Transient behaviour when picking the first note

    I don't know if this is a problem or a feature, but often when I play the first note (let's say after a small break in the song or something), the output led goes red during the pick attack.


    Here is brief test. I am using a factory rig by Keith Merrow, "KM-THRASH". No stomps or effects. Clean sense -6.3, output through spdif to Roland Quad Capture. Noise gate 5.0. Firmware public beta 2.2.0.8917B. Guitar is Schecter Blackjack w/ Seymour Duncan Full Shred.


    The problem (to me at least) is that when lightly touching the strings with the side of the pick (the first eight peaks in the wav), the output goes easily red and I hear a sound that is a bit unnatural and reminds me of actually clipping the output. This doesn't happen if I use similar pick attack while strumming chords (as in 0:03-0:11 in the mp3 clip). In 0:14 one can hear the problem again very clearly, I hope.


    I am pretty sure that the output with headphones behaves ok, so maybe this is spdif related?


    https://dl.dropboxusercontent.…mper-pick-attack-test.mp3


    [Blocked Image: https://dl.dropboxusercontent.com/u/55653919/Screen%20Shot%202013-11-23%20at%2022.43.45.png]

    Edited once, last by laardi: Removed spdif from the title. ().

    I get similar results with the main outputs as well... The waveform is pretty much identical, including the peaks.

    please make a test with stack off : if there's no more weird transient, it comes from the profile itself, if the transient still here, then try with another guitar, with different pickups...
    If it's not the profile, neither the guitar...maybe it comes from...well...I don't know...maybe some kind of soft limiter or auto leveller on the input with a too slow attack ? any idea anyone ?

    Edited once, last by lohworm ().

    With the stack or the amplifier off, there is no problem. The waveform is much narrower of course but the spikes are gone.


    It just unfortunate that this happens with almost all good sounding high-gain profiles. :(


    The question is: is this the way real tube amps behave or is this an artefact?

    does it change according to the value of the "pick" parameter of the profile ? or any other parameter of the "Amplifier" section of the profile ?

    About the amp parameters: increasing “clarity" makes the spikes smaller, whereas "tube shape”, "tube bias”, "power sagging” had no effect as far as I can tell.


    The parameter “definition” had a minor effect, but as one might expect, the parameter “pick” affects the peak behaviour the most. Decreasing “pick” from 0 to -1.5 reduces the spikes so that the output no longer goes red. However, for real playing I’d like to be able to set it to +1.5 instead, so I am hoping this is not the only solution...


    Could someone else quickly check this behaviour? Take the profile “KM-THRASH” and see if there is a huge difference in the output level between sudden pick attacks (the spikes) and continuous playing.

    Confirmed. I get the same result, and also with a profile i did myself. I have Pick set to +0.8 on this rig, the spikes are very high with audible clipping. Strangely enough i never have noticed this while recording.

    Thanks a lot HELL-G and others! At least I know my Kemper is most probably healthy ;)


    Unfortunately I don't have access to a tube amp at the moment, so I can't tell if this is the expected behaviour. Anyone willing to comment on this? Does this happen in real life too?

    Here's just a guess... Try putting the Soft Shaper in th X position with its drive only at 0.1 or so. And volume neutral. I find i can feel this reduces spikes. I have on all my rigs.

    That is really strange. I looked through my files and none of them have spikes like that, recording through s/pdif as well. The attack is quite gradual on mine actually, with the waveform looking more like this < on the first pick. Using my own profiles and the clean sense and distortion sense are at factory settings.


    I'm afraid I can't be any more help than that.

    The signal behaviour resembles that of a compressor chiming in with a small lag (and staying engaged when continuously playing). :huh:
    Have you by any chance checked the amp section's internal compressor? :|


    :)

    Viabcroce: the compressor is at "0" (neutral?) default position. Actually I have never touched the compressor setting in any of the profiles I have onboard.


    Nakedzen: my gut feeling is that the spiking doesn't happen with all profiles. Did you test with the profile "KM-THRASH"? Some of my waveforms are indeed spikeless when recorded through spdif, although I can't recall the specific rigs right now. All I know is that spiking happens also with Lasse Lammert's "Bombed!" profile, which is annoying :cursing:


    Djuhntt: this is a good tip, will try it thanks!

    Quote from laardi

    Nakedzen: my gut feeling is that the spiking doesn't happen with all profiles. Did you test with the profile "KM-THRASH"? Some of my waveforms are indeed spikeless when recorded through spdif, although I can't recall the specific rigs right now. All I know is that spiking happens also with Lasse Lammert's "Bombed!" profile, which is annoying :cursing:


    The KPA is at the rehearsal space right now so I can't try them out. I'll give it a go once I get it back home.

    viabcroce: I don't have a chance to try with different guitars and the picking/microphone position did not hugely change the situation based on quick testing.


    Trazan: Are you referring to the fact that all of the peaks point upward or what? If so, then what might be causing it?


    Here is a close-up of the very last spike of the wav in the first post fwiw:
    [Blocked Image: https://dl.dropboxusercontent.com/u/55653919/Screen%20Shot%202013-11-24%20at%2023.15.28.png]

    Edited once, last by laardi ().

    Since it only happens on certain profiles, I think it's safe to assume it's profile related. Might need to tweak it a bit.


    I get turned off some profiles because there seemed to be so much extraneous noise within the profiles. Figured it was something to do with heavy palm muting technique that wasn't suited to my playing style, rather than improper profiling procedure.