I'm playing tthe pathetique and in the exposition the Allegra-Di Molto e con brio after the grave section where there is the c eighth notes repeating in the left hand, I can't seem to get it quiet any tips on how I can get it quieter?
You aren't going to have much in the way of alternative fingerings for an octave tremolo, so work out how softly you can play it - that's your p for this piece - and then base the rest of your dynamics for the piece around it. This may mean that the dynamic range is bit compressed, but, provided the differences in level are still distinguishable and well-controlled, the results should be quite musical.
Decisions like this should be made on a case-by-case basis, because they depend on two things, only one of which is under your control:
- the amount of dynamic control you can muster, in this case for a fast wrist rotation. (See below for a tip on this.)
- the piano's action.
Some pianos are going to have a stiffer action than others, and soft passages will be a bit harder to achieve on them; other pianos are going to have lighter action, which will make very soft playing possible, but make maintaining an even control throughout the dynamic range somewhat more difficult. To achieve a good interpretation of a piece of music, you need to plan around your limitations (which will change with time) and the limitations of the instrument you're using at the moment.
Also, check the level of your hand playing the tremolos. You don't want a high wrist or fingers far from the tops of the keys, especially if, along with difficulties in controlling a p dynamic level, you feel like your forearm has run a marathon all by itself. This chap has pretty much the right idea: Q&A Beethoven Pathétique - Tremolo Tutorial.
If it helps relieve some of the frustration, bear in mind that this passage is rather notorious with far more pianists than just you. <grin>
You should be able to get the dynamics you need using the soft pedal. If you don't have a soft pedal or it is still not quite enough you can relatively play the other parts of the piece louder.
Dynamics in any piece are relative. You don't need to play them at an exact dB level and it is very often that a p or pp in one piece isn't the same exact as in another piece. Because of this just make sure you play the quietest part the quietest and the loudest parts the loudest.