Stacked sub Phase question

[Captainmorgan89]

I just bought another sub for my HT, and when I initially stacked them, I played the Nemo "Darla" scene. I was shocked by how little the sound/pressure output was when compared to the single sub going. After thinking a little, I switched the phase on the top sub to 180 and it fixed the problem.

Does that sound odd to you guys? I would have thought that both the subs moving in the same direction wouldnt cancel each other out, but someone also suggested that the sub may have been accidentally wired out of phase?

For those of you that have done this, did you have to switch the phase for one of the subs?

Thanks!

 

[TLS Guy]

I just bought another sub for my HT, and when I initially stacked them, I played the Nemo "Darla" scene. I was shocked by how little the sound/pressure output was when compared to the single sub going. After thinking a little, I switched the phase on the top sub to 180 and it fixed the problem.

Does that sound odd to you guys? I would have thought that both the subs moving in the same direction wouldnt cancel each other out, but someone also suggested that the sub may have been accidentally wired out of phase?

For those of you that have done this, did you have to switch the phase for one of the subs?

Thanks!

This a really common problem. Some amps a phase inverting and some not. So you have one sub with a phase inverting amp and the other isn't.

This has to be a problem when members are mixing amp, using say preouts and an external amps for the mains, and the receiver for the rest. There is about a 50/50 chance of having everything out of phase, if you don't check relative phase of the amps on the scope. You noticed the problem right away, as the units are in close proximity.

 

[Captainmorgan89]

They are both the exact same sub, thats what has me confused...

 

[TLS Guy]

They are both the exact same sub, thats what has me confused...

In that case, the speaker is either wired out of phase, or the plate amps are of a different generation and different. There are only two explanations for what you have experienced.

I would really check output in both phases with an spl meter, to make sure your observation is accurate.

 

[Captainmorgan89]

The difference is so substantial, its really hard to miss