If you are playing in a "classical" saxophone quartet, I'm not sure that a "hardness" in your tone is what you want. Of course it depends upon the tone of the other three members and the style of music you are playing. In my playing and teaching I have found that putting the top teeth slightly farther on the top of the mouthpiece moves the tone away from a well controlled sound to one that has more of an edge or harshness to it. The whole purpose of the lower lip in a saxophone embouchure is to "dampen" the natural vibrations of the reed. To hear the reed's natural vibrations without this dampening place the mouthpiece in your mouth up to the ligature and blow. That is one extreme. The other extreme is to place your top teeth near the tip of the mouthpiece so that there is very little reed inside the mouth. Most player try to find the spot in between that matches their "concept of sound" they are trying to achieve within the parameters of their set-up. Adjusting the amount of lip rolled over the teeth is another way to "fine tune" the harshness or warmness of the sound produced.