You won't blow it with these 2 knobs or the switch, unless you set the gain way too high.
Gain is otherwise known as volume. Turn it up and the sub plays louder. Try for a natural sound, or better yet get an SPL meter and use a reference calibration disc to tweak all your levels.
Phase is otherwise known as polarity, i.e. positive and negative. If your speakers are hooked up backwards (black-->red, red-->black) then you're out of phase so use rev(erse) on the phase switch. Or, if your bass sounds very weak you can try the reverse phase, but assuming everything works as it's supposed to then use the normal setting. You don't want your satellites pushing cones out while sub is pulling cone in, to put it simply.
The frequency knob is for the crossover frequency, i.e. where should the sub take over and the satellites leave off. If you're using a line level input to the sub you can ignore this - the crossover's for running speaker wires to the sub and having it take the bass up to xx Hertz and sending the rest to the sats. If you're going the speaker wire method (i.e. an older Pro Logic receiver), then you'll have to fiddle with this to get the best sound. The basic idea in setting the crossover frequency is to figure out how low your satellites can go without distorting or dropping off, and have the sub take the lower frequencies. If you have cheap, tiny sats then set it higher, if nice/larger sats then set it lower. 100hz is a good starting point.
Last edited by Gomez; 01-02-02 at 12:02 AM.