How to de-emphasize vocal frequencies before compression?
To de-emphasize vocal frequencies before compression, you can use a parametric or low pass filter to remove the frequency range from your signal.
This will make the compressor less likely to affect that particular part of the spectrum and add its timbre – which is usually desirable when using it as an effect in itself – while also making any other EQs after more effective because they won’t be cutting out these areas.
For example, say I don’t want significant amount of compression occurring at 2kHz–or in other words, I don’t want my voice’s tonal quality affected by this type of distortion–I could cut this area with a parametric filter beforehand so it isn’t included within my sound source.
The vocal range that you want to emphasize is the one before it gets compressed.
You would use an EQ to emphasize this frequency, then compress your vocals accordingly. If reducing these frequencies made them sound unbalanced, a second EQ should be used after the compressor so they can add back in those tones into their original position.