About clipping

yek

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LEVEL and CLIPPING issues: analyzing, deducing and summarizing.

  • Initialized my Axe-Fx: Utility > Reset > Reset System Params.
  • Connected my guitar to the Axe-Fx with a cable. Passive electronics, no need to check a battery.
  • Monitoring OUT 1 through studio monitors. No DAW, no USB, no headphones.
  • I adjust FRONT INSTR level in I/O. Suhr guitar: 50% or so. Gibson: 40%. My Telecaster (single coil): 70%. Which means that I can safely set it and keep it at 40%.
  • While we're at it, let's be clear about setting FRONT INSTR LEVEL: there's NO relation with digital output clipping, or volume, or amp gain!
  • Checked a number of factory presets.
  • When hitting the strings in a normal manner, clean factory presets such as 59 Bassman, Double Verb, Shiver Clean do not distort.
  • When really digging in the strings, using a bridge / neck humbucker, I can make some clean presets distort a little. Nothing wrong here, they SHOULD be getting into distortion at some point, based on their settings. If you don't like that, just turn down Input Drive or Input Trim in the AMP block, that's all it takes.
  • Also, I can make some factory presets clip, indicated by the OUT 1 Clip LED.
    Don't mistake the IN LED going into red for digital clipping!
Any questions from the audience?

Why and when are some presets clipping?
The signal level is already high in these presets. Easily checked by looking at Utility > Status Meters where the Output Level meter for these presets is touching the top. Combined with high output pickups, especially when hitting low notes on the low strings, the signal reaches a critical point and the clipping warning appears.
Note that (digital) clipping is something completely different from amp distortion!

Is clipping strange, weird, terrifying, should I hide my children, or is my Axe-Fx broken?
No. It's only the digital preset level being too loud. Easy to adjust, see below.

How do I solve digital output clipping?
Do NOT decrease the Input Level in I/O, because it's NOT related to the overall signal level (different from the Standard/Ultra days).
Adjust the preset level by turning down Level in the Amp block, or by turning down Level in Layout > Output > Main. In fact you can turn down Level in any block that's in series on the grid (such as Cab), but using one of the aforementioned parameters is recommended.
Note that decreasing the signal level by turning down Level in blocks before the Amp block may have an impact on Amp gain. But otherwise it won't hurt your precious tone in any way.

But what if I do this and the preset gets too soft when compared to other presets I use?
You have to adjust the other presets too then. The preset closest to clipping should always be your reference.

I hear clipping (or I think I do) but the Out 1 Clip LED doesn't blink?
It ain't the Axe-Fx clipping. You need to check other variables:
  • CPU usage (Utility menu). You may hear crackling noise because the CPU gets overloaded because of too many effects, even before the CPU Overload warning appears. Keep presets < 90% to be safe. An USB connection always add some CPU usage too.
  • Verify that the output of the Axe-Fx is not overloading / clipping the input of your monitor device, audio interface or DAW. Easily checked (if you're running analog out) by turning down the front panel Output level knob. If this makes the clipping sound disappear, it's the input of the connected device.
  • If you're using headphones, it may be your headphones which aren't able to handle the signal.
  • Try another USB port. Or remove the USB hub or extension cord.
EDIT: Forum member Chris of Katsu Kuri made THIS VIDEO about gainstaging and preventing clipping.
 
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I'd like to add one thing to this.

The GAIN fader in the GLOBAL Graphic EQ can also be used to handle output clipping (the OUT1 or OUT2 CLIP LED.)

This has the advantage of handling all your presets at once.

It has the disadvantage of being a bit of a hack in that the box won't really offer unity gain anymore, so treat this as more of a possible temporary solution.
 
So, is it possible to digitally clip a signal even though the output is not clipping?

i.e. setting the output level of a block to +20 into something like an eq, and then reducing the preset's output level?

e.g. Amp -> Cab (Out +20) -> PEQ (Out +20) -> Out (Output Level 1 -20, Main -20)

Extreme example of course, but can you clip the internal digital "signal" without clipping the output?
 
Possible? Yes. Likely? Not very. The Axe has more than 1400 dB of dynamic range internally, compared to 110 dB or so at the output. If it's clipping, it's your output that's doing it. :)
 
I'm having issues with both my PRS McCarty guitar with upgraded Gibson PAF humbucker pickups AND my bass (Ibanes SR800) with active pickups clipping on the input stage. I have to turn the input level way done or turn the volume down on both my guitar/bass but I feel a loss of tone. I let it clip just a bit but if I strum hard then it will clip a lot (again on the input) stage so its very awkward.

Do I need to keep turning the input level almost all the way down or is there something else I can do without loosing tone using the software?
 
I had same kind of problems also when i started using my unit (Axe FX II mark 2) Every preset clips against output and had to roll the I/O input down from 50% to 22%, now im just paranoial of the shit clipping all the time, or at least im "hearing" it but it shouldn't be there :D

Read this also, might help. http://forum.fractalaudio.com/cliffs-notes/78003-about-speaker-lf-resonance.html

I have a really heavy mahogany bodied gtr and have to compensate the LF frequency and MV settings monitoring the BASS settings also so i can get my desired clean thunk without farting low frequency, what i originally thought of a normal clipping issue from the hardware...
 
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It should be really hard for a pickup to clip the Axe's input. Is it an audible clipping, or something you're seeing on the Axe's input meters?
 
Not at all unusual. If the red light just flickers a bit when you spank it, that's called "tickling the red." It's actually the ideal spot to be in from a signal-to-noise viewpoint. The red input LED lights up when you're a couple of dB below clipping (the red output LED, on the other hand, lights right at the point of clipping).
 
It flickers a lot more with my PRS than any other guitars but still sounds good. So PERFECT, that's really good to know... Thank you Rex.

This thing sounds amazing through s/Pdif . Now I just need to figure out how to get rid of the jitter on my RME FF800 when I sample to 48 Khz...
 
Thanks you. After two days staying up late and trying everything to fix the jitter issue, I ended up giving up and turning my computer off.

Well, guess what, I turned the computer back on and so far no jitter... hehehe... I guess sometimes life its more simple that what we make it...

Ok time to play now!!
 
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Hey,
i have a question about Front Input Level and changing a Git. on a Gig.
Well got a new Git. Passiv with Humbucker... and it is not so Hot as my Active Parker...
So do i have to care about when we are Giging?
My Axe is adjusted to my Parker because it's my Main Axe...
The new One is not so hot as the Active Parker... do i loss sound quality if i not adjust the Front Input Level to the new one?
thanks!

Stefan
 
Thought I'd post in case someone else runs into this...

I ran into an issue where I was getting a subtle but unpleasant bit of distortion that sounded like clipping in the high-end. Took me a while to sort out, but I found that sometimes when I turn on my XL, it causes my sound card to switch to 44k. If I then use the control panel for my sound card to set it to 48k, everything sounds great. I now recognize the sound when it happens, and it's very easy to correct. :)
 
Question: I normally leave my input level around 50..which seems to be good for guitar. I would assume turning it up would cause the LED's to move into the red and clip..but I can't really tell a difference audibly or with the LED's. I recently used it for a bass gig and noticed my bass wasn't pushing to the red at times..so I turned the input level up and nothing changed. Am I missing something? I could literally turn my bass input to 100% and nothing seemed to change.
 
Question: I normally leave my input level around 50..which seems to be good for guitar. I would assume turning it up would cause the LED's to move into the red and clip..but I can't really tell a difference audibly or with the LED's. I recently used it for a bass gig and noticed my bass wasn't pushing to the red at times..so I turned the input level up and nothing changed. Am I missing something? I could literally turn my bass input to 100% and nothing seemed to change.
From yek's original post above:


  • While we're at it, let's be clear about setting Input Level: there's NO relation with digital output clipping / decreasing signal level / adjusting amp gain!
 
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