The T100 scale by M. Welte & Söhne (Freiburg) was the first reproducing system of its kind and caused a worldwide sensation in 1904/1905. T100 refers to the 100 holes in the tracker bar. 80 notes are played; 20 perforations are used for the complex expression control. “Red” and “green” derive from the characteristic color of the roll paper – it was usually red for T100 rolls and usually green for T98 rolls. However, rolls of each format were also made in other paper colors.
Most recordings were made for the Welte red system – for the Welte green scale, introduced only in 1924, the existing Welte T100 (red) recordings were re-encoded into the smaller roll format and recut.