Posts by Grinch

  • Two questions regarding Kemper Support and Stage

    1. Is there a better way to contact Kemper other than this form ? I've submitted two support requests about my broken Stage over the past two days and have yet to receive even the typical courtesy "we got your email" response.


    2. Is the Stage a lemon? Honest question. I'm nervous about selling my rack if this thing turns out to be a POS. I vastly prefer the form factor of Stage, but after 10 minutes of using it, one of the switches died. Googling turns up other users with the same problem. Apparently Kemper will RMA it and get me a working one, but are they actually replacing these buttons with less failure-prone ones, or are Stage owners just waiting for inevitable failure of poorly made switches? How long does Kemper warranty their hardware?

  • Rack essentials?

    Quote from strabes

    The "power conditioner" in the second picture is basically a power strip in a box.


    Yeah, I'm aware of that. I'm using an FCB1010, which requires a power cable, so I'm going to need a power strip anyway. Might as well have it in my rack. Tidier.

  • Why does the "refine" step exist?

    Quote from nightlight

    Basically you're saying the Kemper has a base amp and all the other amps are derived from it.


    No, I'm saying that all digital amplifiers use a computer model of an amplifier, or of some black box that transforms an input signal to an output signal. That's just what the term "model" means in computer science.


    Whether Kemper has 1 or 100 internal models is irrelevant. It's a digital model of a physical process that transforms a signal in a particular way.


    If you understand this, it's clear that this is what Chris is talking about in the linked interview. Rather than creating/parameterizing models by hand, he came up with a process of finding the parameters for a model programmatically by analyzing how an amplifier affects an input signal.


    I have no idea how this relates to AxeFx, and am not talking about nor am I interested in any fanboy partisan drama about competing products. I'm just relating, as a software engineer, how such software necessarily works.

  • Why does the "refine" step exist?

    Quote from Lokasenna

    Different amps and distortion circuits will react to chords and palm mutes differently, and bursts of almost-static don't necessarily stimulate the amp in the same way.


    Yeah, I guess the question is why the Kemper doesn't itself produce noises that "stimulate the amp in the same way". I mean, if it doesn't matter what guitar is used, it could have built-in guitar vamping that it uses to profile. I just don't understand why a human player has to be involved at all. The device knows better than we what it's looking for to configure its model.


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    Quote from HappyKemper

    Where did you hear about any internal amp models?


    All digital amps use internal models. That's just the computer science term for a software simulation/representation of a real world thing/process.


    Chris talks about the developing models in the interview you linked to:


    Quote from Chris Kemper

    simply too many interdependent parameters, and it would have taken ages to model just one or two dozen amps. As a basically lazy person I spent my time trying to find an automated method, rather than modeling amps by hand.


    He defines "model" as virtual version of an amp:


    Quote from Chris Kemper

    By philosophy, “modeling” was used as a marketing term by some companies. It says: “Here is a valid virtual copy of a valuable original”.


    He then defines "profiling" as (1) process of creating that virtual copy automatically and (2) the ability to then A/B it against the original:


    Quote from Chris Kemper

    Profiling is an automated approach for reaching a result that is probably too complex and multidimensional to achieve by ear. [..] Profiling, in our sense of the word, is a promise to create a virtual version of your original, but with the ability to qualify the results by a fair A/B comparison. You get what you want, and you can check what you have just got.


    It doesn't necessarily make sense to talk about "models", plural. You can think of the code that simulates amps as the software model of an amp which is then configured by the profiling process. The different amp "models" in something like an AxeFX can be thought of in the same way.


    As for Cliff's opinion about how Kemper works, I just googled the name and see that he's the creator of AxeFX. So I'd say there's a 99.99% chance that his guess is better than yours or mine, because he's smarter than you or I and knows more about simulating guitar amp than most people on Earth.

  • Why does the "refine" step exist?

    This is purely a technical question.


    Profiling works by the Kemper feeding a signal into an amp and listening to the responses to determine how to set the parameters of an internal model. I always presumed that the Kemper sweeps through the entire range of frequencies that guitars can produce and multiple volume levels to get a complete picture of how the amp will respond to various inputs.


    So why would subsequently feeding it a random guitar signal -- which should be less comprehensive coverage of amplitudes/frequencies than the original profiling signal -- make the profile better?


    Is it that the original profiling signal is less comprehensive than I imagined, and the guitar is filling in the blanks? Because that would indicate that a refined profile is only ever going to be truly accurate with that specific guitar. Is that the case?


    Why can't the original profiling signal be more comprehensive, so that it covers every possible guitar signal?


    I'm willing to hear people's speculation, but I'd be especially interested to hear if Kemper himself has every commented on this particular question.

  • Rack essentials?

    I've got a Kemper rack shipping today (so excited!). I've never owned rack equipment before, so I'm not sure if I should go for a tidy 3-space rack or something bigger.


    I plan to run a Behringer FCB1010, which will require mains power, so I was think I might want a power strip in the rack. Then I can run one extension chord to the rack and a regular power cable to the Kemper.


    Anything else I should be thinking about before I make a purchase?


    Cheers,
    Eric