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SUSTAINTONEVOLUME

125B · 3 knobs

Aion FX

VulcanOctave Fuzz

Based on the fOXX Tone Machine· 4 other boards clone it

Category
Fuzz· Octave Fuzz
Controls
Sustain · Tone · Volume
Difficulty
Easy
Price
$12.50in stock

From the vendor

A classic untamed fuzz from the 1970s that adds an octave-up overtone.

The Vulcan Octave Fuzz is a recreation of the fOXX Tone Machine, first released in 1971 and discontinued in 1978. The Tone Machine is a thick fuzz that uses a phase splitter and complementary rectifier to create an octave overtone.

The Tone Machine has a lot in common with the Fender Blender, but with a more pronounced octave and smoother tone, as well as the ability to disable the octave by turning off half of the phase splitter. And the tone is not unlike the Superfuzz, although it uses a different method of octave generation to get there.

The Vulcan is faithful to the original, but with two added modifications. First, the octave switch (normally just “on” or “off” in the original) now has a 3rd setting allowing you to bypass the series diode in non-octave mode. See build notes for more details on this.

The second modification is to the tone control. The tone control of the original is somewhat similar to the Big Muff, but many people find it’s difficult to get good sounds from the treble side of the rotation. By increasing the value of the treble-side tone capacitor, it improves the usability. A switch has been added to let you choose between two different capacitors in addition to the original.

Note: The PCB-only version of this project uses a type of capacitor that has been temporarily discontinued by WIMA. Please see our news article about the issue and the substitution spreadsheet for project-specific recommendations. We are stocking a limited supply in the mean time. The build document has not yet been updated to reflect this. It does not impact the kits.

Schematic

The schematic is in the vendor's build document. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 63 rows

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RefValueNormalizedTypeNotes
Resistors 26
R11M1MMetal film resistor, 1/4W
R247k47kMetal film resistor, 1/4W
R31k1kMetal film resistor, 1/4W
R447k47kMetal film resistor, 1/4W
R5100k100kMetal film resistor, 1/4W
R6100k100kMetal film resistor, 1/4W
R74k74.7kMetal film resistor, 1/4W
R84k74.7kMetal film resistor, 1/4W
R912k12kMetal film resistor, 1/4WJumper to increase maximum sustain setting.
R10100k100kMetal film resistor, 1/4W
R11100k100kMetal film resistor, 1/4W
R12220R220Metal film resistor, 1/4W
R13150k150kMetal film resistor, 1/4W
R1415k15kMetal film resistor, 1/4WSome variants have a 1n capacitor in parallel with R14.
R151k1kMetal film resistor, 1/4W
R1610k10kMetal film resistor, 1/4W
R1722k22kMetal film resistor, 1/4W
R184k74.7kMetal film resistor, 1/4WJumper for more control over bass range.
R19470k470kMetal film resistor, 1/4W
R2047k47kMetal film resistor, 1/4W
R2110k10kMetal film resistor, 1/4W
R221k51.5kMetal film resistor, 1/4W
R23100k100kMetal film resistor, 1/4WModification to prevent popping when switching the octave mode.
R24100k100kMetal film resistor, 1/4W
R25100R100Metal film resistor, 1/4WPower supply filter resistor.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 17
C1100n100nFilm capacitor, 7.2 x 2.5mm
C21n1nFilm capacitor, 7.2 x 2.5mm
C3100n100nFilm capacitor, 7.2 x 2.5mm
C41uF1uFilm capacitor, 7.2 x 3.5mm
C51uF1uFilm capacitor, 7.2 x 3.5mm
C61uF1uFilm capacitor, 7.2 x 3.5mm
C71uF1uFilm capacitor, 7.2 x 3.5mm
C822uF22uElectrolytic capacitor, 5mmSee build notes for capacitor value.
C91uF1uFilm capacitor, 7.2 x 3.5mm
C101n1nFilm capacitor, 7.2 x 2.5mm
C112n22.2nFilm capacitor, 7.2 x 2.5mm
C1215n15nFilm capacitor, 7.2 x 2.5mm
C1347n47nFilm capacitor, 7.2 x 2.5mm
C141uF1uFilm capacitor, 7.2 x 3.5mm
C151uF1uFilm capacitor, 7.2 x 3.5mm
C16100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C17100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 5
D11N58171N5817Schottky diode, DO-41
D2BAT46BAT46Schottky diode, DO-35Substitute. Original uses 1N34A or other germanium.
D3BAT46BAT46Schottky diode, DO-35Substitute. Original uses 1N34A or other germanium.
D41N34A1N34ADiode, germanium, NOS
D51N34A1N34ADiode, germanium, NOS
Transistors 4
Q12N50892N5089BJT transistor, NPN, TO-92Modern substitute. The original used 2N3565 or 2N5133. For best results, sort for hFE (gain) of 400 or more.
Q22N50892N5089BJT transistor, NPN, TO-92
Q32N50892N5089BJT transistor, NPN, TO-92
Q42N50892N5089BJT transistor, NPN, TO-92
Potentiometers 3
SUST.50kBB50k16mm right-angle PCB mount pot
TONE50kBB50k16mm right-angle PCB mount pot
VOL.50kBB50k16mm right-angle PCB mount pot
Switches 2
MIDSPDTSPDTToggle switch, SPDT on-onModification to improve usefulness of tone control. See build notes.
FSW3PDT3PDTStomp switch, 3PDT
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 3
IN1/4" stereo1/4" STEREO1/4" phone jack, closed frameSwitchcraft 112BX or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountMouser 163-4302-E or equivalent.
Hardware 2
BATTBattery snapBATTERY SNAP9V battery snapOptional. Use the soft plastic type—the hard-shell type will not fit.
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

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