EL84 valve much bigger in size than normal?

[michaelc]

Hi guys,

I bought a vintage EL84 Mazda valve from ebay last week.

It is marked in white:

Mazda
Valve
EL84
Foreign
BVA

On the base it is marked '13' and what looks like a upsidedown 'U'.

The bottle is much bigger than a normal EL84. The wire valve holder won't fit over it, for instance.

The sound is fantastic. I have it in a Vox AV4tv and I can't really get it to distort much! Huge headroom with this valve.

I can't find any info on the web about a similar valve like this anywhere. Can you help?

Cheers,

Michael.

 

[kodabmx]

I found the same thing when I bought new Tung Sol 12AX7. They are Russian and are slightly fatter than a NOS 12AX7 that the shield doesn't like to fit. Perhaps it's a reissue?

 

[michaelc]

Thanks for the info, kodabmx, but it is definitely a vintage Mazda valve from '60's, I would guess. Came with 60s style box too....

 

[michaelc]

Hopefully you'll see the difference...

 

[kevinkr]

Discussion centers around a tube used in a guitar amp, so thread moved to I & A per forum policy.

 

[Sorento]

I had a similar case with a Siemens tube having different glass.
It turned out to be a re-labeled Tungsram, excellent quality though.
Tungsrams are the only tubes I know of which have a small square shiny metal tag with a 1 or 2 digit number welded onto a support or plate structure.

 

[michaelc]

My partner who has better eyes than me says the markings at the bottom of the tubes where the pins are is:

a larger 'u' shape:

Then underneath that U is smaller symbols:

a backwards '7' shape and a '1'

 

[boobtube]

Does that upside down U have a dot in the middle? If so, then it was made by EI in Yugoslavia. Or that backwards 7 could indicate Mullard Supply. See the bottom of this: Mullard, Philips, and Valvo Tube Codes
Many tubes fall under the umbrella of Mullard/Phillips. But that BVA marking does indicate a vintage tube whoever made it.
This guy has some good info as well: The Tubeking's Guide to NOS and Vintage Audio Tubes | eBay It's a whole other deal identifying tubes with all the rebranding.

 

[michaelc]

Boobtube, thanks for that great information. I had been looking for those webpages ... thank you.

The U doesn't have a dot in the middle. I think from the info you linked that (perhaps) the 'U' indicates Thorn AEI Radio valve co. and the backwards '7' indicates Mullard Supply with the '1' indicating year 1 - '1961'?

 

[boobtube]

Yes, that sounds right considering there's no dot in the middle of the U which would have made it EI, Yugoslavia. I guess the EI is closer to a horseshoe shape with the dot.
Here's another couple of sites to go along with the others for Euro tubes: Deciphering European tube date codes - Tube Maze
Tube Classics - Audio Tubes