Speaker phase - how to test if out of phase ?

[Buckster]

<EDIT> was mostly user error - I had "Dolby upmixer" set on rather than straight Multichannel In - with it set off the speakers are correctly in phase

how odd - but must be part of the way the upmixer works


please can you help me interpret the results - these after time alignment and I did double check my wiring to my AVR (Denon X7200W).


first screenshot shows the Left speaker wired out of phase, Centre is the Genelec 8030C, the Right speaker in phase (green)

second screenshot shows the Left speaker wired to AVR in phase Green and out of phase Blue

 

[Keith_W]

To tell if two curves are out of phase, pick a point on x-axis. Read how many degrees it is. Then read the other curve. Subtract one from the other. The curve you posted are out-of-phase.

A really easy way to tell is to tell is to sum the curves. In REW, Trace Arithmetic A+B.

I did a quick simulation for you to show you what you should expect to see. In red/green is the measurement for L/R speaker.

In brown, we have the summation of the L/R speaker. There are no phase issues, and the result curve looks nice.

In blue, the horrible curve at the bottom: I inverted the polarity of the right channel then summed it with the left. You can see copious comb filtering.

 

[Buckster]

thanks very much for your reply - I'll try the sum of the curves in REW thanks

I updated my post to say I found that the speakers were out of phase with centre when Dolby Upmixer set to On - as in Multi In + Dolby Surround

no idea why must be part of the way it works

with Upmixer set to off - all in Phase

 

[Andysu]

crossover frequency division on behringer DCX 2496 no filter at the lower end only crossover at middle range of the LF 24dB L-R 499Hz - HF 24dB L-R 499Hz to 20,000KHz