I recently put subs in my car, what do each of the eq levels adjust? 60Hz, 150Hz, 400Hz, 1KHz, 3KHz, 7KHz, and 15KHz?
They adjust the volume of the sound frequencies closest those indicated. If you have no idea what audio components do, why are you screwing around with them? In most cases factory car stereos produce better quality sound than your ear is capable of appreciating. Oh, you just want it louder.
They should be adjusted to whatever level creates a realistic audio reproduction in your particular listening environment. That depends on the furniture in the car, passenger compartment volume and other speakers in the whole system. Also, all recordings are not alike. Some CD's are very dynamic and some are compressed, and each radio station may be adjusted to however the DJ likes to sound. The adjustments are there on the stereo to tailor each performance.Don't get too busy with it and pay attention to your driving. Finally, it will sound different if your windows are open of closed.
They are just different frequencies of sound. So say you play a 30hz bass tone, it will sound a lot “deeper” than a 60hz bass tone. If you set it to 30hz, it will try it’s best to play 30hz the loudest. It all depends on what subs you have as to how you adjust the setting.