Automatic Gain Staging for Input

The AxeFX already has input gain parameters. This would just be a way to provide some automated help in setting that gain. This feature has been done in other products, so this has already been demonstrated to be useful. Anyway, as an optional feature, it wouldn't take anything away from how the AxeFX currently works, so you wouldn't be losing anything. After all, the whole point of a digital modeler is to provide flexibility that can't be achieved with a tube amp.
 
Most people know that as you adjust the input sensitivity in the Axe-Fx, what you are doing is basically padding or boosting the signal sent to the AD/DA converters. What a lot of people do NOT know is that as you do this, the volume is adjusted equally but oppositely in the digital realm.

Basically, if you adjust the Instrument Input sensitivity downwards and pad the front input by -5 db, then at the same time on the other side of the AD/DA conversion, that signal is boosted equally by +5 db.

This means that your guitar is always set to UNITY GAIN going into the Axe-Fx. The only thing you're actually doing by adjusting the Input Sensitivity control is optimizing the Axe-Fx's ability to detect as much dynamic range from your guitar as possible.

In other words, the Axe-Fx's Amp Block is already optimized for your guitar's level by default.


However, it could be cool for this setting control to adjust itself. Turning it on could maximize the Input Sensitivity and every time your guitar clipped the Input, The Input Sensitivity would back off just a bit until it no longer senses clipping.
 
GreatGreen said:
Most people know that as you adjust the input sensitivity in the Axe-Fx, what you are doing is basically padding or boosting the signal sent to the AD/DA converters. What a lot of people do NOT know is that as you do this, the volume is adjusted equally but oppositely in the digital realm.

Basically, if you adjust the Instrument Input sensitivity downwards and pad the front input by -5 db, then at the same time on the other side of the AD/DA conversion, that signal is boosted equally by +5 db.

This means that your guitar is always set to UNITY GAIN going into the Axe-Fx. The only thing you're actually doing by adjusting the Input Sensitivity control is optimizing the Axe-Fx's ability to detect as much dynamic range from your guitar as possible.

In other words, the Axe-Fx's Amp Block is already optimized for your guitar's level by default.


However, it could be cool for this setting control to adjust itself. Turning it on could maximize the Input Sensitivity and every time your guitar clipped the Input, The Input Sensitivity would back off just a bit until it no longer senses clipping.
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This request is not about the Instrument Input, it is specifically about actually adjusting the level seen by the input... As if you increased Input Gain or the Level of the Input block.
 
unix-guy said:
This request is not about the Instrument Input, it is specifically about actually adjusting the level seen by the input... As if you increased Input Gain or the Level of the Input block.
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You said "it's not about the Instrument Input, it's about adjusting the level of the input."

Which input do you mean?
 
GreatGreen said:
You said "it's not about the Instrument Input, it's about adjusting the level of the input."

Which input do you mean?
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Exactly what I said.

The Instrument Input (as you noted) is compensated. When you adjust it, the actual level doesn't change (again, as you noted).

This post is about the audible signal level of the input, not the optimized AD input level (just like Input Gain).

Hopefully that is more clear?
 
unix-guy said:
Exactly what I said.

The Instrument Input (as you noted) is compensated. When you adjust it, the actual level doesn't change (again, as you noted).

This post is about the audible signal level of the input, not the optimized AD input level (just like Input Gain).

Hopefully that is more clear?
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I see. The original request is asking for the guitar's level, immediately after it has been digitized and placed in the Axe-Fx's Grid, to be automatically adjusted to some "optimal" value that differs from the natural volume of the signal the guitar sends to the Axe-Fx. In that case I don't think it's possible to do, at least in terms of automation.

There are several problems here. First, the Axe-Fx cannot see or know what is plugged into it, so it can't know when you change guitars and therefore when to adjust the level. Additionally, any hypothetical "optimal" level would be entirely arbitrary. What's optimal for you might be entirely different for me. Some people like louder guitars, some like quieter guitars. At first the answer to that might seem intuitive. Why can't you just create a parameter that could do something like "always set a guitar's natural volume to plus or minus X dbs from unity?" Well, the functionality of that control would depend on the Axe-Fx being able to know how loud your guitar naturally is so it can make the adjustment, which again the Axe-Fx it does not and cannot know. Guitars are extremely dynamic instruments. If you were to try and program some way for the Axe-Fx to automatically set every guitar for some specific volume adjustment so it lands at some target level, by what values should the Axe-Fx use to determine how loud the current guitar naturally is to know how far to adjust it? Should it listen for transient volume? Average input volume? Average volume over how long? Seconds? Minutes? What frequencies should be used for this calculation? When should it listen for these changes? Constantly or when the user presses some button to tell the Axe-Fx to start listening because a new guitar has been plugged in? There is just no way to perform that kind of function consistently and reliably, compared to the Axe-Fx's already built-in solution for this problem.

To me it seems the best "automated" solution for this problem has already been implemented. Players are able to build unique sets of patches for each of their instruments, and in each patch, they can set the Input Block's Output Level to whatever they like. Have a single coil guitar that's too quiet for you? Create a set of patches for just that single coil guitar and crank the Input Block's Level in each of those patches, etc. That's about as close to the OP's request as is feasible. If it would require a button press or some other additional action taken by the player at guitar changes anyway, that action might as well control doing what the Axe-Fx can already do... changing to a new patch where the user presumably has already boosted or cut the guitar's signal to a patch-determined optimal level already.
 
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This feature has already been done in other products. It's not some new unproven technology.
 
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GlennO said:
This feature has already been done in other products. It's not some new unproven technology.
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Eh, just because it may have been done doesn't mean it's necessarily good or reliable. Actually, it inherently cannot be because it would depend on wildly inconsistent variables to work every single time it would happen. And more importantly, it wouldn't be better or even easier to use than the infinitely simpler function of "use your ears and set the volume how you like."
 
I'd wager that unity gain input isn't going to change anytime soon on Fractal products.

Easiest alternative is to add the Input Gain knob to your Global Performance page and do a little testing with all of your guitars to determine the setting each will need to reach the input level you want for your particular presets. That puts you two page button presses away from adjusting the input gain anytime you change guitars.
 
mr_fender said:
I'd wager that unity gain input isn't going to change anytime soon on Fractal products.

Easiest alternative is to add the Input Gain knob to your Global Performance page and do a little testing with all of your guitars to determine the setting each will need to reach the input level you want for your particular presets. That puts you two page button presses away from adjusting the input gain anytime you change guitars.
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The problem I believe this feature would help solve is the one about sharing presets. You might be right about it not ever appearing in a future firmware update though. This feature would be simple enough to implement and it would be darn effective, but I don't think building a preset sharing community has ever been a high priority for FAS.
 
GlennO said:
The problem I believe this feature would help solve is the one about sharing presets. You might be right about it not ever appearing in a future firmware update though. This feature would be simple enough to implement and it would be darn effective, but I don't think building a preset sharing community has ever been a high priority for FAS.
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Would this not also solve the problem of the unexpected guitar switch, or am I misunderstanding the original request? Had a jack problem with a guitar in the middle of one show, and had to play a second guitar with a different output (going back and forth between presets made for guitar 1 and guitar 2). Would've been nice to just have the input gain automated. Yes, I know the Performance Page can assist with this, but if it can be automated, why not?
 
GreatGreen said:
Players are able to build unique sets of patches for each of their instruments, and in each patch, they can set the Input Block's Output Level to whatever they like.
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You can simply adjust the global Input Gain control which was created for this purpose as well.
 
unix-guy said:
Huh? I'm not sure you're thinking of the right thing.

I'm talking about Input Gain not Instrument Input.
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I am.

I'm saying that if you have a main guitar you want to adjust the input Level for, so every patch will default to that specific input level adjustment, you can control that parameter here:

L9IZH4s.png



Then, if you have additional guitars you want to adjust the input levels of separately from the main guitar, you can do that per-patch here:

bzurQBA.png
 
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GreatGreen said:
I am.

I'm saying that if you have a main guitar you want to adjust the input Level for, so every patch will default to that specific input level adjustment, you can control that parameter here:

L9IZH4s.png



Then, if you have additional guitars you want to adjust the input levels of separately from the main guitar, you can do that per-patch here:

bzurQBA.png
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There's nothing preventing you from changing the Input Gain whenever you want.

I would propose you leave the default value as-is for your main guitar and dial your presets for that. Then adjust as needed for other guitars.

I have it on my Global Performance Page. Works perfectly...

However your method also works. Just different approaches ;)
 
GlennO said:
IMHO, yes it would. The reason I mentioned the preset sharing problem is because there's no workaround for that.
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I think sharing a DI sample and output sample along with the preset is the answer to preset sharing delemmas and also completely solves the "why doesn't my Ax3 sound like LT's (or other) syndrome" - we just need Axechange to allow uploads of companion DI and output sample(s) along with the preset to be shared, as well as a place for description of guitar used. A little more effort for the sharer, but, provides the sharee with everything they need to replicate a tone.
 
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