I've been noticing that the sound output from the apple2e driver has a lot of "pops and crackles." It must be coming from the Mockingboard because it disappears if I bring up the ` volume sliders and set the volume for each AY channel to zero. It has a very regular pattern, almost like someone typing.

Is there a way to disable the Mockingboard from the command line as it seems to be hard wired in the driver? Like -sl4 empty_slot? I suppose I could always just comment it out and recompile.

MCFG_A2BUS_SLOT_ADD("a2bus", "sl4", apple2_cards, "mockingboard")

You can hear it in this video in the background: