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.
I like the Telefunken 12AX7 for most mic preamps. It's just about the cleanest, most transparent 12AX7 ever made. They make "new" and counterfeit versions of this tube, so you'll have to be careful. The original is what you want. But it's highly coveted in the hi-fi community because of its crisp detailed highs (without being harsh) and full lows (without getting mushy). It's not cheap though.
12au7's tend to be a good bit cheaper. I don't have as much experience with these tubes, as I don't own any devices specifically made to use it, and it's such a low gain tube that I don't really like it as a substitute for the others. However I have a few RCA's and they sound pretty good to me.
Thanks for your thoughts. The original is a Sovtek 12ax7wa although I've had someone suggest a Phillips 12ax7wa saying that it's a lot quieter. It's also 4 times more expensive .. I need to get something as the mic is technically useless given that it has random spurts of noise. I'll check out the other options and let ya know what I get (and anyone else with any other good ideas, please feel free to chip in! )
A tube I don't see mentioned here is the JAN Philips 12AT7WC which is one of my faves for tube mics. Super smooth mids and presence. Even in shootouts I've posted, most of my friends picked the tracks where I used the Philips tube, and they're totally affordable.
another 12ax7 tube i would recommend is the siemens from 1960's.
I have 3 of them in a TLA vl1 unit which i pass some of my summing channels through.
this uses just half a tube per channel but at full voltage + i cannot hear anything bad about them, i like what i am hearing.
haven't really sat there and fully analysed them.
but i think like telefunken , the 60's german made siemens tubes are going to give you a nice clean sound.