Why Can't Modern Tube Manufacturers Make a Proper Tube?

Hard disagree. I have a huge collection of vintage tubes and modern Russian production are excellent, imo. Even some of the Chinese tubes are quite good. Some of the worst sounding tubes in my collection are actually vintage RCA, late Sylvania, or those Philips ECG. 

The old tubes were built to a higher standard of quality and consistency, I'll give you that. Even the insides of most old tubes tend to be meticulous and gorgeous. They can also take more abuse and keep ticking. But to replicate that today would be impossible due to exorbitant costs and environmental regulations. For what you get in great sound and reasonable reliability (after lots of screening) the Russian tubes are really a bargain. Our amazing sounding modern high-end tube amps and preamps exist largely thanks to affordable Russian tubes supporting that industry.

My uncle who I am estranged from was a stereo and TV repairman and  has a basement full of tubes.  Hundreds of not thousands. 
 

A while back I said we should go through those , test them and make some money. 
 

He said that’s stupid, no one’s buying those.  He has some holy grail stuff and is too lazy to sort through it.  
 

there’s guys like him here and there.  That stuff is likely to get thrown away.   A friend does clean outs.  He used to drop off tubes here and there.  Most were junk but stuff like new 6v6 rca definitely are not.  Those days are long gone 

It’s true about some of the new tubes   Some are really good but you may have to go through a few mediocre ones to get a great one.  

I won’t toss the baby out with the bath water. There are actually some terrific current production vacuum tubes as well as some not so terrific. I would not generalize. I have used current production EML 300b tubes in my SET mono blocks for many years. First pair lasted nearly 12 years with very heavy hours of use during that time. Simply splendid sound quality and zero reliability issues.

The 101D DHT tubes In my preamplifier are current production Psvane.W.E. Replica. Again, splendid sound quality and very reliable under very frequent/heavy usage. So it depends on which current production tubes one is referencing.

The amplifier’s rectifier and driver tubes are 1950s vintage. Same era (1950s) of tubes in my DAC. I’ve been very happy with this mixture of current and vintage tubes n my audio system. The sound is intoxicatingly natural.

Charles

many current production tubes are fine. some new production sound better than some old production. 

now youve learned something

@mulveling and the availability of JJ small signal tubes,  EL34...