We all like more bass. It sounds good on headphones, and on a large system can be truly mind blowing. But the issue is, bass frequencies don't play well on small speakers, so if you want your track to sound bassy on a small system, you are going to have to do more than just turn it up. This article focusses on the bass guitar as an example but works for synths, pianos, and anything else that has a tasty bass sound that you want people to hear.
You see, the issue with small systems, is that they simply cannot play back low frequencies. Even if you turn the bass up, there's very little chance of them suddenly managing. In fact, if you turn the bass up too high, on a larger system, only the bass will be heard.
So, what can we do?
The first thing to realise, is that sounds almost always have harmonics. These harmonics are what we can use to bring out the bass on smaller systems. So, what is a harmonic?
Simply put, every sound has it's main frequency, but there are higher frequencies present in it too. This can be heard when you say "ooo" and morph it into "aaa". You are changing the harmonics expressed by your voice, even though the note is the same. This is what we want to do to make the bass more apparent.
Seen here is the main note, with it's much quieter harmonics.
Changing the relative volume of each harmonic will change
how it sounds.
So let's go back to the small speakers, they can't play bass notes, but they are great at playing mid-range notes. Luckily, the harmonics of bass notes sit in the mid range. If we boost these, then we will have a much more apparent bass sound.
The easiest way to do this, is just to boost the mid-range of the bass guitar in the EQ. This will bring out the harmonics a bit and it will suddenly be clearer on small systems. However, depending on the bassist's tone, there may be very little harmonic content to start with. This is where saturation comes in.
When you saturate and distort a signal, you square off the wave's tops. This adds higher frequency harmonics which will make the sound more audible and brighter. Obviously don't over saturate or you will sound like a metal-head trying his new bass distortion pedal for the first time. Combine this gentle saturation with a mid EQ boost and you will suddenly find it a lot easier to hear the bass in the mix.
If you start to look like this, there are larger problems than
your bass mix.
One thing to watch out for is making your mix muddy. The main culprit frequencies are ~200-250Hz and so dip around there if it get's too thick. Try boosting frequencies as high as 1000-2000Hz and you'll get the clangy string sound which will emphasise the note hits when the bass is played.
A harmonic exciter is also a good tool to use, though be careful with them as they have less control than an EQ and saturator combined. I like to use it as the lazy/speedy method of making a bass sound clearer, though I more often than not use it on higher pitched instruments to enhance their low end.
Another technique to try, if you have the time, would be to double the bass track and pitch one up by an octave. Then use that as the modulator in a vocoder on some white noise. Then very conservatively mix that vocoded noise back into the original bass track.