The Spaceman Effects Gemini IV is a Dual Fuzz Generator: a fuzz pedal that houses two distinct fuzz circuits running in parallel, one pure silicon and one pure germanium1. Instead of picking a transistor type, you set each fuzz independently and then blend the two with a central Si/Ge mix control1. The germanium side is built with vintage germanium transistors in a handmade, hand-wired circuit1.
The pedal is based on the Gemini III from around 2012, which Spaceman describes as "infamous and now unobtanium," and is a redesigned and expanded version of it1. Spaceman lists the Gemini IV as sold out1.
Two fuzzes in parallel, one silicon and one germanium
The Gemini IV's core idea is running two complete fuzz circuits side by side rather than stacking or switching them. One is pure silicon, the other pure germanium, and both are always in the signal path, blended to taste1. Delicious Audio, covering the pedal in December 2021, described the concept as putting "two fuzz circuits (a germanium and a silicon one) in one pedal," calling both "epic"2.
The germanium fuzz circuit is the smaller of the two boards inside the pedal and is home to two NOS AC128 transistors, according to Premier Guitar's 2023 review3. Germanium and silicon transistors behave differently in a fuzz circuit, and the Gemini IV's design puts both characters under one roof so a player can move between them or combine them.
Controls
Each fuzz side has its own set of controls, and the pedal adds shared controls for blending and phase. Premier Guitar's review described the pedal's control set as "blend, gain, and filter arrays" plus a phase switch3.
| Control | What it does |
|---|---|
| Gain (per fuzz) | Independent full Gain control for each fuzz, covering "soft wooly tones to blistering sonic destruction"1 |
| Filter (per fuzz) | Independent Filter for each fuzz; at noon a full pass tone, clockwise rolls off highs, counterclockwise a massive mid-scoop4 |
| Volume (per fuzz) | Volume control for each side5 |
| Si/Ge mix | Central control that blends the two fuzzes1 |
| Phase toggle | Controls how the two fuzzes react with each other1 |
The Filter controls are worth noting for players who shape fuzz with their amp's EQ. Spaceman says the counterclockwise range offers a massive mid-scoop, while clockwise rolls off highs and noon is a full pass tone4.
On That Pedal Show's demo video, Mick Taylor and Daniel Steinhardt walked through the layout, noting "gain and volume and filter control for each which is kind of interesting"5.
How it differs from the Gemini III
The Gemini III, from circa 2012, is long gone from Spaceman's lineup, and the Gemini IV is its redesigned and expanded successor1. The main changes:
- Independent Filter controls for both fuzz circuits, replacing switches2
- Full Gain controls for both fuzz circuits, instead of switches2
- A slightly larger enclosure to accommodate the additional features1
Premier Guitar's review framed the independent filters as the heart of the update, saying the Gemini IV "expands its tone palette primarily by providing independent filters for each of the parallel fuzz circuits"3.
Editions and availability
Spaceman lists the Gemini IV as sold out1. Each pedal is signed and numbered on the inside, with a hand-hammered 1-of-1 number tag on top1. Beyond the standard version, Spaceman made a one-of-a-kind 24k Gold edition, plated in real 24 carat gold with an aged gold finish, marked #1/11.
The Gemini IV is sold out at Spaceman Effects1. The Gemini III it is based on is described by the maker as unobtanium, so neither version is currently available new from the maker1.
What reviewers said
Premier Guitar reviewed the Gemini IV in September 2023 and was positive about its versatility and build3:
"Bellowing, blendable, high-horsepower silicon and germanium fuzz tones. Effective filtering. First-class construction."
Premier Guitar's pros list, 20233
The same review concluded that "it's easy to imagine making the Gemini the only fuzz you ever use"3.
That Pedal Show demoed the pedal in September 20195.
Videos
SpacemanEffects
AndyDemos
R.J. Ronquillo
Questions
What does the Si/Ge mix control do on the Gemini IV?
The Si/Ge mix control sits in the center of the pedal and blends the two parallel fuzz circuits, one pure silicon and one pure germanium. Spaceman describes it as where the real fun begins, since you can dial in any balance between the two voices rather than choosing one or the other1.
What does the Phase switch do on the Spaceman Gemini IV?
The Phase toggle switch changes how the two fuzz circuits react with each other. Because the silicon and germanium fuzzes run in parallel and are blended together, flipping their phase relationship changes how the combined signal interacts, giving what Spaceman calls a whole new level of control over the two fuzzes1.
How is the Gemini IV different from the Gemini III?
The Gemini IV is a redesigned and expanded version of the Gemini III from around 2012, which Spaceman describes as unobtanium. The IV replaces the III's switches with independent full Gain controls and independent Filter controls for each fuzz, and it sits in a slightly larger enclosure to fit the additional features1.
Is the Spaceman Gemini IV still available?
No. Spaceman Effects lists the Gemini IV as sold out1. The pedal was handmade and hand-wired with vintage germanium transistors, signed and numbered on the inside with a hand-hammered number tag on top1.
Does the Gemini IV have separate gain controls for each fuzz?
Yes. Each of the two fuzz circuits has its own full Gain control, replacing the switches of the Gemini III. Spaceman says the independent Gain controls cover a lot of ground on their own, from soft wooly tones to blistering sonic destruction1.
Sources (5)
- Gemini IV: Dual Fuzz Generator, Spaceman Effects
- Spaceman FX Gemini IV Dual Fuzz Generator, Delicious Audio, 2021-12-17
- Spaceman Gemini IV Review, Premier Guitar, 2019-09-28
- Gemini IV, Spaceman Effects
- Boss DD-200, Revival Drive Compact, Fender Bubbler, Spaceman Gemini IV, That Pedal Show (YouTube), 2019-09-24
