I got this looping tip from Mike Balance. Thanks Mike!
This is really long so if you think it might be confusing and don't want to
use it then thats's cool. I just find this method to work really good and I
want to share it with other MPC users. Also keep in mind that some breakbeats
might not work so good with this but it's perfect for house and disco loops.
These instructions are refering to the regular 2000 but it should work the same for the XL.
1. Loop your sample the usual way at first in trim mode and make note of the tempo provided by the BPM feature (or whatever you've changed it to) then turn the "LOOP" off.
2. Precisely pinpoint the very end trim point of the loop; make sure there's no unwanted sound or waveforms at the end that you can't hear (you'll see why later).
3. Take the start trim point of your loop back like 4000 samples (or a number you can remember easily) if possible so that later on if you want to change the start point your not stuck with what you originally cut it to. I like to call this pad.
4. Hit "LOOP", "FIT", "DO IT" + "TRIM", "CUT", "DO IT". Now you should be left with the exact end of the loop and 4000 samples of pad at the beginning (which you'll ignore for now).
5. Make a copy of your sample, in zone edit make the zone fit the whole sample and reverse it.
6. Go back to the original sample, go back to zone edit, set the start and end zone points to the very end, hit "EDIT" choose "INSERT SOUND->ZONE START", choose the copy you just reversed, and "DO IT".
7. Now you should have the original sound with 4000 samples of pad at the beginnig (if you used any) and the same sound backwards tacked right on to the end.
Before you do anything else-DO NOT change the end trim point! However, set your "PLAY X" to "ALL" since the ending trim point will not reflect what you just added on to the zone end. Hit "PLAY X" and make sure there isn't a pop or a weird glitch where the two sounds meet (if there is, take the end trim point back about 100 samples and repeat steps 4-6, sometimes it takes a couple of tries but it usually works).
8. Once you've succefully merged the original sound with the backwards copy right on to the end, take your start trim point forward 4000 samples (or whatever number you used for pad if any), take your end trim point all the way to the end and assign the sample to a pad. Set the "OVERLAP" to "NOTE OFF".
9. Set the tempo of your sequence according to what the auto BPM feature provided on step 1 and record your sample on to a track.
10. HERE'S THE MOST IMPORTANT STEP OF ALL: After you record your loop/loops in a sequence, go to step edit and adjust the duration of each note using the 96 parts per quarter note equation:
Sample lasts two whole measures=D:768
Sample lasts one whole measure=D:384
Sample lasts 1/2 a measure=D:192
Sample lasts 1/4 a measure=D:96
and so on...
Steps 2-8 are so you don't get a gap of dead space at the end of your sample when your trying to loop it in a sequence set to the tempo that the BPM feature provides. Or if it's looped in trim mode you won't get that popping sound a the end when its's looped in a sequence, instead you're just telling it to play exactly the amount of duration time allowed for note off overlap using 96 ppq.
I know it seems kinda complicated but once you do it a few times you'll realize it's pretty simple and the end result makes your whole track sound pretty good.
Also, leaving 4000 samples of pad at the beginning of the sample isn't necesary for this to work but I do it on all my samples and it does come in very handy.