The Monolith Fuzz Oracle is a fuzz pedal built on a two-transistor PNP germanium circuit. Guitar FX Layouts, the independent technical site that published a stripboard layout for it in February 2014, describes it as "a nice aggressive sounding fuzz": a Vox Tonebender, specifically the two transistor MK 1.5 circuit, "with all of it's lovely midrange-heavy goodness mixed with the throaty low "huumphh" of an early Big Muff"1.
The controls: Density, Color and Output
The Oracle keeps things simple: three pots on the top panel1.
| Control | What it is | What it does |
|---|---|---|
| Density | Gain pot | "lots of different sounds as you turn the knob," per the layout notes1 |
| Color | Tone pot with push-pull switch | Pulling the switch changes the mode1 |
| Output | Volume pot | Sets the pedal's output level1 |
The Density control draws particular praise from the layout's author: "Density is a great control, lots of different sounds as you turn the knob"1. Because it is the circuit's gain stage, the pot's taper matters. Per johnk, "the gain works better with reverse log 1 meg pot," which spreads the sweep more evenly across the knob's travel1.
Building it: transistors and the Color switch
The circuit runs on PNP germanium transistors. On the published layout, IvIark reported using a set "that was about 100hfe for q1 and about 300hfe for q2 like the original," so Q2 around 300hfe matches the original circuit's gain structure1.
The mode switch on the original is "a push pull on the Color pot"1. Builders have two alternatives if they prefer something else:
- A 250K switched pot for the Color control
- A DPDT 2 position toggle in place of the push-pull switch1
The published layout is a DIY stripboard (vero and tagboard) project from Guitar FX Layouts, dated 8 February 2014, not a factory-built product listing. Specifications such as power draw, bypass type and enclosure size are not part of that document1.
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Questions
Does the Monolith Fuzz Oracle use germanium transistors?
Yes. The circuit uses PNP germanium transistors. On the Guitar FX Layouts build, IvIark reported using a set measuring about 100hfe for Q1 and about 300hfe for Q2, with Q2 around 300hfe matching the original circuit. Germanium parts vary from unit to unit, so the exact transistors used shape how the fuzz responds.
What does the push-pull Color pot do on the Monolith Fuzz Oracle?
On the original, the switch is a push-pull on the Color pot, and pulling it switches the pedal into a second mode. Builders who want a different arrangement can use a 250K switched pot for the Color control, or a DPDT 2 position toggle in place of the push-pull switch.
Which Tonebender circuit is the Monolith Fuzz Oracle based on?
The Monolith Fuzz Oracle is based on an Italian made Vox Tonebender, specifically the two transistor MK 1.5 circuit. Guitar FX Layouts describes its character as midrange-heavy, mixed with the throaty low end of an early Big Muff.
Can the Color switch be built with a toggle instead of a push-pull pot?
Yes. The layout notes give two options: use a 250K switched pot for the Color control, or alternatively just use a DPDT 2 position toggle for the switch. Either arrangement does the same job as the push-pull on the original.
What pot works best for the Density control?
The Density control is the circuit's gain pot, and per johnk it works better with a reverse log 1 meg pot. That taper spreads the usable range across the knob's travel instead of bunching it at one end.
Sources (1)
- Guitar FX Layouts: Monolith Fuzz Oracle, Guitar FX Layouts (tagboardeffects.blogspot.com), 2014-02-08