MarkIII ground switch position

[powerlord]

My head has a ground switch that says A,B,or off.Which one is for what and why?And how do you guys run yours?Thanks in advance!

 

[powerlord]

Nobody?I did a search and found nothing on this.

 

[kaluablue]

In the MKIII manual it says:
'GROUND Switch
This switch is often helpful in reducing buzzes which originate in the AC power wiring outside the amplifier. We recommend leaving the switch in its center OFF position unless position A or B definitely helps. In the center OFF position, your Boogie cannot be the source of annoying "ground shocks" to the microphones etc.'

 

[powerlord]

Thanks brother!