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
Thanks Jazzerdave, I will only replace the tube on the phono stage and keep my eye out for the good ones.
Miketuason - If you don't feel like replacing all the tubes, the most important place for the 5751's would be to replace the 2 12AX7's in the phono stage. Theoretically, they'd make the biggest difference there as the decrease in noise would be most helpful there.

If you've got the amp still under warranty, it might be a good idea to just watch out for good buys on some of the 5751 or 12AX7's that have been discussed here. If you go out hunting for specific tubes (and want them now), you'll pay a lot. But just keep an eye out for all of the good ones and try to snipe them at great bargains.
Hi guys! been following this forum and learned a lot from you guys. I just bought the McIntosh C220 tube preamp that also uses the 12AX7 tubes, as soon as the warranty expires I might try and change it to the 5751, we will see. Thanks.
The Amperex are working out very well for me. They have taken the edge off of the cd's I really had trouble tolerating before.
This is the first set of tubes I have bought so I dont know what to expect with break in etc. They seem to have opened up a bit in the right places and stayed smooth on the top end which is exactly what I needed.
Lets just say they restored some order in my set up. Looking forward to adding the GE 5751 next.
Mechans
Rich and mellow compared to the Golden Dragons is a good description. For my set up rich and mellow is a good thing. Once I compare side by side, I will share my thoughts.
Thanks
There is an acid etched code on the tube that will tell you where the tubes were really made. Phillips owned both Amperex and Mullard brands and cross labled many of their tubes. If they were made by Phillips they will flash upon start up and have typical cross molding marks in the glass on top of the tube. In any event if made in Great Britain it should sound rich and mellow like the Mullard tubes do. The Amperex Holland tubes have a cleaner and 3d imaging with better detail in the top end. All the comments on sonics are IMHO of course.
From what I know, different models are best from different sources. For instance the best "Amperex" 5AR4's were from GB (they're actually rebadged Mullards). Their best 6DJ8 was from Holland. Also keep in mind that Amperex never actually made a tube called "Bugle Boy". If those words actually appear anywhere on the box or the tube itself, it's probably an eastern knock-off. Those might be fine tubes, but they're not genuine. Anyway, I don't know what source is the best for 12AU7's or 12AT7's. I can say that I've never heard anything bad about an Amperex from Britain, France, or Holland.
I started listening to the Bugle Boys today. Right out of the box the overall presentation is smooth compared to the Golden Dragon. Any ideas on a decent break in period?
Im gonna wait a bit and do A/B comparison.
I guess it is no big deal...but the posting I responded to had the 12at7's listed as made in France. Then they are labeled GR BRITAIN. I really dont know enough about tubes to know the tricks of the trade...Are all bugle boys labeled GB?
The Holland tubes are reputed to sound the best. That has been my experiece with 12au7 Bugle Boys.
The Amperex Bugle Boy 12AT7s arrived yesterday. Does anyone know if there is a significant difference in tubes labeled/marketed France, Holland,....mine are labeled GR BRITAIN ??
I have not had a chance to listen to them yet. Thanks
Mechans,
I have often wondered the same things, hence, never bought from him. I want ongoing communication and if I fast pay desire fast ship...tubes appear to be good, even if top-tier cost. I've scored some real bargains here on the A'Gon.
I have often wondered about his very short descriptions which indicate to me a person who is not prone to using the laguage well to express themselves either. So I am not totally surprised. It is good to know his tubes are good. The tubes look like pulls, very often and price wise are not exactly a bargain. He certainly seems to know how to market his wares though, look at the numbers of sales. I just can't believe all of his tubes are the "best" as he often advertizes. I wonder if this post will make it beyond the sensors??
I have a friend who bought from him. Poor communication & it took awhile for the tubes to arrive . I have similar experience. Saw something I like . Make an enquiry. Responded after a few days & agreed to buy. When totally silence . Not the best of communicator. However his tubes is good & seems reasonably price
hiya guys,

mac i`ve no experience with amperex tubes but let us know how they sound when you get them.

i`m keeping an eye open for the c9`s mechan. i thought i`d found some on ebay but they turned out to be the 12ax7b`s.

does anyone here have any knowledge/experience with mullard M8137`s? i`ve heard great things about these. i`m putting them on my shopping list when i have the money.

meanwhile i`m still enjoying the golden dragons immensely in my amplifier. i had the volume up quite high for a while yesterday. they sound wonderful and detailed. i forgot to mention the bass. the bass is amazing with lots of detail and depth and texture. i don`t feel i`m left wanting for anything.
Mikirob,
Amperex made a 12AU7 variant in the early sixties called 7316. When I tell you they do what the other Amperex do only a lot better, believe me. The problem is that a lot of people other than myself really like them and the price is quite high. As if the regular Amperex 12AU7s didn't cost enough already.
@ Grayf and Mcpherson. Shuguang made a 12AX7 a couple of years ago that I actually liked. It was called the 12AX7 C9 or 9th edition it was clean and accurate with a good strong signal, not warm but really very good. Then they stopped making them for some reason and now you can only seem to get the 12AX7 B8. I never understood what happened, but if you can find them (C9s) buy them you'll prolly like them.
Mikirob
Sounds good. Hope I have similar results with the 12at7's. After that I am gonna replace the tung-sol 12ax7 with the GE triple mica black plates.
No experience with those tubes, but I just put Amperex NOS Bugle Boys12AU7s in my Primaluna Dialogue1 and Wow! Wow! Wow! Just like the old song, "What a Difference a Day Makes," what a difference a tube makes! Huge well- layered sound stage. Tone, timbre, airy, clear, detailed yet sweet, fuller with more weight, I'm really enjoying the overall musicality of these tubes. Now, I must find another pair of these for backup. These replaced RCA Clear Top Side getter which were very good. Also put in Yugoslavian Telefunken 12AX7s, slightly bettered the the Canadian NOS Telefunken 12AX7s rebranded Northern Electric that they replaced.
I am gonna try the Amperex bugle boy 12at7 in place of the Golden Dragon 12at7's that came in my pre.
Any thoughts or experience with these?
hiya mac i`m really not sure. at a guess i`d say mullards. the reason i say that is because i read somewhere that these golden dragons are based on the mullards, but i don`t have any experience with mullard tubes although they are on the list of "to get" tubes. i`ve been looking into mullard tubes with the blackburn codes on them. they`re supposed to be the ones to go for. mullards are supposed to have a beautiful warmth allied to great detail. these golden dragons sound like nothing i`ve heard before!
Grayf
Thanks for really messing me up!! The Golden Dragons are what came in my pre. The strengths you describe do sound spot on to what I hear. If you were to move just a click to the warm side with the strengths of the G/Ds...what tube comes to mind??
hiya all,

i bought a pair of golden dragon 12ax7`s and finally got them this morning. these are the cheapest by far of all the tubes i have.

i can`t believe i`m going to say this but these have blown everything away! by quite a way too! the lack of noise floor is unbelievable! instruments come out of an inky black background and the imaging is explicit and very very vivid. everything has been pushed forward that comes out of my speakers by quite a way now. the height of the soundstage is natural height, the width goes way beyond the boundary of the side walls and there is an incredible natural sense of depth. but the soundstage is so different from all the rest of the tubes. the images seem to be carved out into the soundstage. the images are razor sharp too. these tubes are extremely explicit in the information they produce. you`re hearing everything in spades! the atmosphere they produce has to be heard to be believed! there`s one aspect of all this that really shocked me was the extra inner detail of every note coming out of every instrument in the soundstage. that blew my mind!!! and it gives the soundstage an extra dimention! it`s more like 4d!

when i mentioned that these tubes are explicit in the detail they drag up, don`t go thinking they`re cold sounding, they have a natural warmth and they are smooth as hell. cymbals sound just like cymbals in all their glory. the extra detail on offer from dave gilmours guitar on the track "where we begin" is nothing short of stunning sounding! extremely expressive! there`s so much more life to everything i hear and everything sounds so natural and real. there`s a natural rawness on offer that gives the sensation of the performer actually standing there in front of you and the same goes for every other instrument in the soundstage. you can pick out any instrument you like in the soundstage and follow it with the greatest of ease and that instrument will be there in it`s own spot in the sounstage with so much air around it. the seperation of instruments is truly jaw dropping! voices sound just about as realistic as you can get!

i have to say the improvement over the telefunkens is stunning and the telefunkens are excellent in their own right. these golden dragons produce a soundstage that is so different from all the other tubes i have heard and they sound so alive.

i cannot believe the difference in sound and for such little money. my system sounds spectacular!
good info there jazzer, thats something else i`ve learned now.

i`ve found a great tube store here in the uk and the guy is so knowledgeable. karl from karltone. i`ve had a couple of very lengthy chats on the phone with him. i don`t think i`ve ever had a phone chat with a nicer person! he actually recognised and remembered my voice from our previous chat from about a month back! i`ll let you all know how the golden dragon ecc83t`s sound in my system when i get them. probably be at the weekend sometime i`d say.

in the meantime i couldn`t help myself but put the telefunkens back in my amp. i had a good listen last night. the combination of the telefunkens, the brimar 6sn7gty, rca vt231 and the black treasure kt88-z`s are simply mindblowing!!! clarity, depth, slam, punch, warmth, detail, smoothness, imaging, soundstage, realness, it`s all there! this combination picks up on the most subtle of details. i`m not going to say i`m hearing things i`ve never heard before. i will say i`m hearing it all with the greatest of ease. i listened to pink floyds wish you were here cd. welcome to the machine sounds soooo menacing now more than ever! the guitar on shine on you crazy diamond is pitch perfect and this combination of tubes draws out the pure emotion of the guitar not just on that track, but all the way through the cd. ok all of these tubes are pretty pricey, but you gets what you pays for. every cd i play now is more like a journey with this combination of tubes. there`s just 3 or 4 tubes i`ll be looking out for when i have the funds and they are telefunken ribbed plate, raytheon 5751 windmill getter tubes, sylvania 5751`s and if i can stretch far enough i might go for psvanes kt88-t`s. i`m very interested in the raytheon 5751 windmill getter tubes i have to say.
Xti - The input making a bigger difference than the drivers is a common conclusion. It definitely works that way in my headphone amp.
+1 Check with the manufacturer first. I have a 5751 in place of my 12ax7 and the manufacturer of my Octave states the 12au7 can be used in place of the 12at7's. So what I have gathered is a lower gain should work in place of a higher gain tube. But I don't think I would want to put in a higher gain tube than what came with it. For the volume differences is so minor it doesn't matter to me. I like the tube that sounds the best.

Now I'll admit I seem to be the oddball here because I've started swapping output tubes before the drivers or input when I got my amp. To me so far the input tube makes the biggest difference in sound.
Mcpherson -

If you're only considering gain factor, the 12AX7 family falls like this:
12AX7 - 100
5751 - 70
12AT7 - 60
12AY7 - 45
12AV7 - 41
12AU7 - 19

Many circuits can function with any of these, but straying too far from the original gain isn't usually good for the sound. A general rule of thumb would be to substitute as follows:

12AX7 - 5751 / AT7 / AY7
5751 - AX7 / AT7 / AY7
12AT7 - 5751 / AY7
12AY7 - 5751 / AY7 / AV7
12AV7 - AY7 / AU7
12AU7 - AV7

You should always check with your manufacturer. The 5751 and 12AX7 are identical in their limits within a circuit (voltage/amperage) but that's not the case with the others. In most applications you're safe, but you may find it easiest to stick to the 5751 and 12AY7 if you want to try out some different tubes within the family.
X
Does that mean they are interchangable? If so I wonder which is preferred...less gain/more volume OR more gain/less volume.
It was suggested to me that the 12at7 Golden Dragon tubes may be my weak link.
What is the difference between 12at7 and 12ax7 ?
I asked Brent Jessee that question but added the 12au7 also. He said the 12ax7 has the highest gain followed by the 12at7 then the 12au7.
I have the golden dragon 12at7's as the stock Thor tubes.

What is the difference between 12at7 and 12ax7 ?
oops need to correct a mistake! the chinese dragons are ecc83t`s the "t" standing for trustworthy
oh i forgot to mention (yet again as usual lol) i did order a pair of 12ax7`s earlier today. very cheap too! i ordered a pair of golden dragon 12ax7`s. heard some very good things about these and they`re the second cheapest tubes i`ve ordered too! i should have them within 48 hours so i`ll let you all know how they sound.
hiya all,

i`m drawing a line under breaking in the kt88`s. i`m really not hearing any changes in sound now. there may be changes but my ears cannot hear those differences and i`m extremely happy with what i am hearing! plus 300 hours is a lot of breaking in!!!

with that said, i tried out the jan phillips 5751`s today. very very nice sound. extremely clear, pin point soundstage. the bass is very deep and clear. there`s no added warmth at all that i can detect anywhere. these tubes make sense of complex guitar lines in the soundstage. there`s also nice depth to the soundstage too. i do prefer the extra warmth some tubes give but i wouldn`t be disappointed with these in my amplifier.

jbs and mechans, you`re dead right! i absolutely love the telefunkens. they tick so many boxes and they`re a very addictive sound. the ei elites are along the same lines as well as the psvanes. mechams are you psychic??? my investigations have lead me to the raytheon windmill getter 5751`s!!! been looking at them all day online! i can`t afford them right now but they`re on my "to get" list! as are the sylvania`s. i`ve had a load of bills come through so i`m going to have to abandon getting any expensive tubes for a good while to come. mechans, your info on the raytheons and how they sound has really stood out to me. i love strong presence in the soundstage. once i get my finances straight again i`ll be looking into those and the sylvania`s and the other odd thing is i was thinking about getting single tubes today too! spooooky!!!
Grayf,
I have a hunch that given your current delight with the Tele 12AX7s that you might really like the Raytheon windmill getter 5751s. Since those are very rare and costly, you can almost approximate them with Raytheon mid 60s 2 mica regular getter BPs. They have a red painted label and some are yellow label. I was fortunate to aquire some WNDMills a while back and have some of the 2 mica non WNDMills as well. They have the strong presence you seem to prefer with excellent articulation but have a noteable increase in soundstage IME.
No I am not selling. BTW allways snatch up Sylvania TMBPs when avail at a low price- some might be only "OK" but you eventually hit on some good ones and then you are in for a treat. I can give you a little tube hunting hint. In the long run it is worth buying singles at a very reduced prices and collecting enough to match or approximate pairs. I was able to put together several different tube sets this way I couldn't find in pairs at least not at a price I could pay. Good Luck
Grayf,

As you can obviously tell from all of my posts, I have found it very difficult to get past the Telefunkens too.

JBS
Grayf
Glad you liked them. Both of those cds are good beginning to end which is rare...at least for me!
i just hope i have enough funds in the bank to get them! but yes i`ll certainly let you know if i decide to part with them if they`re not suited in my system. it`s going to be a thrilling time once the treasures have broken in. 242 hours to go!!! and counting! how sad am i!!!
Thanks for the info GrayF. If you decide to sell the Sylvania give me a shout out. Best!
mikirob, the ge`s are definately not right. i put them in when i tried out the telefunkens. when i switched the amplifier on it sounded like distant thunder rumbling. i put on a cd and again i got that distant thunder sound so i took them out. they sounded really nice but that rumbling left me feeling a little uncomfortable. i had the same thing when i had the electro harmonix kt88`s in my amplifier too with the ge`s. i actually did think it was thunder in the distance!
GrayF, yeah, sell me the Slyvania 5751 and GE pair, that way you replenish some of your investment. That is one of the great pleasures of tube rolling, you can usually recoup some of your money if a certain tube doesn't work out.
i like francesca battistelli`s voice and fantastic song. very up beat! i like! i`ll check out kari jobe too in a while
good idea!!!
i don`t mind any kind of music though i`m not religeous, but i`ll certainly check them both out. have a listen to this dave gilmour track......you`ll see why i love it so much. amazing guitar tones! http://www.youtube.com/watch?v=86py0X_o2gs&feature=related
Grayf
Sell some tubes and move!!!!haha
I know this is a bit off topic but they had a Dave Gilmour concert on last night on HD Net. I wouldnt have known who it was except for this thread.
I am trying to pull some strings myself right now to get some tubes...without my wife having a heart attack.
I dont know how you feel about Christian music but there are two female vocal cds I recently got that are very good
-Francesca Battistelli "my paper heart"
-Kari Jobe "kari jobe"
You may checkem out if you get bored
i must start by offering my apologies! i did say the psvane tubes are staying in for the duration of the burn in process. but somethings been niggling away at me. well the treasure tubes sound has really calmed down a lot to the point of being smooth, soooo, i thought i`d put the telefunkens back in! a very good move! as it is now, they offer a truck load of detail, but they don`t sound sharp, they sound very smooth. like the psvanes they have a beautiful warmth but these telefunkens add class. it`s very hard to describle. it`s like the sound has more life to it. they seem to have more texture and more realism. more true to life sound. pity the neighbours are in now! this is crying out for more volume!
thats fantastic advice guys. going to the bank tomorrow to see if i have enough funds to buy them. the treasure kt88 tubes are breaking in quite nicely. they sounded very upfront when i first fitted them in and they`ve smoothed right out now. they still only have 52 hours on them so they still have a fair way to go yet. and i had more fun this morning with all my neighbours out again! i listened to it quite loudly! amazing sounds!
Mikirob, the comment about the GE's was the OP's, not mine (although I agree). I was quoting Grayf in order to explain my recommendation of the Raytheons which I think would be more to his liking. I do have a pair of GE's, but they are not for sale; sorry.
PS, if your price is right I will pick up Agon fee. I don't quite know how to do that , but I wll find out provided either of you want to sell the Sylvania or GE.