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
Xti16 thank u so much for that info thats invaluable. i really will have to draw the line at the treasure tubes because of the expense. i did some digging for info on decent kt88`s yeaterday and the ones you have are a fantastic collection and i can only imagine how much enjoyment you get from all the different sounds available to you. i`m so impressed by all the different sounds i get with all these tubes i have too. it`s like a whole new world has opened up to me and i`m just as impressed with all the advice i`ve had from the tube amplifier community and i`m so pleased to be part of that.

i completely agree with you about the fact that there are really no bad sounding tubes and i can also say that what doesn`t work in my amp will work in others sound wise. but the beautiful truth so far is i haven`t really come across anything that hasn`t worked decently in my amp apart from when i switched positions of the brimar cv1988/rca vt231 6sn7 tubes but that was literally down to just switching positions.

gonna cut this short now, i just got the telefunken 12ax7`s through the post! i`m like a kid with a new toy lol. i`ll post a review of these later today guys and thankies again Xti16 for that fantastic info. chat later guys
i cannot contain myself here!!! i put the telefunkens straight in the amp and to my sheer luck i heard my neighbour that lives below me going out! talk about a stroke of luck! and these tubes? WOW WOW WOW!!! so far these are the kiddies! i put my usual fav cd on dave gilmour. more twang to his guitar, more detail, the bass growls, gorgeous tones and to my sheer surprise an even lower noise floor. i can see why these are considered as some of the very best of 12ax7`s. this sound stage just keeps getting freakier and freakier! the seperation is just spot on! deadly accurate. if these tubes can be likened to the armed forces then these are the special air service of the tube world lol. truly elite!!! the ei elites are very very similar, it`s just that these telefunkens go that extra mile and definately worth the expense and i gotta say i got an amazing bargain. i got these very cheap compared to the prices i`ve seen them go for. god only knows how the ge 5751`s are going to stand up to these! the ge`s really are going to have to go some to beat the sound of the telefunkens......thats if they ever get here!!! oh did i mention i got the bass slam back again! the ei elites and telefunkens draw level when it comes to bass slam, i can`t hear any difference here. oh man someone please wipe this smile off my face lol my face seems to be stuck in smile mode lol. i simply cannot believe the sound coming out of my speakers! Mcpherson put these on your shopping list. these are amazing!
Last the Ei KT90's used to be my least favorite output tubes. Only after swapping out the drivers (2 Rca 12at7wa and input 1 Sovtek 12ax7) with Gec CV6091 (military version of the A2900) and Rca triple mica black plate 5751 did I really start to like the Ei's. So I believe with the right combination of tubes anything can be made to sound better :).
So have fun