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NOS Tubes - Ecstasy or Agony

I have been running tube amps for many years and have built a number of SETs and other tube amps, kit's mostly.  My main power tubes have been 2A3's and 300bs and I have used mostly new manufacture tubes including JJ's and EML 300b's (great tube btw).  I did use NOS driver tubes and headphone amp tubes.  Never really had a problem.

I just transitioned to a Don Sach's 6sn7 based preamp and McCormack SS power amp.  The preamp is very nice and sounds great with Shugang tubes. Of course, I wanted to try some NOS tubes, went online and did my research.  Now the DS2 is a great preamp, the drawback is it uses 4 6sn7s and so I need to get pairs.  Would  have love to get my hands on the Dehavilland, uses one tube!

First Pair - I ordered some Sylvania's from TC Tubes. Advertised as 50's vintage, ,when I received  them they were marked 60's. Hmmm.  So I tried them and they sounded pretty darn good except after a couple hours one of them developed a high pitched hum, like a florescent bulb. So I sent them back.  

Second Pair - ordered from Brent Jesse - has a good rep online and a really informative website.  Received them and one was dead on arrival, they were also clearly of different construction. So they are going back.

Next will try Andy at Vintage Tubes Services, he also has a solid  reputation so hopefully I can get something that works.

I am curious what experiences others have had. Maybe its COVID, or are these dealers just unreliable, or is just 6sn7's?  Really thought I could just buy some NOS tubes and experiment, I can't even get two to work.

I don't really want to disparage these dealers but I do think all the claims of testing are maybe overblown.
drewh1
daveyf's avatar
daveyf
2,858 posts
 
Some NOS tubes I have seen have clearly been used in some kind of electronics for decades. If you look at the tube pins, they are not only corroded, but also generally not that straight! The only 'New' thing about them will be the new owner who acquires them in the sale! Luckily, it seems that a lot of the better 'NOS' euro tube manufacturer's made tubes with enough quality to last for multiple insertions and hours....Too bad this doesn't seem to be the case with today's manufacturer's. 
audioguy85's avatar
audioguy85
2,018 posts
 
Bought numerous "NOS" tubes, mostly through Ebay. Some from the Tube Store, and some from upscale audio. All of them have been as described. Some from Ebay I already knew were not brand new, as the seller disclosed this, despite being listed as NOS. I am loving my combo of GE 12au7, RCA 7025, and my Sylvania 5751 with disc getter. Sounds wonderful through my Tavish Design the classic.
sgreg1
612 posts
 
NOS is not only a marketing ploy. Tubes do have an end life to them. I would expect when I buy a “new old tube” that I can expect 100% of its life expectancy. Not 80 not 50 but 100. There is no test that can tell me this. I can run a tube for 3 years and it will test the same as one never used. I have made pease with the fact there is always some luck of the draw with anything electronic and the evil gremlins that can be there. Electricity is kinda like Mother Nature. They are and always be undefeated all I want is for them to be on my side.
6SN7 tubes my pre take 4. I run sylvania 1950 bad boys in my gain and brand new tungsols in the buffer. Sound is detailed wide and 3-d. My dream would by finding the holy grail of telafunkins but can’t justify paying more for a tube than I did for my preamplifier. Have used T/C tubes and have no complaints.
mapman's avatar
mapman
22,149 posts
 
I see any tube as a gamble to a certain extent. Much like all the rest, just somewhat higher risk I would say.

If you must drop a lot of $$$s on tubes, buy only from reputable sources with a rep for good customer service. Or else go cheaper when possible and risks not so great.

In recent years I’ve only bought tubes from two sources: 1) Audio Research or 2) Guitar Center to play with cheaper options where practical. Sometimes it is practical, sometimes not. For example, tubes used in a phono section probably need to meet higher tolerance standards than those in the line stage. In my Audio Research sp16, 1 of three phono section tubes must meet higher tolerance. Only pricey tube from ARC will do for no audible background noise. All others (5), not nearly so much.  If you buy all six,  that one costs more and is marked for use in the proper place.

I do not do tube power amps to-date so no recent experience there.
mglik
906 posts
 
In the past, I have had great success with NOS tubes. But recently, have had consistent failures of 12AT7s. Bought 3 pair from,I thought a reliable source.
Have made a note of Brant Jesse. I have been told that NOS, especially for a preamp, are rarely quiet enough. Normal testing only reveals the main functions of a tube and not how it will sound. Believe a complete test must include actually putting the tube in a component. And hearing it for several minutes. I doubt that many or any tube sellers will do this.
Manufacturers may do this for their stock tubes. But, I think, most will use cheap new stock tubes that they buy by the hundreds in order to find the good ones. Am getting a new preamp with 18 tubes: 8 12AT7s and 10 6SN7s! They will all be new, all Chinese I think, tubes that were sorted out and “completely” tested.
Maybe Brent can supply tubes sorted. I am very hesitant to replace the stock tubes. Psvane offers some tubes that have been sorted out from many. Don’t know if they do a complete test but they do charge a lot for these “premium” tubes.
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