..you can pretty much do AHs on any fret, depending on where you place the finger (from the pickinghand). I guess it helps having like three mics. I have three and that does it for me atleast. I always do AHs hehe. I also find it much more comfortable and better (for me) to use like the ringfinger instead of the thumb. I, easily, get a better harmonic out of it. But then again, that's just for me.