Latest old stock 12ax7 find!

[cap47]

From left: Mullard EICO 12ax7 915/1022 1959 Blackburn B9A with box, EI marked Phillips has the upsidedown U with dot in middle which means from EI plant. 2A1/U7E smooth plate late 60s. With Phillips box. Middle is a Tungsram which I broke while taking pics, wind blew the tubes and styro over. Date was Oct 84. 4th tube is Sylvania sq. getter long shiny black plate. Marked 3A and Westinghouse labeled. 5th tube is Matsushita with two top seams, Japan and labeled possibly Realistic over Lifetime, can't verify Realistic as the "is and c" are rubbed off.
What a shame I broke the top off the Tungsram, oh well $10 a piece, out only $10. I tried all in V1 of my SS fender and they all sounded good with no buzz or microphonics. The EI had the most gain.

[cap47]

Back side reverse order.

[Jeff West]

I've dropped one and broken the tip off like that before, leaving a pinhole. It was interesting to see how long it took for the getter to oxidize, pretty quick but not instant.

[cap47]

Originally Posted by Jeff West

I've dropped one and broken the tip off like that before, leaving a pinhole. It was interesting to see how long it took for the getter to oxidize, pretty quick but not instant.

I could see it change within seconds and continued to get whiter in the first minute or so as the getter coating dissipated. It is the 2nd one I broke like that in the last 2 years.

[BLUECASTER]

Hello!!!

Cap47, that Sylvania (labeled Westinghouse) black plate tube could be a RCA?
Why do you think it is a Sylvania?
It looks very similar to my RCA JRC 12AX7 1950 with long black reflecting plates.

The getter wire, the micas, the flash of the getter, the plates, all look the same.

Take a look:





_____________________________________

How do you like this tube? Did you try it?
Could post a couple more pictures of it?

Thanks!!!

[Timbre Wolf]

Originally Posted by BLUECASTER

Hello!!!

Cap47, that Sylvania (labeled Westinghouse) black plate tube could be a RCA?
Why do you think it is a Sylvania?
It looks very similar to my RCA JRC 12AX7 1950 with long black reflecting plates.

The getter wire, the micas, the flash of the getter, the plates, all look the same.

Plate details:
The plate tabs (part of the plate that emerges through the mica disk) are one specific point to note: Sylvanias are rounded, and those are flat. Other details to note are that the Sylvania plate edge is perfectly straight, whereas those of the tube in question are slightly curved. And finally there is the size/proportion of the staple hole in the plate.

For comparison, here is a photo of early-'50s Sylvania 12AX7, thanks to Tubemonger:


- Thom

[cap47]

Bluecaster, I concluded it was the same construction as a known Sylvania JHS I have. I researched with Tubemonger photo with exact markings and they call it a Sylvania. It is also common for different suppliers to make tubes with other brands marked on them. It is really hard to know who made them at this point! You could be right!

[cap47]

The plate edges on my tube are necked down where they enter the mica. My JHS Sylvania is straight so you are probably right about it being RCA! Other than that they are dead ringers!

[BLUECASTER]

Dead ringers?
Is this a good thing ?

[BLUECASTER]

"Plate tabs"!!!

Thanks a lot Thom , I didn't know how to call these..

[Timbre Wolf]

Originally Posted by BLUECASTER

"Plate tabs"!!!

Thanks a lot Thom , I didn't know how to call these..

That's a term I came up with - I don't know what the convention would have been back when engineers discussed these things, as I've not seen any diagram that refers to them separately from the plates.

Originally Posted by BLUECASTER

Dead ringers?
Is this a good thing ?

That's the kind of question I ask when people discuss killer tone.

"Dead ringer" means visually indistinguishable.

- T

[cap47]

With my eyes anything is a dead ringer!

[Tele Wacker]

I always like it when someone finds a stash of tubes, especially me!