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Ooooh... Charts and Graphs

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vangrieg

Power User
The alternating current coming in through the power plug gets rectified to turn it into direct current that the circuits can use. Rectification results in a signal that's rich in 3rd-order harmonics. The 3rd harmonic of 60 Hz is 180 Hz.
It has nothing to do with aliasing performance though?
 

guitarmike

Experienced
Thanks Yek! As usual, you present timely and helpful info for the community once again. Upon studying up on this subject, I realized that this old man had forgotten some stuff!!! I find most electronics to be fairly intuitive, but the digital conversion process, not so much.There is also a ton of bad info out there on this subject. It is a good thing that we have a company that does understand this stuff and offers its customers real information and products void of ignorance and hype. In a world full of bullshit, I find Fractal Audio to be quite refreshing.
 

Daveis

Inspired
Would the aliasing be present if you intentionally band pass all your presets between 100hz and 4.4khz? By placing an EQ or IR block near the end of your signal chain... Lots of "other thing" presets I see have this... maybe to cover up fizzies up top?
 

jlglespaul

Member
I am always amazed when a new firmware is released, i do not understand the technical side, although years back my tech would try to explain his mods. What i do understand is you can hear how this affects the string and chord characteristics that seem to breath with clarity and respond more naturally . . . sounding more like a beautiful animal. A big thanks to Cliff . . i never thought i would be playing something other than my Marshall 800 . . you've opened a new world of fidelity for all of us.
 

rodzimguitar68

Fractal Fanatic
@ Cliff, why are the readings for Fractal lower than the "other" until the 10K explosion? Is this an indicator of idling quietness?????
 

BillyZeppa

Power User
@ Cliff, why are the readings for Fractal lower than the "other" until the 10K explosion? Is this an indicator of idling quietness?????
If I may, it's not idling noise. It is a form of distortion that results only when a signal is present. It is way lower than threshold of hearing for almost all of the II graph, and all of the III graph.
 

vangrieg

Power User
@ Cliff, why are the readings for Fractal lower than the "other" until the 10K explosion? Is this an indicator of idling quietness?????
This is meant to show better aliasing performance. Aliasing isn’t idling noise, it’s a set of nasty unmusical seemingly random frequencies which are, however, a product of the sound being played. You may not discern them but they make things sound like cheap digital crap.

The way to fight aliasing is oversampling, running effects internally at higher sampling rates, which costs CPU cycles.

So that “competitor”, judging by the file name, is Helix. It has the same type of DSP chip as AX8, but lets you use more effects simultaneously. More effects means more CPU cycles, so there’s a trade off. Line 6 apparently sacrificed oversampling. That’s why you have less crap in the top end in Axe-FX.
 

yeky83

Power User
So that “competitor”, judging by the file name, is Helix. It has the same type of DSP chip as AX8, but lets you use more effects simultaneously. More effects means more CPU cycles, so there’s a trade off. Line 6 apparently sacrificed oversampling. That’s why you have less crap in the top end in Axe-FX.
Wow, file name... nice detective work! :p
 

vangrieg

Power User
Everything else is aliasing (undesirable).
180 Hz is ground loop, so not everything is aliasing, apparently.

I don’t understand the graph, or at least much of it. Beside the ground loop, there’s all this noise at -80 dB or so - it can’t all be aliasing, can it?

But for regular noise, there’s too much of it, where did all the dynamic range go?

Also, the graph shows dBu - what does that even mean in the digital domain? Or is it measured at output, after D/A conversion?
 
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