The Amptweaker FatMetal Pro is a distortion effects pedal made by Amptweaker, released in May 2016 at $320. It is a dual-footswitchable version of the company's FatMetal pedal, and MusicRadar described it as voiced to suit black metal, sludge and doom metal1. Amptweaker's own product page for the later Fat Metal Pro II says the design is aimed at "low end distortion used in Black Metal, Doom Metal, etc."2
The pedal is no longer made. That Pedal Show lists the Fat Metal Pro as discontinued3, and Amptweaker's page for the Fat Metal Pro II, the version that followed it, showed the product as out of stock as of May 20252.
Distortion voiced for black metal, sludge and doom
The FatMetal Pro builds on the FatMetal, a metal distortion pedal from Amptweaker that adds a thicker sounding distortion for black or doom metal tones, with a Black gain switch to help get tones that typically use tremolo- or flutter-picking with less hard-stopping attack4. Guitar World's reviewer found that "the FatMetal produces thick, rich distortion with a warmer overall tone than Amptweaker's TightMetal pedal," and that the sound doesn't suddenly disappear when playing with a full band5.
That low-end focus is deliberate. MusicRadar's NAMM 2015 coverage explained that a special Black gain switch was added to the FatMetal to help get Black or Doom metal tones that typically use tremolo- or flutter-picking, with a less hard-stopping attack4. The Pro carries the same intent into a dual-footswitchable format1.
Guitar World gave the original FatMetal its Gold Award, with the verdict: "If you desire huge, rich distortion tones that don't get lost in the mix, the Amptweaker FatMetal delivers the goods in a professional-quality package that expands the versatility of any rig"5.
The controls: three-band EQ, preset switches and dual boosts
MusicRadar's launch coverage laid out the control set1:
| Control or feature | What it does |
|---|---|
| Three-band EQ | Bass, mid and treble shaping |
| Smooth edge switch | Quick EQ preset for smoother highs |
| Thrash switch | Quick EQ preset for thrash-style tones |
| Mid-boost switch | Quick EQ preset pushing the mids |
| Pre-gain boost | Boost placed before the gain stage |
| Post-gain boost | Boost placed after the gain stage |
| Boost footswitch | Activates both boosts at once |
| Gain, Tight and Volume | Core controls (listed on the Pro II page)2 |
The two boosts are the headline difference over the original FatMetal. One sits before the gain stage and one after, and both can be activated simultaneously from the boost footswitch1. That gives a player three levels of push from a single pedal: the base sound, either boost alone, or both together.
The later Fat Metal Pro II page also lists a Balanced DI output among the design's features2.
Power: 9V to 18V
The FatMetal Pro runs on 9V to 18V batteries or power supplies1. Amptweaker's Pro II page spells out what each voltage does: run at 18V for more headroom, or 9V for more drive and compression2. The Pro II page lists a current draw of 39mA with a 9V adapter, and notes that the power supply is not included2.
The 9V to 18V range means the pedal works on a standard pedalboard supply, but the 18V option needs a supply that can deliver it. A battery works too, since the pedal accepts 9V to 18V batteries1.
Where it came from
The FatMetal Pro was designed by James Brown, whom Amptweaker's product page calls an iconic high-gain amp guru2. MusicRadar's coverage calls him the 5150 amp pioneer, and says his company Amptweaker built the FatMetal Pro in response to requests for a dual-footswitchable version of the FatMetal1. It was available from launch at $3201.
How it differs from the FatMetal
The original FatMetal is a single-footswitch metal distortion pedal with the Black gain switch, a Thrash switch, smoother highs, a reduced noise gate and bass-friendly tweaks4. The Pro keeps that voicing and adds the dual-footswitchable format: the three-band EQ with its preset switches, and the two boosts that can be engaged together1. For players who only need one sound, the FatMetal covers the same territory; the Pro is the version built for switching levels on the fly.
Videos
Premier Guitar
Amptweaker
Dennis Kayzer
Questions
Does the FatMetal Pro run on batteries?
Yes. MusicRadar reported that it runs on 9V to 18V batteries or power supplies1.
Is the Amptweaker FatMetal Pro discontinued?
Yes. That Pedal Show lists it as no longer made3, and the Fat Metal Pro II page showed out of stock as of May 20252.
Who designed the Amptweaker FatMetal Pro?
James Brown, the 5150 amp pioneer and founder of Amptweaker21.
How is the FatMetal Pro different from the FatMetal?
It is a dual-footswitchable version with two boosts, one pre- and one post-gain, both activatable at once, plus a three-band EQ with smooth edge, thrash and mid-boost preset switches1.
Sources (5)
- Amptweaker unleashes FatMetal Pro distortion effects pedal, MusicRadar, 2016-05-24
- Fat Metal Pro II, amptweaker.com, 2025-05-28
- Boss Metal Zone: Part 2 With Rabea Massaad, That Pedal Show, 2016-06-24
- NAMM 2015: FatMetal distortion pedal from Amptweaker, MusicRadar, 2015-01-19
- Review: Amptweaker FatMetal Distortion Pedal, Guitar World, 2015-09-21
