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. Ma
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