This 5751 is a drop-in replacement for any 12AX7. The 5751 was designed as a "ruggedized" high mu, dual triode tube with similar specifications as a 12AX7. However, with 30% reduced gain, the 5751 is a fantastic way to tame a distortion stage and tone shape an amp. These "short plate" JJ 5751 utilize a "short plate" design. tubes have great compression and harmonic complexity, perfectly suited for creating articulate midrange and warmer high end response.