Anti Cliping

    After updating to 4.0 and trying a whole bunch of rigs recently I've noticed it's not just me but also a few popular profiles that have an issue with clipping mainly with clean profiles.


    I do pay close attention to this when profiling and I find even in general some sort of level meter would be a useful guide to determining levels withing the unit when profiling also for consistancy.
    As a sound engineer i feel this is a critical but overlooked feature of the profiling procedure.


    Also not sure if there is but a way to alter the level internally ( maybe a editing program Mac/PC) if the profile is clipping after the profile has been created.I find that quite often after making clean profiles with the Kemper impulse algorithm and even refining with no clipping during the process that I can still get clipping using that profile later with the same guitar.
    If this program also have other tools such as phase detection and analise frequency response I'm sure it would help make better profiles.


    My only gripe after having the unit over a year. It's one spectacular piece of work Kemper !

    Problem is there is no way of knowing if it is clipping internally which it likely is. The green to red LED is just way too crude for such an important task.
    I think there really needs to be proper metering in and out for optimum gain staging. This seems a very large oversight in the profiling process as there is technically no difference to recording a guitar track to tape or disk. If you hear clipping going into say pro tools you've most likely gone way over 0db so hears alone are not a good measure. On the other hand clipping can be just the effect your after.


    Other diagnostics in the profiled would also be great to compare the profiled rig with the original. Frequancy analysis would be a handy tool here also.


    Being able to edit these features on a PC or MAC would be invaluble and give so many option to help create better and more interesting profiles.


    Knowing levels and gain staging ARE very important.

    It's impossible to clip the Profiler internally (even a 24bit FP acceptance would require kind of a gain factor in the thousands to clip, and the Profiler goes probably further this), just by the A\D and the D\A converters. The two LEDs show exactly this and, since there's good headroom, unless you see them steady red you can be certain you're not clipping anything.


    HTH

    I know what you mean, even though one can easily say that it's a kind of paranoia to control everything. :)
    The KPA's approach seems more like:
    If (nothing is clipping and) it sounds good, it is good.


    BUT...
    When I feel the need for more control I hook up the KPA to my RME Fireface via SPDIF, set the SPDIF out to Git/Stack and full volume (0,00) and use RME's Digicheck to see the levels of the Guitar Input right at the ADC and the Output Level right before the DAC.


    Because if there are peaks over 0,01 dB at the SPDIF there is clipping at the KPA's converters too - at least in my experience.


    Of course this works just as well for the Master Stereo setting of the output.


    BTW always be careful with positive volume pedal range values, because they really boost the signal internally before the converters.

    It's my experience with guitar players in the studio when setting pedals and multi FX units there is a very poor understanding of gain structure let alone inter sample peaks which can be as great as up to 6db.


    To say it digital unit can't be clipped is absurd. I'm sorry if I'm being a little aggressive on this topic but it needs to be addressed.
    Yes I can use a bit of common sence to make sure this dosn't happen but even then issues seem to arrive later down the track, Ive heard this with many profiles.

    Dave, I did not say you can't clip a chain made of several devices, I said yo can't clip the Profiler (or the Axe FWIW) between the two converters.
    Kemper did not publish their specs in this regard, but the Axe has got an internal dynamic range of 1400 dB and the Profiler should be in the ballpark as well.


    Question: what signal amplitude (voltage) do you get after the guitar's signal conversion by applying a gain of 1400 dB? Do your Maths. That would be the amplitude of a signal able to clip an internal module in the digital domain.

    Quote from ReneLangenhan

    BTW Does anybody know the bit depth the kpa is using internally?
    24? 32? 32 floating point, 48?


    There was already a discussion here for audio interface via S/PDIF and setting resolution in a DAW and the influence to the soundquality of setting the Bit depth in the DAW
    I was suprised that it was not so high as I expected in that moment.
    Could be 24 or 48, but don't bite me, I cannot remember. - I do not use DAW's or S/PDIF ;)
    Maybe you find this thread (I think 2-3 month before)

    Quote from ckemper

    The profiling process controls the volume automatically, as mentioned in the profiling manual.
    A level meter is not overlooked, but of no use.


    How about a general purpose meter then, Mr CK? The LEDs are not much help to us in determining the volume of a profile, so levelling can be a problem. I know that acoustic and distorted profiles have different behaviour in this respect. But it would be great to have some kind of meter to at least give us a ballpark estimate into how loud a profile is. My old GT-8 had a similar feature in the system menu! :)

    Quote from ckemper

    As mentioned in the Profiling Manual, the Profiler sets the volume of an amp automatically, when being profiled.


    Yes, that's good. But it is common experience that some profiles are louder than others, and some are quieter, due to the different profiling methods used.


    A level meter would allow users to match volumes of different profiles in a faster way. Not that it would replace setting the levels by ear. But there's a world of difference between stage and bedroom volumes, and a meter would help get sounds in ballpark range of each other.

    From time to time I like to use rig exchance profiles and you'll never know how users set up and store a rig before uploading.So you got different levels quite often.
    In order to avoid the never-ending task match up hundreds of rigs I use an external limiter behind my beloved KPA. :whistling: Please don't laugh at me - I know it's a compromise.
    How about a limiter in the output section?

    A volume meter will never give you a good hint about the perceived volume, especially in a mix.
    And I doubt that anyone will sacrifice the dynamics of the amp, for the sake of unifying the volume.


    I truly trust your ears!

    On a side note: