Mono - Left Out vs L+R into PA

[PianoManChuck]

Assuming a single mono PA for both examples, can someone explain the technical differences between the two following mono scenarios?

 

1) Left Out -> PA Ch1 input

 

2) Left Out -> Pa Ch1 input, and Right Out -> Pa Ch2 input

 

Aside from possible phasing problems with the 2nd option, I'm just trying to understand the physics behind these two scenarios.

[Joe Muscara]

Hmmm. Good question. I believe Mike has said elsewhere that using Left Out only sums the two outputs to mono internally, and that the PX-5S does it well without phase issues.

 

Theoretically, scenario 2 would do the same thing (assuming volume, balance, and cabling match enough). However, if the internal sum to mono does more than just combine the two signals, then it could be different.

 

Have you tried both methods?

[Mike Martin]

Assuming #2 has no panning, there would be no difference between #1 and #2. 

[PianoManChuck]

OMG!  I just can't believe that I didn't even think of panning!  As soon as Mike mentioned panning, everything became 100% crystal clear to me.

Thanks, Mike!

[Joe Muscara]

Assuming #2 has no panning, there would be no difference between #1 and #2. 

Thanks for the clarification & info, Mike. Now I am an expert.

 

(Actually, I read PMC's post as going into two inputs on a single PA-type speaker, like inputs 1 & 2 of a QSC K10 or similar. So they would have been summed there. The full PA scenario would have been slightly different, or could be. But in that case without panning as well as mine and the single Left out, the result is the same.)

[b3maniac]

I run both outputs of my PX5S to the FOH using two adjacent channels on the board. Both channels are not panned, and the keys sound great out front. I haven't run into any cancellation or phasing issues at all.

[PianoManChuck]

Thanks B3Maniac, that's good to know... and encouraging!!