JSC1205,
Welcome to the Forum.
In general, you would try to get the subwoofer to handle frequencies below the ability of the other speakers with a bit of overlap. Furthermore, a crossover is a slope (i.e. 6dB/octave, 12dB/octave, etc.) and not a wall (i.e. all below and none above). The specified frequency (80Hz, 90Hz, etc.) is normally the -3dB point. This is the frequency on the crossover slope where about half the sound is sent to the speaker and half to the subwoofer.
One last consideration is when a subwoofer is asked to produce sounds above ~120Hz it starts to be localized. This means you are able to note where the low frequency sounds are coming from (i.e. where the sub is; not a good thing) instead of these low frequency sounds blending into the background and appearing to emanate from the other speakers.
- If the AVR/preamp only allows one global setting I would expect the best setting to be in the 80-100Hz range. Experiment a bit to see what sounds best to you. One technique I like is to start with the crossover setting at one extreme (i.e. lowest allowed, for example 40 Hz), then alternate to the other extreme (i.e. highest allowed, for example 250Hz), and go back and forth gradually narrowing in to what sounds best--you kind of train your ears to hear the differences by doing this. It is a bit like the eye doctor routine of which is better, A or B, then C or D, . . .
- If the AVR allows separate crossover settings than I would start with about the following:
L&R speakers capable to 80hz, set crossover to 90Hz
Center capable to 80hz, set crossover to 90Hz
Surrounds capable to 87hz, set crossover to 100Hz
Ceiling capable to 100hz, set crossover to 120Hz
- Why more overlap on this last one, you astutely ask? I would expect the ceilings to be the least capable at low frequency production, so the extra overlap shifts the curve a bit.
Cheers,
XEagleDriver