This module combines the functions of preamplifier and volume control with tone control. It therefore allows you to act independently on bass, midrange and treble via different potentiometers. It incorporates two DIP8-mounted LME49720 OPAs, easily interchangeable according to your preferences in terms of sound rendering or your needs in relation to your Hi-Fi installation. It also incorporates a 7812T voltage regulator, an HK19F relay and 2 TL431AC low-noise Class A linear voltage regulators coupled to BC139 and BD140 transistors. Note that a bypass mode is available by turning the treble control potentiometer to the far left until it passes a switch position, which disables the tone control function.

Signal input and output are via two screw terminals. The module is powered from a voltage range of 12-0-12V to 18-0-18V AC via a screw terminal input.