Cabs are all different, but by far the most common set up is to have the speakers in front of the glass, both in Arcade cabinets and MAME cabinets. Where that is on the speaker panel is a different question though. Some route a line straight across the bottom of the panel so that the glass can rest inside. Others put the glass behind the panel and place something else behind that to hold it in place. The one consistency though (at least as far as I've seen) is that the speakers are always always always in front of the glass.