Build - Pedal Project: Rangemaster

The Dallas Rangemaster was one of the earliest guitar effects. Originally built into an amp-top box, the Rangemaster was often used in an “always-on” fashion, contributing heavily to the trademark sounds of both Brian May and Tony Iommi. It is a favorite of many for driving the input of a tube amp.

The Rangemaster boosts the treble of the signal by filtering out some of the low end via an input high pass filter and then boosting the resulting signal with a simple common-emitter transistor gain stage. The input high pass filter is formed by the 5nF capacitor and the input impedance of the transistor in parallel with 470k and 68k. A common modification made on modern Rangemaster builds is to have various input capacitor values on a switch so the user can move the cutoff frequency of the filter, allowing for a more full-range boost or one with even more lows cut. It is a good component to experiment with to see what you like there.

1M pull-down resistors have been added to the input and output of the effect. These are present to prevent the pedal from popping or clicking when the effect is engaged. In original units, it was not a concern given that they were not meant to be toggled mid-song, but rather kept either engaged or disengaged. When using the effect in a modern true bypass pedal, they may be desirable. If you’d prefer to keep the circuit original, both 1M resistors can be left out.

This is a PNP build and uses battery power only. With no LED indicator, this pedal will last a very long time on battery power. If you would like to build this pedal with a DC jack, please see our PNP "Positive Ground" Pedal Considerations tech article.

Figure 1: Turret board layout of the Rangemaster.

Figure 1: Turret board layout of the Rangemaster.

See Figure 4 in our Guitar Pedal Footswitch and Jack Wiring article for the recommended footswitch and I/O wiring.

Figure 2: Rangemaster Schematic

Figure 2: Rangemaster Schematic

Parts List

50 µF2C-ET50-50-MODElectrolytic
10 nF1C-MKT-D01-400Film cap
5 nF1C-MD0047-630Film cap
10k Audio1R-VAM10KA-SSVolume Control
1 MΩ2R-J1MCarbon Comp Resistor
3.9 kΩ1R-I3D9KCarbon Comp Resistor
470 kΩ1R-I470KCarbon Comp Resistor
68 kΩ1R-I68KCarbon Comp Resistor
OC411P-Q2N404Germanium Transistor
Other Items
Black 1590B1P-H1590BBKEnclosure
Carling DPDT1P-H497Footswitch
Greencell 9V1S-9V-GCELLBattery
Vinyl battery snap1K-P155Battery snap
Mono jack1W-SC-111XOutput jack
Fairchild arrow knob1P-K347-52Knob
Stereo jack1W-SC-112BXInput jack

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