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Subs not hitting in sync.
Subs not hitting in sync.
I have 2 12" kicker comp vr's, dual 4 ohm. I'm running them on a memphis 1000D amplifier. What causes subs to hit out of sync, I was watching them and one hits before the other, kinda causing a flutter type problem. Seems like its causing me some sound also.
Are you sure that they're wired right... one might be opposite the other.
-Michael
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Could be one of a few things.
1) optical illusion.
2) subs are wired out of phase with respect to one another.
3) if DVC subs, possibly one VC is bad on one of the subs.
4) box could have a leak, or sub could be leaking at it's gasket.
5) one of the pole vents on one of the subs could be blocked/constrained.
I'd start by checking whether the subs are wired in phase or out of phase. Get your hands on a 9v battery (rob the smoke detector at home). Disconnect the subwoofer speaker wire from your amplifier, and touch the battery to the speaker wire, positive to positive, negative to negative. Watch the cones as you do - they should move out, and then stay there until you remove the battery. If one of the subs moves out, and one of the subs moves in, you found your problem - one of the subs is wired backwards with respect to the other one. This test is absolute and infallable...
...the exception being that it doesn't test for whether one of your voice coils is bad or not. If you had a bad voice coil, you might be able to observe one of the subs moving a bit more slowly in and out as you connect and remove the battery, but generally not. Really the only way to test for that is [assuming your wiring checked out OK with the previous test] to remove each sub from the box, and touch the battery to each terminal on the sub, again positive to positive, negative to negative, and observing the results. The cone should again move out (or would move in, if you flipped the battery around
), and should do so for each voice coil. If you find one that doesn't, that means you have a bad voice coil.
When you remove the sub, look at the magnet. Is there a pole vent (hole in the back of the motor)? If there is, what diameter is that vent? You need to leave an equivalent distance unobstructed behind the sub, or cone motion will inherently be choked off. So, if you have a sub with a 6" mounting depth, and a 1" pole vent, you really need at least 7" of mounting depth. Measure your mounting depth and make sure you've got that clearance inside your box.
While you are in there, look around the inside of the box. It is nearly impossible to visually check for leaks, but poor contruction can cause issues too. The sub is dependent on a predictable amount of air "spring" value inside the box, and if it has a small leak somewhere, that "spring" factor is negatively affected, and possibly not evenly across the entire enclosure.
...don't think that ported boxes are any different - there are actually greater pressure forces at work inside a vented box than a sealed one, making leaks just as much a factor.
Of course, the leak could be occurring simply because the sub is mounted to the box, perhaps not evenly sealed to the box. The best seal is a flat, hard surface on a flat, hard surface, despite what intuition might tell you. Textured finishes, carpeting, and rubber gaskets can actually create more opportunities for leaks, and makes a proper tightening sequence more important. You might be able to feel air leaking from around the sub's gaskets, or you might have stripped a screw and not know it.
If you have gone this far and not identified a problem, don't rule out "optical illusion". Those subs are cycling in and out somewhere between 20 times every second, and 100 times per second, and movies that fool your eye do so with only 24 frames per second.
1) optical illusion.
2) subs are wired out of phase with respect to one another.
3) if DVC subs, possibly one VC is bad on one of the subs.
4) box could have a leak, or sub could be leaking at it's gasket.
5) one of the pole vents on one of the subs could be blocked/constrained.
I'd start by checking whether the subs are wired in phase or out of phase. Get your hands on a 9v battery (rob the smoke detector at home). Disconnect the subwoofer speaker wire from your amplifier, and touch the battery to the speaker wire, positive to positive, negative to negative. Watch the cones as you do - they should move out, and then stay there until you remove the battery. If one of the subs moves out, and one of the subs moves in, you found your problem - one of the subs is wired backwards with respect to the other one. This test is absolute and infallable...
...the exception being that it doesn't test for whether one of your voice coils is bad or not. If you had a bad voice coil, you might be able to observe one of the subs moving a bit more slowly in and out as you connect and remove the battery, but generally not. Really the only way to test for that is [assuming your wiring checked out OK with the previous test] to remove each sub from the box, and touch the battery to each terminal on the sub, again positive to positive, negative to negative, and observing the results. The cone should again move out (or would move in, if you flipped the battery around
), and should do so for each voice coil. If you find one that doesn't, that means you have a bad voice coil.When you remove the sub, look at the magnet. Is there a pole vent (hole in the back of the motor)? If there is, what diameter is that vent? You need to leave an equivalent distance unobstructed behind the sub, or cone motion will inherently be choked off. So, if you have a sub with a 6" mounting depth, and a 1" pole vent, you really need at least 7" of mounting depth. Measure your mounting depth and make sure you've got that clearance inside your box.
While you are in there, look around the inside of the box. It is nearly impossible to visually check for leaks, but poor contruction can cause issues too. The sub is dependent on a predictable amount of air "spring" value inside the box, and if it has a small leak somewhere, that "spring" factor is negatively affected, and possibly not evenly across the entire enclosure.
...don't think that ported boxes are any different - there are actually greater pressure forces at work inside a vented box than a sealed one, making leaks just as much a factor.
Of course, the leak could be occurring simply because the sub is mounted to the box, perhaps not evenly sealed to the box. The best seal is a flat, hard surface on a flat, hard surface, despite what intuition might tell you. Textured finishes, carpeting, and rubber gaskets can actually create more opportunities for leaks, and makes a proper tightening sequence more important. You might be able to feel air leaking from around the sub's gaskets, or you might have stripped a screw and not know it.
If you have gone this far and not identified a problem, don't rule out "optical illusion". Those subs are cycling in and out somewhere between 20 times every second, and 100 times per second, and movies that fool your eye do so with only 24 frames per second.
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Ryan from Ohio
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Ya I wouldnt be so quick to believe that.
If you had literally a few hundred feet of speaker wire, maybe...
If you had literally a few hundred feet of speaker wire, maybe...
-Ryan
www.caraudiocentral.net - Your #1 Car Audio Resource on the Net!
www.caraudiocentral.net - Your #1 Car Audio Resource on the Net!
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geoffwhite18
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solacedagony
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Interesting discussion on wire properties: http://www.diymobileaudio.com/forum/sho ... php?t=7517jonnyb wrote:the length of speaker wire doesn't affect timing, it affects voltage.
And no, a short wire like that won't have any effect on anything.