Renew Your 5150 III — or Other Amp — with EVH Preamp Tubes Each ECC83/12AX7 tube pair by EVH is rigorously tested to support your favorite compatible high-gain amplifier, including EVH 5150 III amps (these are the stock 5150 III preamp tubes used by the manufacturer). The tubes feature a 9-pin triode design and are sure to supercharge high-gain amps with a powerful personality that supports everything from monster riffs to marathon tapping runs. Guitarists at Sweetwater have also had luck bringing their older amps back to their former glory with these tubes. Moreover, EVH tubes are rigorously tested and checked for microphonics, hum, and other undesirable imperfections. In short, these are the go-to tubes for high-gain attitude and performance worthy of the legendary EVH name.EVH ECC83/12AX7 Tube Pair Features: 1 pair of ECC83/12AX7 preamp tubes with a 9-pin triode design Perfect for high-gain amps, especially 5150 III signature amplifiers