Crackling distortion/weird fizzy overtones

    I know this has already been discussed.
    But the problem could not be solved.


    With most profiles, (Kemper Profiles, And44 Profiles) I notice weird crackling distortion, or some kind of fizzy clipping correlated with the sustain of soft picked chords...
    It's always there, with some totally clean sounds it's not noticeable, and the fizzy noise will be buried in fully distorted sounds.
    But still it's really annoying.


    It does not have to do with Cables/PUs/Connection.
    Even if only listening with headphones it's there.


    As others noticed, it has something to do with the amplifier section of the Kemper, above all the Pick knob influences the crackling.
    But even when set to 0 it's there a little.
    Only disengaging the amp section helps - but this is not an option ;)


    How you can reproduce it:
    Use the "Fischers Extacy3" Profile.
    Deactivate all stomp boxes, effects.
    Only AMP/EQ/CAB in the middle stays on.
    Play a soft chord picking and let several strings oscillate at the same time.
    Concentrate on the crackling distortion in the background of the actual sound, attached to the sustain of the notes.
    If you can not hear it, go into the Amp section and turn the pick setting up to +5.
    This will intensify it.


    I hope that the problem doesn't come from the actual algorithm of the kemper itself.
    It sounds so digital and ugly - and it seems the noise sets in after the actual sound has already been produced by the kemper. Please help me to remove the sizzling.


    Thanks!

    Funny you should post this I've just posted a thread regarding the same kind of sound I think. To me it sounds like a ripped speaker that's how best I can describe it and it only happens on some profiles. If I play an open A chord and let it ring it seems like the strings E,B,G cause this strange noise. Does this sound like the same noise your hearing I'm going to post a clip tomorrow



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    To me the crackling is worst with some clean profiles. I'm also quite certain that the behaviour has changed with firmware-releases. Some if the rigs I configured for use in performance-mode last summer are now practically useless. My signal-chain normally includes a L6 G90 wireless, but the crackling is just as bad without.


    The noise does vary slightly with the impedance seen on the input. My wireless-system tries to simulate varying cable lengths and that setting makes a slight difference. Different guitars behave different, but there's always some crackle. My LPC with burstbuckers (2+3) is the worst among mine. I have recorded the signal going into the KPA to my computer through a RME audio-interface and can't find any cracling there no matter how I twist the signal.


    The worst rig that I've discovered is one called 'AcusSim GSP2 Hall. Delay and reverb enhances the crackle but effects are not the source. There's still considerable crackle with Stomp and Effects sections off. Almost, but not absolutely, all of the crackle disappears when Stack is turned off. To me it seems as if the noise originates some somewhere around the A/D-converter (because impedance is a factor), and then gets amplified in the Stack-section. Turning off the Amp-sim reduces it a bit, EQ makes no difference, and most of the noise is gone with Cabinet off.


    The problem is also audible on some higer-gain rigs, for example the Engl Blackmore Lead that I use quite a bit. Not so obvious, but irritating.

    Quote from heldal

    To me the crackling is worst with some clean profiles. I'm also quite certain that the behaviour has changed with firmware-releases. Some if the rigs I configured for use in performance-mode last summer are now practically useless.

    Maybe I am wrong about this, but since all the previous Firmwares are available on the support page, why don't you just test what you have claimed and go back in time (firmware wise) and find out whether what you feel is true?

    Quote from joerch

    Maybe I am wrong about this, but since all the previous Firmwares are available on the support page, why don't you just test what you have claimed and go back in time (firmware wise) and find out whether what you feel is true?


    I haven't used the rigs I struggled most with for a long time. Those were mostly attempts to create acoustic-ish sounds from an electric and I have since been using the proper acoustic instruments instead. However, last night I was at a rehearsal where I didn't bring an acoustic guitar and ended up playing acoustic simulation rigs for hours without a crackle. This was using firmware 2.3.3.9457B. The same rigs have been practically unusable with other firmware releases so my problem was definitely software related. My guess is that improved handling of DSP-errors, which was mentioned in the release-notes for 2.3.X, is what has fixed it. Improper or incomplete handling of errors in audio-processing is a common cause for timing issues.

    There was a software version last summer that had slightly different preamp gain response than before, or after - that may the change you are hearing?


    I've not heard any added harshness, compared to the amps I have profiled, but I haven't profiled anything buzzy yet. A friend of mine is loaning me a Mini Recitifier soon, though....... :)


    As far as the Bogner goes:


    "The Bogner has huge low-end, not so much in the way of mids, and a rasp to the top, much higher than the majority of the fundamental sound, that I couldn't dial out"
    from a Rig-Talk Bogner XTC review....


    A buzzy sounding amp with 75 watt Celestions will have some harshness, even if a Sennheiser 421 is used to profile it.

    This issue was noticeable to me with clean profiles and/or gain at 0, not with high gain profiles. And it happens in the tails of notes/chords, not as baseline or amp character noise.