Home theater crossover question

I mounted my surround side speakers on the wall, so I used my Onkyo TX-SR803 receiver's auto configuration feature. I went into speaker setup when it was done and looked at the crossover settings, and now I have a question.

It set the front speakers to 200hz and the subwoofer to 120hz. Assuming the front speakers send everything under 200hz to the sub and the sub only goes up to 120hz, does everything from 121hz to 199hz get lost? Shouldn't the speaker crossover point be the same as the sub? Thanks.
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). :-)

Thanks. I knew that re-routed bass and LFE were separate, but there is no info on the receiver as to the frequency response for the former, so I assumed it was the same. In any case, my subwoofer's frequency response is listed as 29hz-150hz, so I'm not sure it can produce the 150hz-200hz sounds even if the receiver re-routes that range from the other speakers. On the other hand, my receiver wouldn't have put that burden on the sub if it wasn't producing sound in that range during the test, would it?

For now, I've changed the main speaker crossover from 200hz to 120hz. I didn't want to chance missing the occasional 188hz note that will make all the difference. When I have time, I'll A/B Dianna Krall and decide whether to change it back.
I'm having an epiphany at the moment, as I don't think I'm properly processing your quandary. I think you are correct, if your sub doesn't have a bypass, then you're limited to crossing over at or bellow that 120 hz setting. But I could be missing a brain cell on this one. Doh! It must be late.
Anyway, email your sub manufacture.
Let us know.
Kal says "all's well" and Kal knows what he is talking about, but I disagree with him anyway. If your subwoofer puts out anything much higher than 80 Hz, then it will be localizable. In other words, you will be able to hear it thumping away in the corner of your room, or against the wall, or wherever. Sound loses its omnidirectionality above 80 Hz. So you should manually override the crossover settings and set both the subwoofer and the front mains to 80 Hz, for upper and lower crossover points respectively. If your front mains are so small that they can't get down to 80 Hz with ease, then you must have two identical subwoofers, placed beside or under each front main speaker, and then you can make the crossover as high as you like.
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.

Like Kal said, the slope of the crossover is also important. That will take care of the 120 to 200 Hz range.

However. also like Javachip says, if your sub is crossed over that high, you're going to localize it. Even more problematic in my view is the fact that your crossover is is the audible mid-range for human voices, to which the ear is most sensitive.

You may not want to hear this, and you didn't ask in your thread, but I think you should seriously consider new front speakers if they have to be crossed over that high. There are many respectable, inexpensive, smaller speakers that don't have to be crossed over that high. There are too many problems that your settings will cause that will noticeably detract from the enjoyment of your HT.
Thanks for all the responses. My speakers are Infinity TSS-1100s (5 small 2-way speakers and the sub). Infinity recommends a subwoofer crossover setting of 120hz-150hz for the setup, so I reset all speakers to crossover at 120hz. Javachip and Kr4, the small speakers are rated at 125 watts and the self-powered sub at 250 watts, so I guess they can handle lower crossover settings. I may experiment with 80hz and see if it improves midrange response for CDs (2-channel system is off to listening room).

I think my original question has been answered; at 200hz for the front speakers and based on the sub's frequency response, I would lose part of the audio spectrum.
Yeah, what Kr4 said...
I looked at the specs for the Infinity TSS-1100 satellite/subwoofer system, and now I do agree with Kal. Leave the crossover for the front left and right speakers at 200 Hz, if that is what the receiver selected in the auto-configuration. The twin 3.5" woofers in each of the satellites are in danger of getting blown by excess bass energy, regardless of their rated power handling. Also leave the subwoofer crossover where the receiver selected, since as Kal points out, that only pertains to the bass re-directed from the satellites, not to the LFE channel. You will not be missing any part of the audio range.

To recap, the subwoofer will not be damaged by too high a crossover, although the sound quality may suffer. The satellites WILL be damaged by too low a crossover. Just place the subwoofer as close to the front satellites as possible (ideally right between them) and the subwoofer should sonically blend in with the satellites fairly well, especially since you indicate that you do your 2 channel music listening on a different system.
After digesting all of the advice, I compromised and set all crossovers to 150hz. Movies sound great and CDs sound about as good as I can get them to sound with this system, good enough for occasional listening. I still have my 2-channel system for dedicated CD listening. Thanks, everybody.
"I looked at the specs for the Infinity TSS-1100 satellite/subwoofer system, and now I do agree with Kal. Leave the crossover for the front left and right speakers at 200 Hz, if that is what the receiver selected in the auto-configuration"

I dissagree here. It all depends. I'd see where you can get them setup for a solid sound and frequency response first. Then find out where they start falling off, response-wise. If they play well down to a lower point, I'd cross em over down lower if I could. I've had those speakers, as well as the little TSS-750's, and those speakers are pretty dynamic, and handle power well down lower than 200hz from my recollection. I'd try to get em down closer to 120hz range - or if possible, 100hz regioun - if you can get em to couple well with the room. If you can't, than, fine, higher up. The drivers are good, and the sealed cabinet helps control the little drivers, and two woofers also helps cancel out audible distortion.
Read the reviews - even on the smaller ones - and you'll find the reviewers commenting on how dynamic they are, comparatively speaking.
Anyway, tinker and find out what you come up with. With good amplification, crossing over 100hz and above, making sure they are coupling well in the room with your seating positions for strong response compared to the rest of the spectrum, making sure your sub is anchored near the sats, and strong at the crossover point as well, and you should have nothing but well balanced, full dyanamic sound, with no audible distortion.
Still, results vary - even with experience levles - so see what you can come up with. If it where me, I don't see a scenario where I'd be asking my sub to play that high, not the sats that high either.
good luck