Gillian Welch, Brighton Dome

No fuss, no frills. Such is the approach of Gillian Welch and her long-term partner, David Rawlings, who arrive carrying their instruments on to an empty stage. Many players of their stature might employ the services of choirs, orchestras and dancers, but not these two. Sometimes two guitars and a banjo is all you need.

It's been seven years since these purveyors of old-style Americana last played our shores, and eight years between albums (their latest LP, Harrow & the Harvest, was released this summer), leading one to speculate as to what on earth they've been doing in between. Writer's block has been a problem, it has emerged, though they also admit to being slow workers, a single song undergoing months of painstaking adjustments.

Such perfectionism has its rewards, even if there's a sense that we are intruding on a private session between two people armed with the telepathy – a look here, a nod there – that comes with years of living and playing together. They could be at home on their back porch, strumming in their rocking chairs, such is the intimate nature of what they do.

For the first 15 minutes they are silent and serious between songs. But then Rawlings reveals that they have just experienced their first ever "getting to the stage incident" in which he fell on the stairs and, in trying to protect his guitar, landed awkwardly on his arm. "That's why we haven't told any jokes yet," remarks Welch.

Rawlings's arm improves, though the air of seductive melancholy persists. "Orphan Girl", "Dark Turn of Mind" and "The Way It Goes" are wistful and wonderful in their simplicity and starkness. Much of their music features little more than Welch's calmly forceful vocals, the gentle strum of guitar and Rawlings's whispered harmonies. These compositions sound not so much like new songs as old standards scrawled on to dog-eared parchment and passed down through the generations.

Later on, the mood lightens and the pace picks up with Welch putting down her guitar for "Six White Horses" and doing a dainty little dance. Rawlings takes his hat off and then puts it on again. "I told you the second half would be looser," Welch giggles. At two and a half hours it's a long set made for serious Welch fans, of which there are, it seems, legions. All in all, it's pretty much perfect.

Touring to 23 November (www.gillianwelch.com)