EQ, or equalization, is a powerful tool for manipulating the relative strengths of the various bands of frequencies.
You can make a signal more toppy, more bassy, less toppy or bassy, or add or subtract midrange energy.
It's so powerful that it makes you feel that there is nothing it can't achieve in terms of frequency balance.
But there's one thing that EQ can't do – it can't put in something that is intrinsically lacking in the signal. You have to make sure that everything you want is captured in the first place.
And another thing that EQ has difficulty with is in changing the fundamental character of a sound.
However you adjust the frequency, gain and Q controls, the sound always keeps the character it started out with. You can't change a Gibson guitar into a Martin with EQ, for instance.
No, to make a real change on that level you really do have to put down the Gibson and pick up the Martin (you should be so lucky!). There is no weapon in the audio arsenal that can make that degree of change.
But there is one technique that comes close, and it costs absolutely nothing.
Move the microphone!
When a microphone is close to an instrument, then it doesn't pick up the sound of the whole instrument, it picks up the vibration from the parts it is closest to.
So try pointing a microphone at the sound hole of a guitar. Now move it up towards the neck, then move it down towards the bridge.
Listen to the amazing differences in sound quality. There is far more variation here than you can usefully achieve with EQ.
Microphone positioning is an under-exploited art.
We are hammered from all sides with marketing that tells us that we have to have the 'right' microphone, and that if you're not happy with the sound you are achieving, then you should change the mic.
Well yes, microphones do sound different. But not nearly as different as changes in microphone position.
The ultimate is to have the right mic for the job, in the right position for the sound you want to achieve.
The only way to get this is to experiment, and inform your experimentation with experience gained from many previous encounters between microphone and instrument.
So go on… try it out. See for yourself what an amazing range of sonic variations is available for absolutely no cost at all.