Output: L+R Sum vs. Copy L->R

Karl Houseknecht

Karl Houseknecht

Power User
Can someone elaborate on the difference between these two settings as explained in the manual? I'm not sure I understand the subtlety of the summing vs copying. Does the Copy L->R actually result in the same mono signal available at both physical outputs? And how does that differ from summing?

Just FYI, in my rig, I'm running Output 1 as a single XLR send to the FOH, in mono. Output 2, I'm plugging both L and R outputs into the L and R sides of a poweramp, but running in mono so that I can individually control the volume of each monitor. I also have the Copy Out1 to Out2 on.
 
the difference really is only if you have a stereo signal chain like a reverb at the end or 2 rows being panned in stereo. When you "Sum" it it takes the full stereo signal and turns it into 1 mono signal. That's great if you want to hear everything you designed in a stereo patch in mono, but one thing to watch out for is if you are using the enhancer block there can be phase cancellation, and you final tone will be less then what it was in stereo. So be careful.

Copy L to R I'm not sure where this is are you talking about Copy output 1 to 2? This just takes whatever is coming out of one and puts it in the other mono to mono so now you have 2 identical outputs so if you just have a mono signal chain like 1 amp to 1 cab block you can get 2 outputs of that and send them to 2 different destinations like 2 poweramp inputs or whatever you have.

Edit: Oh i see it. I've never used it but I believe it works like Copy 1 to 2 works whatever is coming out of "L" gets duplicated in "R" so if you have patches with enhancers and you want to run 2 mono outputs and DON'T want to SUM because that'll cause problems you can use Copy L->R to get 2 mono signals that play nice together and don't phase cancel.

hope this helps
 
Copy L->R essentially clones the L signal on the R output. So anything that was unique to the R signal is now gone. Examples of where you would lose something: ping-pong delay. You would only hear half of it (the half on the L) so it would sound like the repeats are twice as distant in time from one another (i.e. a 120ms ping-pong delay would sound like a 240ms mono delay)

L+R Sum actually takes both the L and R signal, adds them up together, and pumps that out to both your L and your R output. You do not lose anything. However, this one may cause some phasing issues if you use certain effects blocks or set certain parameters a certain way. Example: the enhancer block is a big no-no when summing to mono, as it causes phasing artifacts that make your tone suck (sounds phasey and thin). Other things to watch out for are any effects that have a phase parameter (chorus, some delays, and the phaser of course).

I use L+R Sum, but I audition all my presets (which are designed in stereo) to make sure I don't have any phasing issues. In some cases, it's unavoidable, and I simply flag those presets as "not mono compatible" and I avoid them when playing a venue with a mono PA system.
 
Dpoirier said:
Other things to watch out for are any effects that have a phase parameter (chorus, some delays, and the phaser of course).
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That's what I was looking for here. Thanks. I do use chorus after the amp simulation on some patches, and sometimes use phaser, although that is typically before the amp. How can I ensure there will be no phase issues and that these effects will sound good in mono?
 
Karl Houseknecht said:
Dpoirier said:
Other things to watch out for are any effects that have a phase parameter (chorus, some delays, and the phaser of course).
Click to expand...

That's what I was looking for here. Thanks. I do use chorus after the amp simulation on some patches, and sometimes use phaser, although that is typically before the amp. How can I ensure there will be no phase issues and that these effects will sound good in mono?
Click to expand...

compare by going from l+r sum and stereo. But general rule, don't use phase reverse in mono
 
Karl Houseknecht said:
javajunkie said:
compare by going from l+r sum and stereo. But general rule, don't use phase reverse in mono
Click to expand...

Thanks, Sean. Is "phase reverse" a parameter on some of those effects?
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Yes. Delay, chorus, flanger, enhancer

The wide parameter in the chorus is something to watch out for too.
 
Thanks again. I see it on delay and chorus, but not on flanger. Also not on quad chorus but I do see that Wide Mode, which I'll make sure is off. Thanks for the tips! Very helpful.
 
Karl Houseknecht said:
Thanks again. I see it on delay and chorus, but not on flanger. Also not on quad chorus but I do see that Wide Mode, which I'll make sure is off. Thanks for the tips! Very helpful.
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Flanger is only a phase for the dry signal (for thru-zero flanging) - that shouldn't have any impact on stereo/mono
 
Thanks again. I'm reworking my gigging patches because I created the first ones when I was brand new to the Axe. Trying to be a little more efficient and make sure I'm doing things right.
 
A few general questions. Which I/O settings should I choose for input 1 mode and output 1 mode if I:

1. Run output 1 to monitor and output 2 to FOH?
2. Run output 1 to FOH and output 2 to a cab?
3. Additionally, do sound guys prefer to receive the signal in mono or stereo? Why not use stereo on input 1 and output 2?
 
Hansen said:
A few general questions. Which I/O settings should I choose for input 1 mode and output 1 mode if I:

1. Run output 1 to monitor and output 2 to FOH?
2. Run output 1 to FOH and output 2 to a cab?
3. Additionally, do sound guys prefer to receive the signal in mono or stereo? Why not use stereo on input 1 and output 2?
Click to expand...

Input mode depends on what instrument or input you're using. if you're using a regular guitar (acoustic, electric, bass, whatever) with a single output, then it's best to choose Left and use either the Front Input or the Rear Input 1 Left.

Output mode depends on how your presets are built and what effect you want to achieve. even with the output mode set to Stereo, i can still send a Mono signal to anywhere by just sending 1 signal using 1 cable - instant Mono. however, if your preset uses a Panning effect, which obviously depends on 2 speakers/Stereo to sound right, sending that Mono signal will make the Panner not sound right (it will sound like a Tremolo instead).

so your #1 and #2 really depends on exactly what you expect it to sound like and what instrument you're using. it could be any mix of stereo, left only, l+r, etc.

generally sound guys prefer a mono signal. the most important reason is that most PA systems are configured in Mono, yes even if there is a speaker on the left and right of the stage. an audience member sitting on the left of the house wants to hear what going on on the other side of the stage, but a Panned Stereo PA setup won't let him! other reasons are # of channels available on the board and effort put in mixing the band.
 
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