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Mic / mic pre 12AX7 tube replacements Keyboard Synthesizers
Old 20th October 2009
Gear Nut

Thread Starter
Mic / mic pre 12AX7 tube replacements

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!
Many thanks,

* 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.
Old 22nd October 2009
Lives for gear

Rca 7025/12ax7 tube is my personal first choice, second is the Amperex 12ax7/ecc83 third is groovetubes 12ax7a gold pins and Electroharmonix 12ax7 gold (same tube just relabled)

rca 12au7a clear top , mullard cv4003/ecc82, JJ tesla ecc82/12au7 gold pin or JJ electonics ecc802/12au7 gold pin
Old 23rd October 2009
Gear Nut

Thread Starter
Old 23rd October 2009
Lives for gear
Colonel Blues's Avatar
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 !

Here is his e-mail :

[email protected]

P.S. : I'm not part in his company, just a nicely satisfied customer…
Old 24th October 2009
Gear interested

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.
Old 24th October 2009
Lives for gear
fhames's Avatar

Old 24th October 2009
Lives for gear
Ca$h Marty's Avatar

another vote for Bowie, let him know what you are shooting for and what you are using - cant go wrong.
Old 29th October 2015
Gear Head

Hi Dan,

Old thread but I'm getting the same problem with my VX2. What replacement valve did you get in the end?


Old 29th October 2015
Lives for gear

Another very satisfied Bowie customer here.
Old 29th October 2015
Lives for gear
Silent Sound's Avatar
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.
Old 29th October 2015
I just put a long black plate RCA 12ax7 + a short black plate RCA 12au7 into my IGS LA500.

it sounds smoother on transients than before (stock JJ's I think), particularly in the highs.

I have a Demeter vtcl 2 also , in this I have telefunken 12ax7 inputs + black plate RCA 12bh7 outputs.
tone on this combo is nice I use it on 2 bus.

I really like RCA black plates for tone but I guess you can't go wrong with telefunken (as long as they are real).
Old 29th October 2015
Gear Head

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! )

Old 29th October 2015
If you go Sovtek, go with the 12ax7LPS. its quieter than the WA.
Old 29th October 2015
Gear Head

Thanks for the tip.
Old 29th October 2015
Got a pair of RCA JRC 5751 tubes

on ebay a while back, 1960 NIB. $60.
They smoothed out everything I tried them in. ART MPA, MXL v69 mic.
Old 30th October 2015
Gear Head

12ax7LPS on order ... looking forward to getting the mic back up and running

Old 31st October 2015
Gear Maniac
Robbiehouston's Avatar


I use Mullard 12ax7s every time. Always sound great.
Old 31st October 2015
Gear Nut

Thread Starter
Bowie was really helpful. I'm based in the UK though, so by the time tax, duty, shipping etc was added in in was prohibitively expensive.

I've just ordered a ECC81/12AT7-MULLARD,

so I'll see how I get on with that. Hopefully that'll fix the noise!

I previously had a ECC83-STR/HARMA CRYO-BALANCED (HARMA Cryo valves) G from the same place.
Old 31st October 2015
Lives for gear
TurboJets's Avatar
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.
Old 31st October 2015
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.
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