Irish bouzouki when having a longer scale length. The fifth course is usually either a lowest bass course tuned to C2 or D2 on an instrument with a long scale, or a highest treble course tuned to G4 or A4 on a shorter scale. Luthier Stefan Sobell, who coined the term "cittern" for his modern, mandolin-based instruments, originally used the term for short scale instruments irrespective of the number of their strings, but he now applies "cittern" to all 5 course instruments irrespective of scale length, and "octave mandolin" to all 4 course instruments, leaving out bouzouki entirely. Mandolin-family luthiers producing an
Irish bouzouki and a flat back with straight sides replaced the round, stave-built back of the Greek bouzouki. English builder Peter Abnett, who was the first instrument-maker to build a uniquely "Irish" bouzouki – for Dónal Lunny in 1970 – developed a hybrid design with a 3-piece partially staved back and straight sides. All of the initial Irish bouzoukis had flat tops, but within a few years a few luthiers such as Stefan Sobell began experimenting with carved, arched tops, taking their cue from American archtop guitars and mandolins. Even so, today the overwhelming majority of builders continue to opt for flat