EQP-1A Vintage Tube Program Equalizer: Tube EQ Plugin by IK Multimedia

The original Pultec EQP-1 was introduced in 1951 as one of the first program EQs based on passive filter circuits. Its gain loss was compensated in the EQP-1A by an output makeup gain stage built around 12AU7, 12AX7 and 6X4 tubes, which the developer credits for the unit's euphonic character.

The modeled version is intended to reproduce that musicality most clearly when you apply broad frequency boosts. The frequency centers, boost and cut ranges and filter bandwidths are modeled to support classic EQ techniques, including the well-known Pultec EQ trick.

As a program EQ, the plugin is aimed at mix bus use, but IK says it works equally well on individual tracks. Examples include adding low end weight to a kick drum or adding presence to drum overheads.

For vocals, the wide filter bandwidths can add color and air. IK suggests pairing it with a sharper Q-based equalizer, such as its own Classic T-RackS Equalizer, to remove unwanted frequencies with more precision.