Filters are often one of the least used features on a console or a plugin. Most of the time they’re thought of as something you use only when there’s a problem. But the fact is they can be one of the best tools you have.
I use them a lot when mixing something which is supposed to sound like an orchestral recording but recorded in a studio. I figured this out when mixing one of these recordings and was trying to get woodwinds to sound like they were back in the orchestra. When recorded, the mics for the woodwinds had been placed close to them and while they sounded good, they were too bright and present as compared to the strings. Adding reverb didn’t do the job. They just sounded like close mic-ed instruments with reverb as opposed to having real depth.
We judge size and distance of what we hear based on how air transmits sound waves. When a gun is fired close to us we hear lots of low and high frequencies. But put that gun fired a few hundred yards away and not only is it softer, but the low and high frequencies have dropped off. Sound effect mixers know this and that’s one way they make a gun sound close or in the distance. Roll off some bottom and top, add some verb and turn it down, and there you have it….a gunshot far away.
So....back to trying to fit the woodwind section in a mix. Since I was trying to make it sound like the listener was in the audience 100’ away from the players, I grabbed some low and high pass filters, rolled a bit of each end, put some reverb on and tweaked till I got that sense of distance I wanted.
That works well for making a studio orchestra sound better, but the fact is heavy, even unnatural filtering is one of the tricks great pop and rock mixers use all the time to give depth and clarity to a mix. If I have a song with lots of background vocals, I’ll put both high and low pass filters to help the parts come through. Sometimes I’ll do it so severely it almost sounds like they’re singing through a telephone. Same thing goes for electric or acoustic guitars. Really, you should consider everything in the mix as something which might benefit from this trick. And when you do this, pick carefully what should have this effect. Do it on too many things though and you’ll lose the contrasts and depth you’re trying to make.