Stubbins model Vito
Serial #16555ABarrel: 66mm
Bore LH joint top: 114.7mm
Bore LH joint at bottom: 14.7mm
I am indebted to woodwind.org’s Ralph Katz for this great information:
William H Stubbins was professor of clarinet at the University of Michigan in the 1940's to the early 1970's. His patent was for an improved mechanism for the register vent with an added tone hole just for the throat Bb. This was commercially named the "SK" mechanism. Stephen Fox can make instruments with a similar mechanism.
Some mentions of Stubbins' works can be found here:
There is a Noblet Stubbins model listed in this collection:
Intonation summary: After I was done, I did pull out at the center and it improved the sharpness of the middle C. This is WONDERFUL intonation. Bear in mind that I never play with a 66mm barrel. A 65 or 64 barrel would be just right for me on this instrument. This is excellent intonation. With a hard rubber or wooden barrel, one could play this in the most exacting symphony and no one would complain. The great advantage of Stubbins’ key compared to Mazzeo’s is that you can use the regular resonance fingerings. (rf in the chart above)
Key work quality: superb, as with all Noblet products.
This was my first time to work with the Stubbins register mechanism. I found it a bit finicky. However there are adjustment screws in all the right places, so there really should be no problem.
This clarinet is most appropriate for: Anyone who hates the way the normal Bb sounds on the clarinet.