The Radian Treble Booster is a modified version of the Dallas Rangemaster, a classic 1960s effect unit that is often referred to as a “treble booster”. In contrast to modern clean boosts, the Rangemaster is pretty gritty, putting it more in the category of overdrives or even fuzzes. Originally designed to add treble content to somewhat dark British amplifiers such as the Vox AC30, it took a life of its own in the hands of Brian May, Tony Iommi, Rory Gallagher, and several other highly-regarded guitarists of that era.
The Radian includes a modification to get additional tones out of the circuit. The original Rangemaster emphasized treble frequencies, but the Radian puts the frequency-setting capacitor on a switch, allowing you to change between the stock treble boost, a midrange boost, or a full-range boost.
There is also an on-board voltage inverter to allow you to use the vintage PNP germanium transistor, yet still power the unit with modern pedal power supplies. This charge pump is optional but highly recommended.