[Steelsix]

I bought a LD MK IV se from an ebay seller in China. Feedback looked good and he was selling many models from Little Dot so I figured he was authorized. Everything looked okay, however I did notice the driver tube tops were not all silver like the power tubes.
 
I pulled the power tubes and can tell they're Electro-Harmonix 6H30Pi, but I'm not sure about the driver tubes. They're supposed to be Mullard M8100:
 
http://i133.photobucket.com/albums/q62/steelsix/IMG_1815_zpsdbfc7121.jpg
 
http://i133.photobucket.com/albums/q62/steelsix/IMG_1813_zps71125083.jpg
 
http://i133.photobucket.com/albums/q62/steelsix/IMG_1814_zps82184ad8.jpg
 
The black marks appear as a narrow band on the top of both driver tubes. Should they say Mullard?

 

[kramer5150]

*EDIT**  Much of my post below is incorrect.  please see corrections below from  Oskari.
 
Hmm no replies?  Tube ID is a die-ing art.  It was not uncommon for production manufacture to OEM supply to others, who in turn re-branded and sold as their own.  So it was a web of cross-path supply chains.  I have AEG branded tubes that are Telefunken and some more that are Amperex-holland.  There was also military supply / surplus and others who simply did not brand anything at all on the tube.  So in other words you really can't trust whats screened on the tube.... or whats not.  Many times the screen printing rubs off over time too, leaving behind just a generic looking tube.
 
Looking at your pics... they are not Mullard M8100, they are CV4010.  Compatible tubes YES... but not exactly the same thing.  The CV was sold to commercial consumer market while the M8100 was a military supplied part.  I do not know for sure what the EXACT / construction and spec differences are between the two.  Hopefully others can chime in for those details.

 

[Steelsix]

I see now in the MFR description they state 8100/CV4010 are supplied; thanks for the clarification on the two. Would be nice to know tube maker, but more curious if those black marks indicate prior use. I bought some NOS GE tubes from 1985 that are all silver on top. I read that white on top means they're done, not sure about black.

 

[Oskari]

Don't worry about the getter flash. It can be, and often is, black, especially on Mullards, which you do have.

 

[Oskari]

Quote:

It was not uncommon for production manufacture to OEM supply to others, who in turn re-branded and sold as their own. So it was a web of cross-path supply chains.

 
That's true.
 

I have AEG branded tubes that are Telefunken

 
Telefunken was a subsidiary of AEG; so, this was in-house.
 

and some more that are Amperex-holland.

 
The correct name for that is Philips. For the Dutch production, Amperex was just a brand applied to the US market.
 

There was also military supply / surplus and others who simply did not brand anything at all on the tube.

 
True. The UK military was not too interested in brand names on their valves.
 

Looking at your pics... they are not Mullard M8100, they are CV4010. Compatible tubes YES... but not exactly the same thing. CV was sold to commercial consumer market while the M8100 was a military supplied part.

 
You've got those two mixed up. CVs are the British Service codes.
 
"The CV4010 is the UK Government code for the commercial M8100 which in turn is Mullard's special quality version of the EF95." (http://www.r-type.org/exhib/aaa0901.htm)
 

I do not know for sure what the EXACT / construction and spec differences are between the two.

 
None. Same thing. Really. Not all M8100/CV4010s were made in the same factory over the years, though. Steelsix's were made at Mitcham. The one shown at the address above was made at Whyteleafe.

 

[kramer5150]

Aah OK thanks for the clarification(s).... See OP it can get VERY confusing.

 

[Steelsix]

Thanks Oskari. Yea Kramer there's a lot to learn on this stuff. It took me fours months of lurking to make a purchase decision, just scratching the surface on this stuff.