Running mono

[JC_MuscleShoals]

Our system at church is mono. What is the best way to run the unit in mono? I noticed there are a couple of different mono options. Do i need to set anything up in the software? I also thought I read where just pluggin it in left out does it for you but I may be mistaken?

 

[javajunkie]

plugging into left will give left signal only. That may be fine a many presets. It may not work for some that use heavily panned stereo effects. You can set the the output copy L to R (same as pluggin into the left only the right out is just a copy of the left. Or you can select sum L+R (it takes both signals, mixes them together, and output them on both channels). With this option you have to worry about phase issues. If the Left and right signals use any effects that may change the phase of one signal to the other, it can really mess with your tone. For example, if you use the default settings on a 2290 delay, one side of the delay is 180 degrees out of phase the with the other. In stereo this sounds huge. In mono, the delays cancel each other out and you get 0 delay level.
The classic enhancer will also cause phase issues (comb filtering effect). So you need to check your patches for mono compatibility (switch between stereo and L+R or copy L > R) to be sure then correct any anomalies going from stereo to mono.

Look for any effects that have phase reverse (delays, modulation) plus the enhancer. They are the ones that can cause the greatest issues.

 

[greiswig]

plugging into left will give left signal only. That may be fine a many presets. It may not work for some that use heavily panned stereo effects. You can set the the output copy L to R (same as pluggin into the left only the right out is just a copy of the left. Or you can select sum L+R (it takes both signals, mixes them together, and output them on both channels). With this option you have to worry about phase issues. If the Left and right signals use any effects that may change the phase of one signal to the other, it can really mess with your tone. For example, if you use the default settings on a 2290 delay, one side of the delay is 180 degrees out of phase the with the other. In stereo this sounds huge. In mono, the delays cancel each other out and you get 0 delay level.
The classic enhancer will also cause phase issues (comb filtering effect). So you need to check your patches for mono compatibility (switch between stereo and L+R or copy L > R) to be sure then correct any anomalies going from stereo to mono.

Look for any effects that have phase reverse (delays, modulation) plus the enhancer. They are the ones that can cause the greatest issues.

Point of clarification: copy L>R does NOT cause these phase issues, but sum does? That was my reading of the manual, but it isn't clear why. The former seems to be a subset of the latter, so I'm confused as to how it would avoid phasing issues on all effects when some are flipped 180 degrees.

 

[dsl]

Point of clarification: copy L>R does NOT cause these phase issues, but sum does? That was my reading of the manual, but it isn't clear why. The former seems to be a subset of the latter, so I'm confused as to how it would avoid phasing issues on all effects when some are flipped 180 degrees.

copy L>R = left in both channels - no phase issues because both L & R will be identical - they will both be "left".

 

[bkrodgers]

I guess a related point would be that you don't want to just convince a sound guy to let you run two XLRs into the board. You want to make sure the sound system is really setup to run stereo, and that he's actually going to pan you left/right. Otherwise, you'll run into the same issues as you would with L+R sum, right? It's just happening at the board instead.

 

[greiswig]

copy L>R = left in both channels - no phase issues because both L & R will be identical - they will both be "left".

Thank you. But what is the difference between this and just running the left output of a full stereo signal?

 

[bkrodgers]

Thank you. But what is the difference between this and just running the left output of a full stereo signal?

This feature is about what you are doing with the right output, not the left. You're right, there's no difference between what happens on the left output. But turning copy L>R gives you a second copy on your right output, instead of a right output that might cause phasing issues in mono.