Petri Suhonen recently posted some good pictures explaining the ‘boost and sweep‘ technique for finding and reducing troublesome frequency ranges. The images are a great way of describing the technique quickly and easily. I do, however, take issue with this statement:
Boosting increases the volume levels of frequencies and it will easily lead to distortion, muddy mix and cause other unwanted artifacts [sic] if you overdo it. Cutting instead leaves more room for the instruments and sounds to ‘breathe’.
There’s nothing inherently wrong with boosting.
Distortion can occur if the EQ boost increases level (i.e. the overall level isn’t turned down to compensate) and there’s a non-linear saturating device further downstream. If you’re reading this blog (and Perti’s blog), you’re probably working in your DAW and the only distortion you’ll get is deliberate (or foolish).
Muddy mixes usually occur if there’s a buildup of lows or low-mids. Yes, you’ll get a muddy mix if you’re inappropriately boosting a lot of tracks down there, but the mud isn’t from the positive gain on the EQ band. It’s from the positive gain and the centre frequency for that band. You won’t get any mud by boosting above 1kHz (you might get honky or harsh sound though).