tube manufacturing

Both the points you mentioned. It's also possible that some material is not available today. The revitalised WE 300B production made mention in their ads that they still had some thoriated tungsten cathode material left from their previous production, and this was important. When it's gone, what then? The skills required to make great valves are quite an art. But surely, it comes down to demand, cost of production and estimated return on investment.

If you have a look at on-line visual tours through tube plants, you will see a lot of old machines. Maybe some of these are not even made anymore.

Another point to consider - there are some seriously dangerous chemicals required in making valves and the overhead in protecting the environment makes the cost much higher these days than in times gone by, when the regulations weren't as stiff.

Regards,

I honestly believe that the so called NOS and NIB tubes and their "superior audio performance" is all a clever money making tool.To pay 300$ and 400$ for a pair of 6922 made in the sixties is simply crazy.Technology gets better and I don't accept the theory that "we no longer can produce equal or better tubes" .Yes the demand for audio tubes is much lower today .That is true.But companies could still produce a high quality tube and charge for it accordingly.There is certainly a market for tubes.Please view ARC website (one of the highly respected tube audio manufacturer)and read their opinion on NOS tubes.I am into tube equipment as well.
Regards
George

Based on everything I have read there was a great deal of "black art" involved in mfg vacuum tubes. A great deal of this information has died with the people involved in the business. Remember these tubes were made long before ISO 9000 was around so not every detail was written down.

There are also issues related material and toxic mfg processes which when tied to todays very low production volumes are factors to consider. Lastly many valves were also produced in Mil Spec flavors which were real quality sensitive customers.

To my ears, in my gear, in some applications nothing current beats NOS in particular when used in line stage applications. Power Tubes i.e. KT88 and others may not be as fussy.

It comes down to your ears in the end.

Yioryos, you state,
"Technology gets better and I don't accept the theory that we no longer can produce equal or better tubes".

If most cases, that is true. However, tubes are essentially obsolete except for specialized applications (radio frequencies & graphite plate tubes used in industrial heating.) In addition, even during the heyday of tubes, matching and testing of tubes for audiophile purposes was unknown.

So how many buggy, gas lamps, or ice-box (precursors of refrigerators) manufacturers do you know of? OBSOLETE! And what about asbestos insulation? NIX! Chemicals and manufacturing procedures used years ago by tube manufactures would be banned by OSHA, due to the hazards encountered. Chemical purity needed for the cathode coatings, are no longer available or cost-prohibitive. Don't forget, tens of millions of general application and military tubes [non-R.F.] were produced annually. The transistor, and later the integrated circuit, made tubes obsolete for almost ALL of their previous applications.

Unfortunately, there are a lot of hucksters and thieves trying to make a "quick buck" of the NOS craze. NOS tubes will produce a marked sonic improvement. Also, NOS power tubes are non-existent or price prohibitive. As Seadzz implies, fortunately you will get more "bang for the buck" on line level and driver tubes.

You might want to check out Vintage Tube Services for some first rate and reasonable priced NOS tubes. In my opinion, Andy at V.T.S. is the best source and reference in the NOS business!

Fatparrot has a valid point.

Yioryos, you state,
"Technology gets better and I don't accept the theory that we no longer can produce equal or better tubes".

If most cases, that is true. However, tubes are essentially obsolete except for specialized applications (radio frequencies & graphite plate tubes used in industrial heating.) In addition, even during the heyday of tubes, matching and testing of tubes for audiophile purposes was unknown.

And EVERY NOS/NIB and even old "used but test good" tube I have ever tried has sounded better, period. That's IMO, and in my system. Now I have not tried them all, but who has? But I have tried Sovteks, Svetlana's and Reflektor. Forget Chinese, too many other options. The only reason I have Reflektor's in my system now is because my pre was designed for a specific tube, and Russian is the only choice.

And the NOS ones sound MUCH better.

Jphii, Re: And EVERY NOS/NIB and even old .....has sounded better, period". Remember todays new production tubes which aren't worth a crap become NOS tubes when everyone has forgotten how bad they were. Want some Sovtek 12AX7 WTB's? And they are military grade tubes! I've got a few dozen. :-)

Newbee,

You know you need to hang on to them. In ten years when all of the "current production" tubes really suck, they'll be worth a fortune!