Tips for Better Loops
If you're creating loops from your own audio source material, you'll need to edit the sound files to produce smooth and consistent results. Here are some things to bear in mind when editing loops:
Cut on the "1" at the beginning of the first beat in the measure or bar. Try to cut immediately before the first cycle of the attack
Don't cut into the transient! Edit immediately before the attack begins or you'll lose some of the instrument's character.
Listen to the loop. Most audio-editing programs have a "loop play" or "audition" feature that plays any selection repeatedly.
If the loop sounds anything less than slamming, check the start and end points.
If the above four tips don't help, and things still sound weak or disjointed, try a different loop. Bands and drummers often make timing errors, so not every recording is loopable.
Loop start and end points should always fall on zero crossings. Zero crossings are points at which the waveform is at 0 dB, represented as the line in the middle of a waveform display.
As an extra precaution, meticulous producers such as Mark Pistel (Consolidated, Meat Beat Manifesto) always perform a tiny fade-in at the beginning of a loop and a tiny fade-out at the end to force the waveform to zero. That is done while zoomed way in; the fade can occur over a single wave cycle.
Be sure to indicate the loop's tempo and the number of measures in the loop file name when you save or rename the file. I like to use names such as "rockbeat 1-110bpm-4x.WAV" or "reggaepattern2_90bpm_2meas.AIFF."