Question -- working with Direct vs Studio vs Merged Profiles and combining/changing cabinets

    Hello fellow Kemperites,


    I am trying to better understand how to best take advantage of the new Direct / Merged profiling possibilities.


    Now, just to be clear, I do understand the differences between Direct, Studio and Merged Profiles. What I still am a bit confused with, is how to best audition, combine and/or change a given amp profile with different cab profiles. In reading other threads related to "Merged" profiles, I see a lot of people making a Copy of the Cabinets from the Merged Profiles (contained in the Factory Profiles of the new Firmware release), and pasting them onto studio profiles (whether free or commercial). However, if I understand the Direct -vs- Studio profiling methods, the only way to authentically switch and swap Cabinets contained in a Merged Profile, is to match them only with a bona-fide Direct profile. If I understand this correctly, it is because the KPA can only separate the cabinet profile from the amp profile, with 100% accuracy, when working with Merged profiles (since they were made separately by combining a Direct profile with a Studio profile).


    However, Studio profiles are a mixture of an amplifier and cabinet profile, and involve the Kemper's CabDriver algorithm. So, wouldn't copying a cabinet from a Merged profile onto a Studio profile (versus a Direct profile) be less then "authentic"/"accurate", since there is no way that the Kemper can remove the cabinet contribution from the Studio profile, without invoking the CabDriver algorithm??


    If (and this if a big "if") what I have stated above is correct, then this seems to go against and contradict the following statement from the Kemper Profiler Addendum 3.0 Manual, page 14:


    Quote

    Your Merged Profile now features the authentic “amp with cabinet” sound of the Studio Profile, whenever the Cabinet Module is active. If you switch off the Cabinet Module, you will get the authentic, “amp only” sound of the Direct Amp Profile to be fed into a physical guitar cabinet. The original Direct Amp and Studio Profiles are now fully contained in the Merged Profile, so you are safe to delete them now, if desired.


    A positive side-effect is that the Cabinet of the Studio Profile has become an “authentic” cabinet, comparable to one based on an imported impulse response. If you copy a “merged” Cabinet Profile such as this into another Studio Profile later on, it will not undergo the usual approximation of the CabDriver algorithm.


    In other words...how the heck can the KPA purely and authentically subtract the already incorporated cabinet contribution from a different studio profile, when combining it with just the cabinet profile of a Merged profile. I mean, it seems like the CabDriver algorithm would still come back into play, in order to perform this subtraction process. Which means, combining a cabinet from a Merged profile with a Studio profile will never be as "accurate" / "authentic" as doing the same, but with a bona-fide Direct amp profile.


    Hoping you experienced Kemper users can set me straight, here, and I would appreciate anyone thoughts on this.


    Thanks in advance.


    Cheers,
    John

    Edited once, last by Tritium ().

    It can't. At least I don't THINK it can. When making the new 3.0 version of a profile, if you are just taking a Studio profile and copying the cab to another studio profile, it is an approximation of the frequencies that make up the cab portion. When merging with a DI, it's a "clean" source with no cab coloration. What I am guessing the Kemper does is keep those "0000111101's" separated somehow so the preamp/poweramp sound comes though your cab on it's own. Hope that makes sense. I am sure I am a little off in my thinking.

    Quote from JerEvil

    It can't. At least I don't THINK it can. When making the new 3.0 version of a profile, if you are just taking a Studio profile and copying the cab to another studio profile, it is an approximation of the frequencies that make up the cab portion. When merging with a DI, it's a "clean" source with no cab coloration. What I am guessing the Kemper does is keep those "0000111101's" separated somehow so the preamp/poweramp sound comes though your cab on it's own. Hope that makes sense. I am sure I am a little off in my thinking.


    Hi JerEvil,


    Thanks for your input. If I have read your reply correctly, you are in agreement with my post. In other words, if someone is looking for best method to take a given amp profile, and mix and match different cabinets, it would be to use a Direct Profile, and copy the cab profile from a Merged profile, and paste into the empty Cab slot of the Direct profile. This, in fact, is made possible now with the 3.0 (and newer) Firmware. Thanks in part to people like Tim Owen (HAWP tread and BE100 Direct and Studio profiles), and yourself (Splawn Quick Rod Direct and Studio profiles), the library of Direct and/or Merged profiles is building up.


    However, I still am hoping a Kemper representative chimes in on this thread, as the section of the manual I quoted, in my original post, still seems to be a bit misleading. That is to say, combining the cabinet from a Merged profile onto a Studio profile, should not provide optimum results. That implies that the Kemper has somehow subtracted the original cabinet profile from the Studio profile, which again invokes the CabDriver algorithm/process. At least, that is how I see it. That is not to say that doing this will yield unacceptable sounds. The CabDriver has proven to work most excellently. I am just saying that, from a first principles perspective, this would now not be considered "ideal". I am wondering if the section from the Addendum manual is a typo, and that Kemper mean't to write:


    Quote

    A positive side-effect is that the Cabinet of the Studio Profile has become an “authentic” cabinet, comparable to one based on an imported impulse response. If you copy a “merged” Cabinet Profile such as this into another Studio Direct Profile later on, it will not undergo the usual approximation of the CabDriver algorithm.

    I agree with you, Tritium.


    An accurate separation can only happen if a direct amp profile was subtracted from a studio profile.


    And like you said putting an accurate cab from a merged profile onto a non merged studio profile would still use cabdriver for separating the cab from the non merged profile.
    In this regard the manual could be a bit misleading when read the wrong way. I read it a bit differently but I definitely see what you mean.

    Quote from Ingolf

    I agree with you, Tritium.


    An accurate separation can only happen if a direct amp profile was subtracted from a studio profile.


    And like you said putting an accurate cab from a merged profile onto a non merged studio profile would still use cabdriver for separating the cab from the non merged profile.
    In this regard the manual could be a bist misleading when read the wrong way. I read it a bot differently bist I definitely see what you mean.


    Thank you, Ingolf. I needed a second pair of eyes on this, and I am glad that you are able to confirm that what I had written is, in fact, correct and accurate.


    Cheers,
    John

    Reading the paragraph from the manual, I'm guessing that the cabdriver algo does not come into the picture because the cab is applied basically as an impulse response. Not much of a guess, just a paraphrasing, hehe...


    But the cabdriver is only relevant to studio profiles, where it is used to determine ... something... about the dividing line... hmm....


    Anyway, another quote from the manual, regarding use of imported impulse responses in combination with direct amp profiles:



    Quote

    An impulse response is the perfect companion of any Direct Amp Profile. While the latter is a perfect reproduction of
    the full guitar amp, the cabinet IR is the perfect reproduction of a speaker cabinet. Combined, they are as authentic
    as a Studio Profile.


    We highly recommend that you select cabinet IRs that have been captured using a solid-state amp, rather than a
    tube power-amp. Since the interaction effects of amp and cab are reproduced by the Amp Profile, it is a good idea
    not to have them reproduced in the Cabinet Profile a second time.


    From this, it seems to me like a kemper cab is basically ONLY an impulse response. That would mean the cab driver algorithm only determines which part of the "overall" static EQ curve is from the cab and which part of it is from the amp. As to the original post, then... I would have to agree that it seems to be at odds with the cabdriver NOT coming into play when slapping a cab from a merged profile onto a regular studio profile - how does the kemper know what part of the studio profile's EQ curve to subtract (the cab) before applying the EQ curve of the "pure" cab from the merged profile....(edit: but see later!)


    But all this is guesswork with no real knowledge about what goes on behind the scenes.


    Looking at the profiling guide's "under the hood" chapter:





    Seems like there is a lot more going on rather than simply a static EQ curve regarding the cabinets. However - is this stored in the CABINET section (making it NOT the same as a simple impulse response)? Or is it stored in the AMP section?


    I'm guessing the latter - and then, while a MERGED profile has the cab disabled, these parts of the AMP profile are disabled along with the cab? That would allow for authentic use of a real cab, and authentic cab swapping on the merged profile. Maybe that data is duplicated in the cab portion of a merged cab? I think the merged KIPR files are bigger than the normal studio ones, right? Than would allow this new merged cab to be AUTHENTICALLY coupled with the amp section of a regular studio profile.



    Sorry for the lengthy post, but I think I have cracked the nut here :)

    Quote from Michael_dk

    Reading the paragraph from the manual, I'm guessing that the cabdriver algo does not come into the picture because the cab is applied basically as an impulse response. Not much of a guess, just a paraphrasing, hehe...


    But the cabdriver is only relevant to studio profiles, where it is used to determine ... something... about the dividing line... hmm....


    Hi Michael,


    I did of course read your entire post, but just quoted the first part. I may have misunderstood your thought process, so correct me if I am mistaken...


    However, my central argument is the following:


    It is understood that the new profiling process allows the amp profile and the cab profile to be accurately and completely separated from a Merged Profile. In which case, it is accurate to copy and take the Cab information from any Merged profile, and combine it with a Direct profiled amp.


    However, if you were to do the same, and combine it with the amp section of a Studio profile, then the CabDriver algorithm must somehow come into play. The reason is that the CabDriver algorithm is the only way to subtract the exisitng "cabinet" section of a Studio Profile. Otherwise, one would be copying a Cab profile (or impulse response) on top of another Cab profile that is already embedded and intrinsic to the Studio Profile. I hope I am making sense.


    Cheers,
    John

    OK, say we have the following fictional parameters "somewhere" in a normal complete studio profile:


    Overall EQ curve = XX
    Power amp/speaker interaction = ZZ
    Speaker cone breakup = YY
    Speaker distortion = UU



    Previously, the cabdriver algorithm was used to determine which part of the EQ curve belonged to the amp exclusively, and which part of the EQ curve belonged to the cab exclusively, so the separation between the two was an approximation / guess.


    Now, you make a Direct amp profile without touching anything, and then you have this (i.e., only the amp part into play here):


    AMP EQ curve (instead of "Overall EQ curve")
    Power amp/speaker interaction (because the direct signal is taken WITH the speaker connected, like recommended by Kemp
    NO Speaker cone breakup
    NO Speaker distortion


    Then you merge the two into a MERGED profile, so you have this:
    Power amp/speaker interaction (from either the studio or the DA profile)
    * Speaker cone breakup (from the initial studio profile)
    * Speaker distortion (from the initial studio profile)
    AMP EQ curve (from the DA profile)
    Overall EQ curve (from the studio profile)
    CABINET ONLY EQ curve (by retracting the amp EQ curve from the overall EQ curve).


    So far so good :)


    During the merge profile, the CAB EQ curve is saved into the cab portion, the power amp/speaker interaction as well as the AMP eq curve is saved into the amp portion of the merged profile. The parameters marked with an asterix (*) above are saved into BOTH! the CABINET portion AND the AMP portion of the merged profile. That means that you have these parameters saved in the cab section:


    Speaker cone breakup (from the initial studio profile)
    Speaker distortion (from the initial studio profile)
    CABINET ONLY EQ curve (by retracting the amp EQ curve from the overall EQ curve).


    So when you apply that cabinet to a regular studio profile, the kemper goes "Hey... that cab profile have the FW3.0 parameters defined... I will now DISREGARD those parameters in the studio profile that John is applying this cab to". Voila, now you use all the relevant parameters from the "merged cab" only; not from that studio profile's original data.


    Was that more clear?


    Hi Michael,


    We are absolutely in agreement, with everything you have spelled out, point-by-point...except, and right up until you reach the final step, that I have bolded, for emphasis. By the way, please make no mistake, you may be absolutely right, and the KPA is able to do your final step (bolded) without implementing the CabDriver algorithm. Heck, you are probably right. However, that crucial final step, I cannot understand happening without a very special-purpose computational algorithm, FFT-based approximation (CabDriver) employed upon the target Studio Profile.


    Here is my thinking...


    Regardless of what Firmware the Studio Profile was saved with...a Studio Profile takes a snapshot of the entire system (amp + cabinet). During this profiling process, I cannot see how the KPA could actively "tag" or discriminate specific data points of this homogeneous signal -- that is, it's associated frequency-response A/D modulated samples, as applying to only the amp portion or only the cab portion of the very same signal. After all, that is the whole purpose of the CabDriver approximation algorithm; to do this discrimination, through a creative, intelligent approximation algorithm.


    My thinking is that the new Firmware doesn't change this fundamental issue. In other words, If you make a Studio profile, even with the new Firmware, the KPA is still analyzing a homogeneous, undifferentiated full-system signal (amp + cab), which it uses to construct the profile . Even with the new Firmware, a Studio Profile still requires the CabDriver algorithm to make a creative, approximate separation between amp and cabinet. That is to say, the KPA is not able to actively filter, separate and assign data samples which are tagged "this is only from the amp" and an other "this is only from the cab". In a Studio profile, the data samples are all combined into a single, universal Set X. It is still the CabDriver algorithm that makes intelligent, but approximate/optimized choices, and partitions samples into pairwise disjoint Subsets Y (I think I am a data sample exclusively from the Amp) and Subset Z (I think I am a data sample exclusively from the Cab). The beauty of the CabDriver algorithm, in actual implementation, is to turn the provisional "I think", into a convincing Cartesian "therefore I am". By all measures, it does a very esteemable job of this.


    Obviously, this is entirely different when there is a separate data file made during a specific amp's Direct Profiling process. In the Direct Profile process (with intention to create a combined MERGED profile) you first make the Direct profile, and then, with no changes to set-up, you immediately make a full Studio Profile. Then, I can understand how the KPA can perform an almost point-by-point extraction process of the Direct profile (amp X) from the corresponding Studio profile (amp X + cab). However, that is not what we are talking about, here...I think. What stumps me, is that last step, where you are taking a perfectly separated Cab data file that comes from the Merged Profile, and try to combine it with an arbitrary Studio profile. How he heck does the KPA know what corresponding data points to use in the discrimination and subtraction process. Sure, everything is theoretically known, bit by bit, in the Cab data taken from the Merged profile. However, given an arbitrary Studio profile how is the KPA able to determine which data point is part amp portion of the over-all Studio profile, and which data point is part of the cab portion of the over-all Studio profile, without using a CabDriver approximation? In other words, if it doesn't first accurately separate (on a point-by-point) basis, that portion of the original target Studio signal applicable only to it's cab...there is no way (even given perfect knowledge of a the Cab data from the incoming Merged profile), it can accurately, and without approximations, subtract away the contributions of the cabinet that already exists in the target Studio profile.


    Ah heck, I have had a few too many pints of Ballast Point Sculpin IPA...so I am probably not thinking clearly while I have been typing this out. I probably have made a complete mess of my thought process. Actually, I am pretty certain I have. :P


    In any case, I like and very much appreciate your explanation, Michael. I definitely can envision that you might have the right answer on this matter. I will look at this with fresh eyes (and brain) tomorrow.


    Cheers, mate.
    John

    Edited 3 times, last by Tritium ().

    Ah.. Well... Humm...


    I think some of that IPA seeped over the internet and into me, because now all of a sudden I'm a bit confused by what I actually meant last night... Was I on to something, or was it a brain fart?


    I don't' quite follow everything in your post, but I get the gist of it.


    Hmm..



    I have as a basic assumption that what is stated in the manual is correct, even though I can't explain how they do it.


    How about this theory, then:
    The cab section of a studio profile in previous firmware versions ONLY contains the static IR response (EQ curve) of the cabinet.
    The cab driver only makes a distinction about what frequency curve belongs to the amp and what belongs to the cab.
    All the other cab characteristics of an "old" studio profile were actually stored in the amp section.
    A cab "preset" from a MERGED profile now IN ADDITION to the frequency curve contains all these cab relevant parameters
    When applying that cab to a studio profile, it does what I outlined before - but more specifically ignores those parameters that are already stored in the AMP section of the regular studio profile
    And when turning off the cab section on the kemper, then the kemper knows to also disable those parameters in the amp section. (I mean, I'm sure the kemper does not make a distinction about what belongs to where, that's just for our benefit)


    Would that make more sense?

    The OP is actually right. The manual is inaccurate by saying the cabinet stays authentic when brought into another studio profile. While the said is true, it is to be mentioned that the amp portion of the studio profile will not be authentic. It will stay authentic as well, if the cabinet is brought to a direct amp profile or a merged profile.


    We will add this to the manual. Thank you.

    Quote from ckemper

    The OP is actually right. The manual is inaccurate by saying the cabinet stays authentic when brought into another studio profile. While the said is true, it is to be mentioned that the amp portion of the studio profile will not be authentic. It will stay authentic as well, if the cabinet is brought to a direct amp profile or a merged profile.


    We will add this to the manual. Thank you.


    OP here,


    Wow, I didn't expect a confirmation from the Man, himself. :thumbup:


    Thanks for your feedback, Christoph!


    Cheers,
    John

    Edited once, last by Tritium ().