You might check that you are not trying to use the same angle of the mouthpiece in the mouth for tenor sax that you use on bass clarinet. On the tenor, the mouthpiece should go straight into the mouth, not slanted downward. If sustaining a "G" on the tenor mouthpiece alone is difficult, try playing "E" concert on the mouthpiece and neck. This also gives you the correct embouchure tightness for the tenor. If your tenor tone is harsh and difficult to control, try taking a bit less mouthpiece in the mouth and putting a bit more bottom lip over the bottom teeth. My opinion is that you will have an easier time when doubling by using the same (single lip) embouchure on both tenor and bass clarinet. To try switching back and forth on instruments that are so similar in size is just throwing another variable into the mix to make it harder that it should be. Again, this is just my opinion.
On your tenor, if you can get a nice full sounding low Bb without honking, and then play the entire register of the sax with the same embouchure and throat, I think your tone and intonation problems will solve themselves.
John
On your tenor, if you can get a nice full sounding low Bb without honking, and then play the entire register of the sax with the same embouchure and throat, I think your tone and intonation problems will solve themselves.
John