Galician Rodrigo Romani can’t be accused of overselling the group he brings to Edinburgh International Harp Festival next weekend. Its instrumentation includes two “toys” and its sound, he says, is a result of trying to make 68 strings behave. The 68 strings belong to the trio’s two harps, an instrument that Romani helped to reintroduce into Galicia’s traditional music during the 1970s through the influence of Celtic harp revivalist Alan Stivell and Irish musical ambassadors the Chieftains.

Anyone who caught the wonderful Galician folk orchestra SonDeSeu at the opening concert of Celtic Connections this year will have experienced one of Romani’s more daring moves to integrate the harp with other instruments from Galician culture. A 70-strong ensemble playing instruments including the emblematic Galician bagpipe – or gaita – plus hurdy-gurdy, fiddle and one of the aforementioned “toys” – the tambourine, SonDeSeu came out of another of the quietly industrious Romani’s endeavours, the harp class he set up at Vigo University in 1996 that led to the establishment of a traditional music school, ETRAD, in the city.

We’ll get to the tambourine and its far from toy-like properties in Romani’s native culture in a minute but what has become this sometime guitarist’s main interest, the harp in Galicia seems to share a similar history to its cousin in Scotland. It can be seen on stone carvings dating back two thousand years or more and Romani’s research shows the instrument being referred to in ancient manuscripts. After this it disappears until the 18th century when romantic bards accompanied their poems on the harp but working in an oral tradition, they left nothing in the way of written musical example.

It was the arrival of the Breton musician Alan Stivell onto the European folk scene in the early 1970s that piqued Romani’s interest in the instrument that Stivell would not only promote vigorously but take into the rock music arena, appearing on television programmes in the UK such as The Old Grey Whistle Test. At this point Romani was a guitarist with a particular interest in medieval music. The album that he made with two colleagues, Milladoiro gave its name to probably the most influential of Galician’s groups which formed with the merging of two sets of musicians shortly after the album’s release.

“At that time I was looking for an instrument that would help to create a distinctive sound for this new group,” says Romani down the line from Vigo. “I played guitar and keyboards so it made sense for me to try the harp but back then, harps were very difficult to find in Galicia.”

Eventually he found a harp that had all its strings but was completely out of tune.

“The strings had no tension and I didn’t know how to tune it, so with hardly any harp players around, let alone harp teachers and harp makers, I had to work it out for myself,” he says. “Fortunately, the harp is a very kind instrument. Even if you can’t play it properly, if it’s in tune, it’ll sound okay. It’s not like the fiddle where you have to find the note for yourself. So I worked on it and it soon began to fit well into the sound of the band. Then, in 1978, about a year after I bought the harp we made the first album that it featured on. I wasn’t playing anything amazing. It was quite basic but it was effective.”

Forty years on, Romani makes no great claims for his harp mastery. His pioneering work, however, alongside that of another Galician, Emilio Cao, who also fell under the spell of Alan Stivell and the Chieftains’ mad professor of the harp, Derek Bell, has created a strong presence for the harp in Galicia and particularly in SonDeSeu, where the harp section can be almost as much a source of energy as the percussionists.

“SonDeSeu was an experiment,” says Romani, who as well as being an inspirational musician has made his mark as a record producer with artists including the group Treixadura and gaita player and Celtic Connections visitor, Susana Seivane. “We had established the school of traditional music here in Vigo and we wanted to bring together all the instruments that were being taught at the school but hadn’t been played together before. We thought it would be interesting to have a hurdy-gurdy section playing with a gaita section and of course a harp section but there was no music for such an ensemble, so we had to invent it.”

A feature of one of the other sections of the orchestra, as well as of the trios Romani has been working with since Milladoiro ceased touring after some twenty years of taking Galician music to the international stage, is the tambourine.

“There are two main branches of Galician traditional music,” he says. “One is the gaita, which has famous players like Carlos Nunez, Susana Seivane, Anxo Lorenzo and others, and the second branch is women singers in groups who accompany themselves on the tambourine. People often think of the tambourine as a joke, a toy but these women singers play really intricate and very musical accompaniments. It’s like in Brazil, where the tambourine is regarded with the same respect as any other instrument. Our percussionist doesn’t play tambourine a lot – it’s just one of several colours she brings to the group – but it’s more than a toy for her too.”

The other “toy” in the group is the ocarina, which Romani himself plays. An ancient variant of the flute whose biggest moment outside of its native Italy, where it got the name “little goose”, came when Reg Presley of the Troggs played one on the band’s 1960s UK top ten hit (number one in the U.S.), Wild Thing.

“The ocarina is probably even more of a toy than the tambourine in a lot of people’s eyes,” says Romani. “But I really like the sound it makes and it has quite a fascinating background. It became really popular in Italy in the early twentieth century after it was developed into its submarine shape and it was actually quite fashionable, especially in and around Torino. There were ocarina groups there and sometimes there would be seven, eight, nine, even ten players – ocarina orchestras in fact. I suppose it still has a certain novelty value attached to it but it brings a nice colour to the music we play.”

For Romani, sound and texture are as important as virtuosity, maybe more so, when playing Galician music.

“What we do in the trio is actually quite simple,” he says. “We’re not trying to be like the folk orchestra because we can’t make that kind of sound. They have sixty-eight or more players, we have sixty-eight strings. Our idea is to create a sound that can be readily identified as Galician music and to present songs that, although people might not speak the language they’re sung in, they’ll still understand them through the way they are presented.”

The Rodrigo Romani Trio plays Edinburgh International Harp Festival on Saturday, April 6. The festival takes place at Merchiston Castle School from Friday, April 5 to Wednesday, April 10. For full details, log onto www.harpfestival.co.uk