These are the standard clarinets of the late Classical-early Romantic era, ca. 1790-1820.
The number of keys ranges from five (register, throat A, Ab/Eb, F#/C#, E/B; for performance of music composed before ca. 1800) to 12 (additionally, C#/G#, trill, Bb/F, B/F#, L3 Eb/Bb, upper F/C, throat G#; suitable for post 1800 music). See below for some thoughts on the number of keys required.
It is common practice to purchase alternate upper and middle joints giving, for example, five and 12 keys, with a common lower joint, bell and barrel.
Two basic models are offered-
- five or six key clarinets by the Viennese makers Theodor Lotz (in Bb; Musée des instruments anciens, Geneva) and Kaspar Tauber (in A; Nicholas Shackleton collection, Cambridge);
- five to 12 key clarinets by Heinrich Grenser of Dresden (Bate Collection, Oxford; Nicholas Shackleton collection, Cambridge; Haags Gemeentemuseum, Den Haag).
clarinets are supplied with mouthpieces (manufactured by Ed
Pillinger) modelled on a "cleaned up" version of an authentic original
specimen and made from a synthetic material.
For any music by Mozart (with the exception of that intended for the basset clarinet, of course), Beethoven, the Stamitz family and other composers of the ca. 1770-1800 period, five keys are always sufficient.
From around 1800 onwards, "cutting edge" clarinets were built with an increasing number of keys added onto the basic Classical model, though extra keys were still regarded as undesirable by makers, and conservative five key clarinets continued to be produced for several decades longer. Frequently, clarinets originally made with only five keys were later modified with the addition of more keywork.
The sixth key to be added was usually C#/G# in Continental Europe, but the throat trill key in England.
As examples of what is required to perform advanced solo repertoire dating from around 1800, Bernhard Hendrik Crusell used Grenser clarinets with ten keys (basic five plus trill and cross keys for F/C, Eb/Bb, C#/G# and Bb/F), and Heinrich Baermann - the dedicatee of most of Weber's clarinet music - played on Griessling & Schlott clarinets with 12 keys (as described above except with a longitudinal rather than cross key for upper F/C).
By about 1820, newer designs with more ergonomically shaped keys and other constructional and acoustical changes had been introduced. This process was hastened by a dramatic sharpening of pitch levels, which rendered older instruments largely unplayable.
The chronological perspective of the Classical clarinet is outlined on this site. Further information can be found in books such as The Early Clarinet: A Practical Guide by Colin Lawson (Cambridge University Press).