The Terra Firma is a distortion pedal from UK maker Zander Circuitry, described by the company as its heaviest distortion to date, packing what it calls pure, unadulterated power-amp distortion. It is built around the LM386 power amp chip, which Zander says offers the right blend of character and raw output volume. The pedal is voiced specifically for down-tuned guitars, and the maker positions it for big, beefy and slightly fuzzy stoner and doom rock tones at big volume. It lists for £149.00 GBP on the maker's product page as of 30 October 2025.1
The controls
The Terra Firma keeps its front panel simple: four knobs covering gain, voicing and volume, plus the rotary diode selector that gives the pedal most of its range.1
| Control | What it does |
|---|---|
| Gain | Gain control |
| Scoop | Mid-range focus |
| Tone | High/low pass filtering |
| Input | Second-stage input gain adjustment |
| Level | Output volume |
| 1-8 | Clipping diode selector |
Two footswitches sit alongside them: Engage turns the pedal on and off, and Blast activates Blast mode.1
The diode rotary switch
The Terra Firma features Zander's signature diode rotary switch, which lets you choose between eight clipping types, numbered 1 to 8. Clipping diodes shape how a distortion circuit breaks up, so each position changes the character of the drive rather than just its amount. The maker describes the positions as follows:1
- Germanium: smooth, sweet, and classically amp-like
- Asymmetrical germanium: a more aggressive version of germanium
- Transistor/MOSFET: similar to silicon, but sweeter and crunchier
- LED: louder again, with less saturation and more punch
- Asymmetrical LED: a more aggressive version of LED
- No diodes: loads of output and much less gain
In practice, that means one pedal can move from a smoother, amp-like drive to a louder, more open low-gain sound without changing anything else on the board1.
Blast mode
Blast mode is the Terra Firma's second footswitch function. The Blast footswitch turns the gain all the way up and activates a second volume control for seamless transitions, so you can set a heavier, higher-gain level and bring it in mid-song without bending down to turn knobs.1
Power and practicalities
The Terra Firma runs on a 9V DC center-negative supply and draws 125 mA. That current draw is worth checking against your power supply: a low-current output on a daisy chain may not run it comfortably, so give it a supply output rated to cover 125 mA. The in/out jacks are top-mounted, which keeps the pedal's footprint tidy on a board, and the enclosure measures 67 mm wide by 122 mm long by 60 mm tall.1
The Terra Firma is a compact single pedal, but at 125 mA it draws more current than many standard overdrive and distortion pedals, so plan your power supply accordingly.
Where it sits in Zander's range
Zander Circuitry has built a line of high-gain pedals around flexible clipping and gain staging. The Cranium is a multi-mode RAT-style distortion, the Cranium Dual Gain Distortion put the company on the map with its dual-gain design, and the Cafetiere and Cafetiere V4 Distrofuzz take a Harmonic Percolator-style circuit through multiple clipping modes with a boost footswitch. The Terra Firma is the maker's heaviest entry in that family, aimed at down-tuned stoner and doom playing rather than general-purpose drive.1
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Zander Circuitry
Zander Circuitry
Zander Circuitry
Sources (1)
- Terra Firma, Zander Circuitry, 2024-01-01
