Combining loops using retuning
One of the most creative techniques in sequencing is combining two drum or percussion loops. The results can be unpredictable, but unpredictability is often where creativity is to be found.
One method of combining loops is to load up the two loops into a sampler, a software sampler should be OK as long as it has a retune feature.
A sampler stores the loops in RAM (random access memory) rather than playing them from disk as in traditional audio sequencing. The advantage here is that either sample can be retuned. Retuning alters the duration of the sample. It also alters the pitch, but this can open the door to new sonic textures.
It is not advisable to loop the samples in the sampler as it will be difficult to synchronize other tracks to them. Instead, assuming the samples both last two bars, trigger both samples via MIDI to play at the beginning of the first bar of the sequence and at two bar intervals after that.
You will have to set in the sampler for the samples to play all the way to the end, even though triggered only momentarily.
Now set the tempo of the sequence so that the first sample plays repeatedly, in time and with no gap between retriggers; no overlap either.
Plainly, if the second sample is not exactly the same length, then there will be a gap or an overlap as it loops, and the whole thing will sound like a terrible jumble.
But now, carefully adjust the tuning of the second sample. As you tune it, its duration will change. Simply find the point where it lasts exactly the right duration for it to loop neatly at the tempo you have set.
With any luck, you will find that the beats magically align, entwine and possibly even syncopate. If it doesn't work out, try another loop.
One of the bonuses of combining loops in this way is that your work is bound to be original. It would be a remarkable coincidence if anyone else had tried it with exactly the same original material.
Of course there are other ways of synchronizing two loops. Retuning has the advantage of being perfectly smooth and glitch free.