Irish bouzouki Johnny Moynihan (apparently in an attempt to replicate the open, droning sound of Appalachian "clawhammer" banjo) first on the mandolin and then transferred to a Greek bouzouki. It was later picked up by Andy Irvine and Dónal Lunny, and quickly became the next thing to a standard tuning for the 4 course instrument. Other tunings used, although by a minority of players, are "octave mandolin" tuning G2 D3 A3 E4, and "Open D" tuning A2 D3 A3 D4. "Open G" G2 D3 G3 D4, is used by some players and has proven useful for "bottleneck" slide playing. The GDAD tuning
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