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
Guqin strings silk and also they were louder and more stable. A set could last many years and not break. The only drawback for traditionalists was that the strings had a harsh metallic sound which was considered inelegant. Another factor was that the strings could eventually wear the lacquer out requiring the qin surface to be repaired more often. Around 2007, a new set of strings were produced made of mostly a nylon core coiled with nylon like the metal-nylon strings, possibly in imitation of Western catgut strings. The sound is similar to the metal-nylon strings but without the metallic tone to