- Posted by neolith (A) on June 30, 2009 at 09:19:03
In Reply to: RE: the reversed mid-driver posted by play-mate on June 30, 2009 at 04:57:08
The reason for inverting the mid driver is due to the phase shift caused by the filters. Consider a classic 2nd order Butterworth symmetric crossover. The LP and HP filters are 180 degrees out of phase so at the crossover point the signals subtract and cancel each other out leaving a hole. If one of the filters is wired in opposite polarity the phases are now the same and the signals add to each other resulting in a 3db bump at the crossover. If one uses a 12db L-R then the net output will be flat. With other filters, the decision to invert depends on the paramaters. The idea is to get a flat curve. As Davey has pointed out this is just the electrical response and the accoustic response must be figured in. It is the acoustic response of the drivers that determines the -3db points, slopes and orders of the filters. The whole thing is pretty much trial and error, as best as I can tell.
I plan to procrastinate my demise for as long as possible. In the meantime, I practice by putting off all the little stuff.
Edits: 06/30/09
