alon PENUMBRA User manual

PENUMBRA BASS FUZZ 1
PROJECT NAME
PENUMBRA
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
ZVEX Woolly Mammoth / Mastotron
A full-frequency silicon fuzz, originally designed for bass but just as suited for guitar. Famously used by
Chris Wolstenholme of Muse.
Bass fuzz 1.0.0 (2022-01-21)
BUILD DIFFICULTY
This documentation is for the kit version of the project. If you purchased the PCB by itself, please
use the PCB-only version of the documentation instead. The circuit is the same, but the instructions
are completely different due to the specialized parts and assembly methods used in the kit.
IMPORTANT NOTE
Easy
VOLUME
BASS FUZZ
FUZZ
9V
LOW
PICKUP
OFF ON
SIMULATOR
TONE PINCH

PENUMBRA BASS FUZZ 2
TABLE OF CONTENTS
1Project Overview
2Table of Contents
3Introduction
4Packing List
5Packing List (Cont.)
6Tools Needed
7Component Identification
8Hardware Identification
9PCB Assembly Overview
10 Resistors & Diode
11 Transistors
12 Capacitors (Non-Polarized)
13 Wire Headers
14 Capacitors (Polarized)
15 Transformer
16 Footswitch PCB
17 Input/Output PCB
18 Enclosure Layout: Panel Mounts
19 Enclosure Layout: Panel Mounts (Cont.)
20 Enclosure Layout: Main & Footswitch PCBs
21 Enclosure Layout: Input/Output PCB
22 Final Assembly & Testing
23 Schematic
24 Full Parts List
25 Troubleshooting Information
26 Support & Resale Terms
27 Legal Information & Document Revisions

PENUMBRA BASS FUZZ 3
INTRODUCTION
If this is your first pedal, welcome to the hobby and thank you for choosing Aion FX. You’ve just joined
a community of over 40,000 people around the world with a passion for building homemade noise
machines using obsolete electronics technologies, and we’re glad to have you!
If you’ve done this before, it’s great to see you again and we’re confident you’ll find this build experience
an enjoyable one.
Aion FX kits are designed to empower anyone to build a high-quality pedal, no matter the skill level.
The pedalbuilding hobby has traditionally had a steep learning curve, but don’t be overwhelmed—we’ve
done all the hard work for you. All you need to do is follow these instructions and you’ll be on your way
to transforming your tone.
There are a few things to go over before you get started.
• You’re going to have to get your hands dirty—there’s no way around it. Nothing here comes
preassembled, and you’ll have to learn the skills to put it all together. This document will walk you
through everything you need, but be prepared to learn a few things along the way.
• This will take time. Plan on about two hours start to finish. It may take even longer if it’s your first
time building. Don’t rush it. If you find yourself getting frustrated or overwhelmed, take a break
and come back in a couple of hours or the next day.
• No direct technical support is offered. There are several DIY forums and Facebook groups with
thousands of members who enjoy troubleshooting and teaching. But please be sensitive to the
fact that the staff at Aion FX is minimal, and every minute spent helping individuals in private is
time that can’t be spent on new project development.
• There is no implied guarantee of a final product. Aion FX provides the ingredients and the recipe,
but you are responsible for putting everything together to make it work. We’ve tried to make the
process as clear and accessible as possible, but it must be expressly stated that purchasing the kit
is not a guarantee that you will end up with a working pedal.
It’s recommended to read through all of the instructions before you start, particularly if you’ve never
built a pedal before. If you familiarize yourself with the entire process ahead of time and you know what
the goal looks like, each step will make more sense.
Now, on to the fun stuff!

PENUMBRA BASS FUZZ 4
PACKING LIST
This is a list of all the parts that are included with the kit, grouped by value. For a list of all the parts
based on their PCB part numbers, please see page 30.
If you find that any parts are missing or damaged, please fill out the Missing Parts form.
Film Capacitors
NAME QTY
1n (0.001) 1
10n (0.01) 2
33n (0.033) 1
68n (0.068) 1
220n (0.22) 2
1uF 1
Electrolytic Capacitors
NAME QTY
100uF 4
MLCC Capacitors
NAME QTY
100n (marked “104”) 1
Diodes
NAME QTY
1N5817 1
Resistors
NAME QTY
100R 1
1k 2
2k2 1
4k7 1
5k1 1
10k 2
22k 1
56k 1
1M 2
2M2 1
Transistors
NAME QTY
PN4303 or 2N5457 1
2N3904 2
Transformer
NAME QTY
42TL019 1

PENUMBRA BASS FUZZ 5
PACKING LIST (CONT.)
Potentiometers
NAME QTY
5kC 1
10kB 2
500kB 1
Dust cover 4
Knob, 3/4” 2
Knob, 1/2” 2
Mounting nut, potentiometer, 0.44" 4
Lock washer, potentiometer, 0.5" 4
Outer washer, potentiometer, 0.475" 4
Other
NAME QTY
LED bezel 1
LED, blue 1
9V battery snap 1
DC jack 1
Input/output jack 2
Mounting nut, jack, 0.54" 4
Outer washer, jack, 0.6" 2
Lock washer, jack, 0.5" (thin) 2
Enclosure 1
Enclosure screws 4
PCB, main circuit 1
PCB, footswitch 1
PCB, input/output/DC 1
Switches
NAME QTY
Toggle switch, SPDT on-off-on 1
Toggle switch, DPDT on-on 1
Mounting nut, toggle switch, 0.36" 2
Lock washer, toggle switch, 0.4" 2
Dress nut, toggle switch, 0.375" 2
Stomp switch, 3PDT 1
Mounting nut, stomp switch, 0.6" 2
Lock washer, stomp switch, 0.6" 1
Dress nut, stomp switch, 0.77" 1
Wiring
NAME QTY
3-strand wire assembly, 70mm 2
4-strand wire assembly, 108mm 1
3-pin wire assembly header 2
4-pin wire assembly header 1

PENUMBRA BASS FUZZ 6
TOOLS NEEDED
SOLDERING IRON
Temperature-adjustable is
recommended. The optimum
soldering temperature is 700-725º
F (371-385º C) for leaded solder, or
750º F (400º C) for lead-free.
WIRE SNIPPERS
Also called nippers or wire cutters.
The Hakko CHP-170 is the best you
can get for less than $10.
SCREWDRIVER (PHILLIPS)
Used for the enclosure screws. Get a
powered driver if you’ll be building a
lot of pedals!
SOLDER
Preferably 63/37 or 60/40 leaded
solder. Lead-free is more difficult to
use, so if that’s the only type you can
get, it’s best to watch tutorials that
are specific to lead-free solder.
NEEDLE-NOSE PLIERS
These are used for bending leads on
components and other general uses.
Use the smaller type with a tip that’s
approximately 0.05” (1.25mm) wide.
FLAT SCREWDRIVER (SMALL)
This is used for tightening the set
screws on the knobs. The tip should
be no more than 0.1” (2.5mm) wide.
DIGITAL MULTIMETER (DMM)
Most cheap ones in the $10-30 range
are fine for what we’re doing. Make
sure it has audible continuity testing
(i.e. it beeps at the lowest resistance)
and transistor hFE measurement.
FLAT-NOSE PLIERS
Many general-purpose uses, but par-
ticularly tightening the nuts of pots,
switches and jacks. Quicker than
changing out sockets on a ratchet.
RUBBER BAND
Yes, a plain old rubber band. This is
used to tighten the dress nut to avoid
scratching or denting it (which can
happen with metal tools).

PENUMBRA BASS FUZZ 7
COMPONENT IDENTIFICATION
If you’ve never built a pedal before, you’ll need to know what all the components are. These are shown
actual size. (Not all of these types of components may be part of this kit.)
RESISTOR TRIMMER POTENTIOMETER
FILM CAPACITOR
SILICON DIODE
ZENER DIODE
LED
DC JACKWIRE ASSEMBLY HEADER
LED BEZEL
WIRE ASSEMBLY
ELECTROLYTIC CAPACITOR
GERMANIUM DIODE
OP-AMP / IC
TANTALUM CAPACITOR
SCHOTTKY DIODE
IC SOCKET TRANSFORMER
MLCC
RECTIFIER DIODE
TRANSISTOR OR JFET
Not polarized. Color may
vary by brand and type.
Not polarized. MLCC stands for
“multi-layer ceramic capacitor.”
Some Schottky diodes
also look like this.
These are very fragile, so be
careful when handling them.
Polarized. The positive side
is marked.
Polarized. The negative side
is marked.
Charge pumps and delay chips
also look like this. They may
have more than 8 legs.

PENUMBRA BASS FUZZ 8
HARDWARE IDENTIFICATION
The hardware comes unassembled, so you’ll need to sort & identify each of the pieces. The diagrams
below are actual size, so you can set them against the printed page to identify them if needed.
I/O JACK
TOGGLE SWITCH
POTENTIOMETER
(SINGLE)
FOOTSWITCH
POTENTIOMETER
(DUAL)
MOUNTING NUT
MOUNTING NUT
MOUNTING NUT
MOUNTING NUT
DRESS NUT
OUTER WASHER
DRESS NUT
OUTER WASHER KNOB
LOCK WASHER
LOCK WASHER
LOCK WASHER
LOCK WASHER
DIAMETER: 0.54” / 13.7mm
DIAMETER: 0.36” / 9.1mm
DIAMETER: 0.44” / 11.2mm DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.6” / 15.2mm
DIAMETER: 0.375” / 9.5mm
DIAMETER: 0.475” / 12mm
DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.4” / 10.1mm
DIAMETER: 0.6” / 15.2mmDIAMETER: 0.77” / 19.6mmDIAMETER: 0.6” / 15.2mm

PENUMBRA BASS FUZZ 9
PCB ASSEMBLY OVERVIEW
Now it’s time to start building!
The first thing you need to do is snap apart the PCBs
into 3 separate boards (if needed) and break off the
tabs from each using needle-nose or flat-head pliers.
You should be left with the PCBs shown to the right.
The general principle for PCB population is that you
want to work in layers from shortest components
(i.e. lowest-profile) to tallest so that when the PCB is
upside-down, everything is making contact with the
work surface and is held in place.
Generally speaking, you should populate the
components in this order:
1. Resistors
2. Diodes
3. MLCC capacitors
4. Film capacitors
5. Transistors
6. Electrolytic capacitors
7. Transformer

PENUMBRA BASS FUZZ 10
RESISTORS & DIODE
PART VALUE
R1 1M
R2 1M
R3 10k
R4 1k
R5 56k
PART VALUE
R6 1k
R7 2k2
R8 22k
R9 10k
R10 5k1
PART VALUE
R11 100R
RPD 2M2
LEDR 4k7
D1 1N5817
Using the parts list above, populate the resistors by pushing them through the holes and bending the
leads outward at an angle to hold them in place. Resistors are not polarized, so they will work in any
direction. Turn the board upside-down to keep the components held in place while you solder.
You’ll use this same technique for most of the other components as well.
If it gets too crowded, just flip the board and solder everything you’ve done so far, then cut the leads
using the wire snippers to make room for more.
If this is your first time soldering, watch tutorial videos on YouTube and make sure you get it down
before you begin. You don’t want to practice or experiment on this board!

PENUMBRA BASS FUZZ 11
TRANSISTORS
PART VALUE
Q1 PN4303 or
2N5457
Q2 2N3904
Q3 2N3904
Now we’ll do the transistors. If the legs are not already bent into 0.1” spacing, use your needle-nose
pliers to bend the outer two legs as shown.
Bend the outer leads of the transistors to hold them in place on the board. Then, solder them and clip the
leads. The two 2N3904 transistors are interchangeable and it does not matter which one is used for Q2
and which one is for Q3.

PENUMBRA BASS FUZZ 12
CAPACITORS (NON-POLARIZED)
After the transistors come the box film and MLCC capacitors. These are all several different heights, but
there aren’t as many, so just do them all at once. Bend the leads at an angle to hold them in place.
MLCCs and box capacitors are not polarized and will work in any direction. To keep things neat, though,
it’s best to put them all facing the same way so the values can easily be read.
Note: The blue box film capacitors (C2 and sometimes C4 and C7) have the value printed on the top,
while the red capacitors have the value on the side. The text on the side of the blue capacitors is not
related to the value and can be ignored.
PART VALUE
C1 1uF
C2 1n
C3 220n
C4 10n
C7 10n
PART VALUE
C8 220n
C9 33n
C10 68n
C13 100n MLCC

PENUMBRA BASS FUZZ 13
WIRE HEADERS
Install the two 3-pin headers (wire connectors) as shown above. These have a polarity pin, so as long
as they are pressed all the way down, there’s only one possible way to install them. They do fit pretty
tightly in the holes, though, so press firmly.
There’s also a 4-pin header on the I/O board that we will do in a later step.

PENUMBRA BASS FUZZ 14
CAPACITORS (POLARIZED)
Populate the electrolytic capacitors. They are polarized (i.e. they will only work in one direction), so note
the vertical mark that indicates the negative side. The longer leg is positive and fits in the square pad.
PART VALUE
C5 100uF
C6 100uF
C11 100uF
C12 100uF

PENUMBRA BASS FUZZ 15
TRANSFORMER
The transformer is the last of the on-board components. Before installing it to the PCB, scrape off any
wax on the leads. You don’t need to be terribly thorough since it will melt away with the heat of the
soldering iron, but we don’t want the wax getting in the way of a good solder joint.
The primary and secondary coils of the transformer have different properties, so the transformer must
be facing the right direction or it won’t work correctly. In this case, the primary is marked with a “P”
and the top of the nylon bobbin is colored black on that side. The primary side should line up with the
“PRIMARY” label on the silkscreen (in other words, facing toward the top of the PCB).
As with earlier components, first bend the six legs to hold it in place as shown in the diagram below.
Solder the legs and the two outer tabs and then clip them short.
PART VALUE
XFM1 42TL019

PENUMBRA BASS FUZZ 16
FOOTSWITCH PCB
Next, it’s time to finish up the footswitch board. You should have done most of the on-board components
on this board in a previous step, but if not, go back and do those.
There will be one longer assembly with 4 wires and two shorter ones with 3 wires. The longer one goes
in the middle and the shorter ones go on the left and right sides. The wire assemblies should then be
soldered to the footswitch board as shown.
Once all three wire assemblies are soldered, set the footswitch PCB aside. We’ll solder the actual
footswitch and LED in a later step.
PARTS
3-strand wire assembly (2)
4-strand wire assembly
STEP 3
Then, solder the wires from the top.
This is the trickiest part of the whole
build. You want to solder the pads
without touching the iron to the
wires themselves and risking burning
through the insulation. It helps to
use a sharp or narrow tip on the
soldering iron.
STEP 2
Next, bend the wires back upward
and fit the ends of the wires into the
solder pads.
On the top side of the PCB, bend the
exposed wires backward so it holds
the wire in place. Pull the header
back up through the slot partway.
STEP 1
First, thread the wire through the
strain-relief slots, with the blue
side facing outward and the PCB’s
previously-installed components
facing up.
For now, pull it through as far as it
can go.
BLUE
MARKING

PENUMBRA BASS FUZZ 17
INPUT/OUTPUT PCB
Almost done! Get the two input/output jacks, the DC jack and the wire header and snap them in place.
The PCB is designed for them to fit securely, so you can do them all at once before flipping and soldering.
After you’ve soldered everything, make sure to snip the leads on the I/O jacks as close as possible to
the PCB. There’s not a lot of clearance between the bottom of this board and the top of the main PCB
once everything is in place, and you don’t want the pins to short against anything on accident.
Next, we’ll hook up the 9V battery connector. This is optional. Not everyone uses batteries. But, if you
do, this pedal should last a long time on a single 9V so you won’t need to change it very often.
PARTS
Input & output jacks
DC jack
Wire header
9V battery snap
STEP 1
Thread the battery snap leads through the strain-
relief hole twice so it forms a single loop.
STEP 2
Bend the exposed wires back down and solder them
into the pads. Red is positive (+), black is negative (-).
After soldering, pull it tight.
For even more strain relief, you can thread the snap
through the loop to form a knot. (not shown)

PENUMBRA BASS FUZZ 18
ENCLOSURE LAYOUT: PANEL MOUNTS
Attach the hardware to the enclosure as shown. (The I/O board is done in a later step.)
MOUNTING NUT
MOUNTING NUT
DRESS NUT
LOCK WASHER
MOUNTING NUT
LOCK RING
MOUNTING NUT
OUTER WASHER
LOCK WASHER
DUST CAP
FOOTSWITCH
BEZEL & LED
The dress nut fits over the top of the mounting nut and is for aesthetic
purposes only. Wrap a rubber band around it to use as a grip when tightening.
Do not use metal tools on it or you run the risk of scratching or denting it.
You’ll need to hold the bezel in place when
tightening the nut. The top of the bezel is fairly
sharp, so try using a rubber band for grip instead
of pressing your finger against the bottom.
The LED will just
sit loosely inside
the bezel for now.
POTENTIOMETERS
Fuzz: 5kC
Pinch: 500kB
Tone: 10kB
Volume: 10kB
125B
5kC 10kB
FOOTSWITCH
BEZEL
& LED
500kB
DPDT
on-on
10kB
SPDT
on-off-on

PENUMBRA BASS FUZZ 19
ENCLOSURE LAYOUT: PANEL MOUNTS (CONT.)
MOUNTING NUT
MOUNTING NUT
LOCK WASHER
TOGGLE SWITCHES
The dress nut acts as a mounting nut, unlike the footswitch dress nut. Use flat-
nose pliers on the flat sides of the nut to tighten securely.
125B
5kC 10kB
FOOTSWITCH
BEZEL
& LED
DPDT
on-on
10kB
SPDT
on-off-on
500kB

PENUMBRA BASS FUZZ 20
ENCLOSURE LAYOUT: MAIN & FOOTSWITCH PCBS
Why solder everything inside the enclosure before testing it?
“Rock it before you box it” is conventional wisdom in pedalbuilding, and you’ll often hear it
recommended that builders should test the circuit before putting everything inside the enclosure.
However, Aion FX projects are designed to be extremely easy to remove from the enclosure for
troubleshooting, with no desoldering required—so with these kits, it’s actually much easier to “box it
before you rock it”.
If you’ve read the documentation carefully and followed all the instructions, there’s a good chance you
will get it right the first time!
125B
After all the components are affixed to the enclosure as
shown on the previous page, place the main PCB on top of the
potentiometers and toggle switches as in the diagram to the left.
You may need to adjust the position of the potentiometers and
toggle slightly if they are not aligned straight.
Once all of the pins are through their holes and the PCB is laying
flat, solder each of the pins from the top. Be careful not to touch
any of the surrounding components with the soldering iron.
After you’ve finished soldering the pots, clip the leads as close
as you can to the main PCB. This is more important with the
two uppermost pots because the input/output PCB overlaps
them and you need to avoid any of the components shorting.
(The toggle switch lugs do not need to be clipped.)
Next, move to the footswitch board and solder the 3PDT switch.
The LED is last. Before soldering the LED, double-check to make
sure the flat side of the LED is facing to the right, as shown in
the diagram, and that the short leg is coming through the pad on
the right. It won’t work if it’s turned the other way. Then, clip the
leads of the LED.