When you’re working on a project, once you get the initial balance right and you know that all your signals are clean, don’t exclude all the effects and wait till the end to bring them in, especially the ones on the Main Mix Bus. Because the effects, inevitably, will bring in new characteristics to the tracks. They will almost become new instruments that have their own unique timbres which means more harmonics and frequencies you have to consider, tame and balance.
For example, if you happen to add some sort of saturation plug in to the main bus track, or keep some overall mild compressor action going on, it will not affect all the tracks in the same way. Say, drums may end up being compressed more than the bass, or something like that, and this may mean that their relationship which was perfect when they were all dry has changed completely; a new ratio is required. You set them right, the bass and drums are perfect together, but now they over shadow the piano and so on…
That’s why, once I got the basics down, I keep the effects on at all times and try mixing that way. That’s my approach anyway. Because otherwise, after all the work has been done and I turn the effects on, I still have to go back and start all over. Maybe wiser ones know their way around it, but this is how I manage to roll.
Mix on, friends.