Tube shape / bias

1st Official Post
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    The Profiler Model referred to in this thread is ...
    ☑️ Profiler Stage

    There’s been an interesting recent thread about the parameter “definition”, I thought I’d post to ask if anyone had any thoughts about the Tube Bias and Tube Shape parameters, found in the Amp module.

    I’ve been doing a lot of tweaking of my own profiles recently with the controls found in the Amp and Cab modules, some are incredibly powerful and useful. But I cannot hear, for the life of me, what Tube Bias and Tube Shape are doing. I can’t hear them ever making a difference.

    Anyone have any ideas or suggestions? :/

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    • Official Post

    the amount of gain can have an impact on how much impact Tube Shape has

    " Tube Shape
    “Tube Shape” controls the distortion characteristics of the tubes, ranging from very soft to very hard. All kinds of crunch sounds can be dialed up - from warm blues, to singing metallic, to harsh. Depending on the gain setting or the playing style, the resulting effect can be rather subtle; completely distorted sounds are mostly unaffected by this parameter, as are clean sounds. Set the value to 3 to simulate the typical sound of preamp tubes. To achieve a power amp tube character, try setting “Tube Shape” to around 9. Power amp tubes produce a much harder distortion, because the negative feedback in the power amp circuit linearizes the tube amplification, making the distortion curve edgier.


     Tube Bias
    “Tube Bias” influences the overtone structure of the distortion. While the effect on the character of the sound is fairly subtle, you should feel a quite a difference in the distortion dynamics: as you increase the amount of “Tube Bias” the guitar will go into distortion much earlier in the dynamic range, yet still retain a lot of dynamic headroom. At maximum value, the distortion characteristics mimic those of a Tube Screamer™."

    • New
    Quote from DonPetersen

    the amount of gain can have an impact on how much impact Tube Shape has

    " Tube Shape
    “Tube Shape” controls the distortion characteristics of the tubes, ranging from very soft to very hard. All kinds of crunch sounds can be dialed up - from warm blues, to singing metallic, to harsh. Depending on the gain setting or the playing style, the resulting effect can be rather subtle; completely distorted sounds are mostly unaffected by this parameter, as are clean sounds. Set the value to 3 to simulate the typical sound of preamp tubes. To achieve a power amp tube character, try setting “Tube Shape” to around 9. Power amp tubes produce a much harder distortion, because the negative feedback in the power amp circuit linearizes the tube amplification, making the distortion curve edgier.


     Tube Bias
    “Tube Bias” influences the overtone structure of the distortion. While the effect on the character of the sound is fairly subtle, you should feel a quite a difference in the distortion dynamics: as you increase the amount of “Tube Bias” the guitar will go into distortion much earlier in the dynamic range, yet still retain a lot of dynamic headroom. At maximum value, the distortion characteristics mimic those of a Tube Screamer™."

    Thanks for posting, yes I’d seen those extracts from the manual. But experiment as I might, I just can’t hear a change in sound or tone.

    It’s not a problem, I’ve used the Kemper to create profiles of my favourite amps/cabs, and am very, very happy with the results. I just wondered if I was the only one that couldn’t hear Tube Shape and Tube Bias making any difference 🙂