Brostep replaced dubstep's sub-bass emphasis with distorted mid-range riffs as venues grew larger

Brostep, popularized in the US ca. 2011 by Skrillex and Rusko, diverges from classic dubstep in register. Classic dubstep centers sub-bass (20–80 Hz) — physical chest pressure and speaker displacement. Brostep accentuates the mid-register with ‘robotic fluctuations and metal-esque aggression,’ using distorted bass riffs functioning roughly at the same frequency as the electric guitar in heavy metal. Simon Reynolds observed that as dubstep moved to larger outdoor events, sub-sonic content was replaced by distorted riffs that project at mid-range. Wavetable/FM ‘screaming’ and ‘growl’ basses (using formant filters, heavy distortion, resampling) replace the sine sub. Brostep is often used pejoratively; even Rusko, a pioneer, expressed ambivalence.

Examples

Skrillex ‘Scary Monsters and Nice Sprites’ (2011): heavy distorted mid-range growl drops. Classic dubstep: Digital Mystikz ‘Haunted’ — sine sub-bass, space, restraint. Production path: sine sub vs. Serum wavetable bass with formant filter + heavy distortion.

Assessment

Given two bass patches — a pure sine sub and a formant-distorted wavetable mid-range bass — identify which is characteristic of classic dubstep and which of brostep. Explain the production and venue-scale reasons for the register shift.