All of the above is good advise and sound theory. Give it a try. However, my experience has led me to a somewhat different approach.
First, turn off the main speakers and, with the crossover set to 90 Hz or thereabouts, listen to some music. "What music" you say. Yes it's true that most of the time nothing will be coming out of the subwoofer. (Dirty little fact).
Secondly, search through your recordings and find one that does have signal below 90 Hz. How does it sound? Do you really want that in your mains?
Thirdly, think about the high frequency capability of your subwoofer. Is it really all washed up at 100Hz?
Obviously what I am driving at is the suggestion that the 50Hz subwoofer crossover frequency often suggested is too low, at least for my particular system. My subwoofers are my own design, and include 15 inch JBL drivers which are good to 800 Hz, so 90 Hz is a walk in the park. (The somewhat deficient range below 30 Hz is filled in with 12 inch specialized subwoofer drivers). Although most commercially available subwoofers don't claim to go higher than 200Hz or so, limiting them to 50 Hz is unnecessary.
IMHO no aspect of audio exhibits greater disparity between theory and practical tweeking based on listening than does the subwoofer. I am not alone in noting that precisely measured (with a warble tone) flat response to 20 Hz often sounds deficient when music is played.
Finally, with regard to overlap/gap of crossover frequency: I have obtained Marchand electronics modules which have an interesting feature. It is a control that provides a bandpass boost or cut at the crossover frequency. This is supposed to take care of the problems around crossover noted by sean. I have not got the things wired up yet, but I am anxious to see how this feature works.
First, turn off the main speakers and, with the crossover set to 90 Hz or thereabouts, listen to some music. "What music" you say. Yes it's true that most of the time nothing will be coming out of the subwoofer. (Dirty little fact).
Secondly, search through your recordings and find one that does have signal below 90 Hz. How does it sound? Do you really want that in your mains?
Thirdly, think about the high frequency capability of your subwoofer. Is it really all washed up at 100Hz?
Obviously what I am driving at is the suggestion that the 50Hz subwoofer crossover frequency often suggested is too low, at least for my particular system. My subwoofers are my own design, and include 15 inch JBL drivers which are good to 800 Hz, so 90 Hz is a walk in the park. (The somewhat deficient range below 30 Hz is filled in with 12 inch specialized subwoofer drivers). Although most commercially available subwoofers don't claim to go higher than 200Hz or so, limiting them to 50 Hz is unnecessary.
IMHO no aspect of audio exhibits greater disparity between theory and practical tweeking based on listening than does the subwoofer. I am not alone in noting that precisely measured (with a warble tone) flat response to 20 Hz often sounds deficient when music is played.
Finally, with regard to overlap/gap of crossover frequency: I have obtained Marchand electronics modules which have an interesting feature. It is a control that provides a bandpass boost or cut at the crossover frequency. This is supposed to take care of the problems around crossover noted by sean. I have not got the things wired up yet, but I am anxious to see how this feature works.