The TAD 5751 HIGHGRADE is your first choice if you want to improve clarity, smoothness and add vintage tone-character to your guitar amp. With about 85% gain of a standard 12AX7/7025 tube, this super-low-noise and HIGHGRADE- selected 5751 works best in the most sensitive stages of any guitar amp, tube microphone or audio application. This TAD 5751 HIGHGRADE will remarkably improve clean tones with a supporting, big bottom end, a warm midrange and a silky top end. It can replace any 12AX7, ECC83, 5751 or 7025.