our piano, it has a lot of sentimental value, can you come and give it one more tune?'

"I go, 'Oh, alright then, but this is the last time'."