First - what fingering do you use? The 'A' key + register key isn't the best but is improved a bit by adding RH 1,2 & 3. 'A' key plus Bb side key with RH1 is much better as that hole is the right size & in the correct position.
Second - the relevant keys should open 2 - 2.5mm. Less than that & you will start getting a flat & muffled sound.
Third - if the tone holes are getting clogged up with fluff from swabs etc or from poor oral hygene this will have the same effect as 2.
Re: Problem with B flat note on clarinet 11:01 on Monday, May 10, 2010
You have described the exact problem that I am experiencing.
When using the “A” key and the register key the sound is very muffled and flat. There is a slight improvement when using the “A” key and the Bb side key, although it is still muffled and flat.
I have checked that the relevant keys open 2 – 2.5mm.
The tone holes are clear.
It seems to become more muffled as each session that I play goes by.
It has made it virtually impossible to play any music which has this Bb note.
Any additional help to correct this fault would be greatly appreciated.