NOS valves/tubes; How reliable?

[martinw]

I am lucky enough to have been given a selection of NOS valves by a relative whose father used to work for Ferranti.
There are EL84's, ECC83's amongst others, which I could use in my 18Watt. Brands are Mullard, Ferranti, GEC and some others. They date back to the 60's.
I haven't tried them yet and have 2 questions:
Will they be reliable enough for gigging? Difficult question to answer I know, but what are folks experiences generally with NOS valves?
And here's another tricky one Will there really be a noticeable difference in tone?

As an aside, I also inherited a Mullard 510 amp, complete with a radio receiver, pre amp and Goodmans speakers from the mono hifi that this gentleman had built in the 1950's. It still works nicely. He also built a television for his family!

[zaphod_phil]

Envy!

Some people seem to worry about the reliability of NOS valves. If they really are NOS (ie *new* old stock) they will be unused. I have read that the manufacturers of the West, used to thoroughly burn in all their production before shipping them out, which weeded out most of the weak valves. So they should be very robust. IIRC Mullard in Blackburn used to "soak" them for a week on special racks. However in the Communist bloc QA was very hit or miss, and you can't really trust NOS from Russia, East Germany, Czechoslovakia, Yugoslavia, Poland or China, etc. Old or new valves from any of these countries need to be thoroughly burnt-in before any real use. Also bear in mind that some very old valves had lower voltage and power dissipation specs than their later versions - eg original 6V6 vs 6V6GTA.

[KrazyKabs]

NOS Mullards are about the most reliable tubes out there. If you can stand to use them they'll last as long or longer than anything else you can get.

Vendors selling new Russian or Czech tubes insist that they sound as good as NOS, I NEVER hear a vendor claim that new tubes sound better than NOS. I think a lot of musicians would like to believe the new tubes sound as good as the old ones, saving money is one of those odd corners of psychoacoustics.

In practice the difference between NOS and new tubes is like night and day. There are musicians that gig with new tubes and save thrie NOS for the studio.

[pylet2000]

I once scored a box of NOS stuff, too. Of the box of various tubes, I had a few that had lost some of their vacuum and lasted only a very short time after powering them up. The filaments burned out. It was kinda sad, but they weren't the most awesome NOS tubes anyway so it wasn't the end of the world. For free I was okay with a few burnouts.

I have heard of folks applying the heater voltage by means of a variac and slowly bringing the voltage up to 6.3v. This slow application of heater voltage is supposed to "burn off" any gas that may have leaked in around the pins over the many years of inactivity and help prevent heater burnout if full voltage is applied. I've never done it, and have conflict with the idea. IIRC, it's a bad idea to undervolt the heaters, but perhaps that's only with B+ applied. At the same time, the idea of "burning off" any atmosphere that's creeped into the tube by slowly applying heat would need some better explanation to it, too. If your interested in that process, you'll have to Google it or find somebody that has done it with positive results, but I have read there is a prudent way of bringing NOS stuff back to life.

[martinw]

All of these are British made valves, so no worries there. They are also not all "new" old stock as some have been used to some extent.
Thanks for the comments so far.
Anyone regularly gig with old valves?

[rjgtr]

I gig regularly with NOS valves (um tubes). I think NOS can be hit or miss. Some aren't great in some applications, like high gain amps. The newer JJs, Chinese and GTs seem to do better overall in high gain amps. In classic designs, like the 18 watt or even up to 70s designs, NOS tubes work great.

I think JJs and the latest Chinese tubes sound just fine, but they don't sound like "NOS" tubes. Mullards have a special sound no one has matched in new production. Ditto Phillips and RCA.

It all has to do with ears. I had one customer who got a Twin with a good set of RCA output tubes. I thought it sounded great, but he didn't like it until we put those really Cheap Sovtek 5881s (you know, the ones with the wafer base) in it. His old amp had those and he really liked them. I didn't but it's his amp!

[markh]

I had one customer who got a Twin with a good set of RCA output tubes. I thought it sounded great, but he didn't like it until we put those really Cheap Sovtek 5881s (you know, the ones with the wafer base) in it.

I trust you disposed of those punky RCAs for him?

I think we should all start charging a "disposal fee" like the auto repair shops are starting to do. I doubt any old tubes are RoHS compliant!

--mark h

[rjgtr]

Well I offered to dispose of them for him, but he wanted them back!

It didn't matter, I always return bad parts to the customer anyway.

[dartanion]

I use NOS primarily in all my gigging amps and have had very few issues. I don't worry about it...but carry spares just in case.

[zaphod_phil]

I gig with NOS tubes all the time. I rarely use anything else.

[dartanion]

I'm running RCA 12AX7As, Mullard EL84s, and a Japanese EZ81 of some-sort in the MUTANT18. Sounds flippin amazing

Gigged with it on Saturday and it was sounding really nice. I let a friend jam with a couple other folks at the party through my rig (PRS CU24 > MUTANT18) and he just raved about the tone and asked if I could build him one. I told him to get in line . I'm already way too back logged, but I'm sure I'll squeeze it in.

[95strat]

I use all old tubes in my Fenders and have never had any problems at all... I've had my main amp, a Super Reverb, for 4 or 5 years now and play it all the time and the old 6L6s still sound great... yet I've heard of other people replacing power tubes every year or 2. IMO the old tubes tend to last longer AND sound better too. I'd much rather have NOS tubes... and my dad is a ham radio operator so I have access to as many old tubes as I need

[praga]

You want reliable? I had a JJ 12ax7 short on me in the middle of a gig which announced itself with a full volume hum that froze everyone in the club javascript:emoticon('8O'). I've been using my old stock pulls since and never had one turn on me. Always carry spares!

[dotfret]

I have heard a few stories lately from people who have put their amp in for repair, and had it returned in working order but with their old valves replaced - usually they get told the old tubes were shot, the old tubes were invariably Mullards, and the replacements Russian. A friend in Austria lost the ECC83s out of his AC30 - they were Mazda, but with S&H
codes - I am now suggesting to anyone who has old valves in their amps to replace all the tubes before sending it for repair - I think it may be cheaper in the long run.

[martinw]

Pretty resounding vote of confidence then. Good, I'll put a set in.
And thanks!