Phase issue with narrow band pass

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   This is probably common knowledge, but just thought I'd share it. My sub and kick both cover one octave, with the sub using hp 40, lp 80 and the kick hp 80, lp 160. Up until recently I had been using 24db/oct lr filters and found that I had to invert one of the drivers to get them to match up in phase. After switching to 48db/oct I no longer need the inversion. I figure that in the 24db/oct case each of the two filters applied to a driver is exerting an approx. 90deg phase shift at the xover point of the other filter due to the close proximity of the filters. This would cause the drivers to meet at. +/- 90deg rather then the usual +/- 180deg you would get with a wider pass band. Is this generally know about and corrected for?

Edited by Fordy - 26 June 2009 at 8:21am

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Fordy Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 02 March 2009 Status: Offline Points: 365	Post Options Post Reply Quote Fordy Report Post Thanks(0) Quote Reply Topic: Phase issue with narrow band pass Posted: 26 June 2009 at 8:18am
	This is probably common knowledge, but just thought I'd share it. My sub and kick both cover one octave, with the sub using hp 40, lp 80 and the kick hp 80, lp 160. Up until recently I had been using 24db/oct lr filters and found that I had to invert one of the drivers to get them to match up in phase. After switching to 48db/oct I no longer need the inversion. I figure that in the 24db/oct case each of the two filters applied to a driver is exerting an approx. 90deg phase shift at the xover point of the other filter due to the close proximity of the filters. This would cause the drivers to meet at. +/- 90deg rather then the usual +/- 180deg you would get with a wider pass band. Is this generally know about and corrected for? Edited by Fordy - 26 June 2009 at 8:21am