Keep the sub-bass mono and singular — one bass note at a time, because chords in the sub range turn to mud

The sub-bass is the sub-80Hz fundamental, felt more than heard, often a separate clean sine layer from the mid-bass timbre. Two rules govern it: keep it mono (stereo sub smears the low end and sounds weak on big systems, see mono-bass) and keep it singular — ‘one bass note at a time.’ Chords in the sub range turn to mud because low-frequency partials mask each other and the ear cannot separate them. The fix is to put harmonic richness in the mids (pads/chords at a higher register) and keep the low end monophonic and simple.

Examples

Correct: note('a1').s('sine') for a mono sub plus chord('Am7').voicing().s('supersaw').hpf(200) for mid-range harmony. Wrong: chord('Am7').s('supersaw') with no high-pass — chord tones pile up in the sub range.

Assessment

State the two sub-bass rules and the consequence of violating each. Why does moving chord harmony to the mid range rather than the sub range improve the mix?