Mullard CV4004 / M8137 / 12AX7 Box Plate


This Mullard branded CV4004 / M8137 is a ruggedized version of the 12AX7 preamp tube. The box plates are immediately discernible from other 12AX7 variants. This makes for a more bold and upfront soundstage while retaining that famous Mullard smoothness. Made in Great Britain for the English Military, the CV4004 / M8137 is one of the best 12AX7 variants you can use for any type of audio. Whether it's for your favorite guitar rig or HiFi system, you'll be pleased with the performance of this tube.

These Mullard CV4004 have box shaped plates. Also, this lot has the older, wavy style of glass.

Philips Holland Metal Base EL34

Price is for a single tube with standard testing.

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    I don’t write reviews often, but honestly these NOS Mullard CV4004’s are too good not to say something. I replaced a pair of JJ ECC83's with these in my PrimaLuna Prologue Four power amp and right out of the box the results were not subtle. Vocals occupy a clearly three-dimensional space and are unbelievably smooth. The frequency extremes also do not suffer at all. Everything is there in its right place, but presented from a much smoother and altogether larger soundscape. Well worth the cash. I’m actually considering buying more just to stash them away. This short review has taken me about 20 minutes to write because I keep getting pulled into the music playing in front of me. Wow.

    reviewed by: J. Crawley

    Didn't used to believe in the NOS tubes. Bunch of Hype I thought. Man was I wrong. Ever since the first NOS Mullard went into one of my amps now I'm in the process of re-tubing them all with NOS tubes. So far I've tried several and this tube, the NOS Mullard CV4004 is the absolute best in the #1 position of the several amps I've tried it in. It has that famous Mullard smoothness, but just as the caption above says it has a bolder, and more up front sound stage. It is definitely bolder and more up-front! It gives chime, the tone is liquid, but with balls, and in your face gain. Turn down the volume on your guitar and you get smooooth liquid chime. I could go on but you just need to plunck down your hard earned dollars (took me a month to save up for one) and try it for yourself. You won't won't be disappointed, that's for sure. Try it, I dare you. It will be the best $200 you have ever spent. It will NOT be a subtle improvement. It will blow you away how much of a difference this NOS tube will make in your amp. To me, it's the best kept secret in our industry. NOS Mullard CV4004 .... best preamp tube you can get. Period.

    reviewed by: Will Kenworthy

    I am using it on the first stage of my phono amp. In term of noise, it may not be one of the best, it is still very low noise. But in term of all tone range, it is one of the best with good dynamic and clarity, highly recommended.

    reviewed by: Andrew Ma

    Just received Mullard Nos tube; it's the sweet spot of tone.with clarity and midrange for analogue/ digital formats.Hogh recommend '

    reviewed by: Michael Romeo