SPL PQ

The SPL PQ stands as a reference-grade parametric EQ designed specifically for mastering work, where precision and transparency are non-negotiable. Built around SPL's proprietary 120V rail technology, the plugin delivers the high headroom and low distortion characteristic of the original analog unit while operating within your DAW.

The defining feature is its switchable constant and proportional Q architecture. In constant Q mode, bandwidth remains fixed regardless of gain amount, useful for surgical cuts and targeted boosts. Proportional Q adjusts bandwidth inversely with gain, narrowing as you increase boost - a more natural approach that prevents the aggressive frequency sculpting that plagues many parametric EQs. This toggle on each of the five bands gives you genuine flexibility that few digital EQs match.

The 1/4 gain switch is practical mastering functionality, allowing you to constrain the range from ±20 dB down to ±5 dB for the small, critical corrections that separate professional masters from adequate ones. Detented pots ensure repeatable settings.

The plugin extends the original with Brainworx's Extra Unit, adding M/S processing, stereo width control, mono-maker for bass focus, and tolerance modeling technology that simulates real component variance. These additions feel organic rather than bolted-on, expanding the tool's utility without compromising its core character.

The PQ suits mastering engineers, mix specialists doing final touches, and anyone needing transparent EQ with surgical precision. It's not a creative tool - it's the workbench for exacting tonal refinement. At this level of performance, it justifies its position among mastering's essential infrastructure.