here's a very sloppy mix i made with 50s60s70s electronic music mostly: http://www.mixcloud.com/goto80/oldelekt
apart from the stuff already mentioned, have a look at bruce haack and richard hayman (both quite schizo but not just noisy) and alexander robotnick (who made electro before it was invented). less listenable, i suppose, but still interesting is the first record with digital music: 'music from mathematics' (1962) -> http://websound.ru//issues/156_160/music_of_math.zip
i'm making a timeline of 'chipmusic' @ http://chipflip.wordpress.com/timeline which might have some things of interest too.