My main bassoon is made by Bernd Moosmann.
Model: 200 "Soloist Model"
Serial Number: 6345
Several new keys have been added to this instrument after a lot of experimentation; here's an explanation of how it works:
Contra A adjustment screw
(Regulates the key's opening / intonation)
← Contra A
← Contra Bb →
The G-whisper key, is basically the same key as the A-whisper key below. It is however added to prevent the left thumb from jumping over keys to play high F# to G; it's much more idiomatic.
Rollers between all the whisper keys is a big advantage for fast playing in the tenor register and up, the thumb slides very smoothly between the keys. It's not as slippery and uncontrollable as it may appear on the first look, however it took me a week to get used to it in the start.
Octave key adjustment screw, which closes / opens the distance betweent the octave key and the hole on the bocal. This is specially an advantage during frequent changes in climate , and for removing any buzzing sound from the air hitting the key.
Moveable connection between the A-whisper key and the octave key. I normally have the connection down (as on the picture to the left), which locks the octave key when I press the A-whisper key. However if I happen to play more in the very high register, from F#'' and up (4th above the "Rite of Spring" C and up) then I'd disconnect this connection to improve the response.
The Eb trill key between the D and C hole is also extended, which makes it possible to access the same key on the right hand. Placement can be seen on the pictures below of the butt join.
The octave key has been made twice as wide, which gives the possibility to move the bocal in a much larger angle if needed. This is specially convenient in loud orchestra passages where you have to lean back into decibel reducing headphones, which changes the bassoon's & bocal's position quiet a lot.
The four keys for high notes on the side of the wing joint are for high Eb, E, F and F#.
It has been quiet a lot of experimentation regarding these keys location, and the most idiomatic solution is as follows:
Between E and D hole is the Eb-key, behind it is high F, and above it is a second high E. Above the E hole is the main high E key and F#.
The second high E key is added to improve the combination E to F#.
With this system it's possible to play rapid passages even in this high register, and also trill between all the intervals between Eb to F#.
The high Eb key has been desinged wider for two reasons; firstly for reducing the distance between the high Eb and the D hole, which makes it possible to easily slide to the high Eb key. This is specially convenient in f.ex B major thirds & chords.
The second reason it's made wider is so the finger also easily can slide to the high F key, which also has a small roller on it. (The smallest roller to ever be put on a bassoon.) The combination Eb to F is then very smooth.
For the right thumb on the boot joint there are rollers on all the keys. The lowest located key is the Ab - Bb trill key, I find this location better than having it on a second level above and in the middle of the F# and Ab key.
If there happens to be a long trill between the Ab to Bb, then the thumb might get slightly tense because of the rather far strech from the handwrest to the key. This can however easily be prevented by bending the handwrest to the location where it's most comfortable:
The low F# key can be pressed down also for every other combination below E, which f.ex makes a B major chord in the deepest range very easy to play rapidly, and all kinds of other trills and tremolos.
Under the Ab key on the right hand's little finger streches a quiet genius key all across the boot joint until the E key.
This mechanism makes it possible to easily trill between low F# to E, by simply fingering low F# (little finger) and trill with the low E key.
Above the B hole is the normal C# trill key located, however there's also a second C# trill key between the A and B hole. This key is specially convenient for trilling between B and C#. Just below it (also between the A and B hole) is the Eb trill key which also is located between the D and C hole on the wing joint.
C# tr →
Eb tr →
Contra A adjustment screw
Joint extention which lowers the pitch of the lowest third.
Up and left of the low C key is a C# / D# trill key with a roller, by pressing this key the C# key on the little finger get's pressed down, to trill to Eb simply trill with the low Eb key.
The bass joint has the contra A key located just under the C# on the left hand's little finger. A full low A fingering would then be the same as low Bb, and then add the little finger on the A.
Just as on the A-bell, there's also an adjustment screw for improving the key's smoothness.