With the spectrometer, if you observe the frequency spectrum of a snare, in general, you will see that it is quite full between 20Hz and 20000Hz, with a peak intensity around 200Hz.
Like the snare, many instruments have a broad spectrum.
On the contrary, if you observe the spectrum of a sine wave, you will only see a peak of intensity corresponding to the fundamental frequency of the note played.
If the majority of instruments have a broad spectrum, it must be understood that when several instruments play at the same time, their spectrum overlaps with each other. In other words, each instrument loses some of its definition. Maybe you have already noticed that when your track is well loaded, when there are many instruments playing at the same time in the same register, sometimes you do not hear your kick, or your pad, or any other instrument.
Filters and EQ can be used in many cases. But here, the filters and EQ are used in this context of spectral overlap.
The idea is to identify in which part of the spectrum such instrument expresses the most, and to reduce (with EQ) or filter frequencies that are not useful or that impede the intelligibility of the track.
Example: place a high-pass filter on your snare around 160 Hz and play your track. Do you hear an unpleasant alteration of your snare drum? If so, decrease the cutoff frequency. If not, increase it a little. As soon as you hear that your snare drum is altered in a way that bothers you, go down a little bit the cutoff frequency. That's it, you removed or very strongly attenuated the frequencies that are below 160Hz. This allows instruments that are below this threshold, such as kick, to occupy this space without being disturbed by your snare.
Now the problem is that in a normal track, you have several instruments, so possibly a lot of overlap. The EQ and the fitres serve in particular for that: to assign a place to your instruments in the mix, to circumscribe each instrument in a determined frequency range. In this context, you do not really perceive, you do not really hear what you do with the EQ and filters. But in the end, by treating each instrument, each instrument group, it makes you gain in definition and headroom.
And all this is valid for instrument layering. For the design of such a pad, you can take the bass frequencies of a synth, the medium frequencies of another, and the high frequencies of a third, and you get a custom pad from these three layers. There is plenty of way to do it.
What I say is far from complete, EQ and filters can do a lot of things, there are many proven and documented techniques. Just try again and again, read, search, gain experience there too.
Like the snare, many instruments have a broad spectrum.
On the contrary, if you observe the spectrum of a sine wave, you will only see a peak of intensity corresponding to the fundamental frequency of the note played.
If the majority of instruments have a broad spectrum, it must be understood that when several instruments play at the same time, their spectrum overlaps with each other. In other words, each instrument loses some of its definition. Maybe you have already noticed that when your track is well loaded, when there are many instruments playing at the same time in the same register, sometimes you do not hear your kick, or your pad, or any other instrument.
Filters and EQ can be used in many cases. But here, the filters and EQ are used in this context of spectral overlap.
The idea is to identify in which part of the spectrum such instrument expresses the most, and to reduce (with EQ) or filter frequencies that are not useful or that impede the intelligibility of the track.
Example: place a high-pass filter on your snare around 160 Hz and play your track. Do you hear an unpleasant alteration of your snare drum? If so, decrease the cutoff frequency. If not, increase it a little. As soon as you hear that your snare drum is altered in a way that bothers you, go down a little bit the cutoff frequency. That's it, you removed or very strongly attenuated the frequencies that are below 160Hz. This allows instruments that are below this threshold, such as kick, to occupy this space without being disturbed by your snare.
Now the problem is that in a normal track, you have several instruments, so possibly a lot of overlap. The EQ and the fitres serve in particular for that: to assign a place to your instruments in the mix, to circumscribe each instrument in a determined frequency range. In this context, you do not really perceive, you do not really hear what you do with the EQ and filters. But in the end, by treating each instrument, each instrument group, it makes you gain in definition and headroom.
And all this is valid for instrument layering. For the design of such a pad, you can take the bass frequencies of a synth, the medium frequencies of another, and the high frequencies of a third, and you get a custom pad from these three layers. There is plenty of way to do it.
What I say is far from complete, EQ and filters can do a lot of things, there are many proven and documented techniques. Just try again and again, read, search, gain experience there too.