Home theater crossover question

You are confusing two things. The crossover for the fronts will, indeed, send everything below 200Hz from those channels to the subwoofer and the sub will reproduce all of it (assuming the sub is capable).

OTOH, the crossover for the sub is set at 120Hz but that applies only to the cut-off for the dedicated LFE/sub channel signals, not the re-routed bass from the others.

Finally, you should realize, also, that all those settings are not absolute cutoffs but are the beginning points of gradual rolloffs/cutoffs. Thus, a crossover of 200Hz for the main speakers means that those channels will be transferring their content to the sub over a range from 200Hz to 100Hz to, mebbe, 60Hz. There is lots of overlap.

In other words, all's well (except that your main speakers must be fairly wimpy to require such a high crossover). :-)

Kal

Javachip is certainly correct about the localizability of the sub when it is asked to perform much above 80Hz but that was not the problem asked about.

In fact, I see more problems in lowering the crossover from 200Hz to 80Hz, more than an octave, if the main speakers really are incapable of low frequency output. Doing so will force them to reproduce, with requisite power, an octave or more below their abilities. Since we do not know what they are, we cannot be certain but I would proceed with caution.

IMHO, better a localizable sub than blown speakers. The solutions include repositioning of the sub close to the main speakers and/or replacement of the main speakers with more competent ones.

Kal