Скачать или смотреть Tight vs Open lips!

Tight vs Open lips.  This is one of the most important factors of your tone production.If your lips are tight and constantly pushing against each other, the only way to get them to vibrate is by forcing air through.  As long as you play this way, you won’t be able to reach your full potential of tone colors or volume.
So what’s the alternative? 

Opening up your lips.
Try this: engage all your facial muscles from the eyes down - creating a stable platform for your aperture to vibrate.  If the lips are at just the right distance from each other, even a small amount of air can create a free vibration and a full sound.  Your lips create a sort of air tunnel, and that’s where the vibration happens.

When you get this balance right, you don’t need to “push” air through the trumpet.  It’s enough to “release” air to spark the lips into vibration.
For most players, opening up your lips will give you a richer tone quality and more volume output for the same amount of effort.