Should subs be moving at the EXACT same time?

[pawn man 10+ year member]

Not true. Wired 'mono' refers to both subs running off a single amplifier channel. You can do this, wiring the subs together parallel or in series, and still wire one out of phase with the other.

this is true. i was assuming they were in phase.

 

[audioholic 5,000+ posts]

Even at 40 times per second your eyes can discern a difference in their motion. If not, why do we have some people saying theirs run perfectly in tandem, while others dont? If our eyes couldn't discern anything at 40 cycles, we wouldnt be seeing different things from different setups.

The problem is, as someone else already said, most likely in the loading of the cones from the environment they are in (enclosure and vehicle). Certainly a port nearer one speaker than the other can cause uneven stress about their cones. Even having one sub mounted nearer an enclosure's interior wall than the other, or symmetrically about the single cone, can cause asymmetric cone motion.

In high powered applications like serious SPL setups, enclosure designers are careful to place the speaker symmectrically about the enclosure walls, and port, to keep stress on the cone even. Even in single sub setups.

 

[Subst4nce 10+ year member]

Even at 40 times per second your eyes can discern a difference in their motion. If not, why do we have some people saying theirs run perfectly in tandem, while others dont? If our eyes couldn't discern anything at 40 cycles, we wouldnt be seeing different things from different setups.
The problem is, as someone else already said, most likely in the loading of the cones from the environment they are in (enclosure and vehicle). Certainly a port nearer one speaker than the other can cause uneven stress about their cones. Even having one sub mounted nearer an enclosure's interior wall than the other, or symmetrically about the single cone, can cause asymmetric cone motion.

In high powered applications like serious SPL setups, enclosure designers are careful to place the speaker symmectrically about the enclosure walls, and port, to keep stress on the cone even. Even in single sub setups.

I think it might be because of my port, the sub on the right is closest to the opening to the port inside the enclosure so I was thinking whether it would have an effect on it or not, at least I know I'm not going crazy.

Can a bad box design cause this? How can I prevent this with the port opening on the side of the subs?

I'm still going to check the wiring when I get time, just to be safe.

 

[Xprime4 10+ year member]

well if they are out of phase with each other they'll sound like pure shit anyway...

Maybe one is just not connect well. The pressure make it move like the other one but with less velocity (sp???) It happened to me and i could have bet they were both getting power.... yeah the pressure inside the box is impressive

 

[audioholic 5,000+ posts]

I think it might be because of my port, the sub on the right is closest to the opening to the port inside the enclosure so I was thinking whether it would have an effect on it or not, at least I know I'm not going crazy.
Can a bad box design cause this? How can I prevent this with the port opening on the side of the subs?

I'm still going to check the wiring when I get time, just to be safe.

Without rebuilding the box to make it symmectrical about both subs' mounting positions, I dont see any realistic way to avoid the issue with your setup. The good news is its not likely causing any audible differences. One sub is just slightly more cone loaded than the other.
Front loading the subs (adding a loading board) would diminish the difference in their motions somewhat. But imo its not a huge deal. I think about such things when designing enclosures, but you cant always keep everything symmetrical. And unless the problem seemed severe, I wouldn't rebuild my whole setup over it.

 

[Subst4nce 10+ year member]

Without rebuilding the box to make it symmectrical about both subs' mounting positions, I dont see any realistic way to avoid the issue with your setup. The good news is its not likely causing any audible differences. One sub is just slightly more cone loaded than the other.
Front loading the subs (adding a loading board) would diminish the difference in their motions somewhat. But imo its not a huge deal. I think about such things when designing enclosures, but you cant always keep everything symmetrical. And unless the problem seemed severe, I wouldn't rebuild my whole setup over it.

That makes perfect sense, I doubt it would effect much, I'm just afraid if I give them more power it will get worse, but until then I don't see any need to worry, I'm only giving each sub 250 watts anyway.

Thanks for all the help guys!