Mullard CV4004 / 12AX7 Preamp Vacuum Tube

15 Reviews
SKU: MU-CV4004-12AX7

Availability: Usually ships within 24 hours.

USD $‎27.95
1 – 4USD $‎27.95
5 – 99USD $‎25.95
The new Mullard CV4004 / 12AX7 vacuum tube has a short plate construction making it more stable and better able to handle the vibration inside guitar combo amps.

From our review: "The smaller plates reduce noise. They are dead quiet both electrically and mechanically. Nice thick bottles and well aligned internals also help. If you currently like the Tung-Sol 12AX7 preamp tube you will love this tube. The gain is similar but overall it is quieter and a bit warmer to my ears."

From the manufacturer: "The CV4004/12AX7 is a high gain, low noise valve with a short plate structure for reduced microphonics. Excellent for use in high gain Marshall pre-amplifier circuits where noise and microphonics can be a problem. Best for guitar amps."

The Mullard name and trademark have been acquired by the New Sensor Corporation. This new production Mullard CV4004 tube is manufactured at their Xpo-Pul factory (also known as Reflektor) in Saratov, Russia. New Sensor is an American corporation and since taking ownership of this factory has been steadily improving the quality of current production tubes.

Other Mullard tubes12AX7 Types

Additional Information and Downloads

Tube Matching Information:
Matched Sections Service

Warranty Information and Return Policy

Warranty Period: 3 months

All our tubes are guaranteed for 3 months from the date of purchase. (Any exceptions will be noted on that tube's Warranty tab)

If you receive a tube that does not perform to the manufacturer's specifications, please do the following:

- contact us to get a return authorization
- return it via regular mail within 90 days from when we shipped it, and we will provide an exchange or refund of the full purchase price of the tube.

Returns not related to warranty or defect will be considered at our discretion, and are subject to a 15% restocking fee.

We can not accept returns that don't have an authorization, are past 3 month, or are returned improperly.

These guidelines may be updated without notice.

Ratings & Reviews

15 reviews

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Mullard CV4004 / 12AX7 | Excellent in a Marshall Origin 20

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Got a set of three matched and balanced MU-CV4004-12AX7 to replace the stock tubes in a Marshall Origin 20H. Prior, struggled to find settings that weren't harsh. Now, even very trebled out settings sound sweet, clean or distorted. Full and smooth. Delighted with these.

Mullard CV4004 / 12AX7 | KILLER Preamp Tubes


I've used these MU-CV4004-12AX7 in the Preamp section of my Ashdown ABM500 in the past and recently bought 2 to use in my Fender TBP-1 Bass Preamp. The Fender had the original Sovtek 12AX7's in it and these really brought the unit to life. They are clear, warm and punchy and virtually noiseless! Well worth ever penny!

MU-CV4004-12AX7 | Great sounding tube, great price


I got two of these MU-CV4004-12AX7 for v1 and v2 of a Marshall DSL 40 combo. It came with JJ’s which work fine and sound pretty good. This tube is a little warmer and sweeter sounding. Definitely helped bring a little more vintage sound to the amp. I used to chase nos tubes but new production seem to be coming around. So save your money, and by from the ruskies. I will be curious to see how long they last. People knock on JJ’s, but they last forever.

Mullard CV4004 / 12AX7 | Good tube


They look or sound nothing like a Mullard box plate which I think there inspired from. The Mullard CV4004 are my favourite new production 12ax7. I had good results with them not as harsh as the Tungsol and a well balanced smooth sounding preamp tube for guitar amps. Good reliability and better more realistic price point for new production.

Mullard CV4004 / 12AX7 | Perfect for V1 socket in highgain amps

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I contacted the folks at TheTubeStore for a recommendation for a 12AX7 tube to put in the V1 of my Egnater Armageddon to help tighten the amp up but at the same time give it some punch, smooth out the gain and take away the harshness. They recommended the Mullard MU-CV4004-12AX7.

Their recommendation was bang on. Cranked in the amp tonight and what a world of difference compared to the JJ ECC83S that was in the V1. the harshness is gone. The sound is more open and wide, yet punchy and tight. Smoothed the gain out without taking away gain... if anything, these tubes added a bit more useful gain to the amp.

Highly recommended..