[Ericus Rex]

In many years of listening to many different types of tubes, the 6DJ8 tends to be more noisy or microphonic, or become noisy or microphonic faster than almost all other types I've experienced.

I've read somewhere that it's because of the extra-thin wire used for the grid...now, back on topic.

[BFitz]

I see a ton of them for sale but never hear anything about them.
I'm mostly interested in preamp tubes: 12AX7, 12AT7, 6SN7, 6FQ7, 6AH4, that kind of stuff.
Does anyone have any direct experience?

Yep, direct experience. GE made their own tubes. Actually, if you want to go back far enough, GE started RCA, to make sure the radio companies in war time (WWI) were American owned. The origins of RCA were Marconi, a European owned company. 

GE made big radio transmitting, military, and industrial tubes in NY, and after they bought KEN-RAD (Kentucky Radio), made small tubes in their Kentucky plant.
They made large investments in this plant over the years, it was big and production was large. 
They were one of the last tube plants to shut down, along with Sylvania in Emporium, Pa. 

GE factory made tubes are easy to spot, with the tube ID etched/blasted into the glass. It will never rub off.
 
RCA made most of their own tubes, as did Sylvania, but the GE / Sylvania / RCA relationship seemed to be pretty cozy. These 3 guys were the big 3 in the 50's. It is not uncommon to see one name on the tube that was obviously made by the other company. Tungsol and Raytheon were also still around, but declining at that point.

It really depends on the time frame, as there were originally many companies making tubes, then consolidation, and very few left at the end. But you had Raytheon in MA, Tungsol and Bendix (who was military only) along with RCA in NJ, etc. WE was also NJ based, they really focused on making tubes for their own gear, not for consumer stuff. 

I don't think Westinghouse ever made small signal tubes. I think they contracted out their stuff, but not sure who did it. They were certainly not a major player.

   

[Ericus Rex]

Nice info, BFitz!  Thank you!

GEs are fairly cheap because they're abundant; they made millions and millions of tubes for consumers and millions and millions for the military.  While they are relatively cheap, my experience with them has been positive.  I currently have a GE 12ax7 in my Quicksilver GLA and I have tried GE 6SN7s in my Rogue 99.  They are much better than any current production I've tried and are about the same price...or only slightly more expensive.

[galyons]

GE tubes are well made and abundant. Because they are abundant, the price is generally lower.  Much of the tube "brand/structure" hype we hear is really the halo effect from guitar amp chatter.   GE tubes sound good in appropriate circuits.  The good news is that the demand for tubes for musical instrument amps has kept the technology viable and costs reasonable.  Were it not for the musicians demanding tubes, we tubophiles would be in desperate straits.

IMO, the reason that DHT power tubes are so expensive is that there is little, or no, demand from the bigger market, musical instrument amps.  So, the cost of development/manufacture newly manufactured tubes is spread over much smaller production numbers.

Go out and listen to live music, support local musicians, keep your tubes available!!!! 

Cheers,
Geary