Irish bouzouki Dónal Lunny, who replaced the octave strings on the two lower G and D courses with unison strings, thus reinforcing their lower frequencies. Soon after, on a visit with Irvine to the workshop of luthier Peter Abnett, Lunny commissioned a bouzouki to the specifications of a classic, 4-course Greek bouzouki but with unison strings and a three-piece, partially staved back. Since then, the instrument has been adapted for Irish traditional and other styles of folk music. The original Greek bouzouki was a three course/six-string instrument ("trichordo"). In the 1950s, a four course/eight-string ("tetrachordo") version was developed. The newer "tetrachordo" bouzouki
Irish bouzouki was introduced into Irish traditional music in the mid-1960s by Johnny Moynihan of the popular folk group Sweeney's Men. During the recording of their 1968 eponymous album, "Sweeney's Men", Andy Irvine also played Moynihan's bouzouki on the track "Johnston". Shortly after he returned from Eastern Europe in late 1969, Irvine met Dónal Lunny – who had been playing guitar up to that point – and gave him a Greek bouzouki he had brought back from his travels. Being left-handed, Lunny reversed the strings and critically, replaced the octave strings with unison strings, thus fundamentally changing the character of the instrument.