Interesting video where they test the kemper and say its missing the first harmonic in the distortion spectrum

    Quote from Tritium

    Marcus, did you mean to say..."profiling without a microphone". In other words, when making a Direct Amp (DA) profile.


    Please note that when making a DA profile, even though there is no microphone involved, you should always have your reference amp connected to the reference speaker cabinet (via a suitable DI box). This is not simply to ensure the tube amp sees a proper speaker load...but also to ensure that the complex amp/speaker impedance interactions are captured by the KPA during the profiling process.


    Cheers,
    John


    John, that is what I meant yes, and I'm quite aware of what's required and why :D as I said I'm not sure how I would use a DA profile in the studio. I can see live with a speaker might be useful, but I tent to use IEM's live anyways so again, I think having the sound I'm used to with my amps/cabs will still be more useful.


    gianfranco, what I meant by 'is it perfect, no' after the sentence saying I couldn;'t hear a difference was; I'd love the Kemper to be able to take a profile of my lovely old Bandmaster reverb, WIth the great Spring reverb and also the opto tremolo . Those two things set this amp apart from my two Dumbles and Marshall JTM45 and Trainwreck Rocket. I can capture the basic sound of the fender but not the two things that set it apart from my other amps. And no, the built in Kemper trem and reverb are NOTHING like it :D


    Marcus

    Quote from norburybrook

    I'd love the Kemper to be able to take a profile of my lovely old Bandmaster reverb, WIth the great Spring reverb and also the opto tremolo .


    Got it :)
    But Kemper never claimed it can profile effects... it would be like saying that a car is not perfect because it can't go underwater, or fly :D
    Different tools for different results :)

    Sure, but as they're part of the amp I don't consider them 'FX' :D that's the reason I pull out the Bandmaster , putting reverb and Trem on one of my other amps doesn't sound the same, and vice versa, the straight fender sound isn't much different form the Dumble or JTM45 clean sound. The #102 Dumble clean channel is based on a fender amp and the JTM 45 is a fender sf6 bassman so no wonder :D



    It's about time the Kemper had a spring reverb, I mean it is 'THE' reverb for most classic amplifiers!!!!!!



    M

    Quote from deadpan

    How does one test this? I would be curious to compare.


    This test of course is not perfect. But what I did, I set up sine wave generator in Logic Pro, sent this signal to Kemper input. At the same time I was capturing signal from Kemper output and recording it. Then I did spectrum analysis in Logic.

    Quote from guitarist1977

    This test of course is not perfect. But what I did, I set up sine wave generator in Logic Pro, sent this signal to Kemper input. At the same time I was capturing signal from Kemper output and recording it. Then I did spectrum analysis in Logic.


    Thanks, I am curious to compare the Axe Fx to a profile of the Axe Fx.


    I am doing a little reading and not getting very far. I believe I can create the sine wave, did you use the channel eq to analyze? Also, how does one determine if the first harmonic is present? Thanks.

    I did the same test with my BIAS Desktop and it produces 1st harmonic on all modeled amplifiers.


    This 2 images are from Kemper (two different profiles). Sine wave is at 300 HZ


    [Blocked Image: http://s31.postimg.org/q8rhhvc7f/Screen_Shot_2016_04_22_at_1_32_37_PM.png]



    [Blocked Image: http://s31.postimg.org/cp61yf8uj/Screen_Shot_2016_04_22_at_1_34_09_PM.png]



    This images are for BIAS Amp two different amp models. Sine wave at 300HZ


    [Blocked Image: http://s31.postimg.org/p2iw5byiz/Screen_Shot_2016_04_22_at_1_35_22_PM.png]


    [Blocked Image: http://s31.postimg.org/486jni45n/Screen_Shot_2016_04_22_at_1_36_12_PM.png]

    I think there's a bit of a nomenclature problem in this thread. The first harmonic is the fundamental, F. The second harmonic is 2F, the third is 3F, and so forth. The even harmonics are generally attributed to adding body or fullness to sound, while odd orders are often referred to as harsh and inharmonic. Even harmonics tend to be the prominent distortion content present in hifi tube amplifiers, which is partly why they are often referred to as sounding smooth compared to solid state, whose distortion spectrum is often dominated by odd order harmonics.


    Looking carefully at Guitarist1977's tests, it's not just the second harmonic that is suppressed but all of the even harmonics are barely visible. I love my kemper, but these tests are quite simple to perform and the results are consistent across multiple profiles and users.

    Quote from gitarretyp

    I think there's a bit of a nomenclature problem in this thread. The first harmonic is the fundamental, F. The second harmonic is 2F, the third is 3F, and so forth. The even harmonics are generally attributed to adding body or fullness to sound, while odd orders are often referred to as harsh and inharmonic. Even harmonics tend to be the prominent distortion content present in hifi tube amplifiers, which is partly why they are often referred to as sounding smooth compared to solid state, whose distortion spectrum is often dominated by odd order harmonics.


    Looking carefully at Guitarist1977's tests, it's not just the second harmonic that is suppressed but all of the even harmonics are barely visible. I love my kemper, but these tests are quite simple to perform and the results are consistent across multiple profiles and users.


    You are right. It is 2nd harmonic (and all even harmonics that are missing). I just followed the title of the thread.

    Quote from gitarretyp

    I think there's a bit of a nomenclature problem in this thread. The first harmonic is the fundamental, F. The second harmonic is 2F, the third is 3F, and so forth.


    Quote from digbob

    use your ears
    all measuring etc is misleading
    if the sound is right for our ears
    theres no problem
    all other doesn't matter
    my 2 cents


    I disagree. Measurements is scientific based proof. Hearing is very subjective.


    I am not a novice here. My work is related to DSP and as a hobby i build tube amps. And one of the test we do when constructing the amps is feeding the sine wave into the amp and look at the harmonics. The reason - hearing can be misleading. But the waveform and spectrum clearly shows what is going on.

    Quote from guitarist1977

    I disagree. Measurements is scientific based proof. Hearing is very subjective.


    I am not a novice here. My work is related to DSP and as a hobby i build tube amps. And one of the test we do when constructing the amps is feeding the sine wave into the amp and look at the harmonics. The reason - hearing can be misleading. But the waveform and spectrum clearly shows what is going on.



    Furthermore, some people HAVE complained about the sound of the profiler - this could be very relevant.

    Assuming the data presented here is accurate, the Kemper does not output the even harmonics.


    As I'm trying to understand this issue, my question is so what? For years the Kemper has been profiling amps and in blind tests to the profiled amp, most people can not distinguish between the two. If the even harmonics are significant to the amp sound, why can't most people immediately pick out the real amp versus the profile? Why would major studios and major musicians use the Kemper if the sound was deficient due to missing the even harnonics? Is the discussion about the even harmonics in the same category as the thread about "96khz 24bit profiling"? Are we getting "wrapped around the axle" over a technical difference that the ears can't distinguish?


    My questions are intended as legit questions for my own learning. Someone help me understand what my ears are missing.


    Quote

    hearing can be misleading

    . I'm not sure what this means. If I don't hear it, I don't hear it. I can accept that the Kemper is missing the 2nd harmonic. But if I can't hear it anyway, what difference does it make? Educate me.



    Evidently, it doesn't matter to a lot of people - but to some people, it might.


    Also, say it was a bug in the firmware - and it was fixed. Maybe a lot of different rigs that were previously deemed to thin-sounding would all of a sudden be just the ticket. (Conversely, maybe some of the rigs that previously were considered great could become too thick - but see the following paragraph).


    I see this as the "Low Frequency Correction" that Kemper introduced some time ago - there was an "inadequacy" in the profiling which meant that low frequencies weren't being represented faithfully. This was corrected (with an option to keep the old "setting". If the community is too eager to shut down threads such as this, that kind of stuff wouldn't be remedied. Ultimately, it's to the good of the product and hence the company (and us).


    The reason to use a "scientific" method is to remove expectation bias - science don't lie, but our hearing does sometimes :) expecting a profile to sound nice and full will turn our attention to what "fullness" there is - and exaggerate it in our perception. Then after a time, we might notice something amiss, but at that time we might blame it on the monitor, the headphones, a bug in the firmware, whatever. Or just conclude that our tastes have changed


    You are right in your view that "if it sounds good, it is good" - but @guitarist1977 is ALSO right :)

    Quote from alwainwright

    . I'm not sure what this means. If I don't hear it, I don't hear it. I can accept that the Kemper is missing the 2nd harmonic. But if I can't hear it anyway, what difference does it make? Educate me.


    The missing harmonics add to the body of the sound and how it is perceived. In certain cases it sounds good in isolation but in the mix it does not. Then you have to EQ it to sound better.