The Ground Control Audio Amaterasu is a bright pre-amp and boost pedal made in Montreal by Ground Control Audio. It is a JFET-based booster that runs from unity gain up to 18dB of push, with a single Gain knob and a toggle switch that selects between a bright mode and a darker, more colored mode12. Pedal of the Day described it as "a pre-amp/boost/tone-enhancer rolled into one easy-to-use pedal"1.
Ground Control Audio positions it as a utility boost rather than a distortion device: it can give presence to quieter pickups, or push an overdrive pedal harder3. Premier Guitar called it the company's best-selling Amaterasu Bright Pre-amp when the related Tsukuyomi midrange booster launched in 20184.
What it does to your sound
The Amaterasu is a clean-style booster built around a JFET front end. Guitar.com's reviewer, Richard Purvis, described it and its sibling the Tsukuyomi as "JFET-based boosters offering up to 20dB of gain"2. The circuit itself is a unity to 18dB amplifier, so at the low end of the knob it is barely lifting the signal and at the top it is a full pre-amp push3.
The toggle switch is where the "bright" in its name lives. In bright mode, higher frequency content is allowed through for a clearer tone; the second mode colors the signal for a much darker feel3. That makes it two pedals in one: a treble-forward lift for dark amps and pickups, or a warmer, fuller push.
Pedal of the Day found it useful in both roles:
"it can also bring your low-output single coil or filteron pickups to life, adding some extra juice and oomph to those as well"1
The same review noted it "just adds in that certain sparkle that we all look for in pedals of this nature, and really brings your amp to life"1.
Controls and power
The control set is minimal. A single Gain knob sets how much volume goes into your signal path, "from a slight boost in your tone to a balls-out pre-amp tone"1. Alongside it, a toggle switch engages the frequency-specific boost, selecting between the bright and dark modes23.
| Control | What it does |
|---|---|
| Gain knob | Sets boost level, from a slight lift to a full pre-amp push1 |
| Toggle switch | Selects bright mode (clearer, more high-frequency content) or the darker, colored mode23 |
The Amaterasu is mains-powered only: it runs on a 9-volt supply, which is not included, and there is no battery option2. Plan for a power supply output or adapter rather than a battery snap.
The pedal is true bypass, so it drops out of the signal path entirely when switched off2. Pedal of the Day called it "Responsive at heart," and the Living Room Gear demo on Delicious Audio likewise found it very responsive to playing style13.
Where it came from and how it relates to the Tsukuyomi
What reviewers said
Guitar.com's Richard Purvis reviewed the Amaterasu in 2019, using it alongside the Tsukuyomi, and gave it an overall verdict of 7/102:
"Great in full-frequency mode, but a bit OTT as a treble booster"
In other words, the reviewer rated the pedal's darker, full-frequency mode highly, but found the bright mode pushed too hard as a dedicated treble boost. Pedal of the Day's earlier take was more enthusiastic about the bright character, praising the pedal's sparkle and its Eastern-inspired, slick-looking enclosure1.
Videos
AndyDemos
Eirik Stordrange
Pedalboard of the Day
Questions
Does the Ground Control Audio Amaterasu take a battery?
No. The Amaterasu is mains-powered only and runs from a 9-volt supply, which is not included with the pedal. There is no battery option, so it needs a spot on a power supply or an adapter to run on a pedalboard.
Is the Amaterasu true bypass?
Yes. Guitar.com's review lists true bypass among the pedal's features, so when the Amaterasu is switched off it is out of your signal path rather than buffered or colorizing the tone.
How much gain does the Amaterasu add?
The circuit runs from unity up to 18dB of boost, so it can do anything from a slight lift in volume to a full pre-amp push. Guitar.com describes it as a JFET-based booster offering up to 20dB of gain.
Where is the Amaterasu made?
It is made in Montreal, Canada, by Ground Control Audio, a small builder whose range also includes the Tsukuyomi midrange booster and the Noodles Tone Shaper EQ/boost pedal.
How much does the Amaterasu cost in the US?
Guitar.com listed it at $159 in the US, and £159 in the UK, in its 2019 review. The same price applied to the related Tsukuyomi midrange booster when it launched in 2018.
Sources (4)
- Ground Control Audio Amaterasu Bright Pre-Amp, Pedal of the Day, 2016-12-22
- Review: Ground Control Audio Tsukuyomi & Amaterasu, Guitar.com, 2019-06-05
- Ground Control Audio Amaterasu Preamp Boost, Delicious Audio, 2017-07-07
- Ground Control Unleashes Tsukuyomi Midrange Booster, Premier Guitar, 2018-11-21
