12AT7 Electro Harmonix twin triode

The 12AT7 tube is similar to the 12AX7, however, provides less gain leaving more headroom for a cleaner tone. That's not to say it cant provide nice gain for your amp but rather that if you are struggling to control you gain or find more clean headroom then this tube may be for you. 

Try placing a 12AT7 in the first Preamp tube space (often called V1) and see how you like the sound.