ieales, Trikustik-this is a trip! thanks
Critical subwoofer tip
I assume that everyone already knows the importance of phase matching a sub to the main speakers but it’s a little more complicated than simple 90 degrees or 180. The B&W sub that I have has four choices. In every case there has been a definite correct position that can be non standard. My current setup shined at 270 degrees vs the std positions. It’s completely obvious and the other choices would not have been satisfying.
From my lengthy experience I would want a subwoofer with several phase choices. I personally don’t see how one could seamlessly integrate the mains and the sub without this flexibility. No one asked but i thought this info might be useful to anyone purchasing a subwoofer. YMMV
From my lengthy experience I would want a subwoofer with several phase choices. I personally don’t see how one could seamlessly integrate the mains and the sub without this flexibility. No one asked but i thought this info might be useful to anyone purchasing a subwoofer. YMMV
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- 83 posts total
Consider a kick drum on an open field where there are no reflections. The higher frequencies of the beater hitting the head arrive before the full amplitude of the head deflection, yet you still identify it as a kick. You can see a kick waveform here http://192.168.1.160/assets/CblSnkOil/Signal_vs_ACLine.png Putting the same kick drum in a room does not change your identification as a kick, but you are fully aware it is now a kick in a room In a multi driver speaker the frequencies which make up a kick are reproduced by different drivers. The sound begins when the electrical signal starts and in the voice coil plane. The ≈50Hz fundamental starts propagating from the woofer at the same time as the [say] ≈2250Hz beater whack does from the mid. If the voice coil of the woofer is 3 inches back from the mid, the whack is ≈180° out of phase by the time the fundamental starts to reach your ear. Time aligning attempts to minimize these displacement artifacts. Nothing is ever perfect and there are crossover affects to consider as well, but properly aligned systems have a coherence missing in others. Our brain can correct for frequency variation but cannot shift time. Compared to live acoustic sound, all playback sucks. But as Nietzsche opined "Without music, life would be a mistake." So we put up with it. |
@ieales The ≈50Hz fundamental starts propagating from the woofer at the same time as the [say] ≈2250Hz beater whack does from the mid. If the voice coil of the woofer is 3 inches back from the mid, the whack is ≈180° out of phase by the time the fundamental starts to reach your ear.The waves would not reach your ears at the time even if they started at the same point as they are different lengths. And bass takes a few cycles to be heard anyway. |
- 83 posts total