Sampling the guitar presented a challenge since it's not easy to hit the KP3's buttons while trying to play. The solution was a Behringer FCB1010 foot pedal MIDI controller, a long pedal board with 10 switches and two expression pedals. I mapped the first four switches to the KP3's A-D sample buttons. Two more switches turn the KP3's Hold mode on and off, respectively. When Hold is on I can use the expression pedals to control the touch pad's X and Y axes. The only bad thing about this setup is the fact that Korg didn't enable MIDI control of the Sample button. There's no getting around having to arm the sampler by pressing it on the KP3 itself. But that's not such a big deal since it's something I can do at a convenient moment, well before I intend to sample. I've also gotten good at hitting it with the guitar head.
I especially like that the KP3 can record loops of different lengths. Granted, it restricts me to 1, 2, 4, 8, or 16 bars (or fewer, if I'm at a slow enough tempo), but it's fine for how I use it. I generally use TC's trick of sampling things at 1 and 2 bars to establish a rhythm. Anything sampled in 1 bar becomes a kick, anything at 2 bars becomes a snare. Once those are going I apply delay to groove them out. I can resample both down to another track, or just cut them in and out on A and B. Tracks C and D are free for sampling longer phrases. I resample as needed to conserve tracks. I was interested in the Electro-Harmonix 2880, another guitar-friendly looper, until I realized how much I like having control over loop lengths.
Another cool thing about the KP3 is its set of LOOP patches, which continously capture the previous 4 bars of audio. The mini-KP can also do this but it's more useful on the KP3. For example, I use LOOP1 to capture a phrase from a news broadcast, keep my finger on the upper right corner of the touchpad to loop it, then hit Shift+Sample and A to record it to track A. The mini-KP has no resampling capability. I use this technique to fill up all four KP3 tracks on the fly. I keep whichever samples are the most interesting and bring them back throughout the performance.
Hit Shift+A and the touchpad becomes a mixer with four virtual faders. Not only is this a cool, Lemur-like interface, it's practical for when I want to dial one track back without affecting the others -- something that happens often when the send knob is a bit too far to the right. A word of warning, though: When HOLD is enabled, entering the mixer mode will stop playback. This can be jarring, so use it with caution. It would have been nice if Korg had included track panning, but we'll have to wait for the KP4 for that.
The KP3 isn't perfect. For one thing, it's timing isn't great. It's common for its loops to go out of sync with each other even when they're recorded at the same tempo. Hitting Align (Shift + Tap) mitigates this. You can also nudge a sample in time by hitting Shift+A (if it's on track A, for instance) and using the BPM knob to move its start point. The sync problems are worse if you're syncing the KP3 to an external clock. For instance, I had problems using an ER-1 as a clock master. That was surprising given they were both Korg boxes. After 5 minutes, the KP3 was noticeably ahead of the ER-1, skewed enough to kill the groove. After 15 minutes, it was a full 16th note ahead.
The best workaround, by far, is to upgrade your KP3 operating system to version 2.0 (download it from korg.com) and to set the KP3 to Loop Type 3 (read the documentation included in the OS upgrade). The default behavior is Loop Type 1, in which all four samples play constantly, remaining in rigid lockstep with each other, and pressing the A, B, C, and D keys simply mutes or unmutes them. This is bad since, while they remain in sync with each other, they drift with respect to the external clock. Loop Type 3 is different in that the samples begin playing when activated, starting from the point of activation. For instance, hitting the button repeatedly causes a stuttering effect, playing the first part of the sample each time. This obviously can throw the four loops out of sync with each other, but that's not necessarily a bad thing. I prefer having total control. Sync depends on my ability to hit the button at the right moment. This isn't a perfect fix since loops left on for too long will gradually drift, but it is the difference between the KP3 being useful and being a doorstop.
Another bad thing is how the KP3 sometimes pauses when you apply an effect. For example, the DEL1 delay patch cuts the audio for a moment before it kicks in. Even the mini-KP doesn't suffer from that.
It would be ideal if the KP3 could apply different effects to different tracks, or even apply more than one effect at a time. But that's one reason why I keep a mini-KP downstream.
TC uses his KP3 in much the same way, though he also uses the motion record feature now and then, something I rarely do. Neither of us uses smart cards, which makes sense given that our mission is to improvise. Neither have we used the editor software.
I hope this entry gives folks some insight into this versatile instrument.