Steve Reich & homogenous groupings
Here are a few examples of Steve Reich’s composing, which until about 1973 was almost entirely based around homogenous groups of instruments.
Although it’s not strictly relevant, as a taster for what was to follow, have a listen to the opening of his 1966 hit ‘Come Out’. The first phrase is taken from an interview with a Harlem youth wrongly convicted of murder (later acquitted), and the phrase ‘Come out to show them’ is lifted from a recording of that interview. It’s then looped and played on two separate tape machines, with one running slightly slower so that the music phases. More things happen later in the piece, but they’re not relevant here. I strongly recommend listening to this on headphones.