Volume randomly dropping and hum appearing in signal [NOT A BUG]

giantslayer

Experienced
Volume of guitar signal will drop to a fraction of normal volume. A loud low frequency hum becomes present in signal that was not there before.

- Axe FX II
- I am currently using Quantum 1.01, but this problem first started occurring with firmware I had updated 6-12 months ago.
- Most of the time, everything works the way it should and there is no problem.
- Problem occurs at random times.
- Power cycling unit usually fixes problem (it didn't this morning, which completely ruined one song and made noise issues for the rest of the set).
- Problem occuring on XLR outputs. I have tested both L and R and they both have the problem. I have not had the chance to test other outputs.
- Hum still occurs when using a tuner to completely mute input.

- Most if not all of the noise is coming from amp sims and/or drive sims. Higher gain amps result in more noise. Note that when the unit functioning properly, noise is not normally an issue on the same settings.
- Problem is likely occurring within amp modeling software. I have a volume pedal set after the amp modeling and pulling that down mutes the noise. I had initially suspected a ground loop or XLR output having problems, but if that were the case, the volume pedal within the software wouldn't fix the noise.
- I almost always use the Plexi 100W Normal amp.
- It appears the amp models are receiving a full signal for overdrive to occur. If gain is increased at sound board, the tone sounds the same except with a truckload of noise added in.
- It feels like somewhere at the end of the amp modeling, it is somehow throwing away most of the good signal while retaining all the natural noise and adding an additional hum to it as well.


I suspect this could be related to some of the other problems people are reporting.

As it stands right now, I cannot rely on my Axe FX II and will probably have to stop using it. I love my Axe, but if I can't count on it producing sound consistently, I can't keep using it. Please help.
 
What hardware version? XL? Mark II? Mark I?

It's probably best if you can test the 1/4" outs of Out 1 and also turn on the Echo function (set to Out 1 in the I/O Audio menu) and test the 1/4" outs of Out 2.

Could you also post a preset just in case?

Have you ever reset your System Settings in the Utility-Reset menu on the front panel?
 
Is the noise present in headphones? (Try with phones with all other monitors/amps etc disconnected from the outputs)
 
Sounds like a hardware problem. Certainly not a bug. Sounds like a bad cable. Change all your cables. If that doesn't remedy it contact support and arrange for a check-up.
 
Thanks for the quick replies everyone.

What hardware version? XL? Mark II? Mark I?

It's probably best if you can test the 1/4" outs of Out 1 and also turn on the Echo function (set to Out 1 in the I/O Audio menu) and test the 1/4" outs of Out 2.

Could you also post a preset just in case?

Have you ever reset your System Settings in the Utility-Reset menu on the front panel?

Mark II.

Next time, I'll set up a DI and try using 1/4" outputs as you described if/when it acts up. Hopefully next time will be during practice and not during the live set.

I uploaded my main patch onto here. Hopefully the upload works ok.

I was thinking about resetting something, but wasn't sure what to reset. Am I correct in understanding that after I reset that, I would use Fractal Bot to send my system.syx file back to my Axe to get my settings back?


Is the noise present in headphones? (Try with phones with all other monitors/amps etc disconnected from the outputs)

I haven't had a chance to try it with headphones. It has yet to happen to me at home (including just now). In the middle of a live set or band practice, I've just power cycled the unit and until today, that has fixed it, so I hadn't gone into deeper troubleshooting.


Sounds like a hardware problem. Certainly not a bug. Sounds like a bad cable. Change all your cables. If that doesn't remedy it contact support and arrange for a check-up.

I tried three XLR cables today. It is unlikely they all had the same problem.
I double-checked my 1/4" cables and tuner using the unit with headphones and no problems whatsoever (it just simply isn't acting up right now).

I forgot to mention earlier: the input LEDs were lighting up to their normal level, so a full signal was entering the unit. The amp modeling was overdriving as it would with a full signal.

Muting the input (turning guitar volume down or using external tuner to mute) normally quiets up whatever noise is present in my patch. When the unit was acting up, muting the input signal literally did nothing to the noise level, yet changing to a higher gain amp or turning on a drive pedal made a substantial increase in hum.

It was like there was some other way for a loud hum to enter into the signal path either after the noise gate or between the tuner and the unit and loud enough to make it past the gate. That still doesn't account for a full guitar signal entering the amp block and a diminished guitar signal (with full hum somehow) leaving the amp block, however.

The earliest point in the chain where anything affected the problem noise was the volume block after the amp. Anything before that did nothing to the noise. All of the noise is occurring before reaching the volume block.

One other note that I didn't explain well enough in the original description. It may feel like it enters this state at random, but it does not leave this state at random. Today it was acting up for a solid hour and not once did it return back to normal, even for a few seconds (which would have resulted in a big volume spike).

Just to be clear here, the unit has gone from working fine to having the diminished signal and increased hum, then back to fine after power cycling, with literally no variables changed whatsoever. This has happened several times over a number of months, and today was the first time I couldn't get full normal functionality restored by simply power cycling.

It is a frustrating problem to say the least and I do wish changing cables would have fixed it or that a bad cable could at least explain everything, but it doesn't.
 

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Same thing with mine was using using at band prac when it suddenly started increasing in volume n now is making heaps of noise whenever you have amp block ingaged.thought it was my atomic but have found it to be a problem with the unit,don't what to do as I can't use n now without a rig with effects because I sold everything analog ...
 
You didn't answer my question, though.

Before you blame the hardware, always expect a user error. Because from my experience 90% of the bug reports and hardware issues reported here turn out to be user errors in the end.
 
Since originally making this thread, I've only had one incident with the issue (granted, I play out about 2 times a month). This incident, the buzz was not affected by the volume pedal as it was the one incident I was reporting on previously. I fixed the issue by power cycling multiple times.

At this point, I suspect it was a bad input at the sound board. A week after the more recent incident on my guitar, we had a problem with an acoustic guitar on the same channel where the volume had dropped dramatically and later came back suddenly (although there wasn't any power cycling involved like with my axe). I wasn't able to confirm 100%, but I am about 95% confident the issue was at the sound board.
 
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