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?
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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.
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