@Scarfmeister it's definitely pricy, but it works like so: route your VCO's square wave out to a mixer and to the NCOM, then the NCOM into the mixer too and adjust relative volumes for taste. It creates fat subharmonics that can be either octaves or sort of like intervals in which case you get interesting chord like effects. Maths and in general function generators can do this too, but IMHO NCOM just does a pretty spectacular job of it.