amtrpt

Hi,
Rolf Smedvig said once that it's always easier to go up than down. I really find that to be true with my playing. When I am going upwards towards a note I know that I am going to have to work harder in order to get the result I want. When I am going down however I often forget that I need to use the same focus only in reverse. Think of it as a standard transmission car. As you go faster you shift to a higher gear. As you slow down you have to down shift or the car will stall. In this example imagine that the air is the transmission. As we go up the air needs to be faster. As we go down the air needs to be slower. With both directions you will need effort. That's pretty simplified, but I hope the point makes sense.
Here is what I would do specifically for your question. First of all don't worry about getting the slurs perfectly clean. In fact I would suggest that you put in more notes. Take an C octave downward slur for example. Before you play the interval play the scale from middle C to low C slurred. Pay attention to how your air will slow down and your lips will relax to get the right vibration as you descend. Now try it as a arpeggio taking note of the same thing. What we are going for is a very smooth but also quick transfer of air speed and a relaxation of the lips. Now try playing C-E-C. Then C-Db-C. Really try an keep the air relaxed and natural. I do this practice routine going in either direction.
I hope that you find this helpful.
Best,
Andrew