Blow all the way through that horn!!!! For those low notes you have to get that air all the way through the bell. Play down the horn from high F to the bottom. You have to keep the that air flow sustained. Then practice hitting those low notes from jump street. Get a copy of Land of a Thousand Dances" by Wilson Picket and play with it. Bark the lowest note that fits they key that it is in. It will be BOMP BAAAAAAAA every other measure. That wil get you used to getting that quick air flow needed to hit the low notes. I think a 5 Otto link metal would be a good starting point. Don't use Rico Reeds, as they are junk. Use La Voz medium soft for right now and later medium. Some day you will use Vandoren, but they are either great or junk. You have to hand pick Vandoren reeds. Best of luck to you :) Also, you don't want to drop your jaw for those low notes, but it is ok to relax you emboucher a little bit.