Instrument Input Volume?

Jeremy Johnson

Jeremy Johnson

Member
Hey guys!

So my buddy told me to put the instrument volume all the way up. He says it gives it a fuller sound and the Axe-Fx keeps it from clipping and to not worry about the red lights coming on. However, the manual says to avoid the red lights and go for a consistent yellow light. Thoughts?
 
Just tickle the red a bit and you'll be OK. As for "just turn the instrument volume all the way up..." not really. I use the guitar volume all the time, but rarely ever all the way up. If you are going for the "wall of noise" sound, by all means turn it all the way up. If you want to really enjoy the voice of a guitar, I go anywhere from barely on, to pretty well cranked, and enjoy all the wonderful tones in between.
 
Which red lights? Input or output?

Side note: Sounds fuller with the volume all the way up? That depends on how you've dialed in your preset. Some people keep the volume knob around 5,and roll it up for leads.
 
Rex said:
Which red lights? Input or output?

Side note: Sounds fuller with the volume all the way up? That depends on how you've dialed in your preset. Some people keep the volume knob around 5,and roll it up for leads.
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I can't remember without looking at it, but it's the two sets of lights right next to the screen.
 
Jeremy Johnson said:
Hey guys!

So my buddy told me to put the instrument volume all the way up. He says it gives it a fuller sound and the Axe-Fx keeps it from clipping and to not worry about the red lights coming on. However, the manual says to avoid the red lights and go for a consistent yellow light. Thoughts?
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So your assuming your buddy knows more about the unit than the people who created it and wrote the manual ?
 
I'm sure it won't hurt anything, but you are most likely destroying the dynamics of your guitar signal by blasting the input like that. Everything will sound like it is squashed to death by a brick wall limiter. If that's your idea of "fuller" then go right ahead. 24 bits of dynamic range doesn't do much good when you only utilize the top 10% of it.
 
Jeremy Johnson said:
I can't remember without looking at it, but it's the two sets of lights right next to the screen.
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I was trying to determine whether its's the input clip light or the output clip light that you're looking at. It sounds like you're referring to the input clip light.

It won't hurt your tone if the input clip light comes on a little, but you don't want to drive it solid red. There is no tonal advantage to any setting of input levels. When dialied in optimally per the manual, you get the best signal-to-noise ratio out of the Axe-Fx. But chances are that, at any setting, your guitar will make more noise than the Axe will.
 
Jeremy Johnson said:
I'm assuming that my friend who has had an Axe-Fx for over a year knows more about it than me, yet I wasn't sure, so I posted here.
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The input 'Instrument' level is only to get the best 'signal-to-noise' ratio going into the 'Analog-to-Digital' converters. It is 'compensated' at the output, meaning the higher the level going into the 'A/D' converters the lower the output and and vise-versa, in an attempt to preserve the gain structure of your signal chain so that your guitar will react with the models much like their 'real world' counterparts.

BUT......This 'compensation' is not perfect at the extreme ends of the range, Turning it up all of the way up will simply result in more signal entering the grid and driving the amp a little harder. This is the same as increasing the 'Input Trim' in the amp block, or the 'Level' parameter in the 'Input Gate', or adding a 'null' filter block at the beginning of the grid with it's level increased, or???.............But without loosing most of the dynamic range of your guitar signal......;)
 
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Agreed. There are much better ways to skin that cat that don't come at the cost of dynamics. I think I remember reading somewhere here on the forum that the internal processing of the Axe uses floating point numbers, so the effective dynamic range in the digital realm is far wider than that of the A/D and D/A converters. You need to watch your levels at the input and output, but in between on the grid you can get pretty crazy with the boosts and such.
 
mr_fender said:
I think I remember reading somewhere here on the forum that the internal processing of the Axe uses floating point numbers, so the effective dynamic range in the digital realm is far wider than that of the A/D and D/A converters. You need to watch your levels at the input and output, but in between on the grid you can get pretty crazy with the boosts and such.
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Yep. 32-bit floating-point arithmetic means the Axe has more than 1400 dB of internal dynamic range.
 
Rex said:
Yep. 32-bit floating-point arithmetic means the Axe has more than 1400 dB of internal dynamic range.
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I'm not sure that's true. Having finer gradations between points doesn't change the range. For instance, the difference between the freezing/boiling point of water is 180° on the Fahrenheit scale, but 100° on the Celsius scale. Same range of temperature, just different number of divisions.

I don't remember the dynamic range of the Axe Fx offhand, but let's say it's 120db. If I represent that with an integer, I'd have 121 points between 0db and 120db. If I represent it with a floating point value, I could theoretically have an infinite number of points. Doesn't change the range.
 
Cagey said:
I'm not sure that's true.
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It is.


Cagey said:
Having finer gradations between points doesn't change the range. For instance, the difference between the freezing/boiling point of water is 180° on the Fahrenheit scale, but 100° on the Celsius scale. Same range of temperature, just different number of divisions.

I don't remember the dynamic range of the Axe Fx offhand, but let's say it's 120db. If I represent that with an integer, I'd have 121 points between 0db and 120db. If I represent it with a floating point value, I could theoretically have an infinite number of points. Doesn't change the range.
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The Axe's dynamic range (>110 dB) is limited by the input and output converters. But in between—internally—the sky is the limit.

Putting it another way: have you ever had to worry about internal clipping inside of your Axe-Fx? Do you care whether the Cab block is causing the Rotary block to clip? Nope. There are LEDs to show input and output clipping, but there are no indicators for internal clipping, because it's a non-issue: the internal dynamic range is crazy big.

My old Roland GP-100 is a different story. You can check for clipping between each block, because sometimes you have to. No floating-point math. No 1400+ dB dynamic range.
 
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Rex said:
Yep. 32-bit floating-point arithmetic means the Axe has more than 1400 dB of internal dynamic range.
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Turn the volume if the amp block all the way up and reduce the volume in the next block by the same amount, that way the output will not change and the led will not display clipping but you get internal clipping, just try it and listen.
 
Cagey said:
I'm not sure that's true. Having finer gradations between points doesn't change the range. For instance, the difference between the freezing/boiling point of water is 180° on the Fahrenheit scale, but 100° on the Celsius scale. Same range of temperature, just different number of divisions.

I don't remember the dynamic range of the Axe Fx offhand, but let's say it's 120db. If I represent that with an integer, I'd have 121 points between 0db and 120db. If I represent it with a floating point value, I could theoretically have an infinite number of points. Doesn't change the range.
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Actually, additional divisions or points is exactly why it has a wider dynamic range. With more possible numbers, you can express a wider range of values.

dynamic range in dB = 10 times the base 10 log of the square of number of possible values.

16 bits would be 2^16 = 65536 possible values
dynamic range = 10 * log10( 65536^2 ) = about 96.33 dB

24 bits would be 2^24 = 16777216 possible values
dynamic range = 10 * log10( 16777216^2 ) = about 144.5 dB

dBFS is relative to the maximum possible signal level. Additional bit depth does not make the signal larger in the sense that the output at the DAC will be at a higher voltage. It's actually closer to the opposite. It means the noise floor is lowered, which effectively increases the total dynamic range.
 
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