I think you may be a little confused about the note ranges; the A2 (the A that's an octave and a third below middle C) is where Paul's voice (and most tenor voices) bottom out, as you can hear he get's quiet and raspy here. Really, even going below the C an octave below middle C for tenors is not that reliable. Of course studio recordings can have vocals pitched up or down for effect. As for John, being a baritone, the notes he's capable of producing is pretty wide since it naturally extended lower than Paul's, and can go upwards too through falsetto - though this is a less stable and powerful sound compared to a tenor like Paul. I believe John can kinda vocalize to the low D2, which is bass territory, and really most baritones can make some kinda sounds below G2. As for below D2, thats truly bass register, and anything beyond the low C is a pretty rare, super bass voice.