mtrycrafts said:
Well, make sure your speaker wires have a way to identify the positive and negative side of it so they are not out of phase. Depending on your speaker size, when you follow the manual and setting it up, small or large speakers, definitely indicate 'yes' for a sub.
You need to volume level match all the speakers with internal or external test tones and an SPL meter. Radio Shack has an analog one that is very common and should be part of your audio toolbox
Others may have other suggestions more specific.
This is great advice, except in this case, the receiver has YPAO, which is an automatic setup feature. If he wants to manually check it, he should do as you say.
hchytd, do as jcPanny says regarding checking the settings. YPAO sometimes sets the crossover frequency too high, and sometimes does other undesirable things (like setting the main speakers to large when they should be set to small), though it usually is good at properly setting the levels.
You will want to make sure your subwoofer crossover is set to "bypass" or if there is no bypass, to its highest setting, and hook up the subwoofer to the line level output of the receiver. Set the subwoofer volume level to about half way up to start, though you will need to adjust it to match the sound output of the main speakers (YPAO may adjust the output for you, though if it is far from its normal setting, you will want to change the level on the subwoofer and run YPAO again).
This kind of stuff is probably in the manual, and I recommend that you carefully follow what they say. Run YPAO before you play any music, but do double check things like crossover settings and speaker size and such. Basically, you want the crossover as low as you can have it with your speakers, ideally at 80 Hz or below, but if your main speakers don't go that low, it must be set higher in order to reproduce all of the frequencies at an appropriate level. If the -3db point of your speakers is, say, 75 Hz, I would set the crossover to 80 Hz. If they only go down to 95 Hz, I would set it at 100 Hz.