The Spaceman FX Gemini IV is a fuzz pedal that puts two complete fuzz circuits in parallel: one pure silicon, one pure germanium. Instead of choosing between the two classic fuzz flavors, you blend them with a single Si/Ge mix knob, and a Phase toggle changes how the two sides interact. Spaceman Effects describes the result as mixing "the velcro attack of the germanium fuzz with the smooth sustain of the silicon fuzz," creating rich, complex textures1.
The pedal is completely hand-soldered and handmade in Portland, Oregon, and is currently listed as sold out on the maker's product pages1.
Silicon and germanium fuzz in parallel
Most fuzz pedals commit to one transistor type. The Gemini IV runs both at once, side by side, and sums them. The germanium side uses two NOS AC128 transistors on the smaller of the two internal boards, according to Premier Guitar's review3. The silicon side is the second circuit, and the two are blended rather than switched, so any point between all-silicon and all-germanium is available.
Premier Guitar's reviewer characterized the two sides by reference to familiar circuits: the germanium fuzz is massive-sounding for a germanium circuit, with more range at the high- and low-gain ends than a Tone Bender, and punchy, concise, rich colors at half gain reminiscent of a Jordan Boss Tone or Maestro FZ-1. The silicon side exhibits some of the sizzle of a vintage silicon Fuzz Face and the muscle of a triangle or ram's head Big Muff3.
On That Pedal Show, Mick Taylor and Daniel Steinhardt demoed the pedal, describing it as a "very interesting fuzz parallel fuzz blend of silicon" with gain, volume and filter control for each side4.
The controls: Gain, Filter, Si/Ge mix and Phase
| Control | What it does |
|---|---|
| Gain (one per fuzz) | Independent gain for each side, from soft wooly tones to blistering sonic destruction2 |
| Filter (one per fuzz) | At noon, full pass tone; clockwise rolls off highs; counterclockwise gives a massive mid-scoop1 |
| Si/Ge mix | Blends the two fuzz circuits to any desired mix1 |
| Phase toggle | Controls how the two fuzzes react with each other2 |
The gain knobs replace the 3-position gain switches of the Gemini III, which Premier Guitar called a move to "more nuanced and flexible gain knobs"3. Spaceman's own framing of the mix control is direct:
"The real fun begins when you utilize the Si/Ge mix control in the center of the pedal. Here you can blend the two fuzzes to your heart's desire."1
Premier Guitar's reviewer found that the blends "tend to sound rich, complex, and very different," and reported that their favorite tones were 50/50 mixes of wide-open silicon and half-gain filtered germanium3.
Power and connections
The Gemini IV runs on 9V DC, drawing 4.5 mA engaged and 3 mA in bypass, with a 1 Meg Ohm input resistance1. Signal passes through open-frame Switchcraft jacks1. There is also room for a battery inside the enclosure, situated just below the footswitch, as Premier Guitar's review noted3. Switching is true bypass via a mechanical footswitch1.
From the Gemini III to the Gemini IV
The Gemini IV is a redesigned and expanded version of the Gemini III, a pedal Spaceman dates to circa 2012 and describes as "infamous and now unobtanium"1. The new version is housed in a slightly larger enclosure to accommodate the additional features, principally the independent Filter and Gain controls that replaced the Gemini III's switches15. Delicious Audio, covering the pedal in December 2021, credited Spaceman with "the brilliant idea of putting two fuzz circuits (a germanium and a silicon one) in one pedal"5.
The standard enclosure is cast aluminum with an engraved vinyl faceplate and a large jewel indicator light1. A one-of-a-kind 24k Gold edition was also built: a single unit, number 1/1, plated in real 24 carat gold with an aged, pre-oxidized finish, a black and gold engraved faceplate, and a 1960s aerospace indicator on top, signed and numbered on the inside with a hand-hammered 1-of-1 number tag2.
What reviewers said
Premier Guitar reviewed the Gemini IV in September 2023 and summed up its strengths and its one drawback:
"Bellowing, blendable, high-horsepower silicon and germanium fuzz tones. Effective filtering. First-class construction."3
The same review listed "Expensive" as the con, against a $299 street price for the silver edition3. On versatility, the reviewer's verdict was strong: "The many possible colors that result make Gemini IV one of the most satisfying and flexible fuzzes you can buy at any price"3. The review also praised the enclosure graphics as functional, sturdy, and easy to read and navigate, and said the quality of construction and sounds in Spaceman pedals "never fails to impress," with a range of fuzz color that would be impressive by any builder's standards3.
Videos
SpacemanEffects
SpacemanEffects
AndyDemos
Questions
What transistors does the Spaceman Gemini IV use?
It runs two fuzz circuits in parallel: a pure silicon fuzz and a pure germanium fuzz. The germanium side uses two NOS AC128 transistors, according to Premier Guitar's review of the pedal.
Does the Spaceman Gemini IV take a battery?
Yes. Premier Guitar's reviewer noted that there is room for a battery inside the enclosure, situated just below the footswitch. It also runs on a 9V DC supply, drawing 4.5 mA engaged and 3 mA in bypass.
Does the Gemini IV work on bass?
Spaceman Effects says the Filter control's counterclockwise position gives a massive mid-scoop that is excellent for bass. Each fuzz circuit has its own Filter, so a bass player can shape the two sides independently.
What does the Phase switch do on the Gemini IV?
The Phase toggle changes how the two parallel fuzz circuits react with each other. Spaceman describes it as giving a whole new level of control over the interaction between the silicon and germanium sides.
Is the Spaceman Gemini IV still available?
The maker's product pages list the Gemini IV as sold out. It was priced at $349.00 to $369.00, and Premier Guitar cited a $299 street price for the silver edition in 2023.
Is the Gemini IV true bypass?
Yes. Spaceman Effects states that the Gemini IV uses true-bypass switching with a mechanical footswitch, which the company describes as the highest quality available.
Sources (5)
- Gemini IV, Spaceman Effects
- Gemini IV: Dual Fuzz Generator, Spaceman Effects
- Spaceman Gemini IV Review, Premier Guitar, 2019-09-28
- Boss DD-200, Revival Drive Compact, Fender Bubbler, Spaceman Gemini IV, That Pedal Show (YouTube), 2019-09-24
- Spaceman FX Gemini IV Dual Fuzz Generator, Delicious Audio, 2021-12-17
