General purpose high-mu low-gain twin triode with ultra-low microphonics, by Sovtek. Replacement for all circuits requiring 12AX7/ECC83 types.
Sovtek tubes are quite simply the absolute best. We design and manufacture our tubes, engineered for demanding high fidelity, reliability and overall warmth. Be sure to insist on genuine Sovtek vacuum tubes the next time you retube -- you'll be getting the absolute best possible tubes for any demanding application.