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
Bouzouki better suited to the kind of virtuoso playing he was famous for. Today, the tetrachordo is the most common bouzouki used in Greek music, though a few traditionalists still prefer the trichordo, particularly for the older "rebetika" style of playing. In addition to developing the modern tetrachordo bouzouki, Manolis Hiotis was a pioneer the use of amplification for the instrument, which he may have been using as early as 1945. However, the earliest documented use of amplification for the bouzouki comes from a 1952 photograph, showing Vasilis Tsitsanis and Yiannis Papaioannou playing bouzoukis, each with an electric guitar-style pick-up attached