Vacuum Tube EIN Codes - Interesting Discoveries!

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Too Many Notes
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Apr 26, 2012
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In another thread I got into a little research about the tubes I was recently sent. What was interesting is what the tubes' EIN codes told me. Every one of the tubes my friend Tom send me checked out, and there were some cool discoveries.

Back in the day, tube manufacturers often had several plants, and also labeled tubes for other manufacturers, as well as customers. Thus, a tube labeled, say, RCA could have been made by Sylvania; a tube labeled for the hi-fi manufacturer Fisher could be a Mullard, and the ones labeled Mullard could be Philips, Amperex, or some other manufacturer.

The EIN codes on older tubes tell you, regardless of branding, who actually made the tube - I'm sure there are forgeries, but for the most part, this and other clues tell you the origin of a tube.

Back when I was playing Two-Rock (pre-2014 when the HXDA rocked my world), Bill Krinard sent me a few different older tubes to try to see what I liked. These were not brand new NOS. Two tubes were clearly labeled Telefunken and GE. The third tube he thought might have been Chinese; most of the lettering was gone, but it sounded good. Cool. I put them in my amp, and the amp sounded great.

When I sold my last T-R, I told the buyer there was a GE tube in V1, the Telefunken in V2, and an unknown tube in the PI socket. He wasn't interested in that one, so I took it out and installed a new JJ for him. Later I used the unknown tube in my Lone Star's PI socket when I took out the Chinese Mesa tubes.

Yesterday, while messing around with a little tube-rolling with the Lone Star, I decided to try a different tube in the PI socket, and figuring the unknown tube was just an old tube from god-knows-where, I figured I'd put it into the "spares" box, where stuff like the Mesa or other tubes that come with amps go to be forever forgotten in my storage room.

But since I recently learned more about the EIN Codes and what they mean, I was curious and got out a magnifying glass. I figured if I could find and decipher the EIN Code, as there was enough of the red ink visible to see a few things, I might learn what the heck it is.

The EIN numbers were 274. The red lettering is worn, but some is readable. There is the EIN code, and the word 'Electron' barely visible. Just before it is an almost invisible 'A'. There's an etched 'stop sign' with the tube type, 12AX7. Hmmm. All signs point to possibly an RCA.

I checked it against one of the more useful tube charts on the web: https://www.vivatubes.com/identifying-vintage-nos-vacuum-tubes-by-brand-country-and-eia-code/

Sure enough, '274' means it's an RCA-made, RCA-labeled, US tube that works well without any hum or noise.

I'm glad I checked, or chances are this tube would never have seen the light of day again! So now I have two spare RCA preamp tubes, this 12AX7, and the NOS 7025, in my stash, waiting to be used.

This is great timing, because I recently ruined an unused, NOS RCA I'd been saving for a year. I pushed it into the socket with the tube turned the wrong way - as you'd expect, one of the pins bent. I then broke it off when I clumsily tried to straighten it, so I had to toss a $200, unused, NOS RCA into the frickin' trash. Typical me. :rolleyes:

Now I don't feel so bad - I was sitting on buried treasure!
 
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In another thread I got into a little research about the tubes I was recently sent. What was interesting is what the tubes' EIN codes told me. Every one of the tubes my friend Tom send me checked out, and there were some cool discoveries.

Back in the day, tube manufacturers often had several plants, and also labeled tubes for other manufacturers, as well as customers. Thus, a tube labeled, say, RCA could have been made by Sylvania; a tube labeled for the hi-fi manufacturer Fisher could be a Mullard, and the ones labeled Mullard could be Philips, Amperex, or some other manufacturer.

The EIN codes on older tubes tell you, regardless of branding, who actually made the tube - I'm sure there are forgeries, but for the most part, this and other clues tell you the origin of a tube.

Back when I was playing Two-Rock (pre-2014 when the HXDA rocked my world), Bill Krinard sent me a few different older tubes to try to see what I liked. These were not brand new NOS. Two tubes were clearly labeled Telefunken and GE. The third tube he thought might have been Chinese; most of the lettering was gone, but it sounded good. Cool. I put them in my amp, and the amp sounded great.

When I sold my last T-R, I told the buyer there was a GE tube in V1, the Telefunken in V2, and an unknown tube in the PI socket. He wasn't interested in that one, so I took it out and installed a new JJ for him. Later I used the unknown tube in my Lone Star's PI socket when I took out the Chinese Mesa tubes.

Yesterday, while messing around with a little tube-rolling with the Lone Star, I decided to try a different tube in the PI socket, and figuring the unknown tube was just an old tube from god-knows-where, I figured I'd put it into the "spares" box, where stuff like the Mesa or other tubes that come with amps go to be forever forgotten in my storage room.

But since I recently learned more about the EIN Codes and what they mean, I was curious and got out a magnifying glass. I figured if I could find and decipher the EIN Code, as there was enough of the red ink visible to see a few things, I might learn what the heck it is.

The EIN numbers were 274. The red lettering is worn, but some is readable. There is the EIN code, and the word 'Electron' barely visible. Just before it is an almost invisible 'A'. There's an etched 'stop sign' with the tube type, 12AX7. Hmmm. All signs point to possibly an RCA.

I checked it against one of the more useful tube charts on the web: https://www.vivatubes.com/identifying-vintage-nos-vacuum-tubes-by-brand-country-and-eia-code/

Sure enough, '274' means it's an RCA-made, RCA-labeled, US tube that works well without any hum or noise.

I'm glad I checked, or chances are this tube would never have seen the light of day again! So now I have two spare RCA preamp tubes, this 12AX7, and the NOS 7025, in my stash, waiting to be used.

This is great timing, because I recently ruined an unused, NOS RCA I'd been saving for a year. I pushed it into the socket with the tube turned the wrong way - as you'd expect, one of the pins bent. I then broke it off when I clumsily tried to straighten it, so I had to toss a $200, unused, NOS RCA into the frickin' trash. Typical me. :rolleyes:

Now I don't feel so bad - I was sitting on buried treasure!
Well done!
 
In another thread I got into a little research about the tubes I was recently sent. What was interesting is what the tubes' EIN codes told me. Every one of the tubes my friend Tom send me checked out, and there were some cool discoveries.

Back in the day, tube manufacturers often had several plants, and also labeled tubes for other manufacturers, as well as customers. Thus, a tube labeled, say, RCA could have been made by Sylvania; a tube labeled for the hi-fi manufacturer Fisher could be a Mullard, and the ones labeled Mullard could be Philips, Amperex, or some other manufacturer.

The EIN codes on older tubes tell you, regardless of branding, who actually made the tube - I'm sure there are forgeries, but for the most part, this and other clues tell you the origin of a tube.

Back when I was playing Two-Rock (pre-2014 when the HXDA rocked my world), Bill Krinard sent me a few different older tubes to try to see what I liked. These were not brand new NOS. Two tubes were clearly labeled Telefunken and GE. The third tube he thought might have been Chinese; most of the lettering was gone, but it sounded good. Cool. I put them in my amp, and the amp sounded great.

When I sold my last T-R, I told the buyer there was a GE tube in V1, the Telefunken in V2, and an unknown tube in the PI socket. He wasn't interested in that one, so I took it out and installed a new JJ for him. Later I used the unknown tube in my Lone Star's PI socket when I took out the Chinese Mesa tubes.

Yesterday, while messing around with a little tube-rolling with the Lone Star, I decided to try a different tube in the PI socket, and figuring the unknown tube was just an old tube from god-knows-where, I figured I'd put it into the "spares" box, where stuff like the Mesa or other tubes that come with amps go to be forever forgotten in my storage room.

But since I recently learned more about the EIN Codes and what they mean, I was curious and got out a magnifying glass. I figured if I could find and decipher the EIN Code, as there was enough of the red ink visible to see a few things, I might learn what the heck it is.

The EIN numbers were 274. The red lettering is worn, but some is readable. There is the EIN code, and the word 'Electron' barely visible. Just before it is an almost invisible 'A'. There's an etched 'stop sign' with the tube type, 12AX7. Hmmm. All signs point to possibly an RCA.

I checked it against one of the more useful tube charts on the web: https://www.vivatubes.com/identifying-vintage-nos-vacuum-tubes-by-brand-country-and-eia-code/

Sure enough, '274' means it's an RCA-made, RCA-labeled, US tube that works well without any hum or noise.

I'm glad I checked, or chances are this tube would never have seen the light of day again! So now I have two spare RCA preamp tubes, this 12AX7, and the NOS 7025, in my stash, waiting to be used.

This is great timing, because I recently ruined an unused, NOS RCA I'd been saving for a year. I pushed it into the socket with the tube turned the wrong way - as you'd expect, one of the pins bent. I then broke it off when I clumsily tried to straighten it, so I had to toss a $200, unused, NOS RCA into the frickin' trash. Typical me. :rolleyes:

Now I don't feel so bad - I was sitting on buried treasure!

You shall be known as “Captain Jack”.

 
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