Mullard CV4004 / 12AX7 Preamp Vacuum Tube

I have 1 of these Mullard CV4004's and I found a use for it in V2 in my Peavey Valveking 2 100 Head. 'Took off some of that low end and really drove into nice distortion. I don't know why, because in V1 it is pretty tame, and that's with swapping V1 and V2 around (use Shuguang/Ruby in V1, even in my Dark Terror, which provides creamy distortion).
I bought a Joyo Mjolnir the other day, and it came with stock Sovtek EL84 and JJs in the preamp slots. Sound wasn't quite what I wanted right out of the box, but I didn't give up on the sob and spent the whole evening swapping around almost every kind of preamp tube (have 10 different or so).
Finally, I found some creamy, nice distortion with the Mullard in V2, just like with my VK. Wasn't quite right, though, so I did what I do with all my amps: I slammed a Ruby in V1. That almost nailed it. Now, the Ruby that I have in V3 in the DT or the JJ and Preferred Series that I use in my VK (it was almost), the Sovtek LPS (not at all, too clear and lost distortion), and everything else, didn't balance it out out while maintaining creamy grain and crunch. Of them all the Tungsol came to the rescue and nailed it. Had not found a use for the Tungsol earlier, but now I'm glad I bought it. Also, the Mullard that I put over in the Mjolnir was replaced by the EH for V2 in the VK, which I now see as a cheaper version of the Mullard CV4004.

I have a 2011 Jet City HDM with the SLO mod running through a 2x12 loaded with Eminence Lynch Super-V's... I had been running it with Mesa Boogie branded 12AX7's for about a year, and it was pretty great. A friend suggested I drop in a Mullard CV4004 in the OD Gain (V2 position), and good god, it was instant Wicked Sensation tones from above!
The note separation at high gain is even more obviously Soldano SLO Valhalla!
Couldn't be happier!

Was looking to get rid of my Marshall Class 5 head because it was just to harsh sounding the more you drove it. I have a Vox AC4TV I re-tubed and play them both through a 1x12 Greenback cabinet. The Vox just sounded smooth and sweet with that beautiful Vox chime. So I thought I'd try some tubes first before giving up on the Class 5.

The Class 5 came stock with a Marshall brand JJ ECC83 in the V1, a Marshall brand Sino 12AX7 in the V2 and a Marshall brand JJ EL84. I put this tube in the V1, moved the Stock JJ ECC83 to the V2 and put a Mullard EL84 in the power. Wow! It's like a new amp. It just took all that quack and harshness out. It is now off the chopping block. It was the combination I was looking for.

I think the Sino tube was the culprit and might have been fine with just replacing it and making the switch in the pre amp but I think the Mullard EL84 makes it much better.

Just for fun, I dropped kicked a Mullard 12AX7 into my Bellari VP129 outboard Phono PreAmp and it was like reaching out your hand and touching the face of God!!! $27.76 for a ticket to heaven.

I then called my A-Hole neighbour Frank over to here my new valve and he just wrinkled up his nose. Fifteen minutes later he returned with this scruffy looking box, removed my Mullard valve and inserted a $400.00 Telefunken NOS valve from the early 60s....Bloody Septic!!! He did that on purpose, the swine!!! If Ya ain't gots the coppers, the Mullard will more than do.

I've rolled this tube in a few amps and I think this is one of the best new production tubes for the V1 spot. I play mostly metal/hard rock and I go for more of a vintage vibe. This tube and the JJ ECC803S are the only new production 12AX7's under $25 that I like now. The Tungsol's are good but I find these better balanced with better warmth.