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.