Stereo Cab block question

unix-guy

Master of RTFM
Yesterday I was playing around with the ML Legends cab pack (great, by the way!).

I normally use a stereo Cab block with a different IR panned hard left and hard right.

When trying the new IRs using the same preset, I didn't want to change both the left and right slots to the same IR, so I muted one and panned the other dead center.

It felt to me as if there was a noticable volume increase with 1 IR panned center versus 2 copies of the same IR panned hard left/right.

Is this expected? If so, can someone explain?

I was playing via my Matrix and 2 passive Xitone wedges sitting right next to each other.
 
Two sides being slightly out of phase?

Is there a noticeable volume difference when you use 2 different IRs panned hard right and left?
 
Two sides being slightly out of phase?
Possible, but not by any settings I've made. They are all identical...

I should check headphones, too. Make sure it isn't a phase issue with the amp or wedges.
Is there a noticeable volume difference when you use 2 different IRs panned hard right and left?
As compared to putting them both in the center? I didn't test that... But I will.
 
I should note that I have both stereo chorus and stereo delay and a reverb block after the cab, in case that matters...
 
I have noticed that on several different modelers (Boss GT10/100, Helix LT, Axe FX2) over the years. I have tried it on the AXE3. Not sure if it a perceived volume difference or real.

Edit: Meant to say I have not tried on the AXE3.
 
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There was a thread about this just the other day. It's annoying, but someone pointed out that from the manual it's a feature; not a bug or issue. The block keeps the "relative volume" equal; so if you mute one side, the other side blasts in volume to 'compensate.' It makes it impossible to determine the tone/volume contribution of an individual cab in a stereo setting, but I guess the powers that be have a good reason for making it this way.

Maybe there's some way we could add this to the wish list to make this not happen...
 
There was a thread about this just the other day. It's annoying, but someone pointed out that from the manual it's a feature; not a bug or issue. The block keeps the "relative volume" equal; so if you mute one side, the other side blasts in volume to 'compensate.' It makes it impossible to determine the tone/volume contribution of an individual cab in a stereo setting, but I guess the powers that be have a good reason for making it this way.

Maybe there's some way we could add this to the wish list to make this not happen...
I think you're talking about the "relative mix" feature of the Cab block... But I'm talking about using the same IR in both slots with the same volume.

Only difference is in the panning...

Maybe it is related, but I don't know. :confused:
 
I think you're talking about the "relative mix" feature of the Cab block... But I'm talking about using the same IR in both slots with the same volume.

Only difference is in the panning...

Maybe it is related, but I don't know. :confused:
Yep. Same IR, same volume, each panned hard stereo. As soon as you mute, say, the left one, the right one blasts in volume and vice versa.
 
Yep. Same IR, same volume, each panned hard stereo. As soon as you mute, say, the left one, the right one blasts in volume and vice versa.
That is not what I'm describing. Kind of the opposite...

I'm talking about 1 IR panned to the CENTER being louder than the same IR in 2 slots and panned L/R

Of course, maybe it's anytime you change from 2 IRs to 1?
 
There is an auditory phenomenon called binaural summation, which gives the perception of a volume increase when your hearing stereo/dual mono to both ears vs equal loudness from a mono source/one ear.

Could be what your noticing, sometimes our perception of sound differs than what is actually happening with sound, kind of like how there are so called optical “illusions” which can trick the brain into thinking a pattern is spinning when it’s really perfectly still.
 
There is an auditory phenomenon called binaural summation, which gives the perception of a volume increase when your hearing stereo/dual mono to both ears vs equal loudness from a mono source/one ear.

Could be what your noticing, sometimes our perception of sound differs than what is actually happening with sound, kind of like how there are so called optical “illusions” which can trick the brain into thinking a pattern is spinning when it’s really perfectly still.
I dunno... Maybe.

I think it's probably something to do with the "spatial" nature of panning.

The signal is still stereo as my delays are still "bouncing" between the speakers.
 
I know that in many DAW's, you can choose the pan laws, and if not they all have a default setting. Perhaps this is coming into play even if your not using a DAW.

https://en.wikipedia.org/wiki/Pan_law
Interesting reading, but again this is not what I am experiencing... Unless the Axe Fx has no compensation as described in that article. That would explain why there is a (perceived) volume increase when panned to the center.
 
A 3 dB pan law and 6 dB output adjustment for 1 IR vs. 2 would explain it.

Say you're getting -10 dB output in each channel from two IRs panned L/R. Then Disable IR 2:

L -4 dB, R muted

Pan IR 1 to center:

L -7 dB, R -7 dB
 
A 3 dB pan law and 6 dB output adjustment for 1 IR vs. 2 would explain it.

Say you're getting -10 dB output in each channel from two IRs panned L/R. Then Disable IR 2:

L -4 dB, R muted

Pan IR 1 to center:

L -7 dB, R -7 dB
Sounds logical.

I've never heard anyone from Fractal mention a pan law before... But after reading the previously posted link, I assume that must be a part of the Axe Fx.

Would be good to get an official comment.
 
A meter could also be used to verify this. Send a test tone through the cab block and note the left channel output level at each step. Axe-FX II cab Pan L/R controls use a 6 dB pan law BTW.
 
I believe this is by design as the cab block normalizes the individual slots so that the mix has the same relative loudness... from the manual:

"
Cab 1, 2, 3, 4 Level – This parameter may seem straightforward enough, but it can actually be a bit tricky until you understand how it works. Rather than simply controlling the overall level of each Cab IR as you might expect, this sets relative levels between the IRs when more than one is loaded. The final blend is then normalized1 and controlled via the Level parameter on the Mix page—a master control for all four Cab IRs. So, for example:

  • ƒ When only ONE Cab IR is in use and the other three are muted, this control will have no effect since relative level doesn’t apply without two or more Cab IRs to compare.

  • ƒ When TWO (or more) Cab IRs are loaded, you only need to adjust the one(s) you want quieter. Think about it: reducing Cab 1 to –2dB and Cab 2 to –4 dB is the same as leaving Cab 1 alone and setting Cab 2 to –2 dB. Only the difference counts!

  • ƒ With more than one Cab IR in use, you will hear the tonal blend change, but the overall volume will remain relatively the same because again, the blend is normalized as you adjust. Do keep in mind however that because of their frequency contents, some cabs may be perceived as louder or quieter than others.
1 Normalization in this case makes the output signal as loud as it can be without distorting."


If you're soloing one cab IR its level control is bypassed... that being said, turning down the Level of the block on the mix page by the corresponding amount of the solo'd IR's level, might have a similar effect?
 
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