that explains the black keys at the bottom end. first time i've seen that explained. so it wasn't so monophonic after all. thank you !!!

I'm working on a composer's archive that dates from the early 70s. Synth sounds on his tapes seem to be Arp and photos confirm it to be the Arp 2500 model. There is an "exam" in the archive files, that he gave at the New School, asking his students how to patch certain sonorities. Could you get two ...