Mullard CV4004/12AX7


Availability: In stock

Quick Overview

The CV4004/12AX7 is a low noise valve with a short plate structure for reduced microphonics.

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Mullard CV4004/12AX7

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The CV4004/12AX7 is a low noise valve with a short plate structure for reduced microphonics.

Customer Reviews

Marshall SV20 Review by Josh
Hey Doug!

Just got my Mullard CV4004 RI in. Have to say I really enjoyed the buying experience as a first timer at your shop. I’m wanting to buy my next round from you but I thought I’d reach out to pick your brain.

So far I am enjoying the CV4004 but it might be a bit too much gain in this amp. It is allowing something through tone wise that I can only describe as “balls” on the low strings. It sounds phenomenal there.

I’m thinking I might like the long plate Mullards to lower the gain a bit but still get that frequency coming through. I have this one I’m V1 right now and V2 & V3 are Chinese Marshall’s. I’m also open to NOS but not too picky there. I saw your mix and matched used NOS section and was considering that route for 2 or 3. I play a lot of southern rock and Americana if that helps. The SV20 sounds like a smaller superlead to me. Anyways let me know what you think good sir! Have a great day!


- Josh (Posted on 9/10/20)
Peavey 6505 MH retube Review by Dave
Hi, thanks for your recommendation on the Peavey 6505 MH tubes. I'm really happy with the change the new tubes have made in the amp's sound!


Dave (Posted on 5/11/18)
Fender Pro Reverb Review by Mat
Hello Doug, I have to say your Mullard ri and ehx preamp recommendation for my old pro reverb delivers the goods. Once again you knocked it out of the park.

Mat (Posted on 10/9/16)
Fender BF Champ Review by Morgan
Just wanted to say thanks again. The Mullard sounds awesome in my Champ, very musical.

(Posted on 2/13/16)
Vox AC30c2/x retube Review by Frank

New tubes for my AC30 C2/X arrived on Wednesday. Installed and spent
Wednesday afternoon and evening, and lots of time yesterday with the

Your recommendation for me to use Sovtek EL84Ms, V1 = Mullard 12AX7 CV4004,
V2= Ruby 12AX7 7025SS HG, and V3= Mullard 12AX7 long plate is a HUGE
improvement compared to the JJs that I had in the amp, and far superior to
the OEM tubes.

As we discussed, I use my AC30 C2/X primarily for early British invasion
stuff, and your tubes certainly deliver that tone.

During my research to discover what tubes to use for the early "Beatles"
tone, I found that on forums the answers are all over the map, and mostly
did not make any sense at all. I know there are other players like myself
that look for the early Brit invasion sound from their late model AC30s -
maybe you should think of offering this as a tube set as the answer.

I'd like to mention, that to get that sound, guitars should be plugged into
the LOW input - especially for Casino's, Rickenbackers, and Gretsch's.

I am very pleased and excited with the tone, and I thank you!


Frank B.
Ormond By The Sea, FL
(Posted on 9/4/15)
Metropoulos 50 watt(V1) Review by Bob
Hey Doug,

Thanks for the advice and the tubes. I'm REALLY happy with this purchase. My amp sounds badass... I can't stop playin'!!!

Bob S (Posted on 8/8/14)
Mullard CV4004 in Marshall 1923c Review by James
This tube sounds terrific in my DSL 50 combo. I put it in V1 with a tung sol in V2. While I love the Tung Sol RI's, these tubes sounded nearly identical, except they had a tiny bit less midrange. The tube did seem quieter breakup wise than the Tung Sol with more headroom too. The cv4004 really shined on the red channel of the DSL 50. It attenuated some of the higher frequency grain these amps have, especially higher up on the fret board, and on the high e and b strings. Excellent tube, I will purchase more. Great for the classic and ultra gain channel, cranked of course. Hard rock and metal players should check these out, but classic rock, blues, and country players shouldn't shy away. The tone is there. (Posted on 5/26/14)
My new favorite Review by Tom
I use this tube in V1 and V2 of Vox AC30CC2X and the results are fantastic! Preamp distortion is smooth but still high gain. The amp maintained all its chime and gained a nice grind at lower volumes. These are low noise and have resisted the AC30 torture chamber.

Great tube in every respect, a little pricey but it is worth it for the preamp gain magic that happens. (Posted on 5/7/14)

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