Anyone know what brand this 12AX7A might be?

[catnine]

 It just says usa on the top and when I use it in either amp I have it really puts out .

[firemedic]

I have a few tubes like that too, no-name USA. And they sound good.

[eleventeen]

The "12AX7A" octagon sure looks like an RCA to me. To really confirm that I suppose you'd have to measure/compare the internal height(s) of the plate sections and visually compare the bendiness of the wires underneath the sections.

[andrew_k]

Another vote for RCA

For comparison:

[HotBluePlates]

That's most likely an RCA.

But you should look beyond the label, because RCA wasn't the only company to use an octagon.

Construction/labeling features which may help in identification: label, label font, plate construction, plate size, plate material, getter shape, getter location, number/style of mica spacers, etc.

[PRR]

While RCA had HUGE production facilities and made most of their own tubes, all the tube makers horse-traded. If RCA got a huge rush order for B-47 radio tubes, on top of their standing orders from regular customers, RCA would get a truck of bottles from GE or Sylvania and run them through the RCA stamper into RCA boxes.

BTW, this is the second reason the markings rub off easy. So a "GE" could be rebranded "RCA" without strong solvents or scrubbing. (The main reason was employee pilferage: the type-number was not put on until the last moment, so most of the workers did not know what tubes they handled.)

[tcoil]

pretty sure it's an RCA

[eleventeen]

I remember visiting the RCA tube factory in Harrison, New Jersey on a junior-high school field trip probably in 1967 or so. It was quite fascinating to see the tubes being made, although It was also apparent that the novelty of watching the big carousels they were made on advance, stop, advance, stop, advance, stop all day long would wear off very quickly and prolly turn a person into a complete zombie. The carousels they were made on were maybe 6 feet across. The raw glass was fed in, in the form of what looked like a champagne flute, with a long hollow stem and straight sides. The bases with all the glass-to-metal seals were about the size of a dime or penny. The insides were made from reels of wire or thin plate. All these itty bitty pieces came together with cam-and-lobe driven arms and grippers and spot welders and things that formed the plates and crimped them together to form a box, applied the micas, then heated up the parts, sucked out the air, and flashed the getter with an RF oscillator. Quite fascinating. It must have taken hundreds of hours or really painstaking work and tweaking for the engineers to set up those machines and all their little grippers and benders properly.

It was pretty interesting though. The brick factory buildings were really old, possibly from the 1890's, and they were enormous. And pretty dirty.