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
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
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!
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
Grayf the Treasure Z's you are getting are supposed to be a very good tube. A big step up from the EH KT88's. Now I'll be honest I don't have or heard the Treasure Z's but from everything I've read they seem to be a step down from the EAT KT88 and a step up from the EH SED and Gold Lion re-issue). I also have a few original Tung Sol 6550 solid black and grey plates. Very different - more seductive and a little less detailed. It just amazes me that I can swap some tubes and change the type of sound. In my PERSONAL opinion the EAT's are the best (won't have the Gec/Tesla for up to couple more weeks to compare). I have a pair and a quad of the EAT's (which I bought used) and after 300 hrs I only have 3 stable tubes. 2 with a bias drift and 1 that puts my Octave into protection mode. So I can make a quad but have to monitor the bias every hour or so.

OK that's the long story - Short story unless there is a real dissatisfaction with the Treasure Z's (very unlikely) just be happy with what you have. You have a lot of combinations of tubes to play with.

Have fun because tube rolling can be a real treat ;)
Disclaimer: I own SED EL34 - 6550 and KT88's Gold Lion reissue KT88 original Tung Sol solid black plates and solid grey plates - EAT KT88 diamonds and Ei KT90's. There is NO bad sounding tubes. Only better sounding ones!!!
Grayf
The upgrades included replacement of all signal caps with V-Cap CUTF/OIMP
MUNDORF silver/gold hook up wire
WBT Nextgen RCAs for 2 inputs and output
DACT 24 STEP Attenuator

I would contact Ted at highendaudio.com for any upgrades.
He is part of the new owners of Thor Audio and you couldnt ask for a more available and polite person to deal with. I plan on sending my unit to him to do some housecleaning.
They work on all units though.
The particular unit I bought had a bit of history b/c the upgrades they offer/suggested were done by another outfit. Long story short I think I came out ahead due to the fact that Thor didnt do the upgrades...otherwise a 5 year warranty and stamp of approval would have driven the price up.
This is really an incredible preamp. My sound floor is at 1 on the volume. ALL the sound is there as soon as the volume is engaged. I was a volume hogg because I had to turn it up so loud to hear detail before. Cheap imitation.haha
I think this is a glimple of how a 30 or 60 watt amp can produce quality sound. Just for the record the new Thor will retail at around 17K and the old unit upgraded is supposed to be in the same ballpark. I feel like I got a sports car for a work truck price!
WHERE IS THAT STINKING POST MAN???????
They are good tubes have a few and i like them, I also like the 12ax7 Mini Watt too. Both in my VTL 5.5 pre-amp.
Xti16 stop right there!!!!!! lol. i can`t hear you!!! i kind of had a little delve into the gecs, wow! very expensive! but i bet they sound amazing! let me know what they`re like when you get them it`ll be very interesting. not heard of the EATS, i`ll do a little research into them and the tesla KT88`s. i was thinking of those psvane KT88-t`s too. i`m just looking around my room to see if there`s anything i can sell lol i can see me ending up sitting on a wooden box listening to the only bit of furniture i have left lol. funny enough i do have plenty to sell that will make a good bit of money but my sensible side tells me to keep the money for a rainy day, but then i have this little devil on my shoulder poking me in the ears until i give in!

just a very quick update on those sylvania 5751`s in there currently..... they sound really nice. nice and clear and a really nice focused soundstage. listening to them right now with the volume cranked up a little louder than usual. there`s nothing really lacking in them anywhere. they have a nice punch to them too but not the slam that the ei elites gave me. but there`s lovely detail all through the frequency extremes. damned good considering i only paid $18 for the pair. stunning bargain!
i`m kinda glad too! this tube rolling is getting expensive! i really musn`t order any more!
Oh just wait until you start rolling vintage output tubes or try some current production EAT's!! Then just think of all the combinations with all the input and driver tubes. I just ordered some Gec and Tesla KT88's.
Mcpherson

hiya yes the ge`s are d getters triple mica black plates (the really good ones). i`m waiting to pounce on the postman (not literally!) this morning. i`m so hoping he has at least one package for me! i also ordered the telefunken 12ax7 smooth plates yesterday. should get those tomorrow. i want to see if there`s any difference in the sound quality compared to the ei elite 12ax7`s. thats gonna be interesting!

unfortunately i have no experience with the phillips miniwatt 12at7`s as my amplifier doesn`t accept those types. i`m kinda glad too! this tube rolling is getting expensive! i really musn`t order any more! i`ve already built up a small collection of 12ax7`s and 5751`s. i must say i`ve not heard any lousy sounding tubes out of any of them. they all bring something unique to the sound of my amplifier but i will say the ei elites are truly stunning!

we`re both in the same boat as newbies to tubes! i was kind of the same, i went from a denon reciever straight to a tube amp and i know exactly what you meant saying you were cracking up when listening to the commodores. i`ve been exactly the same with some of my cd`s too. i just cannot wipe this stupid grin off my face when i listen to a cd! i feel like the cat that got the cream!

the funny thing is i was listening to music on youtube through headphones on my computer and listened to some of the tracks off that dave gilmour cd on an island. i actually heard more detail through the headphones and they`re only cheapies too but it`s made me think that all that extra detail maybe is to come when i get all these other tubes i`ve ordered but i`ll have to wait and see. once i`m satisfied with the sound in all this mixing and matching i`ll just concentrate on those certain tubes i`ll be using and get spares. all the other tubes i`ll probably sell but i`ll hold onto them maybe a few years to see if they go up in price and hopefully make some extra money.

i`m really excited at the prospect of getting those telefunkens. i got them at a fantastic price off ebay last night. they`re supposed to be the best.

i have to ask.....did the cap upgrades make a difference. i`m thinking of doing the same for my amplifier using mundorf silver/oil caps in the pre amp stage. i`ll be starting a new thread on this topic once i`m happy with the tube arrangements and sound. i bet that`ll be a very interesting topic. keep your eyes peeled for that one. i`, also thinking of upgrading the speaker cables at some point to chord epic cables but that might be some time off yet as those cables are pretty expensive!
Grayf
Yeah I think this Thor was a steal. Had cap upgrades,etc. Today I was cracking up listening to the Commodores. I went from a Marantz receiver as a pre to the Thor, so my cd collection seems brand new.
Are the GE tubes that you ordered (d getter) similar to the triple mica black plates? I am so new to this..it isnt even funny.
How about Phillips Miniwatt 12at7? any experience with those?
I have a pair of each that test way good.The RCA is Triple Black Plate 1960. Really did not like them in my VTL 5.5 pre-amp. Went back to 12ax7, like some one said in what circuit are you using them in means a lot. They test on a B@K 700 with 22 being minimum good 35/35 and 34/32. The RCA i got from Jim McShane.
01-31-12: Mcpherson
Tpreaves
What is Paul lindermanns user name? Thanks

Paul_lindemann

I goofed up and added an "r" in my first post.
i just googled the thor ta1000 pre amp. wow! very nice looking! and very unusual. i`ll let you know straight away when the tubes arrive i`ll do an initial review of the tubes and then a more in depth review when they have more hours on them and when i can give them a good prolonged listen. you might want to think about the telefunken 12ax7 tubes. the ei elites are apparently based on the telefunkens and made with the same tools that made the telefunkens. i have to say that so far the ei elite 12ax7`s have blown everything else i`ve tried out of the water! a truly stunning sound! just dubious about them turning microphonic after a few months use. so far they`re quiet. one is just very slightly microphonic and i do mean its hardly noticeable. the ei elites are very holographic and very 3 dimentional and the depth of sound and tones has to be heard to be believed. a word of warning though......what works in my amp may sound different in yours but i guess this is where the fun lies in finding what works in your system. so far i`ve been extremely lucky finding what works in my system. definately not skill! i`d hardly call myself skilled as this is my very first tube amp. i hope this helps. more to come very soon hopefully.
hiya guys,

i`m still waiting on those tubes though i got a matched pair of sylvania 1970`s grey plate disc getter 5751`s through the post. i bought them because they were very cheap and have nothing to lose as they were cheap.

the sylvania`s for the price are very respectable. nice and clear, nice bass and lots of detail. they`re not in the same league as the others i`ve tried (12ax7`s and 5751`s) but i wouldn`t say they`re that far behind. they`re a used pair so no breaking in has been required but i have let them warm up a couple of hours. the sound compared to the ei elites is thinner all round but again i don`t want people to think they`re rubbish. far from it! they still have a very nicely weighted sound, just not as weighty as the others.

it`s driving me nuts waiting for the ge 5751`s and the black treasure kt88-z`s. i was lead to believe the black treasures were posted on the 18th but i`ve found out they were only posted on the 29th! so i have more waiting to do! grrrrr lol. the ge 5751`s should be here anytime now.......hopefully!!!
I didn't like the 5751 until I found some good ones. Give A'gon member Paul_lindermann a shout,he will fix you up.
VERY interesting thread. I recently bought a Thor ta1000 and am very impressed with it but would like more of the sound you are describing.(3d and depth) This is my first tube component of any sort and I was told to go with GE 5751 triple mica blacks. If the potential for improvement is anything close to what you have experienced...then I have a lot to look forward to! I am anxious to hear your update when the 5751s come in.
update for the ei elites....

ok one of them (the right side) has turned very slightly microphonic but it`s very slight and not really noticeable and certainly doesn`t affect the performance.

and now for the good stuff! i have about 45 hours on them now and i can`t believe i`m saying this but the sound has improved immensely! the punchy deep bass has turned into a punchy deeper bass with slam when required! the warmth in the bass is just superb. the bass is as seductive as you can get!

the noise floor is even lower! on dave gilmours cd on the track "a pocket full of stones", when he first starts singing there is just his voice accompanied by a piano. both the voice and piano come out of nothingness, blackness, darkness i dunno how to describe it but it`s amazing! you can hear a pin drop. thats the effect it gives you.

the highs are just as high but have more presence as does the midband. voices now sound just a tad more forward than what they were and are just as detailed and deep. by that i mean more depth to the voice in the soundstage.

and on to the soundstage!i said before when i installed the tubes that i initially found the soundstage freaky. i meant that in a very good positive way. well now the soundstage is super freaky!!! much more depth, much more seperation, much more 3 dimentional, more expression and amazing presence and air around that presence. voices sound closer to me in the soundstage. this must have a lot to do with how the ei elites interact with the brimar 6sn7gty/cv1988 and the rca grey glass vt231`s in this amplifier. it is just pure magic.

there`s still no sign of my black treasure kt88-z`s or the ge 5751`s yet. i can`t wait to get them now to see how they fair in this amp. so there`ll be more to come soon :)

i don`t know where these tubes stand in the 12ax7 world of tubes but in this amp they`re incredible
hiya mikirob, it`s a hell of an experience. i wish i could say i achieved it by skill but really it was pure luck! the only thing now is i hope the kt88-z`s add further improvements rather than being too much of a good thing. they must be due any day now too
Congrats, you found that special tube synergy with your system. So many folks never make it.
hiya larryi,

i`ve had a chance to have a proper listen to the ei elites. played my usual cd`s dave gilmour on an island, adele 21, steve hillage green and also had a listen to pink floyds remastered wish you were here. i got the tubes this morning so i had to listen at more conservative levels but this evening i was able to crank the volume up a little to more decent levels that i usually play at. all i can say is wow!!! i know i hark on about hearing more things that i`ve never heard before but this is startling! at the beginning of dave gilmours track "then i close my eyes", there`s sound effects that sounds like someone walking up to a car and opening and closing the car door then walking back. it`s a brilliant sound effect but with these tubes i also hear a group of people talking. i`ve never heard that on any other of the tube combinations i`ve had so far. and what i really like is there is a warmth and smoothness to the whole range of sounds as well as the extra clarity. the weight of everything is just right. this midband is just superb. there`s decent soundstage height too. dave gilmour is no longer 4ft tall!!! the bottom end is outrageous! bass goes lower than whale poo now! there`s a really gorgeous warmth to the bass too and there`s texture not only to bass notes but everything at every frequency. listening to steve hillages cd green has high frequencies like i`ve never heard before. this cd is amazing to check your high frequencies and it`s not a half bad recording considering it came out in 1978 i think. synthesiser notes just hang in their own space in the soundstage. this cd is so magical sounding. some of adeles tracks have such amazing bass drive. there`s a lot of piano work going on in her cd and the weight of each key is just perfect. these tubes appear to have brought extended highs and lows to the table with everything in between just right. i`ll go as far to say the soundstage is freaky! my brain computes that all the artists are there right in front of you in their own space but my eyes can`t see them. i`m also wondering if and how the sound might change as the tubes break in. i keep thinking that the sound just can`t get any better. that`s what i thought using the psvanes and then the jan philips 5751`s! and now using these ei elites it has completely changed the sound that comes out of my speakers. these tubes have been an upgrade! and a huge one! i still have those ge 5751wa`s on their way and they`re really supposed to be something quite special. also the black treasure kt88-z tubes are really supposed to be something that are currently on their way through the post to me.

i have to say too that not only is the amp a real cracker but the speakers i have are really something too! every change i`ve made, this combination lets that change be heard good or bad. mostly mindblowing in this case! the speakers are quad 12L2`s and they are real chameleons. they change sound with every change i make. amazing!

if i ever come across the telefunkens at a decent price i may well go for them. i think my tube rolling spending spree better come to an end before i have to sell the furniture to pay the bills! the journey to where i am soundwise on my system has been probably the most fun i`ve ever had! i so wish i`d discovered tube amplifiers years ago. i`ve been missing so much! and i still have a little tube rolling to do when the new ones get here too. i cannot imagine the sound getting any better! but as i say......i`ve said that one before! more than once!
If clarity, 3d soundstaging, and dynamic punch is your thing, the ultimate tube for those qualities, to me, is the Telefunken ECC803S. But, it can be, in the wrong application, quite lean and analytical sounding (bass is very tight and fast, but not full sounding). It also has a reputation for having an extremely long usable life (something I am counting on).

Also, because of the expense, there are fakes floating around. Supposedly, the fakes are tubes with similar looking internal structures that have been given new markings on the glass. I have not heard of any fakes having the correct embossed in the glass Telefunken diamond on the bottom of the tube, so that might be the way to tell.

I have heard that some Tesla ECC803S tubes are also quite good, but, there are some newer Tesla ECC803S that are not that good and have a much shorter life than the Telefunken tubes (I have no personal experience with the Tesla tubes).

My phonostage came from the manufacturer with 1960's RCA 12AX7s that are also on the punchy and clear side of the spectrum (as opposed to warm and rich sounding). They were decent, but I prefer both the Telefunken 12AX7s and the ECC803S.
i forgot to mention, if 3 dimentional soundstages are your thing then these are the tubes for you! extremely holographic! a huge wide and deep soundstage. the depth is incredible and real! this is something i just love and what i`m trying to achieve out of this system. bring on the black treasures kt88-z`s! also i`m sitting here at my computer typing this and listening to music. i`m very off axis to the soundstage and it`s rock solid and still centralised between the speakers. amazing stuff!
12AX7E EI ELITE NOS just received these tubes today. i bought these because they were made with the exact tooling that the telefunken 12ax7`s were made with. these have been the cheapest tubes purchased yet retailing at £39.00.

you have to hear the separation of instruments in the soundstage to believe it! absolutely stunning! all instruments are rich and smooth in tone. the highs are very smooth. the detail is second to none. the noise floor has been lowered significantly over all the other 12ax7 and also the jan philips 5751`s. absolutely silent back grounds! everything seems to have extra texture. i have to say the ge 5751`s are going to have to be pretty special to beat this! at this point in time i really can`t see these being bettered! but we`ll see. i`ve read that these ei elite tubes become microphonic after so many months of use. we`ll have to wait on that one. at this moment they`re very quiet and i pray they stay that way.

so far these tubes are of amazing sound quality. i know i`ve said that so far all the tubes i`ve listened to are more a matter of taste to the listener rather than one being better than the other. well i make an exception to that here!

the punch and depth of bass is shocking! it`s like taking one to the guts from mike tyson!!! even if these tubes lasted just a year i`ll be more than happy to buy another set. the sound is just incredible and i have to say they leave the others in the dust and the amazing thing about that is all the other tubes really don`t sound bad at all. in fact they all sound excellent in their own right but these are special!!!
hiya all i need a little info.....ok i have the ge 5751`s on order. the ones i`m getting have d getters. i`ve noticed other ge 5751`s have square getters. does anyone know if there`s any difference in sound between these 2?

i have about 30 hours now on the jan philips 5751`s and they`ve opened up very nicely. i have bass in spades now and voices seem much more natural and very well intergrated into the soundstage. i just love the bass i hear although i doubt the neighbours agree on that one!!!

mikirob i really can`t wait to hear the black treasure kt88-z`s. if my system sounds this good now then god only knows what the black treasures will bring to the table! also i just can`t wait to get the ge 5751`s. the jan philips tubes alone are pretty amazing sounding. also i don`t want to take anything away from the psvanes 12ax7-t`s. they are awesome sounding tubes. i reckon its just peoples taste as to what they`ll prefer rather than what sounds better. i`ll be trying the psvanes again with the black treasure kt88`s as i`ve heard they`re a very good match that helps bring out the best in the black treasures.

i`ve also got my eye on another pair of brimar 6sn7gty/cv1988 tubes. i`d say they`re the best tubes i have in my amplifier at this moment and i just love the tones it brings and all the openess. incredible tubes!
Yes, when you change out the EH KT88s you will get more improvement.
Best of luck in getting the best out of your system.
just another quickie update. with just 7 hours on the jan philips tubes and things have changed! wow and i mean WOW! everything sounds much clearer, as if they didn`t sound clear enough before! the extra clarity makes each instrument sound as if they are in their own spot within the soundstage and you get the sensation that you can see right into the recording. i don`t hear any extra information on the cd`s but the information that is there is far more pronounced and set naturally into the soundstage. just listened to dave gilmours on an island cd and this is by far the best i have heard this cd. throughout the cd his guitar has the most amazing tones that have real bite. i have to say this is a damned good recording that i`m totally addicted to listening to! no doubt there`ll be more to come soon.
oh and one other thing i`d like to mention about the jan philips 5751`s, they run silently with no signs of being microphonic.
hiya guys these are great feedbacks and you`re all helping so much. can`t thank you all enough.

well i also ordered some jan philips 5751`s and got them this morning. of course i put them in straight away!

ok my initial impressions so far and also keeping in mind that these are nos tubes so they will need breaking in. i really like them. they have an added warmth and are just as detailed as the psvane 12ax7t`s. i seem to have lost a little soundstage width but gained some depth. also i`ve lost the added punch in the bass that the psvanes had but the bass is still very seductive, deep and pleasing. listening to adeles cd her voice still has that natural dryness but with these tubes there`s an added warmth and to me there seems more detail and depth to her voice. in the soundstage there is also more precision than the psvanes but less seperation due the soundstage not being as wide but i`m not talking by much. i do have one criticism though, one of my very favourite cd`s steve hillage green, some of the synth notes seems dull and less involving as does his voice on a couple of tracks. i use this cd to check out the high frequencies and these tubes pass with flying colours! every bit as pleasing as the psvanes but it`s such a shame about those synthesiser note and his voice but as i`ve said, these tubes only have about 4 hours on them and they`ll more than likely open up at some stage and that`s going to make this experiment much more interesting! so far if i had to choose between the psvanes and the philips the psvanes would just about edge it so lets see what happens when the philips tubes open up!

the tubes i`m currently waiting on now are the ge tubes, sylvania 5751`s and the kt88-z treasure tubes. this is all getting so interesting. i`ll keep you all posted at every stage. i have to say too that i bought the jan philips 5751 tubes from a uk vendor and ordered them over the phone. this guy was fantastic and very knowledgable about tubes in general. we spent the best part of an hour discussing tubes and being given all kinds of advice. i`m having the time of my life even though this is sucking the hell out of my finances!!! you gets what you pays for i think! more to come soon guys :)
Joe' Tube Lore basically says what you posted above, no one really disagrees with what you have stated; but for a newby to tubes, Joe is a good starting point in order not to go broke. There are many tube gurus out there, Jim McShane, Kevin Deal at Upscale, Brent Jesse and so forth, consult with the folks who have solid reps, or someone you know and trust to help with advise and to narrow your search. The Tube Store has also been helpful to me, as well as the others mentioned above.
I agree with Rccc that the only way to really know is to experiment--tube performance is very specific to the particular application, and in addition, there is the matter of individual taste. This can be, unfortunately, quite expensive. The advice of any one user, no matter how many types of tubes were tried, only apply to that particular user's gear and taste.

That said, there are certain tubes that "tend" to be acceptable in a broad range of applications and to a broad range of listener taste. The 5751s discussed above fall in that category. I would also put in that category Amperex Bugle Boy 12AX7s.

I have found, for my particular application and taste, the Telefunken ECC803S to be the best, but, that tube can be excessively detailed, lean and "analytical" in the wrong system (it has also become crazy expensive). I took a big gamble with getting those, because I did not have an opportunity to hear them before purchasing (a friend lent me a BIG selection of 5751s and 12AX7s to try, including Telefunken ECC83s, but no ECC803S).

Have fun, just don't go broke in the process.
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...
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.
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.
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.
Joe states all that in his Lore article; but if you are new to tubes it is a good, worthy place to start.
Joes tube lore is far from the authority on 12ax7/5751( or anything else)The performance of a tube is going to be application dependent. Any one whos rolled tubes can tell you what works in one amp doesnt always work well in another. A 5751 can be quieter in the phono position on some amps but you wont necessarily find them to image better. You could buy used tubes on ebay and experiment using your ears or you could buy from a knowledgeable dealer Im sure this group can recommend reliable dealers, upscale audio comes to mind. Ive heard good and bad examples of almost every tube Joe listed, to experience the general character of a specific brand type you have to listen to several examples in a variety of applications. Brent Jesse's site has good info on a lot of tubes.
i ordered a pair of ge5751wa black plate d getter tubes and a matched quad set of shuguang black treasure kt88-z`s. the ge`s are coming from china and the black treasure are coming from hong kong so i guess i`ll have a bit of a wait.

i`m excited to know how these will fair along with the brimar 6sn7gty cv1988/rca vt231`s combination. the brimar/vt231 combination have so far opened up the sound extremely on my system. at some point in the future i`ll be ordering the Sylvania JHS 5751WA Gold Label triple mica blackplates but i`ll have to start saving! i`ll also see how i get on with the ge5751wa`s first.

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!!!
hiya mikirob, i`ve had those on my mind too! i`ve liked the ehkt88`s in there but when i bought them i`d only done limited research into all the tubes. i`m doing a much more in depth research now. i ordered a matched pair of ge5751 black plate d getter 1950`s tubes today. once they`re sorted i`ll start researching the kt88`s. i wont rush my research like i did when i first got the amp. this has been such a fantastic learning curve researching all these tubes and reading other peoples experiences with different tubes. i still can`t get over the differences made by swapping the brimar/rca vt231 combination. i honestly didn`t think there`d be any difference at all by swapping them around in v1 v2 v3 v4 positions. that was an eye opener for me! all my neighbours were out earlier today so i was able to crank the volume up! i`m endlessly impressed by what i hear now. the only thing i think this amp lacks now is soundstage depth and i`d like to inject a little warmth into it. not much just a little.
As far as your KT88s, also better better brands out there, some warmer than EH.
another quick update and the best one yet! when i was tube rolling i tried the brimars and the rca vt231 together. i had the brimars in v1 and v4 and the rca`s in v2 and v3 on my amp. they sounded pretty awful! well i didnt realise that swapping them around would bring a massive difference! this weekend i put the brimars in v2 and v3 and i put the rca`s in v1 and v4. wow the sound is so clear!!! i wish i discovered this when i first tried them. i`ve lost the warmth i had with the brimar/sylvania pairing but now i can see much further into recordings. all the subtle sounds that were hardly noticable are now much more prominent. recordings are very clear sounding and tonally more realistic. the soundstage is solid and believable. the detail is amazing! the bass is very full, detailed and has this extra punch. my amp sounds completely different now! i can`t believe how much clearer the overall sound is. i heard the most subtle details that i`ve never heard before on david gilmours cd on an island this weekend just gone and the sound effects throughout his cd are just incredible! listening to adeles cd 21 the 1st 2 tracks now have so much drive. the seperation of individuals is just awesome too. i could still do with more depth to the soundstage though. i really am sure it`s the psvanes restricting the depth of the soundstage but i must say, changing the brimars and rca`s around have hugely widened the soundstage though. for the first time the sound goes way beyond the width of the speakers which i have to admit messed with my head at first! anyone that has this amp really ought to try out the brimar/ rca vt231 combination. this is seriously good stuff!
Another thing about the 5751s is that they were designed for the military, so they are very rugged, long-lived, and low in noise. I had the great fortune of picking up a pair of NOS Sylvania Gold 5751s about 14 yrs ago and they now reside happily in my Jolida phono preamp.
another thing i must add......i seem to sit there now listening to music with a big stupid grin on my face most of the time! what a way to escape the stresses and strifes in this life!
wow thank you guys for the wealth of information. the psvane tubes i`m currently using sound just fantastic but i`m sure they`re limited in the soundstage width and depth. i`ve played around with all the other tubes and so far the brimars have had the best results in the soundstage and tone but i`m looking for more depth in the soundstage. thats really why i`m looking into the 5751 range of tubes. i`ve read good things about the soundstage they throw out. tonally i`m extremely pleased with the range of tubes currently in my amp but like everyone out there, if the sound can be improved upon then why not indeed. you only live once! i`ve been considering getting some sylvania 6sn7gt`s too to mix with the brimars. i think the wgt`s will have too much upper attack for my system but i have my eyes on a matched pair of sylvania bad boys. the gtb`s that i`m using right now seem to go hand in hand with the brimars tonally. voices are amazing! i tried the brimars with a matched pair of rca vt231 grey glass tubes but it was an awful match. too much warmth to the point of making it sound dull. i had such high hopes too for this matching.

joes tube lore is making for a very interesting read! i think i`m going to be having a lot of fun experimenting here with different tubes.

i`ve got to say too......i`m having the time of my life listening to different tubes. this being my very first tube amp! i`m impressed at all the different qualities each tube brings to the amp and all the fine tuning that can be achieved. the amp sounded good enough with the standard tubes that came with it but the amp was secondhand and the tubes were very noisy!

also when the psvane tubes were breaking in i was shaking my head in disbelief in the 1st 5 to 10 hours! the sound changed quite a few times! everytime sounded good with the exception of a couple of times the sound seemed to come out of complete darkness and that blew my mind! wish i could get that particular sound back! but thats not really a complaint as i love what i`m hearing now
I am impressed with your choice of 6SN7s. I really like the Brimar CV1988 GTY. See if you can get some Sylvania GTs or Ws as well for 6SN7s. Given your choices with them I would definately recommend that you look into 5751s.
I find 5751s to be more defined and yield better soundstage in my applications. I agree that there are more good ones floating around than most NOS 12AX7s. I also say you should look into it- as no one can assert with certainty what you will like. I have a hunch you will like them. Sylvania triple mica BP are prolly the best but failing that, try some TM BP RCA white lable, Raytheon in general, (yes windmill getter but they are rare) then perhaps lastly GE with some special GE vintage exceptions. The militery versions of all are good.
Second Andr, Joes Tube Lore gives a great summary. I have Sylvania 5751s Gold black plate that made a huge difference in one of my amps; but always trust your own ears.
I've been through experimenting with 12AX7 and 5751 tubes. Gathered a lot of them. Everything you want to know is in this excellent reference :
http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html