Favorite 12AU7 types ?

Hi I had my VTA ST-120 for very close to two years and I bought it from the person that built it. anyway long story short i had problems with it.It turned out to be a problem in the slow start circuit .But now having gotten it repaired. It is so much better than I even expected it to be when I first bought it.I have a quad of KT-120's on the way[can,t wait!]And now that my amp is so much FUN to listen to,Ijust want any input on any 12au7's that you like.I am using a pair of RCA cleartops and a NOS Mullard in the center.thanx I look forward to your replies .Scott in Beautiful sunny Eugene.[Gonna be 92 tuesday]

Current set has been untouched for at least a couple months now ... a closely matched pair of 1940's RCA foil getters, and a NOS Telefunken in the middle. Very clean and killer sound stage.

Next best for me would be a triplet of RCA clear tops, and close behind that would be Gulbransen (Amperex Holland Bugle Boys) and a Marconi in the middle.

I've also got a set of milspec Westinghouse 5963's that are quite tasty and working their way up the list. Thanx for the reminder - just loaded those in and warming as we speak. They're definitely different ... have to leave em in for a while and see if they grow on me.

UPDATE >> Just spent some time going thru an eclectic selection of tunes and the 5963's are definitely standing proud. Some real authority in the presentation. Those were also a real deal I thought at $30 for the triplet.

PS ... while I was digging, I also stumbled across a set of three Westinghouse 12AU7a's that have the factory painted tips to denote low microphonics. Not even sure if I've ever had those plugged in.

I think you are going to really like KT-120s.  They can dig down deep and provide a nice fat bottom without being too much.  I am off the NOS trail having been burned a few times by sellers advertising "new" but really used tubes that tested just OK.  For new production tubes I like the Black Treasure CV181 in the center (with socket adapter).  Has good drive for the KT-120s with nice liquid midrange/ vocals and shimmering top.  Big soundstage and 3D in spades.  It is not a bright tube but I have plenty of those types with their glare and hissy top end silibance.   Also been using Psvane 12AU7s for the phase inverters.  Smooth, detailed, and quiet.  They knocked the CBS/Hytron 5814As out of that position (less grain).  However, that is my system and ears.  These tubes aren't inexpensive but there is hope for new production being as enjoyable or even better than NOS in some cases. Best of luck and share what you discover!

I got a big bunch of RCA clear tops as well as CONN clear tops, so far, they all sound really good in the VTA!
I think the CONN's came out of old electric organs.

Compare the CONN to the RCA internal parts. If they look the same it probably is a RCA clear top relabeled. Although many people made the 12AU7, internally each manufacture made them different.

Bob (& anyone else with experience) in the matter: I've only used 12BH7As in the driver slots for my M-125s. How significant is the gain loss using 12AU7s? I like the clear-top RCA 6CG7s in the preamps, would be tempted to try the 12AU7s in my amplifiers. What's the trade-off? I know this has been addressed elsewhere but can't recall or find the thread.

From my own personal experience, gain is somewhat lower on the 12BH7 series and they tend to be darker ... depends on your musical preferences as to which you prefer. I like the extra punch on prog rock, and if I want darker and mellow, a quick switch to triode mode does the trick for me.

Then again, my version of reality tends to differ somewhat from most ... so take all that with a pound of salt with a bit over the shoulder to keep the monsters at bay ...   

DO try the 5963's if you get a chance. I don't hear much about them, but they've been a pleasant surprise. I'd rank them a step below a typical 12AU7 for brightness, but they seem to have a much more balanced midrange without losing any bottom end grunt. Using a triplet of Westinghouse "stars" now (the milspec version), and very good depth and soundstage. Been working them pretty hard the last couple or three days and I expect I'll be leaving them in for a while.

sKiZo wrote:From my own personal experience, gain is somewhat lower on the 12BH7 series and they tend to be darker ... depends on your musical preferences as to which you prefer. I like the extra punch on prog rock, and if I want darker and mellow, a quick switch to triode mode does the trick for me.

Then again, my version of reality tends to differ somewhat from most ... so take all that with a pound of salt with a bit over the shoulder to keep the monsters at bay ...   

DO try the 5963's if you get a chance. I don't hear much about them, but they've been a pleasant surprise. I'd rank them a step below a typical 12AU7 for brightness, but they seem to have a much more balanced midrange without losing any bottom end grunt. Using a triplet of Westinghouse "stars" now (the milspec version), and very good depth and soundstage. Been working them pretty hard the last couple or three days and I expect I'll be leaving them in for a while.

Skiz, can you suggest a source/brand?
For the 5963s?

Ah ... and therein lies the problem ...

What I got is a matched triplet of Westinghouse "star" ... same production date, etc. Started out as an experiment as I'd not heard much about them.



I got mine offa da bay from a reputable seller for $35 shipped. Just took a peek and I see some 5963's listed, but not the same variety. I see some Westinghouse brand listed, but those are the standard issue white label, probably rebrands, and not milspec. You can expect lower microphonics and more beef in the structure going with those.

I'm sure there's other types that work just as well, but my only personal experience is with these. Might be a bit more rare than I'd thought ... make me an offer I can't refuse!  

i  am always looking for tube upgrades . it is like an addiction . but i see it as experimenting to find the best  sound , you can't do that with solid state . i just put a set of clear top rca 6cg7 / 6fq7 tubes in a couple of harman kardon  mono amps i have and the difference is amazing . they had the harman kardon tubes in there they were probably originals . i will have to be on the lookout for some rca clear top 12au7's for future use .they'll only be going up in price .

mark four wrote:i  am always looking for tube upgrades . it is like an addiction . but i see it as experimenting to find the best  sound , you can't do that with solid state . i just put a set of clear top rca 6cg7 / 6fq7 tubes in a couple of harman kardon  mono amps i have and the difference is amazing . they had the harman kardon tubes in there they were probably originals . i will have to be on the lookout for some rca clear top 12au7's for future use .they'll only be going up in price .

The clear-top RCA 6CG7s are the cat's meow IMHO, tried lots of others in the preamps, including their earlier black-plates. Nothing else (well, maybe there's a $600 Mullard out there) comes close.

after listening to some of my clear top RCA/CONN 12AU7's...they are really so good! Very clear and defined, in some ways 'neutral' for one of the better words, they don't mess up the tones!....me likey!!   

MontanaWay wrote:after listening to some of my clear top RCA/CONN 12AU7's...they are really so good! Very clear and defined, in some ways 'neutral' for one of the better words, they don't mess up the tones!....me likey!!   

I had the RCA/CONN cleartops in for a while and they did sound pretty good.  I finally decided they were too bright for me. I'm using Heresy 3's which likely made the cleartops sound too bright.  
The 12bh7 RCA's were just okay.  
I've settled on NOS Mullards right now, although I want to try a set of Brimars and Tele 12au7's  

If anyone wants my NOS 12bh7's (used them for only a week) pm me!

deepee99 wrote:
Skiz, can you suggest a source/brand?
For the 5963s?

Went back to check my thread a couple months back on the 5963's ...

https://dynacotubeaudio.forumotion.com/t2151-5963-an-option-for-12au7-in-st120

... and forgot that Bob mentioned supplying them with kits at that point in time.

I am presently shipping all the VTA amp kits (for those that want a tube set included with their kit) with either RCA or Sylvania 5963 driver tubes.

Anyone out there that have tried the ECC802S from Tesla? From what I can unnderstand they are replicas of the very expensive ECC802S tubes from Telefunken.

slangoff wrote:Anyone out there that have tried the ECC802S from Tesla? From what I can unnderstand they are replicas of the very expensive ECC802S tubes from Telefunken.

I sell them ( the JJ ones, tesla is a long time ago). And no, they are not copies of the tfk/ECC802S, those were frame-grid tubes.
In fact the JJ ECC802S are more like tfk longplates. The JJ ECC82 on the other hand is
a shortplate tube although not a frame-grid one.

JJ ECC802S is very sturdy and has good resistance against micro-phony, that's why they
fits well in guitar-amps.

I know about the JJ ECC802S tubes. Those are not the ones I am interested in but the old ones manufactured by Tesla in former Czechoslovakia. You see Tesla (not JJ) ECC802S tubes NOS for sale on ebay every now and then.

slangoff wrote:I know about the JJ ECC802S tubes. Those are not the ones I am interested in but the old ones manufactured by Tesla in former Czechoslovakia. You see Tesla (not JJ) ECC802S tubes NOS for sale on ebay every now and then.

Fair enough. There is much confusion between tesla and jj, the later has acquired the tesla audiotube rights.

I can only speak about jj as these i know about and can get delivery's of.

As an amusing detail : telefunken tubes is now on the market again, and jj is the factory that makes them :
http://www.telefunken-elektroakustik.com/products/tubes/

( there is no ECC82/ecc802 offering from current telefunken however )
What a confusing world :-)

not quite 12AU7 but close enough....... but I also really like the RCA 5963, I got a bunch not so long ago, and I think I even like them better than the RCA/CONN clear tops!

Another vote for the 5963's.

I scored a nice set of NOS Westinghouse Stars a while back and they match up very nicely with my system and preferences. The Star is their military version.



It's been several months now since I plugged them in and haven't really felt any need to experiment further. I keep thinking I should start rolling again, but can't be bothered ...

Should save a lot of wear and tear on the sockets anyway ...  

I have a modded Dynaco ST-70.It uses a 12AU7 in the center position.

I've said this before, but it's still true. I really like the Cifte/Mazda vintage tube. I think you can still get them.

'Frank

British made 12AU7s from the '50s and '60s are IMHO the best sounding, longest lasting 12AU7s, with Mullards and Brimars as the tubes of choice. The Brimar 13D5 is extraordinary.

As suitable substitutes, but not direct replacements, the 6CG7 and the ECC40 with 6 volt heaters are quite nice and they're both shielded.  Excellent tone.  Hear an SP13 and you'll know what I mean.

But by far, the very best sounding dual triode I have ever used is the first and original: 6F8G.  Its not even close.  It will pass any ABX test out there by anyone listening.

Could it be the extra/higher currents the 6 volt heaters have and also in the 12 volt octals that make them better sounding than the 12AU7?

Never gave the 6F8G or octal substitutes, so can't comment on that. I do know that rolling the 12AU7 family can get somewhat addictive, as evidenced by my rather out of control collection. Lots of variety for fine tuning the sound to your system.

It's simple enough to substitute some octals into the VTA board though ... just get the right adapter and make sure you match the heater current requirements.

PS ... don't forget the relabels ... you can get some real deals there. I've got some Amperex Bugle Boys that are labeled as "Gulbransen" ...

Does anyone have experience with any of the current production 12AU7s such as Genalex Gold Lion ECC82/B749 or Tung-Sol 12AU7 in the VTA ST-70?

NOS RCA, GE, and Tung-Sol can be had for roughly the same price as the current-production Genalex, and, in some cases for less.

Didn't have any issues with the optional tube set that arrived with my 120 but wanted to see if changing tubes really made a difference. Researching both this forum and many online tube forums I had selected either the RCA Clear tops or the Mullard 12AU7s. Some of the online blogs recommended against the Clear tops if you use speakers with metal tweeters because they can sound too bright. My amp powers two sets of Klipsch, a set of Chorus and Cornwalls so I decided on the Mullards.

Wow - the subtle differences from the perfectly fine optional tube set that came with GE ECC82 tubes is amazing. The sound seems to have expanded in its live sound stage three dimensional sound. I heard things like a background guitar on a Dylan album being softly plucked in the background for the first time. I didn't miss it before, but now to hear that richer mix of music elements stuns friends who know specific albums.

I'm upgrading the GZ34 to a 1962 Mullard next, already in transit. Found a wonderful supplier of tubes in the US: Dave Hollander at Arizona Tube Supply http://www.arizonatubesupply.com/

He tests his tubes for everything we care about, has fair prices and fast shipping. Plus he has been in the business decades which is some nice experience to leverage when, like me, you are fairly new to tube amps. Always used early transistor Marantz before.