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 octave mandolin are more likely to use mandolin tuning machines and reproduce the details and styling of their American-style carved top mandolins. Some luthiers choose to refer to their clearly bouzouki-style instruments as octave mandolins, or even as mandocellos, despite the GDAD tuning. The octave mandolin is usually regarded as having a shorter scale length than the Irish bouzouki, in the vicinity of 20 to 23 inches (50 to 59 cm), while the scale length of the Irish bouzouki most often ranges from 24 to 25 inches (60 to 65 cm). Some instruments have scales as long as 26 or