The 5751 valve has a lower amplification of 70 mu as opposed to a 100 mu of a ECC83/12AX7. This makes it harder for the valve to distort and therefore an ideal choice when the best clean sound is required.

The Philips 5751 has been the number one choice over the years to replace the 12AX7 type in the V1 positions of guitar amplifiers. Particularly in Fender Hot rod series of amplifiers as it tames the fuzzy more drive setting. It also works well in the front end of any amplifier if gain reduction and clarity are your aims.

The reason that the Philips 5751 has been the mo...