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Vintage threads from the first ten years

Why Do NOS preamp tubes sound so good?

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10/4/2005 7:02 PM

Why Do NOS preamp tubes sound so good?

i just yanked a trio of 12ax7's out of a vintage Hiwatt DR103 that i've had fer quite a while(but wasn't gettin much playing time)after inspecting the plate structure,the resident preamp tubes were clearly yugoslav EI's...long plates with the pencil markings on the plates...the amp has had a harsh top end as long as i've had it with these preamp tubes,I always though the power tubes were at fault,along with a clearly replaced power tranny...however with 2 Mullards(a shield logo and a 1970's 'ax7)along with a 70's vintage RCA,the amp has simply come alive..it has a JAN 12at7 for a PI.and a quad of old svetlana EL34's...it kills me(and my wallet) to think these old amps can sound so good with old glass...why do these preamps sound so good?

10/5/2005 8:22 AM

Big question. The tubes are parts where many mechanical differences and material differences create the tone signature. The people who designed and built these tubes i the 60's and 70's are all retired or dead. There was a 20- or 30-year gap between the last designs from the old guard and the new designs coming out from eastern europe/russia/etc. So, all the tiny little things that went into them, processes for plating, gapping the components, windings and wiring, etc., have been lost over the years, and must all be re-discovered. They were developed by people who have simply gone away, and the "tribal knowledge" which exists in any large-scale manufacturing operation has disappeared.

If you've ever worked in manufacturing, you'll know what happens when the older people with experience are laid off or retired. The product quality and performance will usually take a dip for as long as it takes for all the tricks to be re-learned.

It's all down to individual people who know their trades.

rooster.

10/5/2005 10:05 PM
Chuck	I agree. But there is another element at work. Most of the tubes manufactured today are spec. for military use. Rugged and within certain parameters for microphonics and sound quality. Where "back in the day" tubes were all that was available if you wanted to make music. So there were different requrements and probably greater stringencies then than there are now.

10/6/2005 4:26 AM
Pierre Debs	old electrons sound better.

10/6/2005 4:42 AM

Back when tubes were the only thing available for electronic gear, the need for something reliable and long lasting was a bit more than it is now, since there was more demand for it when you needed it for your tv, radio, car stereo, theater equipment, production machines, etc. , in addition to your amp. It helped of course that in order to make them be the best they could be, they also sounded good and lasted longer than today's stuff as a general rule. I doubt if you'll ever see that level of quality again in vacuum tubes, just because the demand isn't as great nowadays.

Greg

10/6/2005 6:19 AM

lots of good reasons already given..
along with that "tribal knowledge" in the factory there were the materials. When tube mfr fell off, there was a whole 'ecosystem' that came undone. The specialized alloys used for plates, the witches brew used on the cathodes, even the mica spacers etc all went away. Folks like RCA, GE/Phillips, MO Valve, GEC, etc had decades of experience trying to outdo each other and make the best parts. Their suppliers had decades of experience making the specialized bits that go into a tube. And on and on. There was an effort some years ago now to re-issue the 300B here in the states to pass along some of this knowledge because IIRC it is still considered strategic to the nation. But by and large it is a lost art. The new factories overseas are only going to get better and better as they go, and hopefully a steady eye towards quality (financed by a strong market to sell tubes) will speed that along. They are already so much better than they were 10 years ago imho

10/6/2005 11:45 AM

plus remember the way engineering college was only for the gifted student back when the first tube companies were established?

Betwen then & now, mostly in the intrest of fairness to those that are not as naturally outstanding, standards for the engineers themselves have declined to ridiculous levels.

Some kids graduating in modern times would have never been admitted to begin with 50years ago.

Plus how many enginers working for any electronic firm would have the ability to develop or even grasp advanced mathematical concepts without powerful enough tools (like computers) to verify their theories before costly experimentation ensues.
So in the old days lots of times things went straight from rudimentary slide rule math directly to experimentation, and if the experiments were promising an improved product could be developed without fully understanding why or having real advance proof that it would have been that significant.

IMHO some of the most critical confidential manufacturing procedures, which were strictly followed by all plant personnel in an almost superstitious way, were those that were not fully undrstood to begin with, but one thing was known, they just worked better than what they had been doing the previous decade and they had statistical data to back it up.

Experimentation costs so much more now, nobody will ever be able to afford that kind of thing again.

Mike

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