subwoofer phase correction

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does anyone make a variable subwoofer phase control that can be tied into the RCA input lines right before the amp(s). swapping wires does the 0 - 180 flip but i was looking for something dial-able along that scale.

built in xover wouldn't hurt either (hell if its got an eq i'll piss myself).

thanx...

-vinnie.

CPHILHOWER

Parts Express has a couple. Made by Phoenix Gold and Profile. However they are 3 way crossovers.
Chris

LILDRAGON

What exactly does the subwoofer phase do? My Rockford 1000bd has that feature. I am running 1 MM124 of of it.

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when speakers are in phase, it makes they are producing sound "in rhythym" with each other. if you swap positive and negative on one subwoofer, but not on the other, and htey are in the same chamber, you'll notice that no matter how high you turn the volume up, your subwoofers will not even move -- this is because as one sub is going "out", the other is going "in" and they PERFECTLY cancel each other out.

if you use a 12 db/ octave crossover, it inverts phase (basically the same as switchign wires) to that speaker or speakers which you have crossed over.

so you'd then have to flip flop the wires on that speaker so as to maintain normal phase.

but phase is also dependant on position. if i am sitting 3 feet away from speaker A... and 5 feet away from speaker B, assume A and B are in a straight line in front of me, speaker B may or may not be in or out of phase with speaker A... most likely, it will be off by some small amount, as the time it takes for the soundwave to go from A to me is going to be different than from B to me. however if the time from B to me is evenly divisible as a coeffecient of the period of teh soundwave, and hte same goes for A (give or take 10%) it should be close enough... but say the time from B to me is 1.5 times the period of the sound... and the time from speaker A to me is 1 times the period of the sound... then they will be out of phase by 180 degrees and i'll hear nothing.

so basicall if your rear speakers (or in this case subs) are just somewhere between that 1.5 and 1 x mark... then u need partial adjustable phase correction, not just a simple wire swap.

CPHILHOWER

So, How do I want the Phase switch set? My two 12's are in the trunk facing rear. I want it set to Positive? I have experimented with the Phase switch in the past. The only noticeable difference I could tell was that in the Negative. Volume seemed to decrease. I see it on a lot of subs. Home and car and never really understood why.
Chris

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well start by leaving it full "normal" or "+" ... and its not so much volume you're looking for as a change in clarity, definition, and "lack of holes" in the music.

if i do not invert my subs then it actually is boomier, louder, but there is a gap -- inverted there is no gap, a slight loss in boomyness, but its clear as hell, very punchy.