KPA downsamples to 22,050hz?

  • Cliff from Fractal claims that the KPA downsamples to 22,050hz due to lack of processing power. Is this true? And if so, why would this be done since it would obviously make for lower quality?


    post #8
    http://forum.fractalaudio.com/…o-amps-less-quality.html#


    can't say if its true or not, but Cliff is threatned by the KPA and is doing everything he can to make it not look good, so I care less what Cliff from Fractal says, Probably Fact is the kemper keeps him up at night I am sure. I will take my kemper, aliasing, and maybe downsampled any day ;0)

  • yeah, i own both so i dont really pledge allegiance either way. but, Cliff has shown himself to be quite a pompous ass more than once and i dont put any weight on what he or anyone else says. i just trust what i hear. i was just curious for an official response to that question.


    cool yeah hope you get the response. Sucks that Cliff has to act how he does. I once had a Fractal and sold it off. While they do have a great product, I can pretty much say I will never go back to Fractal because of how Cliff has conducted himself and how crazy die hard some of the users are and just brutal, just such a turn off to want to support that. Cliff is a smart guy, but I believe he was lying when he went on the gear page saying how his kemper only boots up 10 percent of the time, and all the troubles he was having trying to paint it as a piece of junk. Just very unrprofessional and anyone with half a brain can see what games he is playing ya know. Ok off my soapbox.


  • cool yeah hope you get the response. Sucks that Cliff has to act how he does. I once had a Fractal and sold it off. While they do have a great product, I can pretty much say I will never go back to Fractal because of how Cliff has conducted himself and how crazy die hard some of the users are and just brutal, just such a turn off to want to support that. Cliff is a smart guy, but I believe he was lying when he went on the gear page saying how his kemper only boots up 10 percent of the time, and all the troubles he was having trying to paint it as a piece of junk. Just very unrprofessional and anyone with half a brain can see what games he is playing ya know. Ok off my soapbox.

    i totally agree that Cliff acts very unprofessionally. he constantly berates his customers and acts like he's doing everyone a favor by providing his product. good with numbers, bad with people.

  • I don't know how CK will answer to this, but the only thing that i can say is that i have never seen anyone being so childish in the business world.
    I think that the Axe Fx stuff (i owned a Standard and an Ultra) is one hundred times more professional than its creator.

  • It is really amazing how the Fractal diehards are so quick to agree with all this tech data that is being published. 99.9% have never even tried the Kemper yet are the first ones to take this information
    and claim victory. (keeping score, LOL)
    I guess if it sounds good on a tech spec sheet then it must be better, forget what is actually sounds like, look at these numbers. :D

  • least, when boosting presence and highs i have a lot of energy up to 12khz with presence and eq set to 0, and with presence and eq bossted, 16 and more khz are shown on the analyzer, so 22khz at least can´t be true for the output after the amp-eq section

  • least, when boosting presence and highs i have a lot of energy up to 12khz with presence and eq set to 0, and with presence and eq bossted, 16 and more khz are shown on the analyzer, so 22khz at least can´t be true for the output after the amp-eq section


    Sample frequency has nothing to do with signal in a certain frequency range of the EQ spectrum...

  • i am a bit drunk right now, but regarding bob katz mastering audio book, downsampling must contain a fliter at half the sample rate to eliminate aliases (well, nyquist theorem as much as i know) so that would mean that the amp-profiling section (before eq and cab) downsampling to 22,050 hz would allow for not more than 11khz of audible signal...but tha analyzer shows more than 12 khz. also, as there is should be no signal beyond 11khz, a eq-boost (or presence boost) above 11khz should have no effect, as you can´t boost a signal that is not there in the first place
    but proove me wrong! it´s a interesting discussion, and my theory lessons in digital signal processing happended a long time ago, so i am not quite fit in that filed anymore

  • Tenderboy, I'm not drunk at the moment but I think you are right ;)


    If the sampling rate would indeed be 22k everything above 11k would be horrible aliasing as it would be mirrored at the nyquist line of 11k.


    That would either be blatantly obvious to anybody or it would have taken care of with a steep LP-filter. But then there wouldn't be anything above 11k in the signal.


    Actually that was the case with the first POD. It used to ran at 33k and had a overly steep anti-aliasing filter to mask the aliasing. It's a usual practice for mixing engineers to boost guitars as high as 8-10k. The POD literally had nothing left up there so you just couldn't boost those frequencies and it made the POD sounds unmixable. That's what Bob Clearmountain probably was talking about as well. The Ampfarm plugin used to run at the sampling rate of the Protools session so they could run it much higher and it sounded much better.


    Anyway what I am trying to say is: If the Kemper would really run at 22k (even lower as the original POD), it would never been even near a professional studio let alone beeing used on quite some high-profile recordings.


    If I would be CK, I would give my attorney a call. This is not just aggressive marketing this is already plain out lying about a competitors product.

  • As mentioned at 22k, 11 k would be the highest frequency one should expect without running into less then ideal representation. Guitar really doesn't need a ton of high frequency info as speaker cabs often don't go that high anyway. It's possible that the guitar processing is running at lower sampling rates but the digital out is running at 44.1 I believe so 22k can't be the entire signal rate

  • I think he is talking about internal sample rate not external which does not translate to 22khz. The internal sample rate is supposed to be much higher than 44khz. Kemper said that the internal one is partly much higher. Concretely around 700hz for the tube emulation which is a 16x oversampling. See 2nd post here http://kemper-amps.com/forum/i…page=Thread&threadID=4711. Maybe the rest of the emulation is running at 8x oversampling (352khz) and that's what Cliff is referring to. A Fractal employee confirmed that when using one amp block the Axe does 16x oversampling and half of that when using 2 amp blocks.


    Anyway I would like to see Fractal having enough courage to say the name of the product they are referring to when they give this sort of information.

    Edited 3 times, last by MadH ().

  • I think he is talking about internal sample rate not external which does not translate to 22khz. The internal sample rate is supposed to be much higher than 44khz. Kemper said that the internal one is partly much higher. Concretely around 700hz for the tube emulation which is a 16x oversampling. See 2nd post here http://kemper-amps.com/forum/i…page=Thread&threadID=4711. Maybe the rest of the emulation is running at 8x oversampling (352khz) and that's what Cliff is referring to. A Fractal employee confirmed that when using one amp block the Axe does 16x oversampling and half of that when using 2 amp blocks.


    Anyway I would like to see Fractal having enough courage to say the name of the product they are referring to when they give this sort of information.

    thanks for that info.


    i would like to see Cliff not be such a dick, but im not sure thats going to happen, lol.


    EDIT: the link doesnt seem to work

  • thanks for that info.


    i would like to see Cliff not be such a dick, but im not sure thats going to happen, lol.


    EDIT: the link doesnt seem to work


    Oops, my mistake. I just checked his post and Cliff actually says that it "downsamples to 22.05 kHz" and obviously that has nothing to do with only doing 8x oversampling. If he is indeed referring to the KPA I guess someone is lying then.



    P.S. The forum software is screwing up the link substituting automatically "forum" for "forum/forum". I replaced the link for simple text.

    Edited once, last by MadH ().

  • You have to take care of aliasing when you go from frequency domain to time domain, which means digital world back to analog world. That's where aliasing happens.
    Internally and depending of what you want to achieve you can go up and down.(think about using different plugins into your daw, some do oversampling, some not)
    If internally the KPA goes back to 22khz i wonder how cliff knows it.
    If he knows it right does it mean he is doing reverse engineering?

  • I remember an interview with Christoph where he said that the KPA runs internally on a much higher sampling frequency.


    Quote from http://www.guitar-muse.com/kemper-profiling-amp-2949-2949

    9. Can you talk about what’s under the hood (processors, speeds, sampling rate, A/D conversion etc)?


    The main DSP is a Freescale DSP (formerly Motorola) running at an equivalent of 400 MHz speed. The code consists of tens of thousands of lines of pure assembler code. The global sampling rate is 44.1 kHz, while the internal sampling rate is partially much higher. The algorithm for the tube simulation runs on more than 700 kHz sampling rate (!).



    But besides... I guess 98,72% of guitar players don't even have an idea what sampling rate means. So who cares if it runs on 44.1 kHz, on 22.05kHz or on 1.337 kHz as long as it sounds good (and better than the supposedely higher sampling competitor - but thats just my opinion of course).

    MJT Strats / PRS Guitars / Many DIY Guitars -- Kemper Profiler Rack / Kemper Remote / InEar

  • I don't know how CK will answer to this, but the only thing that i can say is that i have never seen anyone being so childish in the business world.
    I think that the Axe Fx stuff (i owned a Standard and an Ultra) is one hundred times more professional than its creator.

    Fractal has had it easy until now. Their business model selling direct and great customer intimacy has served them well.
    Over the past six+ months the number of reviews, general publicity and internet buzz around the KPA has exploded. Today, I saw the KPA for the first time in a local music store in Norway. Now Cliff has to decide if he wants to play the game or not. If he continues with the current model (vs. retail), then he will be left behind, plain outnumbered/outmuscled. The game is no longer the product, but the distribution.
    Are we seing signs of desperation with his aliasing and sampling commentary? Perhaps. Maybe poor values, judgement or social skills, I don´t know. What I do know is that it leaves me as a customer of his with a bad taste in my mouth.
    Whatever - if the KPA really is as underpowered as he says, then there are some software developer(s) that should be admired as with me the KPA with my favorite strat is getting all the attention these days.
    Maybe thats whats eating him; someone out there is smarter ...