Transistors are light, small, cool, and more reliable than vacuum tubes. However, audiophiles and guitarists choose the Mullard 12AX7 E-Vintage tube for its low-noise design and the warm, rich tones it is capable of coaxing out of amplifiers. This reissued tube is manufactured by New Sensor Corp (Electro-Harmonix, Sovtek). Each tube is double-tested at real-world settings on a Maxi-Matcher tube tester for leaks, shorts, gains, gas, and Gm.