The instrumental is not the sum of drums, bass and other

Music production · SubverseLab

It is the mix with the vocal subtracted. Those are different signals: the four stems do not account for every sample of the input, so adding them together quietly drops whatever the model could not place. Subtracting keeps it. If you are singing over the result, this is the difference between a backing track that sounds like the record and one that sounds slightly hollowed out.

Answers

• Same reason muting the vocal lane in the mixer is not the same as exporting the instrumental — muting plays three stems, the instrumental is the whole mix minus one.