The This Heavy Earth Grim3 is an analog overdrive and booster pedal. According to the maker, it began as an attempt to pair "the warm overdrive of the 808 but precision tone shaping of the ST9 to create anything from tight modern metal to fat blues grit," with an internal charge pump supplying additional headroom. In other words, it sits in the Tube Screamer family of circuits but adds more tone shaping range and more clean headroom than the classic design.1
What it does
The Grim3 is described by This Heavy Earth as an overdrive that covers a wide range of gain territory, from tight modern metal to fat blues grit. The maker's own description puts the circuit lineage plainly: it seeks the warm overdrive of the 808, the circuit behind the classic Tube Screamer sound, combined with the precision tone shaping of the ST9. The internal charge pump raises the available headroom, which is the headroom a player hears as extra clarity before the circuit clips.1
If you are new to this family of pedals, the Grim3 belongs to the broader world of overdrive pedals, where the 808-style circuit is one of the most common starting points.
Power
The Grim3 runs on 9V DC with a center negative plug and draws 41mA.1
At 41mA, the Grim3 draws more current than many single overdrive pedals. A low-output daisy chain supply may not have enough spare current for it, so plan your power accordingly.
Videos
Metalhead Productions
That Sounds Terrible
Max Power's Tasty Tones
Questions
What kind of pedal is the This Heavy Earth Grim3?
The Grim3 is an analog overdrive and booster. According to the maker, it set out to combine the warm overdrive of the 808 with the precision tone shaping of the ST9, covering everything from tight modern metal to fat blues grit. An internal charge pump provides additional headroom, and the pedal runs on 9V DC center negative power, drawing 41mA.
How much power does the Grim3 need?
The Grim3 runs on 9V DC with a center negative plug and draws 41mA. That draw is higher than many simple overdrives, so it is worth keeping in mind when planning a daisy chain or a low-output power supply.
Sources (1)
- Grim3 by This Heavy Earth, RockBoard PedalPedia, 2026