Consider the tubes which were specially selected for HP test equipment back in the 60's. They typically have the HP logo and a dab of paint on the crown.
Back then, HP was THE technology company. They made the instruments that put men on the moon. At one point, they bought tubes from Amperex, Telefunken, built and selected to HP specs.
Then they selected for themselves, so the story goes. According to stories told at the time, HP used to hire engineering students for the summer to test tubes. For every 100 tested, they threw 97 in the dumpster.
That is why a tube from HP cost 10x what it cost from the electronics store - and it was a bargain. Few seem to remember this today - and as a result, HP selected tubes bearing the HP logo are available for no premium. Which is ridiculous. But it may also be that the HP logo indicates authenticity, because the crooks don't know enough to lie about that.
By FAR, the best tubes I have ever used are 1962 TF 6922 with HP seals. Quiet, clean, sweet, detailed, etc. Simply the best.
Back then, HP was THE technology company. They made the instruments that put men on the moon. At one point, they bought tubes from Amperex, Telefunken, built and selected to HP specs.
Then they selected for themselves, so the story goes. According to stories told at the time, HP used to hire engineering students for the summer to test tubes. For every 100 tested, they threw 97 in the dumpster.
That is why a tube from HP cost 10x what it cost from the electronics store - and it was a bargain. Few seem to remember this today - and as a result, HP selected tubes bearing the HP logo are available for no premium. Which is ridiculous. But it may also be that the HP logo indicates authenticity, because the crooks don't know enough to lie about that.
By FAR, the best tubes I have ever used are 1962 TF 6922 with HP seals. Quiet, clean, sweet, detailed, etc. Simply the best.