
The Bach Stradivarius 50AF3 is a double rotor bass trombone with open wrap F and G-flat attachments which can be accessed independently using two ‘Infinity’ axial-flow* valves.
Along with a larger bore and bell diameter, bass trombones are often equipped with a second rotor to extend their low register. There are two double-rotor systems: ‘independent’ and ‘dependent’. An independent system has both rotors sitting side-by-side (or ‘inline’) on the neck-pipe, where they can function alone or in tandem. Dependent models locate the second rotor on the F attachment rather than the neck-pipe, hence the alternative descriptors ‘stacked’ or ‘offset’. In this configuration, use of the second rotor depends on the first rotor being simultaneously engaged.
Also available in the Bach 50B3 range:
Wrap/valve | Bell diameter (inches) | |
---|---|---|
9½ | 10½ | |
Closed / standard | 50B3 | 50B3L |
Open / standard | 50B3O | 50B3LO |
Open / Hagmann | 50A3 | 50A3L† |
Open / ‘Infinity’ axial-flow* | 50AF3 | 50AF3L |
Other model variant: †LT50A3LG
* The axial flow valve began development in the late 1970s as a means of reducing the distortion to the air column created by traditional rotary valves, particularly on trombones. It was the brainchild of engineer Orla Ed Thayer (1920–2009), whose invention (commonly known as the Thayer valve) was first put to the test on a Bach 42B. His revolutionary idea led to further developments in valve technology.
Manufacturer’s website: conn-selmer.eu