The Clarinet in G is an interesting possibility. It is a large clarinet pitched a fourth below the written note. This instrument is most commonly associated with Turkish and Balkan ethnic and jazz music. Historically, this instrument was called a “Clarinet d’Amore” being pitched a minor third below the standard B-flat Clarinet. Most original d’Amores had a bulb bell like the lower oboes. Modern instruments do not have this feature.
All G Clarinets (save for those custom made by makers like Stephen Fox) are in the Albert system. This means that most clarinetists will have to learn a new fingering system in order to play the instrument. I myself have recently picked up the instrument and am facing those challenges currently. That said, once the challenge of learning the new system is in place, the instrument can be a valuable asset.
The True Alto Clarinet
Being exactly midway between the B-flat Clarinet and the E-flat Alto Clarinet, the nomenclature of the instrument can be somewhat ambiguous. In all honesty, the G feels like a true alto voice. It’s a bit huskier than the B-flat, but not as much as the E-flat Alto. Due to it’s small bore, the same as the B-flat, it feels and plays almost like a true, small-bore Basset Horn. In fact, at one time Basset Horns were pitched in G as well as F. The original draft of the Mozart Concerto was for Basset Horn in G.
If we call this an Alto Clarinet, then I really feel that the current E-flat Alto Clarinet should be renamed as the Tenor Clarinet (which is its old English name).
The G Clarinet can have several uses. One, it can bolster or replace the lowest B-flat/A Clarinet parts. I can also serve as an independent solo voice. When a composer wants the darker sound of the A Clarinet, use the G instead. There is minimal to no difference between the B-flat and the A, but there is a substantial difference between the B-flat and the G.
The added range to a sounding B2 gives a few extra notes that are not available to either the B-flat or the A.
Below are a few videos of myself fumbling around in my new Chinese-made G Clarinet. These should not be taken as professional playing, but as a rough outline. Note, I am still struggling with the instrument.