12AU7 and 12AX7 long black plates vs short black plates. Any difference ?

billpete, of course, I asked about both 12AX7 and 12AU7.

@inna Yes, I thought so and is why I passed along my own observations over the last 20 plus years. My main source of info in the beginning was Joe's Tube Lore and I agreed with most of anything that he ever had to say. I was surprised to learn that Joe based all of his opinions on CD listening and I based mine on vinyl listening. Just kind of an interesting sidenote. 

I would always use analogue source to compare anything.

Anyway, it is good that in the age of AI and streaming we are going into detailed discussion about vintage tubes.

There is a set of three Sylvania 5814A triple mica NOS for $150 on ebay right now, if anyone wants to try them. I'll pass, need resources for Mullards XF2.

@billpete 

Mine aren't gold pin. I don't know a lot about tubes.