EQ or compression, which comes first? This question has spurred many debates over the years. Here’s what I think.
In general, I think compression should come before EQ. Compressors are activated by the amplitude of an audio signal. A signal threshold is set, and a compressor starts reducing peaks when that threshold is crossed. An EQ changes the level of certain frequencies, and thus affects the amplitude of the signal. If you put an EQ before a compressor, chances are you’ll have to tweak the compressor’s threshold whenever you make any EQ changes.
This doesn’t mean you should never put an EQ in front of the compressor. In fact, I do this exact thing all the time. The only EQs that should go before compressors are high-pass filters and low-pass filters.
The idea here is there’s no need to compress frequencies that you want to throw out anyway. This is especially true in the case of high-pass filters, where a build-up of low frequency energy can potentially overload a compressor without achieving the desired audio effect.
In summary, only use LPF and HPF equalization BEFORE compression. EQ to shape sound and tone should come AFTER compression.