Baldwin 12AX7 Made in USA AMY 31 13 29

[mike_mccue]

I have several tubes marked Baldwin 12AX7 Made in U.S.A. AMY 31 13 29 in "Sylvania" green paint.

I've used E.I.A. and date codes to id most of my tubes but these codes stump me.

Does anyone have any thoughts about who made them, where and when?

Thank You,
mike

[Enzo]

How about some photos? Maybe we will recognize them. it is certain Baldwin didn;t make them themselves.

[mike_mccue]

here you go:



I also have a few similar 12AU7 tubes:



The paint is very soluble in water. I just worked with some old tubes marked Sylvania and the paint was much more secure.

Thanks for any idea or tips on what to look for.

[Pedro Vecino]

Paint... and internal structure. Sylvania.

[mike_mccue]

I am just learning to be conversant with collections of terms like "long black ribbed plate with halo getter".

What structural things are you seeing that lead you to conclude Sylvania? I'm just trying to learn.

Does the AMY indicate a particular fab plant?

Thanks,
mike

[Pedro Vecino]

The particular shape of the plates and the extension to hold them through the micas. Size and location of small rectangular holes is also indicative.
http://www.tubemongerlib.com/gallery...1959+-+USA.jpg

Sounds strong and solid but do not have a smooth contour in overdrive. Tend to sound open and aggressive. They usually have more gain in relation to others. I use them for Champs