What makes good ambient music? Ambient music, such as that by Loscil, has a melody, but it’s very subtle. It has structure, it has form, but it understates this structure instead of shoving it in our faces.
It is not, or should not be holding down one key on a synthesizer for ten minutes and charging us 5 bucks for 6 tracks of it. That is not ambient music. It’s lazy. Loscil’s newest album, Coast/ Range/ Arc, does just this.
The rest of his albums are great. They have subtle structure and melody, but not this one. Goat Mountain is the only track that has any real structure. The rest... he holds down a couple synth keys for the whole length of the track and that’s it.
I recommend albums like Submers, First Narrows, and Endless Falls. That’s what good ambient music is.
I've also discovered the soundtrack to Schizm. Didn't play the game, but the music is great!
Along those same lines is the soundtrack to Riven. One of the ultimate chillout albums, and obviously the album from which Schizm took its cues.
And I don't know if they count as ambient, but they're pretty damn close. Boards of Canada!