Posts by Laimon

    The Axe (Ultra) combined with KPA just dissapointed me.A Strymon Mobius gave better results, but in many ways the endresult didnt differ that much from the KPA, The Boss gt 001 I found most complimentary.


    There is a thread somewhere here about a new fx only floorboard that Fractal Audio is due to release that could be interesting for you, I reckon its gonna be a lot cheaper than the Axe fx itself,

    You didn't get much better results with the Mobius? I have to try. I'm a huge Strymon fan, own most of their pedals, but I have had the Kemper barely for days so I couldn't yet try them together.
    However, my first impression (without proper a/b comparison) makes me think that Strymon wins hands down. Nothing wrong with Kemper effects, they're very nice and professional, but much more standard than Strymon's, and that's ok, it's not the KPA focus, right? On the other hand I could probably like the KPA delay better than the digital delay on the Timeline, it sounds more pristine.

    Hey Paul, nope, that's not what we are talking about. Yes, there is a lot of hum in the clip, but we're really talking about aliasing. If you have the chance, send the clip without cab sim through a power amp and guitar cabinet, and you'll hear it loud and clear. Also in the clip with cab can be percieved, but you will need maybe some good earphones and listening (all the more because of the hum partially covering it)


    PS: as I wrote in a post just just above, the hum was somehow due to connecting my guitar on the alternate input in the back - connecting it to the front solves the problem. Cables are Mogami, normally dead silent. I had just reworked the whole routing before making those and I was caught off guard by this hum myself.

    This is not digital aliasing - this is harmonic amplification of the 50hz/60hz hum/noise that can be heard before the guitar is being played.


    It is very loud - a distorted profile will amplify and add harmonics to this constant sound. Notes played (and especially bent notes) will cause the harmonically rich constant sound to be consonant and dissonant with the notes that are played.


    Using the Kemper's gate, or adding a gate before the Kemper will not fix the problem. When the guitar is being played, the Kemper will still amplify the noise. There is a bad connection or loose shield on a cable (seems most likely a guitar or pedalboard cable). It reminds me of the sound that an amplifier makes when no guitar is connected to the other end of the cable.

    Sorry to hear for your fingers problem Laimon .
    Why don't you try with smaller strings gauge or tune down to D ?


    Also, I find that soaking finger tips in pure (medical) alcohol can help with calluses stiffness .

    No worries Rescator. In fact, a posteriori, I found your joke actually pretty funny :D in the moment I didn't though, because I really made an effort to record that clip with the fingertip pain.
    Btw, when that comes - and it comes way more often than I would like, once or even twice a month - it stays for a few days before it fully recovers, and it takes rest (well, both finger rest and general rest) and as much oranges and spinach I can take. I will try the alcohol too though, one never knows.

    I am thinking this is an interaction between the hum and the frequency of the notes being played. Sounds like hammering.

    I don't think that is it, the clip has a lot of hum (I discovered later that plugging the guitar from the alternative input in the back generated that, while plugging it in the front does not. And yeah, when plugged in the front of the unit, with no (relevant amount of) hum the problem was still there, and actually even more evident as not masked by the annoying hum.

    I take it back, you are correct - this is some serious aliasing. Slightly evident in the second track as well, as you said.
    Weird, i haven't noticed anything.


    Have you opened a support ticket?

    Thanks Quitty. It's nice to have a confirmation that I am not "hearing things" :D
    I don't really know how to open one, I might try now.

    Hi Armin,


    no, I didn't mike the cab, I don't have mics at home. The "cabbed" version is recorded straight from the Main out of the Kemper (cab on), the "uncabbed" one from the Monitor out (cab off from the output settings). It is no wonder that the cabbed version shows way less aliasing than the other one, as most high frequencies are cut out by the cab sim.


    I know that digital alias is unavoidable. On the other hand, it is well known that preamps generate far higher harmonics than the usual 44.1 KhZ converters, and since the Kemper provides a "direct" output (that is, cab sim off) probably a higher rate DA converter would have solved the problem already (well, provided it covers most distorted preamps harmonics...I am not talking about artificial frequencies produced just to prove that aliasing is still there, of course).


    What do you think of the "anti-aliasing filter" cab idea? I think it could be really beneficial. Do you know how one could make one?

    Yes everything is there as you mentioned it and it is very disturbing for my ears.
    It is like a basic noise covered by your picking (maybe they are right , it is not an aliasing
    problem).I dont know how to help but I remember once I had the same base noise with a
    line 6 dt 50 .It drive me crazy!After a while I found the cause ,my guitar cable!Check every component!

    Hi Redspecial, I think you're rather talking about this background noise (that I have to deal with this afternoon if I find the time), but that's hum, not the wobbling sounds that I am talking about.
    Listen closely right after picking a note (if you can, try sending the signal without cab sim to a poweramp and cabinet, there the effect is far from subtle, sounds like bumblebees on LSD), you will hear strange artifacts that have are not related to background noise, but they clearly come from erroneous interpolation of samples.

    Ok, let's try again from the start. This time I picked a profile from Keith Merrow, KM-ANDROMEDA, because freely available (Kemper download page) and because there the problem is more prominent.
    The signal path is:



    Yamaha Pacifica 821 with DiMarzio Evolution bridge =>
    Kemper (rig KM-ANDROMEDA, no effect on) =>
    Engl Ironball poweramp =>
    Mesa 1x12 Mini Rectifier cab


    Here are clips: https://soundcloud.com/simone-frau-2/sets/alias, with a version without and one with cab sim.
    The one without cab sim shows evident signs of aliasing, because there all higher harmonics are not cut by the cab sim (which acts as a filter).
    The alias in the one with cab sim on is of course way more subtle, but listen with headphones at enough high volume and you'll hear (especially after picking the 3rd, 4th and 6th note) this wobbling sound in the background. (the overall background noise does not make it easy to perceive, and in fact I can not claim I would hear it myself after some of the notes).


    I also uploaded the wav versions of this files, in my google drive account: https://drive.google.com/folde…94cS1KUFNCNEU&usp=sharing
    Feel free to do any analysis.


    Guys, you might think I am splitting hairs.
    When in use with the cab sims on, it is very subtle to hear it, and if I didn't know there was I would not look for it.
    When feeding the signal with cab sim off to a power amp and then to guitar cabinet, it is very very clear.


    I guess I could live with the first (as I don't do any professional recording at home), but not with the second, because I would be playing most often in that setup, where the problem is more apparent.
    The solution I would propose - if anyone knows how to make one, maybe Christoph Kemper himself - is to provide a fake cab IR, something that does not quite behave like a cab but rather as a low-pass filter to cut out the higher frequencies that in the DA conversion would produce aliasing. I think that would be an excellent compromise.

    The only thing I can see (hear) from that clip is that you might consider to work a little bit harder on your bending .
    Good Luck ! :thumbup:

    How cute. I suffer from folic acid deficit which some times leads literally the tip of my nails to detach from my skin, and that hurts like a bitch. You should try that, it'd give you a little perspective.
    I did the clip despite the fact that my fingers were hurting, thinking that listeners would focus on the alias.
    BTW: I've been playing for 20 years, and when I don't have this problem I can bend just fine, thanks.



    Have you heard the sound clips posted on the Kemper forums back when the aliasing issue was relevant?
    I'm not sure what you're hearing is aliasing, and the difference between your 'aliasing' preamp and your Kemper profile of it might just be due to the Profiler's tendency to roll off a little low end, depending on your refining process.

    Yes I did, it was indeed more prominent, but this is clearly audible on my full setup.

    here's the clip:


    https://soundcloud.com/simone-frau-2/alias


    On record it's not as audible as through my guitar cab, but still one can hear this anomalous, descending frequency right after picking each note.
    Noise gate is complete off.


    PS: I would share the rig for you to see what's going on, but it is a commercial one and I don't think I am supposed to.

    Laimon, no aliasing problems here at all.
    Please demonstrate and post sound clips of this if possible. Since you have so short time experience with the kemper maybe you have one of the noise gates up too much?
    I saw you just posted the claims about it also on TGP, post 112. http://www.thegearpage.net/boa…read.php?t=1443961&page=8
    It's always good to use a scientific approach and a good rule is that extraordinary claims require demonstrable evidence.


    Remember, just like any real amp the Kemper can recreate frequencies and harmonics "fighting" eachother which can cause some strange sounds, but that is a real phenomenon with guitars and amps, not a digital one.

    So, I read up on the aliasing discussions that took place and on TGP in the past.
    I understand that the problem was addressed, some say solved (in 1.6.1), and yet it's still very, very audible. I might be doing something wrong myself, in which case any tip would be welcome, cause I find really hard that big shot producers would live with that. Andy Sneap for instance doesn't really go easy on the distortions!
    In a post (Be aware of the digital sonic artifacts (aliasing) in your KPA!) Christoph Kemper wrote:


    "We have a large headroom of calculation power left, that I was planning to keep for future features and improvements for upcoming firmwares.
    However, it takes only three seconds for me to speed up our algorithms for the next firmware"


    Well, personally I would speed the algorithms in a blink of an eye. Somebody even suggested to make it optional, which clearly would be the best solution. Maybe because I care way more about the cleanest possible tone (i.e., without artifacts) than running all 8 effects at a time. Sure, if a Kemper 2 was somehow in the works, with relevantly more processing power... =P (cross my fingers)

    AHAHHAHAHAHAHA
    Sorry to bring this old thread up again, but this might be the funniest modeler related joke I've ever heard...and banning you from the FAS forums shows not only how intolerant and close minded many of them are over there - not all, granted, but I had my share of bashing for ever insinuating that the Axe might not be better than tubes - but also that they really could use some more irony :D

    I know it has been discussed here before. But there's something that I don't quite understand, let me explain my case.
    I own a Kemper since barely a few days. Love it, BTW.
    However there's the Aliasing problem. I know this is an inherent problem with converters, but I don't totally understand where it happens.
    Is it my guitar that introduces higher frequencies in the AD conversion? I don't think so, I don't hear anything on clean sounds, but it could just be not apparent.
    Is it the processing that - in the case of very distorted tone particularly - generates harmonics higher than the Nyquist frequency?


    The thing is: I am experiencing this with all heavy profiles. Most of them show it only on really the highest notes (say, 20th fret E string) or some harmonics, others are apparent even starting from 14th fret on the G string.
    On the other hand, I profiled a preamp - which did generate aliasing when recorded on my PC, so we're really comparing apples with apples - and very surprisingly the resulting profile shows no sign of aliasing!
    Why do you think that happens?

    Hi Andy, you're welcome!
    I have to say that when I started trying the profiles already loaded on the kemper I wasn't superimpressed with the first ones, until I reach one made by some "And44" guy =D I didn't actually know that was the TAF guy (sounds like tough guy!), so I wasn't even biased on judging the profile ;)
    However. I did find a problem with aliasing on the higher notes and on some harmonics. I'll probably do some reading on the forum (I am sure the problem came up before) and I wondered whether that depended on the Kemper itself, on the profiles, or on what...I might start a new thread about it later, make sure to participate ;)

    Uhm, I thought I was agreeing till half of the message, then thinking about it I disagree completely.


    Regarding the comparison between amps: sure it's always subjective but:
    a) does it really make sense to always make relative statements? If you hear an amp that sounds like a fart, would you say "I can't compare it with X" (with X being any great sounding amp)? Anyway, this is out of topic I believe
    b) here we're not really talking about amps, actually, but about amp profiles. And amp profiles can be done better or worse. It depends a lot on the refinement. If you do a very bias refinement (e.g. you do 20 seconds of soloing on the higher strings) you may well expect imperfections regarding the input you didn't feed the KPA during refinement (in analogy with the previous example, you may expect lower strings' attack not to be so defined). So, yeah, you can do better or worse profiles.


    Regarding the second part, I completely disagree. Finger tone is a completely orthogonal characteristic, with respect to amp tone, pickup tone and so on an so forth. A good player may make any gear setting sound well thanks to his skills, sure, but they won't make a mesa sound like a marshall. Rather, you can recognize their finger tone through different amps, that for sure, but it's a totally different story.

    Hi guys!
    So, I'm not really a new user of the forum, but haven't been around much as I didn't own a Kemper and had abandoned the idea of getting one some time ago...until a few days ago.
    Indeed about 10 days ago I saw a friend of mine using it, and the idea started tickling me again, so I looked for some secondhand bargain and...ta daaa, here comes my brand new KPA rack! :)
    So far I had only a few hours to toy with it, here are my experiences:
    On Wednesday I fooled around with the profiles already loaded on the unit. At the beginning I was like "uh, this sounds like shit!" (cab sims were off because I use a guitar speaker, that was not the problem), but I start tweaking the eq and immediately it start sounding nicer, much nicer...in fact, that's one first win: so easy to tweak, in no time I was really getting the best tone. Some profile did not convince me, but those that did really sounded great, extremely realistic, detailed, alive and musical! So first experience awesome.
    Then today I had a short time to try my first profiling session. I profiled my Engl Ironball (only the preamp), and the result is unbelievable! Not to say that it was indistinguishable: there are a few things (sharper attack on low strings for the real amp, boomier overall bass on the kemper) that tipped me off while I was doing blind tests with my gf switching kemper and reference amp at random (nailed them all), but the things is that this difference sound just like differences (and tiny ones, too), not like "flaws". It is still incredibly musical and enjoyable to play. So, second experience, brilliant!
    These first sessions were to decide whether it would stay...you might have guessed that it is staying ;) next months I'll have to study it in a bit more depth and decide if something else is going instead :D

    I have tried the Boss FV-500H and it was good, but maybe too bulky, and ultimately I went for a ME SP1, and I love it. More compact than the Boss, comparable throw, very silent.

    Hi Gianfranco,


    thanks for the explanation, in fact your last sentence fully answers one of my original questions.
    Regarding the interaction amp + cab, it's for me hard to say if the two can ever be split completely and their interaction recreated at a later time, but of course if this interaction is a factor the Kemper must capture this whereas modellers like the Axe Fx - not modelling the whole but single parts - can not ;)

    Thanks!
    I get your points, on the second one you told me exactly what I expected, on the first one however I might not have been fully clear.
    I certainly did not mean that I want to get all type of sounds (including different cabs' sonical footprints) on a non FRFR speaker.
    I meant rather that - as far as I understand - a profile capture the footprint of the whole rig, but removes cab and mic emulation a posteriori based on heuristics, with no actual profiling of the cab and mic used.
    And this is IMO suboptimal, even funny that Kemper would do so much to capture sounds perfectly and would settle for an imprecise removal of cab and mic, when I would expect that profiling the cab and mic alone would give enough info to accurately remove it from the full profile when performing on a guitar cab.