I have an articulated Ab/Bb key on my bassoon with a clutch mechanism the Keith Bowen designed and Chip Owen modified. I'll explain its function below.
Articulated A-flat to B-flat Trill Key: The installation of this key involves making a post connection between the right hand third finger “G” key and the thumb B-flat key so that when the G key is depressed it closes the Bb key. The B-flat key is sprung differently than normal in that the thumb B-flat key mechanism has two springs, a heavy one on the thumb key to close the pad and a much lighter one on the pad that functions to open the pad when the B-flat key is depressed. There are no additional tone holes bored into the bore with this mechanism but it needs to be well taken care of to function properly. If the B-flat pad becomes sticky it may not open when the B-flat key is depressed. This key gives you the following trills and tremolos: F to B-flat, F# to B-flat, G to B-flat and A-flat to B-flat in both octaves.
I strongly suggest that if you consider adding this key to a new or present bassoon you get it with a clutch mechanism that disengages the key when it is not needed. Normal fingerings that involve both the right thumb B-flat key and right third finger (G) key will not function with this mechanism engaged. You also should consider getting extra guards for this key to keep any clothing from touching the Bb key and keep it from opening. The normal thumb A-flat to B-flat trill key gives you a good Ab/Bb trill in three octaves but not the additional tremolos mentioned above. This key involves drilling a secondary tone hole in the boot joint and the adjustment of the key is also fairly critical for the bassoon to function properly.
The trill works very well and gives you several additional shakes besides the Ab/Bb trill. I've had it on my last five Fox 601 bassoons. It is a less expensive option then the normal thumb Ab/Bb trill.
I specifically reference this trill mechanism in my blog post. I don't like the mechanism at all because you eliminate the possibility of opening the Bb key independently (for some common multiphonics) without having to flip the clutch, if you have one (and I've seen many bassoons with this trill with no clutch, so there's no way to disengage it). I also would rather to Ab/Bb trill with only one finger - and a fast finger at that, than have to trill with two fingers.
I'll accept the fact that there are other tremolos you can do with this articulated system that you can't do otherwise. I've encountered quite a few bassoons with this system, and decided I just really didn't like it.
As for the concern over the adjustment screws: I thought about it, but I opted to go this route for now at least because I work in such close proximity to my repair technician. For me it's no problem, and he keeps my horn in good adjustment. This is the single biggest issue with the mechanism - getting and keeping it set up.
Last edited by Trent (2014-08-11 13:38:55)
M.M.A., D.M.A. University of Illinois at Urbana/Champaign: B.Mus. Lawrence University
Bassoon professor at University of Wisconsin Eau-Claire
Maker of the Little-Jake electric bassoon pickup and Weasel bassoon reeds