Originally Posted by Cardiff Kook
Let me Set up my question better...
Some experts recommend that a way to integrate the sub and mains is to start by reversing the phase on the mains and then adjusting the phase on the sub so that the volume in the crossover range is minimized. You then reverse the phase back and you now have them in phase. However, this is possibly not the arrangement which will lead to smoothest frequency response.
The answer I hear you stating is that frequency smoothness should trump timing or impulse response where the two conflict. That the next step is to fiddle with both crossover and volume to seek even FR. Is this correct?
Would it also be correct then that if I have a bass bump in my mains at let us say 6o hz, that I should consider increasing the crossover of the sub (from a much lower frequency) specifically to counteract that hump? Don't get me wrong I am not suggesting a sub is a great way to counteract frequency anomalies in the upper or mid bass, but in the lower mid bass it may be a possibility (note that Magnepan specifically recommends DWMs be used in such a way to smooth even upper bass).
Great discussion. I wish more people would chime in....
reversing the phase helps if your AVR or whatever has limited phase/delay range or you have them set up in such a manner that they need to be out of phase to provide a wavefront in-phase at the listening position. The goal is always to have the sound at all frequencies from all sources arrive in-phase at the listening position.
There is no pat answer to frequency vs. time domain except that they are two ways of expressing the same thing. One does not "trump" the other. If one is perfect, or horrible, the other will be as well. In between you choose but the time and frequency domains are tightly coupled so you can't really isolate one from the other. Frequency domain is easier for most people to measure and understand but if you do the math it doesn't matter. Note frequency response includes phase; most just look at magnitude.
If you have a frequency variation then the solution depends upon the root cause. Could be the speakers interacting with each other or the room, and how they interact is influenced by the phase response, which includes phase shift through the crossover.
I have Magnepans but not DWM's. They are woofers, not subwoofers, and while some really like them for the added bass, and properly placed and phased they can help mid-bass, I would not run them very low in frequency. Like all planar speakers, there is limited excursion available, and they distort heavily when presented with large signals that are the norm in the bass region.
You could certainly try varying the crossover, and if you have Rythmiks, adjusting the sub's phase to optimize their alignment.
HTH - Don