To Roger Kanno,
I was reading your website and was a little confused about speaker crossover frequencies. My left and right speakers have a frequency response of 43Hz-20kHz (+/-3dB), one 6.5" woofer (in each), and a 3500Hz crossover frequency. My center-channel speaker has a frequency response of 38Hz-20kHz (+/-3dB), two 6.5" woofers, and the same crossover frequency of 3500Hz. My rear speakers' frequency response is 80Hz-20kHz (+/-3dB), each has one 3.5" woofer, and they have a crossover frequency of 5000Hz. The sub’s frequency response is 23Hz-180Hz and the crossover range is 40Hz-180Hz with 24dB/octave and 18dB/octave selectable slopes.
My A/V receiver has a quadruple-bass-management crossover and a fixed sub crossover setting at 100Hz. My current settings are 60Hz for the LCR speakers and 100Hz for the rears. The sub is crossed over at the maximum. Are there better settings for this setup? Your help and recommendations would be greatly appreciated. Thanks and take care.
John
You’ve referred to several crossover frequencies. The internal crossover frequency of your left and right speakers (3500Hz) refers to the frequency where the audio signal is split between the tweeter and woofer. This is a fixed frequency arrived at by the designer and you don't really need to worry about it. The same thing applies to the center-channel and rear speakers.
The bass-management crossover frequency of a receiver or processor is the frequency where the signal is split between the left, right, center, and rear speakers and the subwoofer(s). The frequencies around and above the crossover point go to the speakers and the frequencies around and under go to the sub(s). It’s important to understand that this is not a "brick-wall" cut-off, but a "slope" that is usually expressed in dB/octave. For example, a fourth-order crossover has a 24dB/octave slope and a third-order crossover has an 18dB/octave slope. The 24dB slope is steeper than the 18dB slope. The steeper the slope, the less overlap between the speakers and the sub(s).
Setting the crossover frequencies for bass management is not as easy as simply looking at the low-frequency response of the speakers and setting the crossover slightly above that. You have to experiment with various frequencies as well as the crossover slopes and the phase setting to get the smoothest, deepest and most accurate bass response from all channels.
To achieve the best results, you should first find a spot in the room for the subwoofer that minimizes room interactions and provides the smoothest and flattest frequency response. Then experiment with the crossover setting, slopes, and phase control to get the smoothest blend between the sub and the left and right main speakers. I would not worry nearly as much about the other speakers because the process will become too complicated. It’s most important to get the integration between the sub and the left and right speakers correct.
To do this properly, you will need an SPL meter and test disc with frequency tones or sweeps. You will also need lots of patience because the process can be time-consuming. This is why automatic room correction systems such as Audyssey are so popular now. However, finding a spot for your subwoofer with a fairly flat frequency response and getting the best blend between the main speakers and subwoofer is certainly not impossible to do yourself and will only enhance the listening experience. . . . Roger Kanno
