12AX7A preamp tubes - ribbed vs smooth plate

@immatthewj amps use a variety of small signal tubes in their inputs it's also possible the OP is referring to an integrated amp.

I doubt there are 4 rectifiers that doesn't make any sense.

Hey emergingsoul I very well have too many tubes in or out of boxes that said the 12AT7 tube is not a rectifier tube.

That is very sad new indeed I knew Bill had been ill what an audio legend may he RIP.