Try the Alexanders. I'm using the DCs right now, and they are great on low notes. I can take a size 3 and play low Bb at pianissimo for as long as I need and keep it totally even. That wasn't as conceivable with Vandorens. I really like the tone Vandorens produce, but they tend to give out when you get anywhere at or above a high F#.

yeah, just keep you jaw low all the time, geez. you probably got on the receiving end of a bad cane harvest. it happens. that's why la voz are cheap

Well what kind of mouthpiece do you have? La Voz are all hand made reeds (As are vandoren but Vandorens are better :-D) so u could in theory try out like 30 and get different capablitlies out of every single one. I don't like them personally because they are made from Rico and don't usually perform like my boy Vandoren. (Te-He) Blue Box are ok but i would strongly reccommend trying out some Vandoren ZZs or maybe even some Javas if you play on a metal piece. Also your lig will make an enourmous difference. Try some Francois-Louis Ligs. I would scrap the La Voz though, i never can get any kind of good sound out of them.