The SolidGoldFX Imperial BC183 is a silicon fuzz pedal from Canadian maker SolidGoldFX. It takes its circuit design from the classic four-stage Big Muff-style topology, but SolidGoldFX built it around a high-impedance JFET preamp and fitted it with a midrange toggle, which Delicious Audio's demo described as making it "more than just another Big Muff" clone1.
The pedal's name comes from its transistors: a trio of BC183 silicon devices, which the Delicious Audio demo said provides "gobs of detailed mid focused gain"1.
Circuit and transistors: BC183 and the BMP tone stack
The Imperial BC183 follows the four-stage Muff circuit layout: input stage, clipping stages, tone stage and output stage. Where vintage Muffs sit, it "retains the classic BMP tone stack found in vintage muffs," according to Delicious Audio's demo1. The BMP tone stack is the bass/treble scoop-and-shelve filter that gives vintage Big Muffs their familiar voiced character.
Ahead of that tone stack sits the JFET preamp. Delicious Audio reported that this high-impedance front end gives the pedal "incredibly stable buffer friendly operation," meaning it holds its character when placed after buffers or other pedals in a chain, where some vintage-style fuzzes change behavior1.
The three BC183 transistors are the gain elements. BC183s are high-gain silicon transistors; a Tagboard Effects write-up of the related If 6 Was 9 BC183CC notes that the BC183C parts used in SolidGoldFX designs are "high gain BC183 transistors"2. Silicon transistors give a brighter, more aggressive and more temperature-stable fuzz than the germanium parts in vintage units.
The controls: Fuzz knob and midrange toggle
The control set is deliberately simple: a Fuzz knob, the BMP-style tone controls, and a three-position midrange toggle1.
| Control | What it does |
|---|---|
| Fuzz | Adjusted for the smoothest taper possible, dialing in shades of fuzz from crunchy breakup to liquid saturation1 |
| Midrange toggle | Three positions: mids scooped, flattened or boosted, for finer control over midrange content1 |
The midrange toggle is the pedal's main point of difference from a stock vintage-style Muff. Delicious Audio's demo called it "a 3-position toggle that allows for a much finer degree of control over the midrange content," letting a player choose whether the fuzz cuts through a band mix with boosted mids or sits back with a scooped setting1.
Is the Imperial BC183 based on a Big Muff?
Yes, in the sense that its circuit is inspired by the classic four-stage Muff topology and it keeps the BMP tone stack1. But Delicious Audio's demo framed it as more than a straight clone, pointing to the JFET preamp, the BC183 transistor trio and the midrange toggle as the elements that set it apart from a stock vintage circuit1.
What kind of fuzz sounds can it produce?
Delicious Audio's demo, run through a Tone King 20th Anniversary Imperial amp, described the pedal as producing "royally raucous fuzz," covering ground from "the soaring sounds of Gilmour to dark doom bass rumble"1. The Fuzz knob's taper was adjusted so that the range from crunchy breakup to liquid saturation is easy to dial in gradually rather than all arriving at once1.
How it relates to the If 6 Was 9 BC183
The Imperial BC183 shares its transistor type with another SolidGoldFX fuzz, the If 6 Was 9 BC183, but the two circuits are different animals. The If 6 Was 9 is based on the Dallas-Arbiter Fuzz Face circuit and uses two BC183 transistors, where the Imperial is a four-stage Muff-style design with three34.
The current If 6 Was 9 BC183 MKII, introduced at NAMM 2022, carries a much deeper control set than the Imperial:
| Feature | Imperial BC183 | If 6 Was 9 BC183 MKII |
|---|---|---|
| Circuit | 4-stage Muff-style with BMP tone stack1 | Dallas-Arbiter Fuzz Face circuit3 |
| Transistors | Three BC1831 | Two BC1833 |
| Fuzz control | Fuzz knob with smooth taper1 | Fuzz, plus Bias, Saturation and Volume knobs45 |
| Tone shaping | 3-position midrange toggle1 | Tone toggle (tight or thick voicings) and 3-way Body switch (Fat, Treble Boost, Classic)34 |
| Voltage | Not stated | Variable voltage pump, Bias varies operational voltage46 |
| Power | Not stated | 20 mA current draw3 |
On the MKII, the Bias knob varies the operational voltage, and the Saturation knob trims the circuit's input for better cleanup or impedance matching4. Guitar.com noted that the voltage dial alongside the Bias knob lets users tune the fuzz without relying on a dying battery, the traditional Fuzz Face trick5. MusicRadar reported the MKII available at $199 as of May 20226.
A Tagboard Effects layout of the earlier If 6 Was 9 BC183CC describes that circuit as "basically a silicon fuzz face schematic" with small caps across the transistors' collector-base junctions, an external bias control and a two-way tone switch, with vintage-spec carbon comp resistors adding warmth2.
Videos
Pete Thorn
SolidGoldFX | Diamond Pedals
SolidGoldFX | Diamond Pedals
Questions
What transistors does the SolidGoldFX Imperial BC183 use?
The Imperial BC183 uses a trio of BC183 silicon transistors, which the Delicious Audio demo describes as providing detailed, mid-focused gain. The related If 6 Was 9 BC183 pedals use two BC183 transistors instead, in a Fuzz Face-style circuit rather than a Big Muff-style one.
What does the midrange toggle on the Imperial BC183 do?
It is a three-position switch that controls the pedal's midrange content. Depending on where it is set, the mids can be scooped, flattened or boosted, giving a finer degree of control over how the fuzz sits in a mix than a fixed tone stack alone.
Is the Imperial BC183 based on a Big Muff?
It is inspired by classic four-stage Big Muff circuits and retains the BMP tone stack found in vintage Muffs, but Delicious Audio describes it as more than just another Big Muff clone, noting its JFET preamp and midrange toggle as points of difference.
What is the If 6 Was 9 BC183 MKII and how does it relate to the Imperial?
It is a separate SolidGoldFX fuzz based on the Dallas-Arbiter Fuzz Face circuit, using two BC183 transistors. It shares the BC183 transistor type with the Imperial but is a two-transistor Fuzz Face-style design rather than a four-stage Muff-style one. It launched at $199 in 2022.
What kind of fuzz sounds can the Imperial BC183 produce?
Delicious Audio's demo describes it as covering ground from soaring, Gilmour-style leads to dark, doom-leaning rumble, with a Fuzz knob that dials in everything from crunchy breakup to liquid saturation, helped by the midrange toggle and the BMP tone stack.
Sources (6)
- SolidGoldFX Imperial BC183 Fuzz, Delicious Audio, 2017-05-15
- Guitar FX Layouts: SolidGoldFx If 6 Was 9 BC183CC, tagboardeffects.blogspot.com (Guitar FX Layouts), 2017-12-23
- IF 6 WAS 9, SolidGoldFX
- NAMM 2022: SolidGoldFX If 6 Was 9 BC183 MK II Fuzz, gearnews.com, 2022-05-31
- NAMM 2022: SolidGoldFX reinvents its Fuzz Face-inspired If 6 Was 9 Pedal with smart controls, Guitar.com, 2022-06-01
- NAMM 2022: SolidGoldFX refreshes its Fuzz Face-inspired If 6 Was 9, adding a host of player and wah-friendly updates, MusicRadar, 2022-05-31
