British 12AX7’s

[nailer]

Have six Brit 12AX7’s that came as extras with an ARC SP-8 acquired years ago that I’m looking to find some more information about. Four are Amperex branded and say: 12AX7A, ECC83, MADE IN GT BRITAIN, and 75 41 in brownish red; their tops have two raised ridges; and printed upside down in light green at the bottom of the tubes is 163 over B5E3. I remember reading somewhere that Mullard made tubes for Amperex. The other two are Brimar CV4004’s that say MADE IN ENGLAND with BVA underneath and are also marked 83977 (83 is a best guess). Any opinions?

 

[JonL]

My opinion is that I'm really envious of you. Those are great sounding tubes for guitar amps. I don't have an opinion for a hi fi preamp, never tried them there.

 

[nailer]

Need to clarify - looking for more info on what I actually have here, for example who made the Amperex (figure they were made in 75), vintage of Brimar's, etc?

Haven't plugged them in for a listen. Will someday, probably later than sooner.

 

[RossW]

Etched codes, made in GB, and top seams are all tell-tale signs of Mullard tubes. As far as vintage, no idea, but someone with knowledge of Mullard date codes should be able to tell you.

 

[pabs911]

The ones badged as Amperex are actually not Amperex at all, but are short plate Mullards made at the Blackburn plant. They are very good tubes, but not as good as the 1950's long plates.

 

[Bluelobster]

You can compare you tubes with the pictures here to see what you have.
http://www.tubemongerlib.com/gallery2/main.php
The Phillips date codes and their explanation can easily be found with a web search.

 

[golana]

Those Brimar 4004, are the most even and kick ass AX7s going.

 

[analog addict]

B- Blackburn England plant
5 -Year, most likely 1965
E - Month - May
3 - Usually 3rd week. Could also mean 3rd lot

I63 is the code for 12AX7

Should be nice toobs....

 

[FalconEddy]

Ok, I guess I'll run with the Brimar info.

The CV4004's are basically a Mil spec type quality tube. Think Mullard, but better. Longer life, more durable, etc. They're generally Excellent!

The code you found is actually the end part of a Brimar numbering sequence.

Brimar's is:

Number Letter Number/3977

You have 8/3977, so if you can get the first two numbers/letters in front of them, we can get the mfg date code. Oblique lighting can help to get those digits sometimes, or an 8x magnifying loop. I'm speculating mid 60's based on the style of print.

The Falcon has spoken. Do with it what you will.

 

[nailer]

Thanks guys, this is one of the many reasons why I luv AK. Will now be listening to them sooner than later.

Brimar - Used a 4X loop and the remains of two numbers/letters appear before the 8, but not enough to even make a guess.

 

[Sam Cogley]

Mullard and Amperex were both Philips brands.