Phil asked:

>        I have a self-driven magnetic buzzer that i'm using in a
>non-intended fashion. Instead of having the buzzer fully on, I
>pulse it at approximately 60Hz, using a PIC, of course (This had

  (much snipped)

  The main advantage of magnetic buzzers as opposed to the strictly
  piezo ones is the higher spectral content at low frequencies.
  In some environments they are easier to hear.

  But if you don't need the low frequency content, the active
  (self-driven) piezo types have equal db output at MUCH
  lower operating current.

  Reg Neale