Identifying Mullard 12ax7 (without code)?

  • Thread starter Thread starter BesaMoogie
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BesaMoogie
BesaMoogie
Well-known member
Hi,
I realize that there are some guys here that have a much better eye the me when identifying old tubes.
So my question is, is there a way to identify a Mullard 12ax7 tubes if the Blackburn code (or any code) is not visible anymore?
What do you look at? Shape of the glass? Shape of the mica or plates???
Thanks!
 
Here you go guys
 

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It‘s from an Ebay auction. Some Mullards were relabeled as Valvo tubes back then afaik.
I am always looking for Mullards as my Marshalls love them. But prices are insane. Sometimes I‘m able to hunt them down by the Blackburn codes. But I would like to know if there are other signs to look at.
 
There should be evidence of SOME etching if it's a legit Blackburn Mullard. It's not something that wears off, typically. Mullard sold tooling over the years, so you can have Japanese Mullards, and some from India. They won't have any etching but have the rest indicating that it's a Mullard. Good tubes but not as good as BB Mullards.
But, as previously stated the flash upon startup is a tell if it's legit.
 
Yep, I agree…
The Blackburn etching is the last thing to ever wear off on these tubes.
Many times the logos are gone and the type, (example, I 63, I 61, etc).,
but the B code in my experience is pretty darn tough and 99% of the time is always there on a Blackburn tube.
 
Testing data is what you want. Got any of that ?
Just because it may be a Blackburn Mullard doesn't gaurantee its any good.
Mullard UK was painstakingly detailed about Blackburn codes.
Im not to sure you have the real thing.
Eastern block Germany would be my guess with the German written on the box. IE Knockoff.
 
SQUAREHEAD said:
Yep, I agree…
The Blackburn etching is the last thing to ever wear off on these tubes.
Many times the logos are gone and the type, (example, I 63, I 61, etc).,
but the B code in my experience is pretty darn tough and 99% of the time is always there on a Blackburn tube.
Click to expand...
Thanks, so in the end it’s still the etching. I thought there are maybe other construction signs to look after.
 
shar-vell Dan said:
Testing data is what you want. Got any of that ?
Just because it may be a Blackburn Mullard doesn't gaurantee its any good.
Mullard UK was painstakingly detailed about Blackburn codes.
Im not to sure you have the real thing.
Eastern block Germany would be my guess with the German written on the box. IE Knockoff.
Click to expand...
Testing data is not my primary concern. Luckily I invested in a tube tester so I can do the check by myself. Checked tubes usually cost twice as much and I try to avoid them. Of course, final checking always goes by plugging it in the amp, but at least I get an idea about the lifespan of the tube
 
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