4 tubes, matched as quad
The Sovtek 5881 delivers a warm, round tone that "sweetens" any vintage or modern guitar amp design. Chances are if an amp uses 6L6-style output tubes, it has Sovtek 5881's in its sockets. Built to rigid military standards, the 5881 will tolerate higher voltages than any other 6L6. In fact, they're frequently used as replacements for the old 7027 model in vintage Ampegs.