It might help if you release the octave key just a split second before you finger G. But the key is throat control and breath support. When slurring down, you have to have a good breath support and open your throat.
Exercises that might help :
- play E4, go to E5 without using the octave key and back to E4. This gives you the control over your throat. Repeat the same on every note from Bb3 to G4.
- play G5, and try to hit G4 without releasing the octave key. Repeat the same on every note down to C4
Exercises that might help :
- play E4, go to E5 without using the octave key and back to E4. This gives you the control over your throat. Repeat the same on every note from Bb3 to G4.
- play G5, and try to hit G4 without releasing the octave key. Repeat the same on every note down to C4