Tony, There are a lot of tubes sold on ebay as NOS that aren’t There are a lot of lightly used tubes that still test above average new.
Without going too far into the weeds, tubes are usually tested for transconductance to determine how long they will last and to match them. Tube testers, Hickok is the most common brand, come with a scroll that tells you what the average transconductance is for a new 12AT7 tested on that machine.
Nobody has kept track of which tubes have been used and which haven’t. So if a tube tests above average new and the glass and pins look clean, many sellers will sell it as NOS. Others will sell it as "tests above new" but not call it NOS. There have been discussions about how to categorize old tubes that test above new but probably have some use as ANOS, i.e. almost new old stock., but that never got anywhere.
Tube dealers like Brent Jessee or Vintage Tube Services (Andy Bouwman) use more sophisticated testers than the Hickoks I mentioned above, although Hickok did make lab grade testers which are much more precise than the more common Hickok 600s or whatever.
Even with all the uncertainty, many people still feel it is worth it to buy vintage tubes because they had the same experience you did. They like the sound better. There is a LOT to know about vintage tubes, so you’re better off dealing with someone like Brent or Andy than trying to learn it all yourself.
I have been in contact with Brent and I trust he is a professional. I tried the tap fix for flake and it did not change anything. I will try that one more time.
And my 6922's are GL's.
Next time Im at the cabin, Im going to visit this junk yard up there and look for tubes :-)
I bought a tube tester last year and it was an eye opener. Most tubes I got from trusted dealers were as advertised but I had a number of tubes that were duds.
Mismatched triodes, weak, also had a bad 5r4gy (shorted) that would have damaged my new 300b amp. That tester paid for itself that day.
My reasoning to buy it was because I was starting to play with antique tubes like 300b and 274b / 5r4gy types . That amp also uses e180f which is only available as NOS or used. Fortunately that tube and it's variants are easy to find NOS but I want peace of mind before using ANY tube. That said, even brand new tubes get tested before going in any of my gear
Unfortunately I have also received tubesI thought were used .... not from Brent but another well respected dealer.
The truth is that a lot of "NOS" tubes are "pulls" , tubes that were lightly used but still test stronger than new. In the 50's and 60's tons of test equipment and medical instruments had tubes. When these instruments were decommissioned those tubes were pulled and went into someone's stash.
I repair medical equipment and still occasionally come across really old power supplies that are tube rectified and filtered. It was common practice to pull tubes out on a lot of stuff before trashing it
You could have and probably did receive NOS from Brent but another problem is that after 50 or 60 years the silkscreen flaked off. Sometimes just touching the print will wear / wipe it away.
The only way to know you are getting a good tube is to test it. I ultimately ended up buying a tube tester. I have a buddy who does clean outs and occasionally he will drop off some tubes. The last tubes he gave me that I believed to be NOS was a pair of early 60's RCA 6v6. The boxes were rough but the tubes tested strong , better than min. Were they used briefly and put back in a box ? No one will ever know...
Personally for the 6922 I would just buy a pair of Gold Lion or JJ that is matched and tested for noise. Its only a few bucks more but you know you are getting new, strong tubes.
I'm sure Brent will take care of you. I have had a few tubes from him and they were always as described.
NOS tubes will test as new but not always look shiny and new.The reason they are rarely in the original box is the old thin cardboard disintegrated long ago so they often appear in rough shape.Brent will take care of it. He's a good guy.
Calm down, Tony. New Old Stock should be new. Brent will replace the tubes. Tell him that the tubes appear very much used to you.and ask him what his criteria for labeling a tube NOS are.
Preamp tubes are less likely to damage your gear than power tubes, but still don’t put tubes that are making noises or sparking into your gear. I know you don’t know until you put them in the first time, but once you pull them out don’t put them back in.
This will all turn out well. Audio just requires a little patience sometimes.
What I think I have discovered in any event is that the pre seems to be the most important part since the pre w/ the GL's makes my system sound like it did yesterday.
Of course it could be that the Mullards I used as Amp Inputs were nothing special.
Maybe I should just stick to RCA for now, Huh?
OK, so NOS doesn't mean new. Does anyone sell actual new old tubes or is this just the best I can hope for.....which is fine, I just want to know what Im getting into, you know?
@tonydennisonNOS in my view is testing at new level or above used or new. Tubes age with time even in boxes and handling. Pins slight bent are normal for used tubes. Brent tests all tubes with great equipment. Just a one off is my take.
I have some extra tubes you can try out if you want to see how you like different ones. Just personal message me if you are interested. I’m not a seller/dealer just another tuber.
@tonydennisonyep once you go NOS you never go back…yep that is a failed tube and do not use it to avoid any shorts that could impact your pre. Brent has a guarantee and will replace it or them. Old 40-50’s black plate RCA most tube types are fantastic 12at, 12ax, 12au, 6sn7, 6l6….my favs. I have only had one tube fail on me. It was a ‘40’s radiotron tube that came with a new preamp from australia. Tough long trip I guess. On my second use it had a very loud static then pop and became a rattle.
@tonydennison one more suggestion that may or may not work out. I have had excellent results using 12at7 and 5751 tubes in place of 12ax7’s. They are identical except the gain is lower than the AX’s. (You can go down on gain with these tube types but not up) I have used them on a DAC pre, phono stage and can’t tell a difference and they sound great. Not sure if your mono’s need the extra gain or not. 12AX7’s are becoming much pricier and harder to find now.
@tonydennisonKentucky Radio made some excellent tubes. I had ‘50’s 12ax7 blackplates. They sound excellent but harder to fine and can be pricey. I prefer the RCA over them. Ken Rad made some pewter plates in the 50’s that are even better but I never had any. Ken Rad was bought by GE so GE 12ax7 grayplates from early 60’s are really nice and an exceptional value if cost is a concern.
The order of best impact for me would be the order you listed but all are important. Cheers!
Depends on the amount you are willing to spend? I have a Lab12 DAC 1 Reference that takes 2 6922’s. I prefer old stock tubes on the warmer or neutral side with detail. My experience rolling:
$- Amperex Bugle Boy 6DJ8 Holland (excellent value with great SQ)
$$- Amperex 6922 Holland
Amperex 6922 USA
$$$- French Phillips E188cc/7308 labeled RT, RTC, Dario Miniwatt,Mazda=My Fav
Amperex 7308 Holland (or USA) SQ or PQ label best
Siemens E88cc/6922 Germany (little brighter)
Talk to and look at Brent Jessee and his website. Very helpful and informative. Good luck with it all. Tom
I agree with jss... in my Mid Monos a 6922 that may not be really quiet in a Preamp will work fine in the driver pos.
I use JJ in there now and I think its the input tube that make the most difference in these.
I have some early 60's RCA 12ax7 at the input and these amps have never sounded better. When I bought them at about a year old the former owner also really liked RCA because there were early RCA 12ax7 in there.
in integrated or power amp circuits, the input tube is generally considered more important than the driver tubes in front of the power tubes ’being driven’
reason being that the input tube is the actual gain stage, expanding the low level signal, and is first in receiving the incoming signal (thus having more stringent requirements in terms of noise and transconductance/mu) than the driver stage after it, which simply works to stabilize the impedance and signal delivered into the power tubes for them to do their work
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