The Digitech BSW has the right sound for me 90% of the time and I am really very happy with it (it's my 2nd one). BUT... I want to be able to adjust the speed of the quack from "QUACK!" to "quuuuuuaaaaaaaack..." with all other settings in between. Know what I'm saying? I think that is called the speed or rate. I dunno, the different makers all call them different things. So which readily available filter do I want. "readily available" is important in case I want to return it. Thanks!