How to test if an amp's output is in phase?

[Cableaddict]

I have some 2 X 12" subs, and one is about 6 dB too low (just a guess, using my ears. Each sub has a dual-channel Hypex plate amp.

I've tested all 4 amp channels and they seem reasonably close. The drivers also seem OK, so I'm wondering if perhaps one of them is out of phase?

Sure, I can just reverse one and listen if things improve, but is there actually a way run a signal through an amp, and see if the output is in phase?


- I'm guessing, yes, but I'd need a scope, which I don't have. - but I'm hoping for a software solution.


SO?


thx.

 

[rayma]

is there actually a way run a signal through an amp, and see if the output is in phase?

Face two of the subs together, an inch or two apart. Feed them both the same signal.
If the acoustic output drops significantly compared to when they are separated,
they're out of phase with each other.

 

[nigelwright7557]

I use a PP3 battery.
Briefly power the speaker from the battery with battery plus to speaker plus.
The cone should move forward if it is phased correctly.

I have heard of speakers being sold and the phasing was wrong.

 

[TNT]

One of your balanced connection has lost either a cold or hot connection - thats 6 dB.

//

 

[xrk971]

1.5v battery is inescapable proof of polarity/phase of speaker or amp wiring. Put positive signal into amp (voltage divider to get maybe 250mV) input and see which way cone moves. It will tell you if your amp is inverting too.

 

[cbdb]

If you can play something with a lot of kick drum, all the drivers should move in the same direction.