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
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.
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
@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!
@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.
@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.
@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.
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?
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.
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.
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.
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
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 :-)
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.
Those testers are 60 plus years old so I'm not expecting true accuracy. I want to test for shorts first and foremost. That's what will damage your gear.
Tomcy6, you are dead on. No one tracked the tubes that were in those caddies. Repairmen had tons of tubes on hand. It was common practice for a tech to replace all tubes , that way much less chance of a return call. What happened to the tubes that were pulled? They went back in someones caddy and the bad tube was tossed.
My tester is within 50 microhmos of a 6L6 and 12ax7 that were tested on an Amplitrex so that's good enough for me.
Why would you spend the money for a Hickok tester just to test a tube for shorts, a much cheaper tester can do that. You should just buy tubes from Andy from vintage tube service, I've never heard any complaints about his tubes, but I have about everyone else's tubes at one time or another.
I didn't buy it just for that. I test all parameters . I was lucky and found d 9ne that looks like it was in a museum. It was serviced a few years ago by the previous owner.
I'm sure Andy is a good guy and reputable, but if I bought tubes from him I would test them as well. As mentioned earlier my tester is fairly accurate enough to verify I'm not getting screwed
Thanx for the info. Hopefully I wont get addicted to NOS, I just want two sets of AT7, AX7, 6922 and hopefully I’ll be set for life.
As to NEW, I am actually not that hung up on that. I’m annoyed that people list items as New Old Stock.....and they are not new.
How hard is it to say, "I sell used tubes I pull out of old radios. They test New and they’re awesome."
Thats how to do it. What if I sold a used scarred Mac 275 on Audiogon and I list it as NEW? That wouldn’t be right. But if I sell used tubes, I can call them new? Doesn’t make sense to me. Again, I don’t care if they’re used, but don’t piss in my ear and tell me it’s raining.
It is not unusual to have a tube fail soon after install, it's part of the deal using 50, 60, 70, 80 year old tubes......I suspect shipping has a lot to do with the failures. Most important is to have a vendor who stands behind his products, and Brent Jessee is one of the best tubes suppliers I am aware of. I've bought a bunch of tubes from him, and he warranted a couple that were DOA.
There are dozens of versions of the 12AU7/6DJ8 family and they are numbered differently in Japan/Europe/USA/Russia. I personally prefer Amperex 7308 or 6922 "SQ" or "PQ" gold pin tubes. I believe all of these were made at Amperex (owned by Philips) New York plant in Heerlen Holland.....going off of memory. Below is the best 12AU7 style tube information I've ever found and it is from Brent....talks about most all of the different tubes, and their sound characteristics as well
I am ZERO concerned about the failed tube....ZERO. Not upset not agitated not irked. I am not in the slightest bit upset or concerned about the failed tube.
I am sure Brent will do the right thing. I’ve never doubted it. I am not concerned about it.
I have had a few experiences of being demo's 6922/E88CC Tubes, as a result of being loaned valves for a using for Tube Rolling sessions.
All Loaned Tubes were tested, and perfectly matched as pairs.
All loaned Tubes were ranging from a production era from early 1960's - mid 70's.
There were Brands on offer from Mainland Europe, UK and USA.
In my Phonostage and DAC the Amperex Bugle Boy (I recall Orange Print) was a no go for myself and others who were present, the intensity of the high frequencies was too much for the ears to settle with.
As conjecture only, a overwhelmingly Bass orientated presentation might just come out with these as a viable choice to add a noticeable impact on the balancing across the frequencies.
Other Tubes used as comparisons were much more of a 'what's your poison' experience.
My Phon's has selected for use, early 60's UK Tubes and the DAC has early 60's German Tubes as the selected type.
In my last post I meant to say "New York OR Heerlen Holland plants". Also in some Amperex tubes, the tube printing is smeared or even partially wiped off and that is not abnormal. The printing is easily damaged during normal handling.
Tonydennison, I did not mean to imply that you were overly concerned, I meant more to indicate that there were suppliers that do stand behind their product
Pindac, your findings agree with what I have found, that the Orange labeled tubes were not as good as the white label gold pins, and certainly not up to the quality of the SQ or PQ tubes 6922 or 7308. I could not find my listening notes, and I can't recall specific details that I made for those tubes.....just going off of memory there.
I have come to accept the labeling of used tubes as NOS although I think a better term would be Reclaimed Tubes.
All current manufacturers, at least the ones I have used should be utterly ashamed at their ineptness, apathy, ignorance, or whatever it is that makes them seemingly unable to make a tube properly. And I never knew what I was missing.
The 1.5 minutes of listening to Black Plate RCA’s and Mullards in my system (even when one of the tubes was dying at the time) showed me that modern manufactures are embarrassingly inadequate. There is absolutely no comparison.
The current state of world is so pathetic.
Anyway, I have been in further contact with Brent and he will send me a replacement.
All current manufacturers, at least the ones I have used should be utterly ashamed at their ineptness, apathy, ignorance, or whatever it is that makes them seemingly unable to make a tube properly. And I never knew what I was missing.
The 1.5 minutes of listening to Black Plate RCA’s and Mullards in my system (even when one of the tubes was dying at the time) showed me that modern manufactures are embarrassingly inadequate. There is absolutely no comparison.
About 6mos ago I purchased a pair of NOS, RCA Clear Top 12au7 for my Line Magnetic DAC. I purchased them from a shop that I knew was reputable. When they arrived and I opened the boxes I noted both tubes had a serious flash marks. I mean both looked identical in the way the flash was located in the tube. Called to ask why & was told that happens sometimes in testing and that the tubes in question tested as NOS. I was skeptical and had them tested locally. Sure enough as close to matched as if ever seen and both with NOS life expectancy. Both dead quiet and the tubes themselves brought out the very best in my setup and for certain, DAC. What can I tell you... always a roll of the dice when purchasing NOS so make sure you have a dealer you trust.
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