Once upon a time I might have said that it is an interesting way of making music, to sample sections of other records and assemble them into a completely new track. More recently, I might have said that it is a common way of making music. Now, some people actually think that it is the only way music can be made.
Nevertheless, it remains true that sampling can create novel and interesting sonic textures that are difficult to achieve in any other way.
So lets say that you have your Technics SL1200 turntable at the ready, connected to your sampler – hardware or software. One of the things that might cross your mind is to consider whether your samples might all be in tune with each other, and wonder whether the pitch control could be useful.
It does make sense – if you try to combine one loop that is in the key of C with another that is in the key of F# then surely the only result can be cacophony. And there is no telling whether the stuff you sample is actually in a key – it might fall 'between the cracks' due to error or deliberate speeding up or slowing down.
You might even go so far as to make a note of the key of each loop or phrase that you sample. Here's some advice…
What is vastly more important than the key of the sample is the tempo. If two samples are at the same tempo, they stand a good chance of working together. If they are not, then one sample is going to have to be sped up or slowed down so that it is. And doing that will alter the pitch, probably not by a whole number of notes.
So since you are most likely to change the key of at least some of the samples you use, there isn't much point in worrying about it. If you find that two samples work well together rhythmically, but the keys clash, then it is time to start thinking about pitch changing.
Of course some software can alter the tempo of a sample without changing the pitch. But that doesn't mean that you won't get the key clashing problem when you mix samples together. You may still have to pitch change.
In actual real-life music making however, you will find that modern music is not all that strongly pitched. The rhythmic elements are so much stronger, and many sounds are incorporated that simply do not have a definite pitch.
My advice is to concentrate on rhythm, and forget about pitch until you come across a problem that needs to be solved.
Of course if you are combining loops and 'breakbeats' sourced from classical music, things might be different. Is anyone doing that? Any examples?