In most applications you do need some form of box some companies make free air subwoofers that you might want to look up
Many things and nothing in particular. It highly depends on how you define retro and which era you are thinking about. It's generally a watch with a modern movement (mostly quartz, but sometimes...
Its when someone subscibes to another youtuber and they subscibe in return
it means you sub me and i sub you
A sub is a subwoofer it is a large speaker made for playing loud end bass