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Author Topic: Reliable sources for NOS audio tubes  (Read 2864 times)

smashprod

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Reliable sources for NOS audio tubes
« on: September 03, 2015, 08:53:56 am »

My first post here-- I recently picked up an old HHB Classic 80 (a.k.a. TLA PA-1) mic pre that I'd like to use as a bass DI, and maybe for the occasional vocal. The tubes are ancient and microphonic (Siemens EF86 and GE JAN5751). While I'm at it I might as well look for great sounding replacements (don't know if I want to spring for NOS Telefunken EF86s, but maybe..). Problem is, I'm a musician, not an engineer, and don't have the equipment or expertise to test tubes (or match them). Can anyone let me know a good source for matched pairs of audio tubes, either NOS or new? Also when I switch them out are there any adjustments I need to make (i.e. the internal trim pots), or is it "plug & play"?
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smashprod

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Re: Reliable sources for NOS audio tubes
« Reply #1 on: September 03, 2015, 10:58:11 am »

Just did some more testing - it's the EF86 that rings a little bit when I tap it (with the gain all the way up). This is on both channels (how much ring is "normal" on a good 1st stage input tube??); also channel 2 is a hair brighter.
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Fletcher

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Re: Reliable sources for NOS audio tubes
« Reply #2 on: September 05, 2015, 11:42:17 am »

Its not uncommon for EF-86 [a.k.a 6267]'s to ring a bit -- some are better than others, but its still not uncommon.  Over the years I've had pretty decent experiences with both "The Tube Store" and "Tube Depot" -- you might want to give them a shout and see if they can be of any assistance.

Peace
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

oneflightup

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Re: Reliable sources for NOS audio tubes
« Reply #3 on: September 28, 2015, 11:21:53 am »

Hi David,

I'd go with Fletcher's recommendations:
Tube Store or Tube Depot.

A general point about buying tubes on the net.... be careful. There are plenty of shady dealers selling rubbish. Go with reputable dealers over "huge savings".

Best,

Nick

One Flight Up Recording Studios
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djwaudio

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Re: Reliable sources for NOS audio tubes
« Reply #4 on: October 10, 2015, 01:21:49 pm »

I'm putting a tube order together, and my go to is Jim Cross at Vacuum Tubes, Inc.

Look out if you ever get him on the phone, he's got an unbelievable knowledge on the subject and likes to educate customers on the subject.  He's forgotten more than I could possibly know about tubes.
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Specialized Mastering
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McLovin

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Re: Reliable sources for NOS audio tubes
« Reply #5 on: October 26, 2015, 02:33:18 pm »

This is an interesting post  (and my very first response/post in this forum)...

I spoke recently with someone face to face on the matter of NOS tubes, as I mentioned I had the mind to purchase some for some of my gear/amps.  Let me state this source is a very learned man, (with one of those very posh British accents), been working in electronics since 1976 with a BSc (with honours) degree in electrical engineering and is an assistant professor in computer science at our city university.  Having said that, he may be one of the smartest people I know (if by that, you know that he seems to have the correct answer for just about anything I throw at him).  He also use to work in the Mullard factory years ago (pretty sure it was Mullard, over in England, it was some tube place and I think that's what I recall), and he said by standards back then, they would throw out most of the tubes made today as they wouldn't meed their standards.   Interesting...

Still, take what I say with a grain of salt, but for whatever it's worth, his comment to me upon hearing about my NOS tube interest was that it would be extremely likely all these tubes are 'gassy', meaning they have after all these years leaked or taking in/out gasses from the atmosphere.  In essence, he's saying that after all this time, these tubes will not be as they were once long ago.  It doesn't mean they won't work, but that they are not as they were originally for time has had it's affect on them.    I mentioned this once to a tube seller, and I got an earful.  Meh...

So, my sense of things is that, I don't think tubes are as well made today as they once were, and unfortunately all the (or the secret recipe of making such) information that Mullard tubes (for example) was lost over time, as the people that knew how to make these tubes didn't keep records of how they made it and passed on.  And one wonders if NOS tubes are and worth the extra $$.... I guess let your ears decide.   



Just my 2 cents. 
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Fletcher

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Re: Reliable sources for NOS audio tubes
« Reply #6 on: October 26, 2015, 10:06:52 pm »

There are a couple of factories that do exemplary work -- and there are more than a couple of tube distributors that have taken the science of testing tubes to nearly an art form.  That said -- I don't know anything about "gassy" tubes... when the vacuum isn't complete, the tube dies -- if the vacuum is in tact, then the tube should perform as designed [3db].

If it sounds good, its good -- end of story.  If it doesn't sound good, then you need to change things.  What is "good" and what is "not good" is always going to be a personal opinion -- there are a bazillion shades of "good" and "not good" -- these will ALWAYS depend on the opinion of the player, and the production team.  As a consumer of music product, I will often have an opinion as to whether or not I feel something fits together [or not]... but unless I'm part of the production team that opinion means fuck all -- the only opinions that matter are that of the artist / production team as its their names / balls on the line -- not mine.

Peace
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

djwaudio

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Re: Reliable sources for NOS audio tubes
« Reply #7 on: October 27, 2015, 12:41:56 am »

Curious to know if anyone is satisfied with any of the new production tubes in critical audio components?  I tried a couple newer brands and was shocked at how thin and edgy sounding they were in my applications. 

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Respectfully submitted,

Dana J White
Specialized Mastering
www.specializedmastering.com

Fletcher

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Re: Reliable sources for NOS audio tubes
« Reply #8 on: October 27, 2015, 10:47:22 am »

I've had pretty good experiences with tubes that come from the "JJ Tubes" factory [formerly the "Tesla" factory]... it is worthwhile to try a few of each model after a "burn in" / "break in" period... it seems [and I could be hallucinating] that the sound of the tube stabilizes after about 10-15 hours of "break in".

Petce
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CN Fletcher

mwagener wrote on Sat, 11 September 2004 14:33
We are selling emotions, there are no emotions in a grid


"Recording engineers are an arrogant bunch
If you've spent most of your life with a few thousand dollars worth of musicians in the studio, making a decision every second and a half... and you and  they are going to have to live with it for the rest of your lives, you'll get pretty arrogant too.  It takes a certain amount of balls to do that... something around three"
Malcolm Chisholm

Jim Williams

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Re: Reliable sources for NOS audio tubes
« Reply #9 on: October 27, 2015, 11:24:16 am »

Be watchful of NOS GE 6072A tubes used for mics. When Rode designed their Classic tube mic, they selected that tube per my recomendation.

Peter Freedman then bought up all the available NOS GE tubes, about 50k of them. This was back in the later 1990's. After testing/selecting the good from the bad, the rejects were all put back on the market for you to buy.

I use Electro harmonix 6072A's now because I can't trust the NOS GE's.
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djwaudio

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Re: Reliable sources for NOS audio tubes
« Reply #10 on: October 28, 2015, 03:14:57 pm »

I've had hit and miss results from the NOS GE stock as well, Jim.  My Manley Mastering Slam came with them in the 12AT7 slot, and they sounded excellent, but when I replaced them with NOS they didn't have the same clarity/clean sound.  I don't recall the source of those, so it's a little iffy to blame the tubes overall, where I may have landed on a bad batch.

I may give those JJs a go next time around, and test them the following morning. ;-)
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Dana J White
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McLovin

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Re: Reliable sources for NOS audio tubes
« Reply #11 on: November 27, 2015, 03:07:30 pm »

Just some thoughts, I was given this info by someone who has some experience in the tube world...

The problem with old vacuum tubes is the vacuum. For a tube to operate
correctly, a very high vacuum is needed. At the time of manufacture,
this is achieved first by pumping, then by sealing off the pump tube by
melting the glass, and then by firing the "getter", which forms a thin
film visible as a black coating, usually inside the top of the tube. The
getter is capable of absorbing and holding onto any stray gas molecules
left in the tube, and is most effective at doing this while it is being
evaporated, by RF heating, inside the sealed tube, during manufacture.
All this elaboration routinely produces the very high vacuum needed.

Unfortunately, that is not the end of the story. The seals around the
tube pins are not perfect, they have a slow rate of leakage. Even the
glass envelope of the tube is not blameless: gases, particularly light
gases with small molecules, can diffuse through it. The rates of leakage
and diffusion in a well-built tube are extremely low, but they are not
zero.

Many of the NOS tubes now being sold were manufactured in the 1950s and
1960s, so they are around 45-65 years old. Over that length of time the
leakage is important. Tubes were built to be used promptly and last
about ten years, so no thought was given to how they might fare 60 years
down the line. Inexorably, gas has been making its way into these tubes,
and is easily detectable (without destroying the tube) in an appropriate
tester. The presence of this gas degrades tube performance, to a degree
depending on the tube type, the amount of gas, and the circuit in which
the tube is used.

One might think that it would be possible to re-pump the tubes, but
there are two reasons why this is impractical. First, if the tube is
opened to re-attach a pump, a lot of air gets in, and immediately
destroys the cathode coating. Secondly the material of the getter is
exhausted, so it cannot be re-fired. To replace the original source of
the getter the tube must be completely opened up, and a new source
welded in place. It is conceivable to make a machine to do all this,
under high vacuum, but it would be horrendously expensive.

So why not rely on the newly made tubes which are being produced in
increasing quantities? There are two reasons.

Firstly, only a few dozen types are in production, a far cry from the
hundreds of types once produced. If your equipment need a type which is
no longer made, an NOS tube is your only option.

Secondly, the making of a good cathode is as much art as science, and
relies not only on the right mixture of chemicals sprayed onto the
nickel tube during construction, but also on an elaborate multi-stage
"conditioning" process applied to the finished tube, which involves
running the tube for accurately-determined periods at a variety of weird
electrode voltages. Every manufacturer had their own methods and
mixtures, which were held as closely-guarded trade secrets known to very
few. These secrets are lost, with the death of the old geezers who knew
them. The best of modern cathodes is nowhere near as good as the
run-of-the-mill cathode of the 1950s. To give credit where it is due,
the modern tube manufacturers are struggling to make better cathodes,
but they are not there yet.
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Weekend Warrior

Jim Williams

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Re: Reliable sources for NOS audio tubes
« Reply #12 on: November 28, 2015, 12:41:55 pm »

It's just like NOS recording tape. Nothing lasts forever. We are lucky any valves are made anymore.
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