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I'm seriously thinking about the new Rogue RP-1 preamp. It uses a pair of 12AU7s. I had a Hagerman Clarinet line stage and used a pair of NOS Mullard 12AU7s. Loved the sound.
What about current production types? Any candidates? TIA.
Opus 33 1/3
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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."
Most vintage 12au7s (including the Mullards) are available at reasonable prices compared to others like 12ax7s.
I have never been a big fan of this tube. I think Rogue made a mistake using it in all their amps and preamps. When my Stereo 90 was a Stereo 88, it used 12au7s as drivers and I rolled a lot of them, and never found a huge difference in the sound. The 6sn7 drivers used in the Stereo 90 can be used to help voice the amp. They give it a more classic tone. Not so much 12au7s as drivers.
Rogue used to use 6sn7s in their preamps. It is a more linear and big toned tube. Not sure why they switched, maybe because most modern (reasonably priced) 6sn7s suck?
I agree with Mendel.
The best 12au7 i know is from Rft :i have unless 50 of them :
they span from tubey to transistor ,but they are always 12au7:
somewhat dull ,missing magic for 1 hair.
If you want magic ,tubey sound you have to go 12ax7,5751 ,el 34 ,
el 84,5751 ,7868 and so on ,route.
Accepting their limits.
Ecc88/6922 the attempt doin g half way.
I'm not aware of perfection.
Sorry for my broken english and dislessic way of writing
Henry,
Look at the JJ ECC802s. Very good sounding tube with the characteristics you're looking for.
Mike
Opus 33 1/3
For new production tubes the new TungSol's are excellent.
I've been using vintage Slyvania 12AU7 I think the last letter is W ?? I have to check. Next to the TungSols they seem to be the best I've heard yet.
charles
I have often substituted e80CC for 12au7. It depends on the gear involved. The Phillips gold pin tubes have tubeiness and full body way better than 12au7's, and as an added benefit they are very dynamic in the bass and lower midrange. A really great tube.
Talk to Jim McShane about the latest New Sensor offering(s).
JMO, the makers of commercial tubed electronics need to stop "counting beans" and provide sufficient filament current to support 6FQ7s and/or 12BH7s, both of which are in production and beat the living guano out of any 12AU7/ECC82 ever made.
The 12AU7 contains triodes with serious linearity issues. The only HIFI jobs the type is at all suited to is cathode follower and "concertina" phase splitter. In those cases, degeneration (AKA local current NFB) circumvents the linearity problem.
Eli D.
But why would you bother with anything else?
low impedance goes with lo mu valves, because hi mu/hi impedance ones can't conduct current
Low impedance = big current.
The 12AU7 is fine if you use it for what it's for.
Btw you forgot one more important use for those so called "non linear" lo mu triodes.
Cascode stages, where in effect you are recreating a pentode anyhow.
(Top grid connection is SAME as screen grid, bottom grid connection is G1.)
Do you mean "Cathode" ~? As in autobiasing or cathode biasing?
RavenDave
Opus 33 1/3
Most modern gear does not have that 'classic' sound. An exception may be the Gold Lion Russian, which reportedly has a warm presentation. Failing that one perhaps the strategy could be the following
See if you can borrow/acquire some well used early, Mullards made at Blackburn, with long plates.In any event don't pay much for them. Get them from a friend or a tube vendor you truly trust. Check and see if that gives you the sound you want.
+,
Bland you may find
I agree that the 12BH7 and in particular the 6CG7 are better tubes, but if you use either of these tubes in a high sensitivity circuit you are going to have problems with microphonics. At least this will be the case with old stock tubes in these families.
I replaced the three small signal 12AX7s (used for gain and as phase splitters !!!!) in both of my LEAK Stereo 20s - with one input 6DJ8, and two NOS AWA / AWV 6CG7s with a FET CCS in LTP mode.
There's no sign of the slight microphony they had before.
Australia stopped making valves a long time ago.
And, of course both amps have lower total NFB than before.
As the LEAKs are close to the speakers they bi-amp, microphony was likely.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Low microphonics is 1 of the places reliable dealers, like Jim McShane, earn their money. Pay the man his money and get as advertised goods.
The common cathode gain behavior of the 12AU7, 12BH7, and 6FQ7/6CG7 is, for all practical purposes, the same. The 'U7 draws 1/2 the heater current of the other types, which pleases "bean counters", but sacrifices linearity in the process.
Eli D.
I think Eli is on the right track when he mentioned New Sensor as a possible choice. I would narrow that to the Russian Gold Lion, which has a warmer sound than most. Failing that establish a good relationship with a tube vendor you trust. A good dealer will steer you away from junk and point you to really good NOS.
https://www.tubeworld.com/12au7.htm
Scroll down slightly to see a good review of the NOS 12au7 family of tubes. A similar review of 12ax7's can be found here also.
Hope this helps,
Robert
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