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What is the internal processing resolution?

Discussion in 'Axe-Fx III Discussion' started by dumbeat, Feb 10, 2019.

  1. GlennO

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    Your point is that every mastering engineer in the world doesn’t understand dithering? Any truncation will be almost entirely in the exponent.
     
  2. FractalAudio

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    Do you understand what dithering is and why it is used?
     
  3. #23 yyz67, Feb 10, 2019
    Last edited: Feb 10, 2019
    yyz67

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    Cliff, what about the D-to-A conversion resolution and output dynamic range?

    Also, if the (digital) output signal is very low, wouldn't it have relatively less resolution (be grainier) when converted to analog?
     
  4. DLC86

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    Those info are in the specs, last pages of the manual.

    Yes, you basically lose bit depth so the quantization noise level relative to the signal would be higher, that's why it's good to set the level of your presets to be around 0 in the vu meter.
    But a 24 bit signal has enough dynamic range that you'd probably not notice it even if it's set lower
     
  5. decreebass

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    I read everything and I'm more confused than ever. I'm glad you guys understand this. I'mma go back to noodling on my guitar THROUGH the Axe Fx - I'll just assume it's magic happening inside that little black box :D
     
  6. finleysound

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    Yes, but I am not a computer engineer. From my mile high view, the concept of using dither to reduce quantization distortion when reducing bit depth makes sense to me. I’ve done A/B/X listening tests and confirmed dither increases low level details and generally sounds “smoother” to my ears.
     
  7. FractalAudio

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    Precisely. The Axe-Fx does not reduce the bit depth so no dithering is required.
     
  8. GlennO

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    Dithering can be useful, but you seem to be confused about the concept of bit depth reduction. Do you have more details about all these mastering engineers who you say are appalled by the AxeFX? :)
     
  9. unix-guy

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    He didn't say anything about being appalled... He said their jaws hit the floor.

    That can mean various things, such as amazement.
     
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  10. GlennO

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    True. He could be referring to some kind of physical deformity :). The point is: it's nonsense to think that the lack of dithering in the AxeFX is considered a flaw by mastering engineers. Or by anybody, for that matter.
     
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  11. REDD

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    You guys should quit dithering about and play your guitar!
     
  12. lqdsnddist

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    I doubt 99% of users have no idea what it even is, and of that 1% who does know, probably 99% of them don’t care lol
     
  13. finleysound

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    See, I KNEW you had your reasons!
     
  14. unix-guy

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    Again, nobody said that... You are putting words in his mouth.
     
  15. finleysound

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    Not confused at all. *IF* the Axe-Fx processed audio at 32-bit, the audio output *SHOULD* be dithered down to 24-bit. Cliff has clarified that the Axe-Fx does not reduce bit depth, therefore, dithering is unnecessary.

    Mastering engineers *WOULD* be appalled by the Axe-Fx *IF* 32-bit audio was not dithered down to 24-bit. Not applying dither in this case *WOULD* fly in the face of 20+ years of digital audio best practices.
     
  16. lqdsnddist

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    No doubt the way Cliff got where he, and FAS, are today is by not always following 20 year old best practices
     
  17. GlennO

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    Oh my, that's not right at all. The AxeFX of course processes audio at 32 bit. And it outputs to 24 bit. Where you're confused is the conversion from floating point to integer. It's 32 bit *floating* and 24 bit *integer*. There is virtually no truncation with normal audio signals in that conversion.
     
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  18. yeky83

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    Isn't dithering unnecessary with 24-bit integer audio anyway? Quantization noise with 24-bit audio is lower than any analog output noise (thermal noise), let alone the gained up noise level of a guitar amp output.
     
  19. #39 yyz67, Feb 11, 2019
    Last edited: Feb 11, 2019
    yyz67

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    As I understand it, it would truncate depending on the output volume setting. But for nominal (0 db) signals there would be little truncation since 32-bit floating would (IIRC) have 23 bits for the mantissa (+1 for sign) and 8 bits for the exponent (which is a multiplier).

    Also 24 bits corresponds to 144 dB dynamic range which is still very large compared to real world of dynamic range ~110 dB, assuming threshold of hearing of 0 dBA and pain-threshold level of 110 dBA (source: http://chchearing.org/noise/common-environmental-noise-levels/).
     
  20. GlennO

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    That's why I said "normal audio". In theory, you could contrive a case where there would be some truncation, but with abnormal audio like that, the truncation would be the least of your worries :).
     

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