12AX7 - ECC83 - 5751 - 7025
Possibly the most popular preamp tube on the planet, the 12AX7 series offers almost unlimited options.
Compatible Equivalents & Substitutes: 12AX7, 12AX7A, 12AX7EA, 7025, ECC83, ECC803S, 5751 (low gain), CV492, 7058, 12DF7, CV4004, B339, E83CC, M8137.