Eli Duttman said:
The 12AU7/5963/6189s can make stellar audio components. If you cannot get one to be linear over a 1-2V audio signal -- you can't design tube kit at all.
This isn't targeted at any one person, it's just sad to see some tubes get bashed, when it's nothing more than repeating something someone else posted on a page that isn't even correct. This regurgitation of misinformation shouldn't happen. There aren't 10 holy grail audio tubes (300b, 2A3, 807, el34, kt88, 12ax7, 6922, 6sn7, 6l6, 6sl7) and everything else is garbage. It just doesn't work that way. There were literally thousands of tube types made and many, many many of those can make great audio amps -- including the 12au7. I would much rather use it than a 12ax7 and you see those in everything... and everyone thinking its a great audio tube... of which i don't. Not to mention.. i do believe the 12au7 was meant to capture some of the 6sn7's market -- and everyone thinks that tube is great... alas...
Cycline3 said:
The 12AU7 is OK as a cathode follower and as a "concertina" phase splitter. It's mediocre linearity makes it (IMO) a poor choice as a voltage amplifier. The 50% smaller heater draw and identical mu, compared to the 'SN7, makes the 'U7 attractive to a designer, but the plate curves don't lie.
I AGREE that all sorts of tubes can be used to get GOOD audio results. For starters, add the 6V6, 7591, EF86, 5687, 5965, and 12AY7 to that list. Obviously, there are many, many, more.
Eli Duttman said:
This is EXACTLY the nonsense I'm talking about. We are addressing a few volts AC max... at all sections of the amp except the driver and the outputs and you are saying it's not linear. Let me make myself clear - IF YOU CANNOT GET THAT TUBE LINEAR IN A PREAMP YOU CANNOT DESIGN TUBE GEAR. It's that simple. Given that it's not as linear as some... you are talking about a couple volts vs. the ability to swing three digits worth of voltage. The tube curves are over 0 to 300 volts or more... who cares if it's not as linear as another tube... it's straight where you should choose to bias it.. and a 2V AC signal isn't going to change that AT ALL. Further, the listening tests actually bear out that it is a very nice sounding tube as well. The tube curve isnt everything. I have tubes that test identical on my tube tester and in circuit that DO NOT sound the same. Again.. this is nonsense... and I refuse to let these stereotypical analogies of one is better than another persist...
Cycline3 said:
My OPINION of the 12AU7 is not particularly favorable. I think it's blah, not bad. Opinions, including mine, do not equate to absolute fact. FWIW, my view is commonly held. If you like the tube, by all means use it. After all, only your ears matter in your listening room.
Please stop issuing insults. I have not insulted you. Honest differences of opinion are why horse races are conducted.
Nonsense. This is a TUBE that can handle hundreds of volts... you are talking about 2 VOLTS. It is NOT OPINION when it comes to that tube being LINEAR OVER A 2 VOLT RANGE. Absolutely 100% undeniable FACT that it is NOT an opinion. END OF STORY. If you take that as an insult... then it's simply because you are inferring it.. and I assume still claiming that the tube can't be linear over a 2V AC range. Which as I said before is non sense. I also said, none of this was directed at any one person.. but the stereotypical... this tube is bad... should play out... and it should.
Let's look at the curves in question.... as for your measurements... you are 1 person with a few tubes... which is not representative of a whole as well as if we went on sheer measurements alone... we'd be solid state guys and single ended tube audio would not exist. And Im sure there are plenty of gear guys and gals here that would gladly tell you their high THD SE amps stomp the (fill in your favorite expression) out of typical hi fi stuff with great numbers.
An externally hosted image should be here but it was not working when we last tested it.
Curves are generally representative of the model, but not exact for the individual device under test.Cycline3 said:
This is true. However what I did was basically the same as Morgan Jones did in his book, so I don't see how it's irrelevant. Besides, I'll take my measurements over your trying to prove linearity by looking at a set of curves that are so far out of scale for what you're trying to seeCycline3 said:
Who ever said it was? But they are representative of my tubes in my test rig. They are quality samples of good brands. I can't be bothered to get my notebooks out of the workshop to give the exact details.Cycline3 said:
This is funny. Because you're all defensive about the 12AU7, which should only be used in MI amps in my opinion, measurements are useless? There are many ways to measure things and of most interest to me is the spectrum, as well as the levels. I don't do single bit THD measurements except as a quick check for faults.Cycline3 said:
I have no aversion to SS and tubes are not a religious experience for me. I use whatever works best for what I'm trying to achieve.
Brett said:
More nonsense from more nonsense. Why can't you just admit your wrong? I don't know of ANY tube that doesn't have a 2v linear section to the tube curve... zero... regardless of construction or intended use. Saying that a 12au7 is only suitable for a musical instrument amplifier is only illustrative of one thing... complete ignorance of the tube/subject we are talking about!
As far as getting back to the subject, we should do that... but it does point out something FAR more important to the newbie here.. .that many people will spew stupid audio stereotypes without *any* basis in reality because someone somewhere read it and mentioned it at the audio club meeting a year or so ago...or whatever the unproven source....... so *tired* and so utterly lame.
Now you're getting nonsensical. I posted that I had made actual measurements from tube samples and you wish to dispute that based upona highly enlarged scan of a print of a page that represents a tube type. Incredible. I have a degree in electronics and a couple of decades experience working in the field. I find the 12AU7 to find it's best appliction in MI gear. I strongly prefer other types in reproductive electronic systems. If you don't like that I couldn't care less. It consistently MEASURES worse, and therefore a generalised set of curves and what they might mean to you is irrelevant to me compared to the actuality of an in circuit test.Cycline3 said:
I stated I made measurements myself, similar in format to Morgan Jones in VA, and that's hearsay from a club meeting? Incredible. You're making a strawman as your argument has no merit based upon what you've posted.Cycline3 said:
Cycline3 said:
I definitely agree. I definitely take the road less traveled myself, and have come up with some real winners. Two in my current project, in fact, that I haven't seen any one else using, and they sound just great. The prices are right too: $1.30 a pop. Try that with those "holy grail audio tubes"
So far as 'AU7s go, I wouldn't say "never". If these don't work so swell as conventional small signal amps, then perhaps some other topology would suit 'em better: cascode, SRPP, Mu stage, Kimmel, or CCS loaded.
If you know something that others don't, then why do you care? Let 'em think that 12AU7s aren't any good. More for you.
)
Cycline3, It seems to me that you have a lot of design experience and the 12AU7 is something that you know really well.
What can you say of how the 12AU7 was used by Bottlehead in the original Foreplay?
If you woul do a preamp based on the 12AU7, what would it be? Will it be better than the Foreplay or the Foreplay 3?
What can you say of how the 12AU7 was used by Bottlehead in the original Foreplay?
If you woul do a preamp based on the 12AU7, what would it be? Will it be better than the Foreplay or the Foreplay 3?
Cycline3 said:
Well, I am sorry but you will have to do better than that.
It is true that with a properly chosen operting point, expecting only a few volts of swing, a triode can be far more linear than when you want a hundred volts or so, but it is also true that the curves don't lie, neither do the measurements. In many cases the ears don 't either, but they are subject to 'liking' whereas the first two are not. It comes down to how you can achieve this operating point.
If you want to compare the 'AU7 on equal merit, then you have to define the merit. In point of pure linearity, there are more liner tubes - for the same few volts of swing and in some cases for the same general operating point, too. If this is the only criterion, then there are certainly better tubes than the 'AU7.
Once you calculate availability, price and other 'real estate' demand, the 'AU7 becomes more attractive than many 'better' tubes.
It is also undeniable that often the best operating point is not overly practical to achieve - sometimes a 'SN7 will win because ti can do better with fewer components, at which point it's generally higher cost is offset.
Finally, there are topologies, and then there are topologies. Some do very well in compensating the non-linearities of the given tub e by another of the same type - and 'AU7 is not expensive, so it lends itself to this sort of thing where other, more popular tubes, would not.
You won't get any argument from me regarding the hundreds of tube types that are supposedly 'not for audio' just because audiophools can't be bothered to actually understand how things work. As Miles said, more for the ones in the know.
The real point of this discussion should not be shouting with the main argument being that what everyone else is saying is nonsense - rather, it should be about how to best use the 'AU7. If you know something that you feel you want to share, than please do. If on the other hand, you know something and delight in kindergarten antics of the 'i know something and you don't, na na na naaaa na' type, then please respectfully take that attitude somewhere else.
Cycline3, I think you loose the argument that the 12au7 is a good choice based on its linearity.
It is a good tube though because it can take a lot of volts to the plate, does not have too much gain, and is pretty inexpensive. The heaters don't draw too much mA either. All said it is easy to work with and quite forgiving.
It is a good tube to use to learn about tubes.... It has also been used in many designs, so folks know what to expect from it as well.
I don't mind the less than linear aspect so much, but the 12AU7 can be a noisy. If you want one that is quiet then you have to pay more money for special variant or swap them out until you find a quiet one (tube roll).
If you don't need it for the max plate volts, the 6DJ8/ecc88/6922 will beat it every time. The russian 6N1P is a cheap alternative (about a buck each now on fleabay), but you need to run it at plate voltage of 150V to get good results. There is a better version - the 6N1P-EB (or EV if you speak russian) but I haven't tried them. They are probably just the same, but factory pre-sorted.
I used to think that this forum had some sort of bias against 9 pin noval tubes, but that is just not true...
The ecc99 is less known but excellent alternative and can take a lot of volts to the plate. It makes a really great driver, depending on the topology.
I breadboarded a prototype to drive my pse el34 amp and the sound is fantastic. I used 2x pcc88's as a gain stage instead of a single 12ax7 too. but now I can't fit it all into the chassis.
Life is like that.
I have learned a lot by reading through this forum. Search, read and try it out yourself before posting something really foolish.
'nuf said.
It is a good tube though because it can take a lot of volts to the plate, does not have too much gain, and is pretty inexpensive. The heaters don't draw too much mA either. All said it is easy to work with and quite forgiving.
It is a good tube to use to learn about tubes.... It has also been used in many designs, so folks know what to expect from it as well.
I don't mind the less than linear aspect so much, but the 12AU7 can be a noisy. If you want one that is quiet then you have to pay more money for special variant or swap them out until you find a quiet one (tube roll).
If you don't need it for the max plate volts, the 6DJ8/ecc88/6922 will beat it every time. The russian 6N1P is a cheap alternative (about a buck each now on fleabay), but you need to run it at plate voltage of 150V to get good results. There is a better version - the 6N1P-EB (or EV if you speak russian) but I haven't tried them. They are probably just the same, but factory pre-sorted.
I used to think that this forum had some sort of bias against 9 pin noval tubes, but that is just not true...
The ecc99 is less known but excellent alternative and can take a lot of volts to the plate. It makes a really great driver, depending on the topology.
I breadboarded a prototype to drive my pse el34 amp and the sound is fantastic. I used 2x pcc88's as a gain stage instead of a single 12ax7 too. but now I can't fit it all into the chassis.
Life is like that.I have learned a lot by reading through this forum. Search, read and try it out yourself before posting something really foolish.
'nuf said.
Please stop arguing in such an emotional and ideological way about technical matters! No tube is suited for every application. Nobody would use an EL34 in a phono pre-stage. And if the 12AU7 has some kind of nonlinear curves, what does it matter!? It has been constructed for a certain set of applications, especially in the TV/pulse processing sector, where quite nonlinear curves don't matter.
I used (and use) it extensively in my amplifiers, but only in push-pull/symmetrical designs, where de nonlinearities of the mirrored curves mostly compensate. There, it is a great tube, which offers a very clear uncolored sound - it amplifies, but doesn't add too much "sound" to the music - I expect an amplifier to "amplify", but not to sound - its not a musical instrument. I doubt if I would use it in non-symmetrical designs, nor would I use it in sensitive pre-stages.
BTW - JJ offers these tubes in a "ECC88-like" construction - obviously with a rectangular cathode and frame grid(?), too. I use this type in my 6C33CB Circlotron, I am very satisfied so far. Does anyone on this forum know more exactly about them? I would expect their curves to be more linear (with otherwise identical electrical data) compared to the "traditional" construction.
An other (purely emotional) point is, to what you have been used to... Here in Europe, 9-pin Noval all-glass tubes were used in large quantities, and nearly exclusively in some countries (Germany....) during the 50ies and 60ies, Octals being restricted to high-power types. Contrary on the other side of the Atlantic, Octal tubes always have played a most important role. So, I'm not much habituated simply to using the 6 SN 7, although I hear again and again about its qualities... I'm simply "used to" using Novals.... There's no rational reason for that... ok, sometimes I find Octals to be a bit bulky, especially as pre-stages, but - this has nothing at all to do with technical issues, that's pure emotional things... ;-)
Uli
I used (and use) it extensively in my amplifiers, but only in push-pull/symmetrical designs, where de nonlinearities of the mirrored curves mostly compensate. There, it is a great tube, which offers a very clear uncolored sound - it amplifies, but doesn't add too much "sound" to the music - I expect an amplifier to "amplify", but not to sound - its not a musical instrument. I doubt if I would use it in non-symmetrical designs, nor would I use it in sensitive pre-stages.
BTW - JJ offers these tubes in a "ECC88-like" construction - obviously with a rectangular cathode and frame grid(?), too. I use this type in my 6C33CB Circlotron, I am very satisfied so far. Does anyone on this forum know more exactly about them? I would expect their curves to be more linear (with otherwise identical electrical data) compared to the "traditional" construction.
An other (purely emotional) point is, to what you have been used to... Here in Europe, 9-pin Noval all-glass tubes were used in large quantities, and nearly exclusively in some countries (Germany....) during the 50ies and 60ies, Octals being restricted to high-power types. Contrary on the other side of the Atlantic, Octal tubes always have played a most important role. So, I'm not much habituated simply to using the 6 SN 7, although I hear again and again about its qualities... I'm simply "used to" using Novals.... There's no rational reason for that... ok, sometimes I find Octals to be a bit bulky, especially as pre-stages, but - this has nothing at all to do with technical issues, that's pure emotional things... ;-)
Uli
Worthy...
I am SO GLAD to see this has been made it's own thread... it shows the MODs see this as WORTHY.. which I've had doubts of on posts removed before.
I am simply going to say this... a tube curve is from 0 to MAX B+ which is several hundred volts.
*ANY* sharp cutoff tube still has a 3 digit or close to it range of operation. AND THESE ARE THE WORST AUDIO tubes we can define according to the "non linear" dudes out there. A preamp at MOST will see 2.5V of operation. There is no tube with a curve jaggy on every 2v... none. It would never get produced...
By the non linear folks.. the ONLY thing that matters is the tube curve. And by that same argument I am saying NO TUBE ON THE PLANET FAILS THE 2.5V TUBE CURVE LINEAR TEST. It simply shows their ignorance of what really works and what doesn't.
Now.. moving forward to the positive posts... some give me credit... of which I appreciate.. but MOST CERTAINLY have to say.. the only thing that matters are my ears. It's true I have design ideals... but my ears don't always agree with them.
Some time back I got a huge NOS supply of 12AU7 and 5963 tubes. So I used them a great deal. Some of the kit I built was OK... some will make your hair stand on end and your jaw drop... that's enough for me to know the 12au7 sucks myth is nothing more than that... a myth. Would it be my first choice for a driver tube? No. Does that mean it sucks? No. In fact I'd bet a huge amount of money my best AU kit can eat other's amps... as I've built so many over a long period of time.
And that was my WHOLE POINT FROM THE GET GO.. the tube myths need to die... the 300B isn't the be all and end all.. and the 12AU7 isn't the bottom of the tube barrel...
I am SO GLAD to see this has been made it's own thread... it shows the MODs see this as WORTHY.. which I've had doubts of on posts removed before.
I am simply going to say this... a tube curve is from 0 to MAX B+ which is several hundred volts.
*ANY* sharp cutoff tube still has a 3 digit or close to it range of operation. AND THESE ARE THE WORST AUDIO tubes we can define according to the "non linear" dudes out there. A preamp at MOST will see 2.5V of operation. There is no tube with a curve jaggy on every 2v... none. It would never get produced...
By the non linear folks.. the ONLY thing that matters is the tube curve. And by that same argument I am saying NO TUBE ON THE PLANET FAILS THE 2.5V TUBE CURVE LINEAR TEST. It simply shows their ignorance of what really works and what doesn't.
Now.. moving forward to the positive posts... some give me credit... of which I appreciate.. but MOST CERTAINLY have to say.. the only thing that matters are my ears. It's true I have design ideals... but my ears don't always agree with them.
Some time back I got a huge NOS supply of 12AU7 and 5963 tubes. So I used them a great deal. Some of the kit I built was OK... some will make your hair stand on end and your jaw drop... that's enough for me to know the 12au7 sucks myth is nothing more than that... a myth. Would it be my first choice for a driver tube? No. Does that mean it sucks? No. In fact I'd bet a huge amount of money my best AU kit can eat other's amps... as I've built so many over a long period of time.
And that was my WHOLE POINT FROM THE GET GO.. the tube myths need to die... the 300B isn't the be all and end all.. and the 12AU7 isn't the bottom of the tube barrel...
ulibub said:
MORE BS.
Why not? Because it's big? You could use ANY pentode right? And by the 12ax7/12au7 vs. the 6sl7/6sn7 comparison.... more plate area means better sound.. .so why not use a el34?
Stupid stereotypes... break free of them... the best kit out there doesn't follow anything these people will tell me... they try things and push things.. and understand things like the *sheep* dont.
Point is.. im not saying an el34 makes a great LP preamp... but Im saying it could... you can't just write it off because it's a big tube... who knows... a Tung Sol 6550 in the right hands might make the best LP preamp on the planet.....
It's not quite this but it's close... there is no spoon... start using your own brains and experience and not just junk you read on the web...
soulmerchant said:
It's lose... not loose. And no, I didn't. Search I do.. I read all the posts on the tube board before I posted my first. That doesn't even take in to consideration 20 years of tube building experience and a very level head. As for " 'nuf said," well... that seems to sway the argument in my favor no matter how you look at it...
-Sean
arnoldc said:
I hate to respond to this to add fuel to the BS running on here... but here goes... I am not familiar with that design at least by that name... I will google it and let you know what I think...
I have several 12AU7 preamp designs. I would consider the best a Class B by Stereophile standards.... the absolute best 12AU7 implementation I've done is in an amp as the drivers... which swing much more voltage than we have been talking about. I've only heard a handful of amps that could better it... and none of those cost less than $7,000 US.
Still my fav is the 6SN7 of which again, I don't want to fan stereotypes. The idea the 12au7 can't make kick a$$ gear eats me up... when class B is pretty bad a$$ you know? and when you can DIY for just a few dollars.... what's not too love?
I will look at the amp you mentioned.. but remember what I originally said.. your ears are the judge.. nothing else.. I've had lots of sound ideas that failed that test and some dumb luck that rocked it... ultimately.. ears are what defines the best audio...
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