12au7 tube?

Wait, what am I doing??!

Terrible, terrible tube! 

Mattw73, great information. I liked your knowledge and experience on various tubes. Sounds like you’ve done a lot of listening to different types as I have. Well I know these things sound crazy but that’s why this is a hobby. I can’t remember all the ridiculous hours I spent during the day and late at night comparing the difference between one brand of tube against another. Well most of that is behind me. Today I find myself doing comparisons with cables. Give or take, the 1940’s to 1960’s was the era of vacuum tubes. Probably continued up into the 80’s. No where in time did we have so many great vacuum tube companies making quality tubes as we did in the era. Today, we are in a different era,  The era of hifi cables. Many different cables have many different characteristics. With getting the correct tubes in the circuit and right cabling on the components, we have great opportunities to get fantastic sounding systems. I believe getting the correct tubes in a circuit is extremely important but so is the cabling between the components. Of course there is no end to tweaking as I’ve even gone as far as to change Capacitors in my components which is another world of tweaks of its own. 

One point also, we are also in the era of hifi Capacitors as there are so many variety and wonderful and beautiful sounding capacitors being made today from various good companies. 

Audiojan

There are tons of variables for 12 AU7s and 6SN7s, as you've already seen. Whenever I need honest advice and a HUGE selection of tubes, I reach out to Brent Jessee. His tubes are not the cheapest, but he carries a large stock, and stands behind his tubes. Send him a note with your equipment, and ask him for his recommendations; he's been spot on and I've been buying from him for 7 or 8 years

Best combination has turned out to be Melz 1587 and La Radiotechnique 12AU7WA. The perfect combination of air, details, natural sound (and never edgy or dull) and a soundstage that is unbelievably awesome!

I really appreciate these threads for information.

inna commented about some 50s RCA black tops, back in February. I'd recently been trying out 12 AU7s in both an Aric Unlimited II, and a Conrad Johnson PV-11. Battle of the preamps and their line stage tubes. I've got a modest collection, but the black tops arrived last week. I've liked the RCA clear tops, and some Cryotones among the existing crowd, but wow. The RCA black tops provided more of everything. I've stopped rolling for the moment, just surprised.

I had a buddy over a few nights ago, and he was looking around for the large speakers in the basement. They were just the little Dynaudios, pretending to be big.  I give some credit to these tubes for that moment.

Blacktops??

Do you mean black plates?

Yeah, he meant black plates, of course. I think, RCA actually invented both 12AX7 and 12AU7 tubes. 1948-1956 production years are thought to be the best.

I've got a pair of RCA 5814a JRC triple mica black plates. Nice tube.

Also have a pair of clear tops. Wouldn't take another pair if they were given to me.

@thecarpathian a d just as I thought I had the perfect tube you come up with the RCA’s… :-)

Can't win a prize if you don't buy a ticket!

@twoleftears Question: has anyone tried the Apos Ray 12AU7, which seems to be the new kid on the block making a few waves.

Are you aware of who the OEM is for Ray tubes btw?

Not to blow their cover but it’s fairly easy to search and find on the internet. Think large manufacturer who batches their top % of tested tubes and puts a different label on it.. Perhaps the helpful part is they are supposed to be top matched triodes tested [and as good as a guarantee that Ray gives them] whatever that is at the time the warranty is needed fwiw.

Yep. Black plates, not black tops! As opposed to clear tops, and thanks for your patience.

I’ve got to try some more pairs later today. Cheers!

Are you aware of who the OEM is for Ray tubes btw?

Not to blow their cover but it’s fairly easy to search and find on the internet. Think large manufacturer who batches their top % of tested tubes and puts a different label on it.. Perhaps the helpful part is they are supposed to be top matched triodes tested [and as good as a guarantee that Ray gives them] whatever that is at the time the warranty is needed fwiw.

@decooney Yep. There is nothing new under the sun here, and I have to roll my eyes when somebody uses marketing / branding to act like a new tube manufacturer. At least be more up-front: "here is who makes our tubes, and here is what we do to (maybe) make them better than the standard production"

They hide this in the FAQ on their site:

We want to give you the vacuum tubes you need. To achieve that, we work with multiple contract manufacturers across Asia and Eastern Europe. Because no manufacturer covers the entire range, each manufacturer specializes in different types of tubes. No matter where the tubes are made, each one goes through the same strict quality control process.

You have to go to Support, then hit FAQ.

Also this bit of dubious ’technology’:

Magic Coating is a monocrystalline carbon coating that improves sound quality. It cools the tubes, blocks unwanted noise, and speeds up electron transmission for a cleaner sound.

How it can do that when it’s coating the glass is beyond me.

Gotta admit, they have a good marketing department.

They also explain why their tubes are better than all NOS tubes which to me is a blanket statement of nonsense.

Sophia Electric 12au7

I have been using this company's EL34's in my Primaluna EVO 400's and like them very much. Has anyone here ever tried their 12au7's?

Rays select around $180 a pair are very respectable  sounding and come with a 

1 year warranty.

For $180 you can get a NOS matched pair of Mullards or RCA black plates, and probably other brands too, I just didn't look.

"For $180 you can get a NOS matched pair of Mullards” or pretending to be, more likely..

You speak as if these tubes are easy to counterfeit. Just look to construction and the acid etched codes. RCA black plates are fairly common. Mullards are among my least favorite 12AU7s as are the RCA clear tops.

They may not be actually counterfeit but also probably not NOS by any stretch of the imagination.  I have quite a few in my collection and used to own a well calibrated Hickok Military Cardmatic tester that could actually stress the tubes slightly to look for possible longevity.  So many tested high initially but showed they would only be in service for a much shorter time than one wants to believe.  

Well these are called life tests and should be done on all tubes sold. Most likely they are not by many sellers, especially on ebay. Having said this, a very well respected tube seller advertises "new old stock in white boxes", which translated means white boxed tubes testing as typical new old stock. Not the same thing. The same seller claims that Sylvania Bad Boy 6SN7GT varied in construction and included 2 and 3 hole plates as just on example. 

Best way to tell if a tube is NOS is by a close inspection of the pins. Deep grooves or burn marks are signs of use as is baked on lettering which cant be removed easily with a thumbnail or a wipe. Original boxes arent a definitive sign of NOS condition but they are a good start. Some tubes, like JAN tubes, were bulk packed without original boxes, but this is fairly uncommon in my experience. I have had used tubes which tested higher than actual NOS. Not unusual for true NOS test levels on the same tube type, from the same manufacturer from the same production run to vary up to 20%. So typical NOS levels listed on some testers are averages which arent particularly precise.

These were prices from audiotubes.com, a very reliable source of tubes. In fact, RCAs are $100 for a matched pair.