Can I animate typography separate to it's mask?

Hi,

Basically what I'm looking to do is to animate some typography but I need the mask not to animate along with it.

I've basically animated a word dropping down and added a subtract mask so that it will(in theory) come from behind the mask. When you add the mask it moves along with the type though, I've tried a few things like setting keyframes to the mask's path which works ok until you add ease to the inital type layer.

I just wondered if there was a way to keep the mask static and have the associated shape/type animate?

Thanks,

Elliot