This electronic download of the 4020 Retro EQ HD v6 from McDSP is a 4-band EQ and complimentary filter set. The high-frequency (HF) and low-frequency (LF) bands are shelving EQs, with two additional high-mid and low-mid frequency parametric EQ bands. All EQ bands operate on a gain dependent variable Q system for a vintage smooth sound.

The HF and LF filters use a split-octave design that provides a 12 dB/octave slope near the selected frequency, with a maximum slope of 24 dB/octave. The plug-in uses an output stage topology designed to eliminate digital clipping at any output level and produce a smoother distortion characteristic.

The HD plug-in provides AAX DSP for use with Pro Tools HD, but also includes AAX Native, Audio Suite, Audio Units and VST versions for use with other DAWs including Logic, Digital Performer (DP), Cubase, and Ableton Live.