Erafuzz Rangemaster Duellum - Tone Booster



The Rangemaster Duellum is used to drive your already overdriven tube amp to its limits of pure toneful tones, with full overdriven sounds for more sustain and great dynamics. It's two classic treble boosters in a single unit; both accessible from the second footswitch.

The first booster circuit is based on the legendary modified Dallas Rangemaster treble booster used by Tony Iommi (Black Sabbath). This treble booster is a germanium based circuit. It includes two controls (Boost & Range) to adjust the volume and tone. The Range control allows you to use the unit as a treble booster, midrange booster, or a full range bass booster. In addition, it includes two toggle switches. The first toggle switch (from left to right) allows you to select between two germanium transistors with different attitude. The second toggle switch is a low-pass filter that allows you to get the Sabbath tones from the first albums. This treble booster circuit works great in British based high gain amps.

The second treble booster circuit is based on the legendary treble booster used by Brian May (Queen). This treble booster is a silicon based circuit. It includes two controls (Master & Boost). The Boost control works as a volume control but it works as a gain control too. The Master control is a master volume control. In addition, it includes two toggle switches. The third toggle switch (from left to right) allows you to change the unit from treble booster to midrange booster. The last toggle switch allows you to choose between two silicon transistors with different gain and tone.

This treble booster circuit works great with Vox AC30 based amps to get the Queen tones.

The Erafuzz Rangemaster Duellum is build with high quality components. It's true-bypass, and it's assembled using point to point soldering wiring connections on the copper stripboard for a full circuit performance. It operates with a 9V carbon-zinc battery or with a separate standard (negative pin) 9V external power supply. Never use it with a multi-power supply due to its PNP circuits.


  • 2 Germanium Transistors
  • 2 Silicon Transistors
  • 1 1N4001 Diode
  • 2 3PDT Push Button Footswitches / True-Bypass
  • 2 Neutrik Enclosed Stereo / Mono Jacks
  • 9V (Negative Pin Center) D/C Power Jack
  • 4 NKK Toggle Switches / M Series - Miniature Toggles / Mechanical Life: 100,000 Operations Minimum
  • 1790NS Aluminum Pedal Enclosure / 5.70” x 4.70” x 1.50”D
  • Aluminum Preventive Primer
  • Gloss Hammered Green Paint
  • Super Gloss Clear Coat
  • Vinyl Face with a clear-shield laminate
  • 4 Eagle-Plastic-Devices Control Knobs / Sustain, Tone, Volume
  • 4 Alpha Potentiometers / Rotational Life: 15,000 cycles
  • 3 Vishay Sfernice Trimpots / 2 bias controls & 1 tone control for the low-pass filter.
  • Alpha Wire - Solid Single Conductor 22 AWG / Jacket Material: PVC, 300V
  • Belden Shielded Cable - Jacket Material: PVC, Tinned Copper
  • Ohmite Carbon Composition Resistors 5% Tolerance, ½ Watt
  • Mallory 150M Polyester Film Capacitors 5% Tolerance, 630V, 400V
  • Orange Drop Polypropylene Film Capacitor 5% Tolerance, 630V
  • Vishay BC Components Aluminium Electrolytic Capacitors 20% Tolerance, 100V
  • Copper Stripboard with Point to Point Soldering Wiring Connections
  • Qualitek Silver Rosin Core Solder
  • 9V Carbon Zinc Battery Included

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fx pedal stompbox stomp box guitar effects pedal treble booster high frequency booster treblebooster trebleboost high boost hi boost amplification amp amplifier volume/amplification preamp pre-amp
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