12ax7 vs 5751


hi all,
i need some advice. i`m very new to tube amplifiers and i`ve been doing some tube rolling.

i currently have a pair of grant fidelity matched psvane 12ax7t`s in my amp which sound fantastic.

what i`d like to know is which are the better tubes, 12ax7`s or 5751 tubes. i`ve been looking at forums and there are folk out there that say 5751 tubes are better than 12ax7 tubes.

can i have your thoughts on this please and also which are the good 5751`s to go for.

i really like the psvanes but if they can be bettered i`d go for it as my next line up of replacement tubes.

my amp is a yaqin mc100b. the tubes i have installed at the moment are.....
2 x psvane 12ax7t`s
2 x brimar 6sn7gty/cv1988`s
2 x sylvania 6sn7gtb`s
4 x electro harmonix kt88eh`s

many thanks in advance guys.
grayf
Joe states all that in his Lore article; but if you are new to tubes it is a good, worthy place to start.
meantime, the sound is still improving on my system so i guess the brimars are still breaking in as they are nos tubes. i still can`t get over the huge difference they`ve made in my system. i`ll update next when the tubes i`ve ordered arrive. the only thing i`m not that thrilled about is the break in time for the black treasures. 300 hours!!! they`ll take forever!!!
Well the good news is they will only sound better as the hours count down. Personally I found with any new tube you need at least 200 hrs before making any judgements.
I just started listening to a JAN Phillips 5751. So far it's a nice change from 12ax7 tubes. Very quiet, black background with almost the same gain in my amp.
Not saying that Joe's tube lore is the total and final authority. Brent Jesse is another good one with a lot of specifics, historic retrospect and very good general advice on what to look for.

But when it comes to comparing same category tubes between themselves, it was the best reference I could find in a simple straightforward useful reference. I've followed, just for fun, many of his advices both with 6922-7308 and 12AX7-5751 tubes and found out Joe's conclusions were the same on both my systems. Not saying it is the fundemental truth, but subjectively it was to me.

Grayf, your choice of the GE5751WA is a good one. It is one of my favorite. It has a nice laidback sound, deep soundstage with quite a tight crunch of the percussions. Electric guitar on that one is pure heaven. If you lunge for smooth soft jazz or instrumental with the most profound and lush feminin voices, the Sylvanias are the ones to get. The black plated, three mica ones. God I love those ! True, they bring everything forward, in your face, but quite a unique sound. If you get them, do some tube rolling to preserve them as long as you can.
Andr, well stated couldn't agree more; love those Sylvania's, have them in one of my units. Like you, I tube roll them out periodically, for instance, roll in the GE for Neil Young or other guitar stuff...