SPL Passeq

The Passeq is a passive equalizer, meaning the filter network itself doesn't use active components like op-amps to create the EQ curves. This design is prized for its musical, natural-sounding phase response, while the 120V active makeup amplifiers ensure you maintain high headroom and signal integrity after the passive filtering.

SPL’s proprietary 120V technology allows for a significantly higher dynamic range and faster slew rates compared to standard 18V or 24V audio circuits. In practice, this means the unit handles complex transients and high-frequency content with greater clarity and less distortion, which is critical for mastering.

The 72 filters are fixed-frequency points designed for precise, repeatable adjustments. By using individual custom-made coils for each filter, the unit avoids the signal degradation often found in designs that share components across multiple bands.

While it can certainly be used for tracking, the Passeq is purpose-built for mastering. Its stepped controls using Elma and ALPS components allow for exact recall of settings, and its passive design is specifically tuned for the subtle, broad-stroke tonal shaping required in a final mix.

No, the unit is built with high-quality, durable components designed for professional studio environments. Like any high-end analog gear, ensure it has proper ventilation in your rack, but the custom coils and Lundahl transformers are robust and do not require specific user maintenance.