aion VULCAN User manual

VULCAN OCTAVE FUZZ 1
PROJECT NAME
VULCAN
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
fOXX Tone Machine
A classic untamed fuzz from the 1970s that adds an octave-up overtone.
Octave Fuzz 1.1.0 (2020-06-06)
BUILD DIFFICULTY
Easy
Actual size is 2.3” x 1.86” (main board) and 1.78” x 0.86” (bypass board).

VULCAN OCTAVE FUZZ 2
TABLE OF CONTENTS
1Project Overview 7Drill Template
2Introduction & Usage 8Enclosure Layout
3-4 Parts List 9Wiring Diagram
5Build Notes 10 Licensing
6Schematic 10 Document Revisions
INTRODUCTION
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.
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.
The build notes for the Vulcan are pretty extensive, so make sure to read pages 5 and 6 before building.
USAGE
The Vulcan has the following controls:
• Sustain is the overall distortion or fuzz level of the effect.
• Tone pans between a low-pass and high-pass filter similar to a Big Muff tone control.
• Volume controls the overall output of the effect.
• Octave (toggle switch) selects between octave, no octave (original) and no octave (modified).
• Midrange (toggle switch) selects between two tone control capacitors that impact the midrange
frequencies, as well as allowing you to select just the stock capacitor.

VULCAN OCTAVE FUZZ 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts (most notably potentiometers) so the second tab
lists all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 1M Metal film resistor, 1/4W
R2 47k Metal film resistor, 1/4W
R3 1k Metal film resistor, 1/4W
R4 47k Metal film resistor, 1/4W
R5 100k Metal film resistor, 1/4W
R6 100k Metal film resistor, 1/4W
R7 4k7 Metal film resistor, 1/4W
R8 4k7 Metal film resistor, 1/4W
R9 12k Metal film resistor, 1/4W This is the top R9 resistor, immediately below the Sustain control.
R9 100k Metal film resistor, 1/4W This is the bottom R9 resistor, immediately below the other R9.
R10 100k Metal film resistor, 1/4W
R11 100k Metal film resistor, 1/4W
R12 220R Metal film resistor, 1/4W
R13 150k Metal film resistor, 1/4W
R14 15k Metal film resistor, 1/4W Some variants have a 1n capacitor in parallel with R14.
R15 1k Metal film resistor, 1/4W
R16 10k Metal film resistor, 1/4W
R17 22k Metal film resistor, 1/4W
R18 4k7 Metal film resistor, 1/4W Jumper for more control over bass range.
R19 470k Metal film resistor, 1/4W
R20 47k Metal film resistor, 1/4W
R21 10k Metal film resistor, 1/4W
R22 1k5 Metal film resistor, 1/4W
R23 100k Metal film resistor, 1/4W Prevents popping when switching in & out of octave mode.
RX1 OMIT Metal film resistor, 1/4W Modification for more pronounced filter, similar to Big Muff tone stage.
Leave empty for stock, or use 22k here for modification.
C1 100n Film capacitor, 7.2 x 2.5mm
C2 1n Film capacitor, 7.2 x 2.5mm
C3 100n Film capacitor, 7.2 x 2.5mm
C4 1uF Film capacitor, 7.2 x 3.5mm
C5 1uF Film capacitor, 7.2 x 3.5mm

VULCAN OCTAVE FUZZ 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C6 1uF Film capacitor, 7.2 x 3.5mm
C7 1uF Film capacitor, 7.2 x 3.5mm
C8 22uF Electrolytic capacitor, 5mm Original units used 10uF capacitors, but many were off-spec and actually
measured 22uF.
C9 1uF Film capacitor, 7.2 x 3.5mm
C10 1n Film capacitor, 7.2 x 2.5mm
C11 2n2 Film capacitor, 7.2 x 2.5mm Modification - alternate capacitors for tone section, switched in via the
Midrange switch. Use 1n8 for red (late) specs. See build notes for more.
C12 15n Film capacitor, 7.2 x 2.5mm Modification - alternate capacitors for tone section, switched in via the
Midrange switch.
C13 47n Film capacitor, 7.2 x 2.5mm
C14 1uF Film capacitor, 7.2 x 3.5mm
C15 1uF Film capacitor, 7.2 x 3.5mm
C16 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C17 100n MLCC capacitor, X7R Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 BAT46 Schottky diode, DO-35 Substitute. Original uses 1N34A or other germanium.
D3 BAT46 Schottky diode, DO-35 Substitute. Original uses 1N34A or other germanium.
D4 1N34A Diode, germanium, NOS
D5 1N34A Diode, germanium, NOS
Q1 2N5089 BJT transistor, NPN, TO-92 Modern substitute. The original used 2N3565 or 2N5133. For best
results, sort for hFE (gain) of 400 or more.
Q2 2N5089 BJT transistor, NPN, TO-92
Q3 2N5089 BJT transistor, NPN, TO-92
Q4 2N5089 BJT transistor, NPN, TO-92
SUST. 50kB 16mm right-angle PCB mount pot
TONE 50kB 16mm right-angle PCB mount pot
VOL. 50kB 16mm right-angle PCB mount pot
MID SPDT Toggle switch, SPDT on-on Modification to improve usefulness of tone control. See build notes.
OCTAVE SPDT cntr off Toggle switch, SPDT on-off-on Slight modification to the original. See build notes.
LED 5mm LED, 5mm, red diffused
IN 1/4" stereo 1/4" phone jack, closed frame Switchcraft 112BX or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
BATT Battery snap 9V battery snap Optional. Use the soft plastic type—the hard-shell type will not fit.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

VULCAN OCTAVE FUZZ 5
BUILD NOTES
Version 1.1 updates
Version 1.1 of the PCB (April 2020) adds two new resistors, R23 and a second R9. (The second R9 was
labeled by mistake—it should have been labeled R24.) The top R9 is 12k and the bottom R9 is 100k. R23
is 100k. These are the only changes to the circuit board.
Tracing notes: early vs. late version
Since releasing the Vulcan initially, Aion FX had the opportunity to trace two original Tone Machines, an
early blue one and a later red one. The early version is identical to the commonly available schematics.
The differences in the red version are very minor:
1. 12k series resistor added to the Sustain control to drop the maximum amount of sustain slightly.
2. The treble-side tone capacitor, normally 3n3, has been reduced to 2n7.
3. The transistors (still 2N3565) are sorted for higher gain, 400+.
In addition, another thing we noticed in tracing is that the C8 capacitor measured right around 22uF
(nominally 10uF). This did have an impact on the bass content of the tone, so if you want it to sound like
a real vintage unit then use 22uF.
Tone capacitor
The red version of the Tone Machine used 2n7 for the tone capacitor instead of 3n3. Due to the
midrange switch in the Vulcan, the corresponding tone capacitor is a combination of C10 + C11 (1n
+ 2n2 = 3n3). So, if you want to use the red value, we recommend using a 1n8 capacitor for C11 for a
combined value of 2n8.
Transistor selection
While the 2N3565 was the only transistor used throughout the run of the Tone Machine, the gain of
those transistors was very different. Early units had gains around 230-250 while later units were over
450. Here is a chart of the gain (hFE) of the transistors that we measured in two vintage units:
PART BLUE (EARLY) RED (LATE)
Q1 245 549
Q2 230 451
Q3 240 456
Q4 230 455
If you are building to “early specs” then 2N3904 is a good option, though it’s typically a little lower gain
than these. For “late specs”, the 2N5089 or 2N5088 will get you there.

VULCAN OCTAVE FUZZ 6
BUILD NOTES, CONT.
Tone control modications
Midrange switch
The Tone Machine’s tone control is reminiscent of the Big Muff in its topology, but missing a resistor to
ground on the treble side to complete the filter, and with a very low value for the treble capacitor, which
makes it a little harsh on higher settings. By changing the capacitor to a higher value, the frequency
range is increased and the treble side of the control becomes a lot more usable.
Big Muff resistor
As mentioned previously, the tone control is one resistor away from a Big Muff tone control. An optional
resistor, RX1, has been added in case you want to experiment to see how it sounds. Start with 22k as a
value. R17 and C13 can be adjusted as well to match a Big Muff variant.
Minimum bass value resistor
R18 sets the minimum value for the bass side of the knob rotation, setting it approximately 10% higher
than a standard Big Muff tone section. If you want more bass (especially if using modified filter values to
be more like a Big Muff) then you may want to jumper this resistor to give the control more range.
Octave switch
The octave in this effect is generated by splitting the signal into two, one in-phase and one out of phase,
and then rectifying the signals to cancel out half of the waveform of each. The signals are then combined
back together which emphasizes the octave overtone.
The octave switch lets you disable half of the phase splitter to cancel out the octave effect. However, the
non-octave signal still passes through a series diode (D2) which introduces something called “crossover
distortion”. While this crossover distortion is part of the sound of the Tone Machine, it sounds very good
without it as well and justifies having its own setting.
As a result, the octave switch has been modified to have Octave, No Octave (original) and No Octave
(modified) settings.
R23 resistor
In Version 1.1 of the Vulcan, a new resistor (R23) was added to one half of the octave generation path.
This is a counterpart to R10 that ensures that both sides of the octave signal are held at the same DC
voltage.
The vintage Tone Machine units were missing this resistor, so they had a pop when switching the octave
on and off. This can be considered a design flaw in the original units. There is no change to the tone by
adding this resistor since it only impacts the DC voltage, not AC (signal), but it can be omitted if you
want it to be 100% stock.

SCHEMATIC
VULCAN OCTAVE FUZZ 7
GND
1M
1N5817
100uF
50kB
GND
+9V
100n
VA
100n
1n
2N5089
47k1k
47k
GND
100n
VA
100k
2N5089
100k
GNDGND
4k7
VA
4k7
GND
1uF1uF
100k100k
BAT46
BAT46
100k
1uF
GND
VA
GND
220R
GND
1uF
150k15k
2N5089
1k
GND
VA
GND
10k
VA
22uF
GND
1uF
50kB
1n
1N34A
1N34A
GND
22k
47n
GND
4k7
1uF
470k47k
VA
GND
2N5089
10k
VA
1k5
GND
1uF
50kB
GND
22k
GND
15n 2n2
100k
VA
12k
R1
D1
C16
SUSTAIN
1
2
3
IN
OUT
C17
C1
C2
Q1
R2R3
R4
C3
R5
Q2
R6
R8R7
C4C5
R9R11
D2
D3
R10
C6
2
3 1
OCTAVE
R12
C7
R13R14
Q3
R15 R16
C8
C9
TONE
1
2
3
C10
D4 D5
R17
C13
R18
C14
R19R20
Q4
R21R22
C15
VOLUME
1
2
3
RX1
2
3
1
MIDRANGE
C12 C11
R23
R9
GND

VULCAN OCTAVE FUZZ 8
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout assumes the use of closed-frame jacks like the Switchcraft 111X. If you’d rather use
open-frame jacks, please refer to the Open-Frame Jack Drill Template for the top side.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
0 1 2
CM
0 1
INCH
x: -0.65, y: +1.71 x: 0.65, y: +1.71
ø9/32” ø9/32”
x: -0.85, y: +0.66
ø1/4”
x: 0, y: +0.66
ø9/32”
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
CENTER (0,0)
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
125B
VOLUME
MIDRANGE OCTAVETONE
SUSTAIN
FOOTSWITCHLED
x: +0.85, y: +0.66
ø1/4”

VULCAN OCTAVE FUZZ 9
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

VULCAN OCTAVE FUZZ 10
WIRING DIAGRAM
125B
IN +VGND N.C. N.C. OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT
Shown with optional 9V battery. If battery is omitted, both jacks can be mono rather than one being stereo.
Leave the far-right lug of the DC jack unconnected.