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Wish Normalize volume behavior in Cab block

greiswig

Power User
I'm actually not sure whether this is a bug or a wish. Or both.

In the amp block, you can set it up so that on any given channel, slots 1 and 3 are the "left" cabinets, and 2 and 4 are the "right" cabinets. This allows for some interesting possibilities. For example, you can pan the output of the amp all the way to the left and only have cab slots 1 and 3 working. It effectively doubles the available cab options using the same cab block.

But...there are some quirks associated with this. I'll use the scenario outlined above to describe, where Amp is panned full Left (-100), and is being processed only by cab slots 1 and 3:
  1. Muting slots 2 or 4 causes a large increase in volume out for the block as a whole. That means any time you go from two cabs to one or vice versa, it affects the amp that isn't even using those cab slots. It also makes visual alignment of the slots more difficult, because to get only those two lines showing on the visual, you have to mute the others. Then you can see the alignment, but you're listening at twice the volume as before.
  2. Reducing the level on slot #2 also affects the output level on the 1 and 3 slots.
  3. Soloing either the 1 or 3 slot has a similar effect: the output volume jumps by 6dB or so.
  4. Changing the levels of slot 1 or 3 to -40 or thereabouts results in a change in volume and tone that is not the same as what you would get if slots 2 and 4 were muted. Overall volume is reduced.
  5. Centering the output pan on the amp block also roughly doubles the output at the cab block.
So...I guess I wish these didn't happen this way, but there may be a logical reason they have to.
 
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unix-guy

Legend!
As far as I understand the Cab block volume IS normalized across all 4 IR slots.

Your setup is probably less common though, so might be related to those specific settings (stereo input).
 

greiswig

Power User
As far as I understand the Cab block volume IS normalized across all 4 IR slots.

Your setup is probably less common though, so might be related to those specific settings (stereo input).

Maybe I'm using the term "normalize" wrong, then? What I'm after is that there would be no volume change when using the channels this way, just as there is no volume change when the amp output is centered and you add, mute, or solo a channel.
 

Admin M@

Administrator
Fractal Audio Systems
Moderator
You need to just change to each channel and set the LEVEL knob as desired.
Please note that the zoomed in grid view with VU meters allows you to easily do exactly this.
 

greiswig

Power User
You need to just change to each channel and set the LEVEL knob as desired.
Please note that the zoomed in grid view with VU meters allows you to easily do exactly this.

I get that, but it is a labor-intensive workaround and it still isn't clear to me why the channels would behave one way when the amp output is centered, and another way when it is panned hard left or right. Items 1-4 in my original post change their behavior according to amp block panning. I'm not clear on why that should happen that way, and would like it to change as a workaround for not having the ability to mute channels by scene.
 

Admin M@

Administrator
Fractal Audio Systems
Moderator
I get that, but it is a labor-intensive workaround and it still isn't clear to me why the channels would behave one way when the amp output is centered, and another way when it is panned hard left or right. Items 1-4 in my original post change their behavior according to amp block panning. I'm not clear on why that should happen that way, and would like it to change as a workaround for not having the ability to mute channels by scene.

I think you have a few misunderstandings. Try an experiment with the same IR loaded in all four slots.
 

mr_fender

Fractal Fanatic
Each cab is a potential extra signal to be added to the cab block's output. When you unmute a cab, the output level is reduced to compensate. In stereo mode, the input has full stereo separation, but the output does not. You can pan all four cabs anywhere you want even though two are designated right or left. Easiest way to think about it is the normalized output of the block is like a whole pie. The number of unmuted cabs determines how many slices that pie is cut up into. So 4 cabs means each cab makes up 1/4 the total normalized signal. By muting one of those cabs, now you only have 3 slices and each slice makes up 1/3 of the pie. 1/3 is bigger than 1/4 so that cab is now louder. Changing each cab's individual level has the same effect, except now you are moving where each slice is cut and you have pieces that are not all the same size anymore.
 

greiswig

Power User
I think you have a few misunderstandings. Try an experiment with the same IR loaded in all four slots.
OK.
1. "Muting slots 2 or 4 causes a large increase in volume out for the block as a whole. "
Check on this one. Still does the same thing with all four cabs identical.

2. "Reducing the level on slot #2 also affects the output level on the 1 and 3 slots."
Check on this one. Still does the same thing with all four cabs identical.

3. "Soloing either the 1 or 3 slot has a similar effect: the output volume jumps by 6dB or so."
Check on this one. Still does the same thing with all four cabs identical.

4. "Changing the levels of slot 1 or 3 to -40 or thereabouts results in a change in volume and tone that is not the same as what you would get if slots 2 and 4 were muted. Overall volume is reduced."
Partial check on this one: volume does change, but as expected the tone does not (except for F/M effects)

5. "Centering the output pan on the amp block also roughly doubles the output at the cab block."
Check on this one. Still does the same thing with all four cabs identical.

So...changing all four slots to an identical cab seems to largely result in the same behavior. What is it that I am missing?
 

greiswig

Power User
Each cab is a potential extra signal to be added to the cab block's output. When you unmute a cab, the output level is reduced to compensate. (SNIP)

Here's the problem, though: this does NOT happen when the amp block is panned center. The system knows to compensate somehow. I'm only asking that it also do so when the amp output is panned.
 

Admin M@

Administrator
Fractal Audio Systems
Moderator
The fact that you're talking about increments of 6dB should tell you that you're adding two identical signals together somewhere.

What do you have the Input Mode of the Cab block set to?
 

greiswig

Power User
What do you have the Input Mode of the Cab block set to?
Input mode is set to stereo, which is the only way you can get it to respect the panning of the output from the amp block.

Why would muting unused (stereo right, in the case of my example) channels cause the addition of signal in any case? And that's just one of the examples of oddness.
 

Bakerman

Axe-Master
Why would muting unused (stereo right, in the case of my example) channels cause the addition of signal in any case? And that's just one of the examples of oddness.

It's the automatic normalization. The block doesn't know you aren't sending (or planning to send) any signal to IRs 2 & 4, so the overall output level is reduced. Mr. Fender explained the idea well in post #7.

If maintaining a certain output level is important during the "mute 2 slots to see remaining 2 for alignment" step, you can reduce the cab block (not individual IR slots) level by 6 dB then and bring it up again afterward. That would probably be the easiest solution until a normalization on/off switch is (maybe) added.
 

sprint

Fractal Fanatic
Related question - I typically run a centre panned amp block into a stereo cab block with cab slots 1/2 unmuted / hard panned. The cabs are a L/R IR pair with slightly different mic placements. I like the slight stereo effect this provides, and the bigger stereo effect it enables with an enhancer block active between amp / cab, however, I'm challenged to keep the resulting L/R signals similar in volume accross varying input tones (particularly with cleans). I use the individual cab level knobs to roughly equalize the L/R volume (cut vol on the stronger cab slot), but they still drift apart more than I expect at times. Do you guys think this is just the nature of using "stereo" IRs with varying tonal input?, or is there another way for me to better use the cab parameters to control the L/R volume spread in this scenario?

Panning L/R less than 100% reduces the L/R volume spread but doing that seems to degrade the desired stereo effect so I've resisted this option.
 

greiswig

Power User
Ok, so it sounds like the normalization really depends on the amp block being panned center in order to work as expected, and actually causes the issues I am describing here. So I’ll go back to my initial preference, which is to allow scene controllers to selectively mute channels in the cab block.

But I’d still like to hear from @Admin M@ about why he expected a different result in the experiment I conducted this morning with 4 identical cabs.
 
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Joe Bfstplk

Fractal Fanatic
Ok, so it sounds like the normalization really depends on the amp block being panned center in order to work as expected, and actually causes the issues I am describing here. So I’ll go back to my initial preference, which is to allow scene controllers to selectively mute channels in the cab block.

But I’d still like to hear from @Admin M@ about why he expected a different result in the experiment I conducted this morning with 4 identical cabs.
It seems to be an issue with the pan law for the amp block output to me. Pan L or R, 6dB drop compared to center, correct? My guess is that the pan law has both at full volume when centered, which would account for yhe signal doubling. Sometimes, like dual amp blocks panned L and R, for example, that makes sense, but a switch to choose that or a constant-volume law would be handy....
 

greiswig

Power User
It seems to be an issue with the pan law for the amp block output to me. Pan L or R, 6dB drop compared to center, correct? My guess is that the pan law has both at full volume when centered, which would account for yhe signal doubling. Sometimes, like dual amp blocks panned L and R, for example, that makes sense, but a switch to choose that or a constant-volume law would be handy....

I think you're probably right. And @Bakerman probably nailed it when he said that it's because the unused channels aren't aware they won't have signal sent to them, so this pan law is being applied when it "shouldn't" be. So yeah, a switch to flip would be great.

...and/or allow for scene controllers to mute and unmute channels. ;)
 

Bakerman

Axe-Master
The amp balance control pan law is irrelevant in the example given. It's all about the cab block normalization based on number of active cabs and their relative level values.

If you were comparing amp block balance at center vs. either side while all 4 cabs were unmuted, then the pan law would matter, and a different one could possibly keep levels more even as you fade from hearing 2 to 4 cab slots (by moving balance from either side toward center while all 4 slots are unmuted). If you're just balancing the amp block L or R to choose one IR pair or another, it doesn't matter.
 

greiswig

Power User
The amp balance control pan law is irrelevant in the example given. It's all about the cab block normalization based on number of active cabs and their relative level values.

I'm still not getting this. If this were true, then why would it behave "normally" when the amp output is panned center? Or, alternatively, why would it NOT also add to volume every time you added/unmuted a channel when the amp block was panned center?
 

Bakerman

Axe-Master
I'm still not getting this. If this were true, then why would it behave "normally" when the amp output is panned center? Or, alternatively, why would it NOT also add to volume every time you added/unmuted a channel when the amp block was panned center?

Because you're hearing all the IRs then. This does actually apply to point 5 in your original post.

In post #17 I was referring to the amp balance left, mute/unmute IRs 2 & 4 scenario. The amp balance control's pan law doesn't have a role in the level change heard then.
 

greiswig

Power User
Because you're hearing all the IRs then. This does actually apply to point 5 in your original post.

Does not compute. It's official. I'm dense. :confounded:

But anyway, I think this could all be for naught if only my wish to have scene-level control over which cab block channels are muted were implemented. Then we could have up to 8 different IR combinations in one cab block.
 
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