Northern FX Rangemaster

The Northern FX Rangemaster is a germanium treble booster pedal built on the classic Dallas Rangemaster circuit, the design that was popular back in the late 1960s and early 1970s¹. Where the original was a one-knob box, Northern FX's version keeps the single boost control but adds an 8-position rotary tone switch and an on-board bias trimmer for its NOS PNP germanium transistor¹. Delicious Audio describes its character as a "Vintage, warm and creamy boost"¹.

Like every treble booster, the idea is simple: push the upper frequencies of the guitar harder into whatever comes next, whether that is a cranked amp or a dirt pedal. The Rangemaster approach does this with a germanium treble booster style circuit rather than op-amps or digital modeling, which is why the design still gets revisited by builders today².

The controls

The pedal has two controls: a knob and a rotary switch¹.

The rotary switch is the big departure from the original. The first position is a bit more trebly than the Rangemaster standard, the second position is the Rangemaster standard, and the remaining positions are gradually more bassy¹. On the stock Dallas circuit you got one fixed frequency focus; here you can move the boosted range down toward fuller frequencies, which is what makes the pedal work with a wider range of amps and dirt pedals.

There is a third control of sorts inside: the board has a biasing pot to refine the transistor's biasing¹. Germanium transistors drift with temperature and vary from unit to unit, so a trimmer lets the bias be set correctly for the specific transistor in the box rather than relying on fixed resistors.

The Dallas Rangemaster circuit behind it

The Northern FX pedal is based on the classic Dallas Rangemaster circuit, "that venerable vintage circuit originally manufactured by Dallas"¹. The original Rangemaster was a treble booster that came in a folded steel desk top style enclosure³, and it was a one-knob design⁴. R.G. Keen of GeoFex.com wrote a well-known article dissecting the circuit, which is where much of the modern understanding of how it works comes from⁵.

The circuit itself is a single-transistor common-emitter stage. The original used a germanium PNP transistor, and modified versions have used silicon NPN transistors instead⁶. GuitarPCB's analysis notes the Rangemaster uses a 3.9K emitter resistor, probably related to providing greater thermal stability for the transistor⁷.

One practical problem with PNP germanium circuits is power. A PNP transistor wants a positive ground, which conflicts with modern center negative pedalboard power. The Northern FX pedal solves this the same way many builders do: the circuit contains a voltage inverter which enables the use of a standard center negative 9V adapter¹. The same trick appears in DIY layouts, where an ICL7660S voltage inverter provides negative ground operation so you can use PNP transistors with a standard supply⁸. Jack Orman's AMZ work on positive-supply techniques notes the approach may be adapted for designs that use PNP transistors, like the Rangemaster⁹.

The Rangemaster's influence runs wide. MusicRadar notes the Dallas Rangemaster "has inspired a slew of modern pedals" from makers including British Pedal Company, Catalinbread and JHS Pedals¹⁰, and Premier Guitar's review of the Creepy Fingers Doomidrive observed that its circuit shares a lot in common with treble boosters that have a dirty edge, such as the Dallas Rangemaster¹¹. The DIY world has kept the circuit alive too: General Guitar Gadgets sells a replica kit with PNP germanium, NPN germanium and charge pump versions¹², and the tagboardeffects blog has posted compact layouts for the standard circuit, including a negative ground version⁸.

What reviewers said

Delicious Audio's writeup focused on the rotary switch, finding that the eight presets make the pedal very versatile and easy to stack with overdrives and fuzz¹. That stacking quality is the practical payoff of the extended tone range: a stock Rangemaster is a fairly narrow tool, while a switchable one can sit in front of several different gain stages.

For context on where the circuit sits among modern germanium treble boosters, Guitar Pedal X's 2024 round-up praised the Drunk Beaver Hoverla as "a superb extended range Treble Booster / RangeMaster with an absolutely killer feature-set and superior Germanium transistor onboard"¹³, and the same site covered ThorpyFX's Have Blue Germanium Rangemaster, which uses a Range knob to focus on specific frequency clusters across its sweep¹⁴. The Northern FX pedal's 8-position switch is a similar idea in switch rather than knob form.

The original circuit's user list explains the lasting interest. Analog Man's documentation describes it as used by Eric Clapton, Brian May, Tony Iommi, and many more¹⁵, and Gearnews likewise names Tony Iommi, Brian May and Marc Bolan among influential British guitarists who used it¹⁶.

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