The Rage Master (NKT275) is a Treble Booster based on the legendary Dallas Rangemaster (RM) — the British phenomenon of the 1960s and 70s.
It’s the booster that shaped the sound of Jimmy Page, Brian May, Eric Clapton, Tony Iommi, Rory Gallagher, Marc Bolan, Ritchie Blackmore, and many others.
No, it’s not a clean booster, and it’s not a flat booster either. It features a distinct midrange and upper-mid voice that “opens up” the tone, delivering a creamy, cohesive, and well-defined distortion.

Back in the day, amps like the Vox AC30, Marshall JTM45, Blues Breaker, and Laney LA100 were the standard among British guitarists.
Paired with solid-body guitars and low-output PAF-style pickups, they often produced a veiled and muddy high-gain tone.
The Rangemaster became the British favorite, as it boosted the mids and enhanced the amp’s natural overdrive.
Almost six decades later, the RM remains one of the most iconic sonic signatures in the history of guitar and rock music.
You might have never played a pedal like it, but if you’ve listened to Queen, Led Zeppelin, or Black Sabbath, that sound is already etched in your memory.

CONTROLS

BOOST – Controls volume, saturation, and gain of the frequency selected by the MIDs switch.

MIDs SWITCH – Combines capacitors that form the high-pass filter defining which mid frequencies are emphasized:

• B. May – More “vocal” mids, smooth saturation, and controlled low end for cascading gain without muddiness.
  Direct reference to Brian May with his Red Special, Vox AC30s, and Treble Booster setup.
  Tip: When paired with modern amps and drives, it enhances the “vocal mids” and adds a punchy response.

• J. Page – Intermediate mode, with softer, present mids, fuller tone, and moderate saturation.
  Voicing inspired by Led Zeppelin tones.
  Tip: With modern gain stages, produces a tight and cohesive distortion, always maintaining that vintage flavor.

• Cream – Inspired by Eric Clapton’s “Woman Tone”.
  The fullest-sounding mode, offering more gain and saturation, a velvety, thick tone, and even bordering on fuzz at max boost.

ABOUT THE NKT275 TRANSISTOR

The NKT275 is a PNP germanium transistor widely used by boutique pedal builders for authentic reproductions of classic fuzzes and treble boosters.
The original Rangemaster used Mullard OC44, OC71, or NKT275 transistors.
Due to growing demand and rarity, the NKT275 became heavily counterfeited, often through relabeled similar components.
Since identifying genuine parts requires expertise, we’ve chosen to use the NKT275 made by DSI, a German company specialized in discontinued electronic components, known for high quality and strict adherence to original specs.

TECHNICAL SPECIFICATIONS

• Power supply: 9V DC (center negative) – Boss standard

• Current draw: approx. 30mA

• Pedal dimensions: 6.7 × 6.1 × 12.7 cm (W × H × D)

• Box dimensions: 18.5 × 12.5 × 8.5 cm (W × H × D)

• Weight: approx. 490g

• Warranty: 90 days