Mixing Bass Instruments

7th February 2019

When mixing, keep in mind that no one has a ‘playback system’ that can deliver the intensity of an instrument cab – be it bass or guitar. This plays psychological and acoustic games with your brain and hearing – think LOUDNESS curve.

Your mix is rarely going to be played at the SPL of an instrument cab. Bass amps can have anywhere from 100watts to 1000watts and move a shit-ton of air. A consumer stereo system – or eabuds – can’t compete.

In this sense, what we are doing in the recording and mixing process is very similar to what happens in cinematography – we are creating an illusion.

Here are two examples that relate to both electric bass and synth bass.

When you push the preamp circuitry in an instrument amp – before hard clipping – you get either the soft asymmetrical clipping in the graph below (Distortion A) or the near-clipping (Distortion B). Asymmetrical clipping makes even-order OCTAVE harmonics above the fundamental. 

Open E on bass is 41.2Hz – a frequency that no consumer audio system has the ability to reproduce well and with enough power. We have to create the illusion that 41.2 Hz is being reproduced using non-fuzzy Distortion – either A or B in the graph below. The difference you hear in older tube amps versus modern amps is that modern amps are often either too clean or two dirty. But a funky old tube amp has a character that translates in your mix – it takes some of the guess work out because it is harmonic rich. The reason DI bass doesn’t often translate well in a mix because it is too clean. Of course by itself it sounds fabulous, but…

Using synthesis is an easy way to visualize what happened above because you can literally build the bass tone from the ground up. 

Some genres use sine or triangle wave for what feels like subsonic bass – when in reality, you are so not used to hearing 41.2 Hz, that the pure fundamental seems subsonic. To build the type of bass that has thunder on the dance floor and can still be heard on a consumer system, start with the open-E frequency of 41.2Hz, then sneak in another sine oscillator one octave up – at 82.4Hz – until it just becomes audible. Now add one more oscillator at 164.8Hz until it just becomes audible. What you will discover is that to be heard, the 41.2Hz fader is set highest, then 82.4Hz, which is set higher than 164.8Hz. Phew! You just built the equal LOUDNESS curve!

The Green trace represents a pure un-distorted sine wave. Distortion A (Violet trace) is even-order asymmetrical distortion – we hear this an octave up harmonic of the fundamental. Distortion B (Red) still contains a dominant even-order harmonic, but now there are a series of odd harmonics (3rd, 5th, 7th etc).