Perfectly good words—often technical expressions or jargon—frequently get picked up by those who don't fully understand the way the word is used in its professional or technical context, and use it in imprecise ways that manage to muddy its original meaning. I think "source singer" may very well be one of these.

I have always heard the term "source singer" used to designate a traditional singer from whom a folklorist or song collector such as Cecil Sharp or the Lomaxes learned a particular song. But in no way does that mean that the "source singer" is not good enough to sing professionally. Case in point, Jean Ritchie. She grew up in the folk singing tradition, added greatly to the store of American and Anglo-American songs and ballads, and then went on to do concerts and make records and such. I would be interested to hear what she might have to say on this subject.

If I were to learn a song from a recording of, say, Joan Baez or Ed McCurdy, I would not refer to them as "source singers," even though their recording was the source from which I learned the song. But I occasionally hear it used that way.

"Where did you learn that song?"
"Well, my source singer was Bob Dylan."

No, no, a thousand times, no!

At least that's my reading of it.

Don Firth