Akashic Guitar effects circuit lookup
FILTERAGGRESSIONBIAS TRIMVOLUME

Enclosure not stated · 4 knobs

Revolution Deux

Fred Briggs Rangemaster MKII

Based on the Dallas Arbiter Rangemaster· 36 other boards clone it

Category
Boost
Controls
Filter · Aggression · Bias trim · Volume
Price
see vendor
Read the post at Revolution Deux Schematic image

From the vendor

The author's own Rangemaster variant: a low-gain germanium and a medium-gain silicon transistor in a Darlington pair, building on Pete Moore's RangePig. A Filter control slides from treble boost to full range, an Aggression control blends the germanium tone with the harder silicon sound, and a bias trimmer sets the transistor voltages. Covers everything from a stock Rangemaster to an almost Fuzz Face-like boost.

Schematic

The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.

Parts list 15 rows

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Check before you build · 2 values the reader of this schematic was not sure of
  • The taper letters on the 100K Filter and Aggression pots are not clear on the handwritten drawing.
  • Which pot is Filter and which Aggression is inferred from the circuit: pot 1 with the 2.2u cap across the 4.7n input cap (Filter), pot 2 between Q1's emitter and Q2's base (Aggression).
RefValueNormalizedTypeNotes
Resistors 3
R12.2M2.2Mread from the schematic by eye
R2470K470kread from the schematic by eye
R368K68kread from the schematic by eye
Capacitors 5
C147u47uelectrolytic, power filter; read from the schematic by eye
C24.7n4.7ninput; read from the schematic by eye
C32.2u2.2uelectrolytic, in series with Filter; read from the schematic by eye
C447u47uelectrolytic, emitter bypass; read from the schematic by eye
C510n10noutput; read from the schematic by eye
Diodes 1
D1??polarity protection; type not marked; read from the schematic by eye
Transistors 2
Q1germaniumGERMANIUMlow gain, about 50 hFE; read from the schematic by eye
Q2siliconSILICONmedium gain, about 250 hFE; read from the schematic by eye
Potentiometers 4
Filter100K100kPotentiometerpot 1; read from the schematic by eye
Aggression100K100kPotentiometerpot 2; read from the schematic by eye
Bias trim10K10kPotentiometertrimmer, set for -6.6V on the collector; read from the schematic by eye
VolumeA10KA10kPotentiometerpot 3, collector load; read from the schematic by eye

Other boards based on the Dallas Arbiter Rangemaster