Any Valve Experts on here - couple of Mullards I'd like to identify

4114Effects

Just pulled these from a working bit of kit, I know some Mullards can be valuable, no idea which ones though!

First is a 12AX7 - code is I63 B9K4 - which leads me to believe Blackburn factory. 

Second is a 12AT7 - code is VF3 B1D2 - again, looks like a Blackburn. 

What do you reckon - are these good valves? Worth selling?

Cheers!

ICBM

Blackburn made, yes.

You can date them accurately - https://mullard.org/blogs/news/mullard-valve-etched-codes-how-to-interpret-them

Good valves in both cases, if they work properly. If they came out of a working bit of audio kit and were in the signal path then it's a reasonable assumption that they will. If you have any amp which takes a standard double triode in the V1 position - it's a near certainty that you will! - then you can easily test the 12AX7, and if you're sure that the plate resistors are adequately rated then you can test the 12AT7 the same way. Poor gain or tone, noise or microphonics will be very obvious - you don't need a valve tester just for that, and the results from one aren't necessarily that useful anyway for guitar amp applications.

They're certainly worth enough to sell if you have no use for them yourself - but by the same token, if you do have a use yourself I probably wouldn't sell them, they aren't worth a fortune. I sold most of the fairly large number I had not long ago, I did the 12AX7s for £30 each and the 12AT7s for £20 if I remember rightly, after a quick check of Ebay selling prices.

4114Effects

I think I'll hang on to them. I've seen some Mullards go for £100 on eBay, they must be super rare ones :-)

ICBM

4114Effects said:

I think I'll hang on to them. I've seen some Mullards go for £100 on eBay, they must be super rare ones :-)

Or properly NOS (ie not used) with boxes and test data, that puts the prices up a lot.