Best 12AU7?

Brent Jessee and/or the Tube Store will help you. 

Can't tell which one is best, but can tell you that the RCA clear tops are no slouch, and are typically reasonable. How any tube sounds will vary a bit with each system and circuit.  

We can generalize about the sound of tubes, but you won't know for sure until you try them in your system.

The RCA Clear Tops are supposed to be good in the treble.  If you want to spend some crazy money, search for Telefunken G 73-R, a very specially selected 12AU7.  I've never heard them, probably never will.

I like Amperex 7316 but don't think they're airy, more of a midrange tube.

Call Brent Jessee and talk it over.  He'll have something for you.

I used the Brimar 13D5 several years ago and loved them.  In my SET, they were very clean and clear without being bright.  I had the RCA clear tops prior and the Brimars were in another league in my opinion with quite noticeably more detail.  Some have said they are a bit warm.  I did not hear that at all but I did not hear any leanness either.  Images were also more distinct.  They are just a great tube, if your sonic preferences reflect the qualities mentioned.  

I have a pair of Telefunken 802S Platinum Matched Pair Best 12AU7 for sale. Please reach out to me.

Telefunkin ,Siemens , all very good nos tubes from Germany 

I use 12au7 tubes in my DAC... have tried LaRadiotechnique, Brimar CV4003, RCA Clear Top, Telefunken amount others. These are my (4) favorites for sure but right now I have the La Radiotechniqe in and they seem play best with the particular speakers I'm using these days. These were never imported into the US so if you can grab a set, go for it. Not overly expensive either but really a spectacular presentation to to bottom. French tubes have a personality all their own. Just my opinion 

I can also vouch for Radiotechique. I am running the equivalent version produced for the French military, the 6189/12au7 in my Rogue ST100 and I would describe the sound as "Lush".

+1 on contacting Brent Jessee.

I have NOS RCA clear tops and black plates. The clear tops are brighter up top, but the black plates don't lack for treble extension and overall I prefer the balance of the black plates. Good luck with your search.

I asked for similar (not exact) recommendation from Brent Jesse and was recommended the Mazda Grey ladder ribbed. Been super happy with these.

Brent Jessee - 12AU7 in stock

I’m currently trying the Gold Lion gold pin (new) in my pre-amp.  previously had JJs 802’s.  The preamp is a VTL 6.5 and so far, can’t really tell the difference.  Have to burn them in for longer.

My favorite 12AU7 has been the French CIFTE from the early to mid 60's. 

They have gotten expensive and tough to find.

If you are using this in the buffer stage you recently posted about I would not drop a lot of coin into tube rolling.

Maybe try an RCA clear top as they are clean sounding and cheap as chips to see if it makes much of a difference.

I use expensive vintage tubes in my inexpensive kit gear, but in gain and driver stages.

DeKay

Agree Telefunken are the best I have heard for a detailed brighter sound.  Rca cleartops are an amazing value and sound extremely good on the brighter side as well. Can’t go wrong with either.

I really like the mil spec triple mica black plate RCA 5814A I just found. Detailed, smooth, not dull, and not too bright either.

Upscale Audio has very good NOS and new tubes. Check them out. 

Also, Vintage Tube Services - Andy Bouwman. 

I use RCA black plates from 50s in driver position, very balanced and full sound. But I also use Mullards 12AX7 long plates in preamp. Excellent match, anyway, but it won't give the best high frequency extension.

Also enjoying a mil spec grey plate single mica GE 5814A

12au7 in my integrated are phase splitters. My fav is Amperex 7316 long plate. But I just bought a pair  NOS Telefunkins...I am liking right now...probably gonna go back and forth for a while. Basicly a cheaper version of the famed G73-R

Any fans of new Tung Sol re-issue 12AU7W / 6189's?

I see no reason to even consider reissues for small tubes.

I'm using the Tung Sol 12AU7W / 6189 now. I find it bright, but in a very nice, warm and fat way! I keep coming back to this tube.

@olds1959special Not a fan of the Tung Sol re-issue when compared to NOS. But…they are probably one of the better new tubes. I also really like the RCA 5814a TM BP. Top 3 for me but I don’t see it brighter as you said you preferred. It more neutral  towards warmer to me which I prefer. Other good ones I like are Westinghouse ‘60’s long Carbon Plate and Raytheon ‘60’s 5814a TM BP.

I'd also say my 2nd in line behind the La Radiotechnique are the Brimar, CV 4003 gold pin. Its a heavy sound that is totally enjoyable. 100% opposite of the LR 12au7wa - they give my DAC a completely differnt perspective. That's what makes this fun... all the "better" tubes play great, they just come at you from differnt angles & give the presentation a decidely contrasting sound. 

I find it bright, but in a very nice, warm and fat way!

That seems like a contradiction in terms?

I call it fat because of the way it spreads out the sound. I call it warm because of the overall harmonic saturation. But it is basically bright, but more of a creamy, smooth bright!

olds1959special

As already mentioned, reach out to Brent Jessee.....he's the best tube provider I've ever used. He carries a great stock of tubes, but he doesn't give them away. The best 12AU7 tubes are expensive, so be prepared

STAY AWAY from re-issue tubes, go with NOS only

For emphasis on treble (as you indicated) I'd look at: Amperex (Holland made versions) 7316 1950s/1960s, Amperex E800CC/6085 (check with your amp manufacturer that these are okay to use), RCA "black ribbed plate", RCA "clear tops", German Telefunken ECC82s but these are really expensive.....I have only 1 pair.

@olds1959special 

I just bought a PS Audio preamp that uses 12au7’s in its input section. I put out a

some feelers and was given advice from A to Z. So far I’ve tried the PSVANE Art Series, the New Release Tung-Sol  the Gold Lions and some NOS RCA Clear Tops.

To my ears, The PSVANE Art Series were just okay. The Gold Lion were definitely better. The Tung-Sol and the RCA Clear Tops are definitely the best so far, but I want to give the top three tubes 100 hours of play before I A/B them again.

BTW, what are you using them on?

I have the following NOS tubes: 

Brimar CV4003 (upscale audio)

Siemens silver plate (eBay)

Telefunken medical red tips (Brent Jesse)

I prefer the Brimar’s for their overall smoothness, but for your preference the Siemens. Everyone seems to love Tele’s, but IMHO the Tele’s are too forward.

@curiousjim 

I am using a single 12AU7 in a Hagerman Baritone tube buffer. So far, the new Tung Sol tube is working well for me in this circuit. I've tried:

new Tung-Sol 12AU7W

new Mullard 12AU7 (stock tube)

nos RCA 12AU7 cleartop

nos RCA 5814a black plate tri mica

nos GE 5814a grey plate

I got (2) matched pair of NOS Siemens & Halske E82CC ECC802S ECC82 5814 which are an upgraded 12AU7 tube, triple mica, made in Munich, Germany from tubes.rs on ebay. They are outstanding but pricey.

I like 12at7 better

@olds1959special , hi sorry for being late to the game. First off Brent Jesse’s sound description of 12AU7’s is spot on. It’s all personal preference and system dependent. However , I highly recommend the standard Tekefunken smooth plate for a starting point. If I’m correct, you need a single tube ? That makes it easier and less expensive. I own 2 pr of the Telefunken G-73R’s that were mentioned above. I have multiple pairs of Tektronix pairs, and some standard grade, all smooth plates. All the Telefunkens sound the same. The better grades have less noise and are closer matched. Just buy one and see, probably be around $100. Now compared to that the Silver Siemens are brighter overall. The Phillips Holland is more forward on the top third of the frequency range. For the budget conscience the Tungsram and the EI tubes are very close at a fraction of the price. I have about 10 brands of NOS 12AU7’s half of which are American. Personally, I think the European tubes sound better. I’ve not owned Brimar or the higher level Mullard, but the standard NOS Mullard are not to my liking. They sound like someone threw a blanket over my system. Also I’m not a tube snob, I was where you’re at about 8-10 years ago. I was able to buy tubes at a sane price. If I can help you, please pm me and we can talk. Regards , Mike B. 

I just got through rolling a ton of 6922 type tubes through my system (preamp) and still can not get over what a difference in sound they can deliver.  I have a Concert Fidelity Tube DAC that uses a pair of 12au7’s, and decided to roll some through there as well to see what was what.  Again, super surprised in difference in sound.  Spent some time collecting 12au7’s and just started rolling these a couple of days ago; which is to say that I have not gotten through everything yet.  I am a big believer in listening to what your ears tell you and will be working my way through the following:

Genalex B749 (Vintage)

Hivac CV491

Amperex 7316 Long Plate Foil Getter(1958)

Amperex 7316 Short Plate O Getter

Amperex 12au7 Long Plate Foil Getter (1957)

Amperex 12au7 Long Plate Foil Getter (1958)

Brimar 6067 Yellow T O Getter (1962)

Miniwatt ecc82 Long Plate Foil Getter (1956)

Mullard/Marconi B329 Long Plate Square Getter (1958)

Mullard CV491 1593 Welded Long Grey Plate Square Getter (1954)

Mullard 12au7 Long Plate O Getter (1958)

Telefunken ecc82 Long Plate O Getter 

Telefunken/Tektronic ecc82 Long Plate O Getter

Mazda 6189 Short Plate O Getter (1958)

Philips Long Plate 45 degree Foil Getter (1956)

Siemens ecc82 Short Plate 30 degree O Getter (1961)

Sylvania 12au7 Long Black Plate D-Getters (1956)

Valvo Long Plate 45 degree O Getter (1957)

I will try and offer up at least some impressions of what I land on when done.

B.

'I like 12at7 better"

Fitting emergingsoul response.

Did a first pass listen of everything and separated the tubes into “Good” and “Better” categories.

“Better” included: 

Telefunken Tektronic, Mullard 12au7, 7316’s - short and long plates, hivac cv491, Genalex b749, Amperex 12au7 (‘58).  
 

Need to figure out how to post a pic.

Couple of surprises:

1). 7316’s - I expected the long plate Foil D getter to smoke the short plate O getter variety. Not true. Both are really, really good. I plan on spending more time better understanding their individual persoanalities.

2). Telefunken - The standout of the 3 pairs of telefunken’s. Really nice job with vocals compared to it’s brothers.

3). Amperex 12ua7’s - I did not expect any difference in sound quality here, but was surprised to find the 1958’s bettered the 1957’s.

4). Mullard 1593’s - They have not yet hit my mailbox.

I will spend some quality time with this more manageable group of tubes and get more into the weeds on their characteristics.

1. I don’t think the original question can be answered considering the number of tubes available and the equipment that uses them.

2. My personal preferences are European tubes from the 1950s (in my tube components). A second mortgage would be appropriate here, especially since the Ukraine invasion.

If you have not tried the Horizon tubes by psvane, you are missing out. My Mac has never sounded better. 

Telefunken the best. ECC83 the only way to roll for me.