The JAN-Philips 5751 is a great choice for taming high gain guitar amps while vastly improving the clarity, smoothness, and vintage tone. They still have plenty of gain so if you have a high-gain preamp that does not have that classic crunch characteristic, the 5751 tube will do wonders.
In hifi preamps and CD players, the JAN-Philips 5751 will lower noise floor and sound smoother and clearer in place of many 12AX7 tubes.The JAN-Philips 5751 tube is a NOS military version that has low microphonics and noise.
Special note for 5751 tube types: The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They should have approximately 70% of the gain of a 12AX7, and are often used to quiet down guitar amps that have too much gain. If you have gain to spare using a 5751 tube will greatly improve your overall tone without making your preamp excessively clean. You can learn more about this on our tone tweak info page.