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[Fixed 9.01] Wild rumbling/chirping artifacts switching between presets

yyz67

Inspired
Update: I pared the offending preset combination down to bare bones (amps/cabs) that seems to semi-regularly produce the issue. The first preset is fine by itself but incrementing (using VALUE knob) up to the 2nd preset can cause that preset (that only has an AMP block) to create a white noise roar which can vary in volume, sometimes VERY LOUD. Once there was a loud pop and all the meters were maxed out. It occurs with global spillover parameter on or off. This issue is independent of the speaker impedance issue which was left at default.

To reproduce it, I turn Out1 volume down very low (enough to barely hear a struck string) and switch back and forth between preset 1 and 2. Sometimes there is nothing and sometimes I have to have some guitar sound going into the first preset, but almost always there is a loud roar that develops on the second preset that once started seems to go through a 20 sec progression as in the first recording. As I said be very careful with volume, perhaps use headphones but not directly on/in ears. Don't have USB or AE connected as this can interfere with the phenomenon.

I haven't tried going back to 8.00 but might try later this weekend.

In the first recording I'm on one preset and hit my low E string (not loudly) then immediately switch to the next preset which creates a rumble. I then increment to the next preset for a second which has no artifacts then to the next one in which the white noise builds to a maximum rumble slowly resolving into some intermittent chirps eventually dying out with a high pitched whine. If I stay on the preset it can build up again and result in a rhythmic chirping, and moving to a different scene and back then recreates the whole rumble progression again leading to chirping (second recording).

[As a side note, I find these fascinating(!) and wonder if these are nonlinear chaotic processes. Hmm, Cliff, I can see a cool chaotic noise/rhythm/chirp generator block as another exclusive AFX feature.]

 

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Perdikament

Power User
I have to say those are some of the coolest Bugs I’ve ever heard.. seriously makes the imagination run wild as to what it could possibly be.
And to further the bug discussion along, I have not experienced this nor the high pitched squeal in your other thread, however I also have not tried to recreate it. I just haven’t experienced any bug like issues in my day to day use & I have messed with the Speaker Impedance & Transformer Match parameters in both old patches & new fw9 made patches.
 

yek

Moderator
Moderator
This can only be investigated by posting the involved presets.

The artifacts probably can be avoided by turning off Spillover in the Global menu. That’s what I do anyway.
 

yyz67

Inspired
This can only be investigated by posting the involved presets.

The artifacts probably can be avoided by turning off Spillover
Will post today, just want to do a few more tests. The issue is independent of spillover as I have the presets whittled down to just the amp block in each.
 
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FractalAudio

Administrator
Fractal Audio Systems
Moderator
It's because you turned the Bright Switch off on the Badger. The Badger doesn't have a Bright switch. I will fix the model so that turning off the switch doesn't cause instability in the calculations.

Are you trying to break things? All these presets and bugs you are posting have radical settings.
 

yyz67

Inspired
No not trying to break it, this was a random discovery.

I had tweaked the amp/preset to my liking (sounds fine and has no weirdness) and then found this preset-dependent behavior which wasn't there before and only occurs when coming from some presets (such as preset 1 attached) and not others. So there seems to be some interaction or hysteresis involved depending on the previously loaded preset. That behavior seems like it shouldn't occur and because it is so radical (loud) it seemed important to vet and debug the conditions associated with it.

The previous "bug?" post came out because I changed Speaker Impedance on one amp (DR) and heard a phenomenon I wasn't expecting. So I tried to see if it was relatively general and posted a few presets with settings that produced similar issues. I think most of us don't know how these settings interact or if they might cause instabilities. I am not trying to break things or find fault, only help determine if these may or may not be bugs. If they mimic the actual amp / circuitry even with their instabilities, that is cool!

Appreciate all that goes into it and respect that it is tricky to mitigate all the complex interactions (pesky users included!).
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I actually traced this to a biquad not getting reset during preset changes. For some weird reason it gets a large value in the state memory which doesn't decay. I think it's because the first preset has two amp blocks and the second only has the one. It's been fixed for the next release.
 

notalemming

Fractal Fanatic
I actually traced this to a biquad not getting reset during preset changes. For some weird reason it gets a large value in the state memory which doesn't decay. I think it's because the first preset has two amp blocks and the second only has the one. It's been fixed for the next release.
Ah, the old biquad reset conundrum! That would have been my 9,845,908,094,609,687,980,935th guess:fearscream:
 

yyz67

Inspired
biquad not getting reset
Dang, my first guess would have been the unidyad. Otherwise the trihex as a long shot, but never the biquad!

It's an annoying rule of software dev that uninitialized variables account for good fraction of (intermittent/random) bugs.
 
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jon

Fractal Fanatic
Those are some seriously cool artifacts!

This may be (or lead to) an unintentional 'eureka!' discovery!

Some of the best inventions were made entirely from fortunate 'accidents'

Amazing support as always, squishing those bugs, I'm always impressed every time with the firmware turnarounds, and this is even after almost a decade of being a part of the FAS family!
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
I have a preset that does it using the Euro Blue Modern amp with the input trim at 4 and a rat pedal boosting even more.
That's not the same issue. That's a noisy preset because you have the gain at maximum and the noise gate turned off. With that much gain you need to use the noise gate, as you would with a real amp.
 

johnnypig

New Member
The problem is that even turning the guitar volume off the rumble is very, very loud. Turning the guitar volume up and down results in chirping as well, with the gate on at -60 or so it will chirp when it activates. If I reset my Axe III it goes away.
 
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