Surface Agitation with out a transducer?
Well, i'm working on a sound project, the idea is simple, a metal sheet that is agitated by a speaker or a piezo. but it seems that the piezo and the speaker i'm using is still insufficient to shake the metal sheet, and i don't want to spent money importing a transducer from SparkFun.
So the question is, how can I do it? The speaker i'm using is 4ohm 6Wats, do i need a stronger one? if so, stronger ohmd or wats? or both?