Low pass filter not working correctly?
1) You are using a single supply. Analyze the circuit for positive inputs. This requires negative outputs. Where will the - voltage come from?

2) You do not specify your op amp. Most op amps are completely incapable of driving 8 ohms, which the usual nominal speaker impedance. You need a power stage for the output - subject, of course, to fixing part 1).

3) Using 500 ohms for feedback and 150 ohms input is too low. For instance, you need to check to see if your AC source is happy driving 150 ohms. A good function generator will drive 50 ohms, but many sources aren't happy doing that. Use 10k and 30k. This will also let you use a smaller capacitor.