I was gwan start my own thread, but when I saw this thread title, I knew this was a good place to share this excerpt...
(This is BUNNY LEE talkin)

When dub started it wasn't really "dub". Tubbys and myself was at Duke Reid's studio one evening, and a sound-system operator by the name of 'Ruddy' from Spanish Town was cutting some riddims, with vocal. And the engineer made a mistake and him was going to stop and Ruddy said, "No man, mek it run !" And then the pure riddim run because him didn't put in the voice. Ruddy said, "Now tek another cut with the voice." And then, him take the cut with the voice.
Ruddy was playing the next Saturday and I happened
to be in the dance. And they play this tune, they play the riddim and the dance get so excited that them start to sing the lyrics over the riddim part and them have to play it for about half an hour to an hour ! The Monday morning when I come back into town I say, "Tubbs, boy, that little mistake we made, the people them love it !" So Tubby say, "All right, we'll try it." We try it with some Slim Smith riddim like 'Aint too proud to beg.' And Tubbys start it with the voice and then bring in the riddim. Then him play the singing, and then him play the complete riddim without voice. We start a call the thing "version".

This is from Page 52 of the book DUB: Soundscapes & Shattered Songs in Jamaican Reggae by Michael Veal.
I must find more time to read through this great book ! Every chapter brings new knowledge and insight.