Lurssen Mastering EQ: Tube EQ Emulation by IK Multimedia

The 825 emulation is built around smooth, nuanced curves in the high and low ends. IK Multimedia says the preamp section is modeled in detail, which is what the Color control acts on. Color adjusts harmonic saturation, so you can move the sound toward a cleaner result or one with more harmonics.

Shelving filters handle the high and low frequency ranges, while three tuned semi-parametric filters allow more precise shaping in the midrange. The adjustable preamp input level gives you another way to set how hard the emulated circuit is driven.

The plugin keeps the original's independent left and right EQ controls and adds parameter linking for matching adjustments on both channels. Mid/Side processing lets you treat the center and the sides of a mix separately, which is useful for mastering tasks such as tightening the low end or adjusting stereo width.

You can use the plugin alone or inside T-RackS 6 to build channel strips with other T-RackS modules. Signal chains can be saved and recalled, and the included presets from Gavin Lurssen and Reuben Cohen give you starting points you can use as they are or adapt.