Audio Recording Issues – Actual notes that are out of balance Part 2You can use a narrow band Equalizer to control specific notes that are out of control. This could involve increasing the volume where a specific note is too quiet, or lowering the volume if the note stands out. If the Frequency shares too many other elements of the sound in the mix with ambient sound, volume balance, other instruments, reverb, etc., then it affect which approach that works best. You may want to combine EQ with minimal band-limiting. In some cases, we can level out the balance in a mix by making very small changes in slightly wider band "Q" widths instead of honing in just on a single note. In the same situation where a low note on a bass guitar is jumping out too loud, let's assume that the kick is using this same EQ to accentuate the power of the kick's attack.
It may be possible to lower the thin narrow "Q" on this note by a very small amount, and then apply a wider "Q" eq just above, below, or centered on the same note, to revive the low end energy coming from the kick and other mix elements. This can work if the qualities in the low end are consistent with the song. But, if the rest of the low Frequencies come across mushy or too bold, this technique may not work. Another option is to slightly reduce the offending note,and use a stereo signal control. You may find that you can reduce the detail in this frequency by narrowing just the Frequency to center, mono, or simply less stereo information. This does not mean reducing the stereo signal of the entire mix, but only the note that is jumping out too much. This requires a stereo plug-in that is capable of adjusting specific Frequencies.
If it is only coming from a single instrument panned center, then this may not work. The goal is to know the combination of elements that may balance out the primary issue in mastering. By controlling the note itself and considering the balance with other instruments, using an EQ and a band-limiting compressor/limiter, you can tighten up the mix and even increase the potential volume of the mix to balance better with the volume of other songs in the same project. Narrow band EQ is a huge benefit to bringing these details into the proper context and focus.