That ELO (?) backround harmony vocal stacked sound (?)

Yup sheer number of tracks gives the fat chorus effect. record with compression and add a bit on the group too

The good thing today is that in cubase you can easily edit the multi tracks to tighten up the consonants.

btw - I once read a thread, on gearslutz I think, between some guy and the Earth Wind and Fire engineer George Massenburg about how a certain vocal sound was achieve on one of EWFs albums. Guy was convinced it was effects. Massenburg tried hard to convince him it was just sung that way.

I used to record mass vocal harmony on 24 trk machines by copying a rough mix of the tune onto another 24 trk tape and using the other 22 tracks to build up huge overdubs of harmonies. then mix down and spin them back onto the main multi-track as a stem pair.