>03-11-10: Ptmconsulting
I agree, you have to set the crossover point LOWER than the bottom of your regular speaker. Then adjust the integration using the sub's volume control. Don't forget to check the phase of the sub also.
I disagree. You have to set the cross-over point high enough that
1) You don't run out of linear excursion on the main speakers. For a non-ported speaker you get 12dB of head room (you can handle 16X more power) with each higher octave. 5-6" drivers in two ways often need 100Hz+ cross-overs to get good performance at reasonable output levels. Obviously this often calls for fourth order slopes and perhaps stereo sub-woofers.
2) You want cross-over points to work around the first SBIR null from the main speaker (where it's 1/4 wave length from the front wall thus causing a null; for instance at 4' you'll get the first null around 70Hz) and room modes stimulated by main speakers and sub-woofers (for instance you might want a 60Hz low-pass on the sub-woofer and 80Hz high-pass on the main speakers to work around resonances in the 70Hz range).
Achieving good integration is a separate issue which may call for options not available in most consumer gear like asymmetric cross-over points. With subs close to main speakers you may benefit from being able to replace the speaker's inherent high-pass function with a different one using a biquad with digital or analog (Linkwitz Transform) realization.
I agree, you have to set the crossover point LOWER than the bottom of your regular speaker. Then adjust the integration using the sub's volume control. Don't forget to check the phase of the sub also.
I disagree. You have to set the cross-over point high enough that
1) You don't run out of linear excursion on the main speakers. For a non-ported speaker you get 12dB of head room (you can handle 16X more power) with each higher octave. 5-6" drivers in two ways often need 100Hz+ cross-overs to get good performance at reasonable output levels. Obviously this often calls for fourth order slopes and perhaps stereo sub-woofers.
2) You want cross-over points to work around the first SBIR null from the main speaker (where it's 1/4 wave length from the front wall thus causing a null; for instance at 4' you'll get the first null around 70Hz) and room modes stimulated by main speakers and sub-woofers (for instance you might want a 60Hz low-pass on the sub-woofer and 80Hz high-pass on the main speakers to work around resonances in the 70Hz range).
Achieving good integration is a separate issue which may call for options not available in most consumer gear like asymmetric cross-over points. With subs close to main speakers you may benefit from being able to replace the speaker's inherent high-pass function with a different one using a biquad with digital or analog (Linkwitz Transform) realization.