I have a CAD VX2 which I think needs a new tube (I suspect the 12AX7 rather than the 12AU7)* and was wondering if anyone had any recommendations (for either or both tubes). I'm based in England, in case that makes a difference to the recommendations!
* It's making some background noise that is almost like interference and is louder than the self noise of the mic (registering around -40 to -50 on my recorder). For memory, I think it was intermittent - in that it made the noise for several minutes, and then would stop making the noise for a little while before coming back again.
One of the members here is named BOWIE, try to MP this guy, he is actually really fine for choosing a tube corresponding to your needs, your unit, whatever… ! I did twice that choice to go with him, and do not ever regret !
Since your mic is a modern one I'd try "Ei" 12AX7 / ECC83
RCA, AMPEREX etc etc etc are great but, these Ei can provide "more" midrange in new equipment with modern capcitors and resistors.
Try and use the best for you, it's a matter of taste.