The Passeq plugin recreates the original passive hardware equalizer known for its unique approach to audio shaping by offering three separate frequency ranges for both boost and cut stages. Unlike traditional passive EQs with limited frequency options, Passeq features 12 switchable frequencies per band, resulting in 72 distinct frequency choices per channel. This extensive range allows for intricate and precise EQ curves that cover the entire relevant audio spectrum. The design faithfully captures the complex interactions between filters, which are integral to the characteristic sound of passive EQs and distinguish them from active designs.

Featuring two graphical user interfaces, Passeq caters to different workflow needs: a dual-channel view and a compact single-channel mode, which can also control both stereo channels simultaneously. The plugin supports Mid/Side (M/S) processing, enabling separate adjustment of center and side signals for more targeted mix control. This approach is ideal for isolating elements such as vocals or guitars within a mix, enhancing creative flexibility during production. The circular layout of the controls reflects the passive EQ concept, with cut and boost controls physically separated and frequencies arranged logically from low to high, providing an intuitive and visually appealing user experience.

The frequency selection is grounded in decades of expert experience and collaboration with renowned audio professionals, resulting in musically meaningful fixed frequencies rather than standard ISO values. This thoughtful design allows users to create precise 'S curve' EQ adjustments by combining boosts and cuts in closely spaced bands, offering refined control over tonal shaping. Additional features include emulated input and output transformers, fast preset switching through four quick-access settings, and convenient mouse wheel control for fine parameter adjustments. The Passeq plugin brings the warmth and musicality of acclaimed analog equalizers into the digital realm, making it a powerful tool for mixing and mastering.