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Re: Let's REALLY Understand HT Crossovers
Good write-up, John. I had that same sickening experience (the speakers bottoming out during an action flick). My speakers were good to about 28 Hz, so I set my crossover for 60 Hz, thinking that having it an octave above their maximum extension would be safe enough. Wrong. And my external crossover has 24 dB/octave slopes on both sides! IOW, at 30 Hz the bass signal in my mains should have been attenuated by 24 dB.
What people fail to consider is that the signal content of some movies, especially action flicks. The extreme amount of boost at the lowest frequencies can effectively flatten a high-pass filter, or at the very least reduce the slope considerably. The crossover should be able to protect your speakers, even if the slope is significantly diminished, but consider the consequences of not having the crossover on-line. Without its low frequency attenuation, you end up with the same effect as adding a 15-20 dB boost at 25 Hz with an equalizer. No one in his right mind would do that intentionally, but your DVD is effectively doing the same thing.
Regards,
Wayne A. Pflughaupt
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