The Mesa/Boogie MESA 12AX7 is a premium-grade preamplifier tube. It's designed to provide high gain output with an overall balanced tonal quality. You'll also find that the MESA 12AX7 is both consistent and reliable in its smooth, balanced tonal response. The MESA 12AX7 is a lively, open, and expressive tube. - Mesa/Boogie MESA 12AX7 Preamplifier Tube Features:Premium-grade, high-gain preamplifier tube - Delivers a smooth and balanced response across the tonal spectrum - Recognized as an extremely lively, open, and expressive tube - The Mesa/Boogie MESA 12AX7 gives you smooth tube tone that's consistent and reliable!