aion MAELSTROM User manual

MAELSTROM BASS DRIVE 1
PROJECT NAME
MAELSTROM
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Darkglass®Microtubes®B3K
A CMOS-flavored bass overdrive with tones spanning across decades, from vintage warmth to modern
bite and aggression.
Bass overdrive / distortion 1.0.0 (2022-11-11)
BUILD DIFFICULTY
Intermediate
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
VOLUME
BASS DRIVE
DRIVE
9V
BLEND TONE
LOW
HIGH
MAELSTROM

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

MAELSTROM BASS DRIVE 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!

MAELSTROM BASS DRIVE 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 24.
If you find that any parts are missing or damaged, please fill out the Missing Parts form.
Film Capacitors
NAME QTY
1n 2
2n2 3
4n7 1
22n 6
100n 2
220n 2
1uF 2
Electrolytic Capacitors
NAME QTY
47uF 1
100uF 1
220uF 1
MLCC Capacitors
NAME QTY
22pF (marked “220”) 2
220pF (marked “221”) 1
680pF (marked “681”) 1
100n (marked “104”) 1
Transistors
NAME QTY
J201 with PCB adapter 2
Resistors
NAME QTY
100R 1
1k 1
3k3 2
6k8 2
10k 6
22k 3
33k 1
47k 1
100k 3
200k 1
330k 1
470k 3
1M 7
Diodes
NAME QTY
1N5817 1
1N914 2
ICs
NAME QTY
TL072 3
CD4049UBE 1
8-pin socket 5

MAELSTROM BASS DRIVE 5
PACKING LIST (CONT.)
Potentiometers
NAME QTY
100kA 1
100kB 2
100kC 1
Dust cover 4
Knob 4
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
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 2
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, 122mm 1
3-pin wire assembly header 2
4-pin wire assembly header 1

MAELSTROM BASS DRIVE 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).

MAELSTROM BASS DRIVE 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.)
TRIM POTENTIOMETER
FILM CAPACITOR
SILICON DIODE
ZENER DIODE
LED
DC JACKWIRE ASSEMBLY HEADER
LED BEZEL
WIRE ASSEMBLY
ELECTROLYTIC CAPACITOR
IC OR OP-AMP
TANTALUM CAPACITOR
SCHOTTKY DIODE
IC SOCKET TRANSISTOR WITH ADAPTER
RECTIFIER DIODE
TRANSISTOR OR JFET
Not polarized. Color may
vary by brand and type.
Some Schottky diodes
also look like this.
Polarized. The positive side
is marked.
Polarized. The negative side
is marked.
Some voltage regulators
also look like this.
The pins will be soldered to the
adapter during kit assembly.
Charge pumps and delay chips
also look like this. They may
have more than 8 legs.
RESISTOR
GERMANIUM DIODE
MLCC
Not polarized. MLCC stands for
“multi-layer ceramic capacitor.”
These are very fragile, so be
careful when handling them.

MAELSTROM BASS DRIVE 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

MAELSTROM BASS DRIVE 9
PCB ASEEMBLY 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. IC sockets
4. MLCC capacitors
5. Film capacitors
6. Transistors
7. Electrolytic capacitors
Not all of these component types are included in each
kit, so skip them if they aren’t applicable. Some types
of film capacitors are taller than electrolytics, so
those can be done last.

MAELSTROM BASS DRIVE 10
RESISTORS
PART VALUE
R1 10k
R2 1M
R3 100k
R4 1M
R5 3k3
R6 1M
R7 1M
R8 200k
PART VALUE
R9 6k8
R10 22k
R11 470k
R12 470k
R13 1M
R14 330k
R15 3k3
R16 6k8
PART VALUE
R17 470k
R18 10k
R19 1M
R20 100k
R21 33k
R22 10k
R23 22k
R24 22k
PART VALUE
R25 47k
R26 1k
R27 100k
R28 10k
R29 10k
R30 100R
RPD 1M
LEDR 10k
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.
Don’t try to do all of the resistors at once. You’ll want to stop periodically flip the board and solder
everything, then cut the leads using the wire snippers to make room for more.

MAELSTROM BASS DRIVE 11
DIODES
PART VALUE
D1 1N5817
D2 1N914
D3 1N914
Next, you’ll populate the diodes. Diodes are polarized, so make sure to identify the polarity band (which
indicates the “cathode”, or negative side) and match the band to the footprint on the PCB.

MAELSTROM BASS DRIVE 12
SOCKET & IC
Next up are the sockets. You can’t bend the leads of
the socket as with the other components, so it won’t
stay in on their own until they are soldered. Flip the
PCB over and use gravity to hold it in place.
Note that IC3 has 16 pins, but this kit uses two 8-pin
sockets installed as shown in the diagram to the right.
There will be five 8-pin sockets in total.
Installing the ICs
Don’t insert the ICs into the sockets just yet. We will
do this in a later step, after we’ve finished soldering
the tallest components (the polarized capacitors).
This information is just listed here for reference.
The legs of the ICs are bent outward slightly during manufacturing, so they’ll need to be bent back
inward before they can be inserted into the sockets. It’s easiest to do this by laying the IC legs against
the table and bending the body itself so all four legs on the side are straightened out at once. Then, flip it
and do the other side.
ICs may have two different orientation marks: either a dot in the upper-left or a half-circle notch in the
middle of the top side. Some ICs have both marks. This shows which way the IC should be rotated when
inserting it into a socket (the socket also has a half-circle notch).
PART VALUE
IC1 TL072
IC2 TL072
IC3 CD4049UBE
IC4 TL072

MAELSTROM BASS DRIVE 13
TRANSISTORS
PART VALUE
Q1 J201
Q2 J201
Now we’ll do the two JFET transistors. The PCB outline shows through-hole TO-92 outlines, but the
through-hole J201 has been discontinued for many years and most of what is available today is either
fake or outside the ideal specification.
We use current-production surface-mount JFETs which perform identically to those used in the original
B3K pedal. These are mounted to adapter boards so they can be used in through-hole designs such as
this one. However, this does require some extra work since the legs must be soldered to the adapter.
Once the pins are installed, the JFETs can be soldered to the PCB like any other normal component.
Be very careful to line up the D-S-G labels with the markings on the PCB or the effect will not work.
The component side of the PCB adapter should face upwards toward the toggle switches.
STEP 4
Solder the pins (including the
reverse side, if needed). Then,
using wire cutters, clip the
bottom strip from the pins.
STEP 3
Clip the pins to the adapter,
making sure they’re centered
on the pads and pushed up all
the way.
STEP 2
Using wire cutters, cut the pin
strip into two sets of three.
Separate the top panel from the
pin strip by bending it back.
STEP 1
Break apart the adapter PCBs
(you can just use your fingers
for this) and then use pliers to
snap off the tabs.

MAELSTROM BASS DRIVE 14
CAPACITORS (NON-POLARIZED)
After the sockets 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, so they will work in any direction, but to keep things neat,
it’s best to put them all facing the same way.
Note: C2, C11, and C18-21 are usually blue box-film capacitors. For these, the value is printed on the
top rather than the side.
C8, C10, C14, and C16 are blue MLCCs taped to cardboard. The value is written on the cardboard.
C26 (100n MLCC) is always yellow. It can be hard to read the code since it’s so small, so it’s easier to
identify this one by color.
PART VALUE
C1 100n film
C2 1n film
C3 220n film
C4 22n film
C5 22n film
C6 22n film
PART VALUE
C7 22n film
C8 220pF MLCC
C9 100n film
C10 22pF MLCC
C11 4n7 film
C12 22n film
PART VALUE
C13 220n film
C14 22pF MLCC
C15 1uF film
C16 680pF MLCC
C17 22n film
C18 2n2 film
PART VALUE
C19 2n2 film
C20 2n2 film
C21 1n film
C22 1uF film
C26 100n MLCC

MAELSTROM BASS DRIVE 15
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.

MAELSTROM BASS DRIVE 16
CAPACITORS (POLARIZED)
Populate the electrolytic capacitors. These are the tallest components, so we save them for last. 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.
These are the last of the on-board components. Now is the time to go back to page 12 and insert the ICs
into the sockets.
PART VALUE
C23 100uF electro
C24 47uF electro
C25 220uF electro

MAELSTROM BASS DRIVE 17
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

MAELSTROM BASS DRIVE 18
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.
PARTS
Input & output jacks
DC jack
Wire header

MAELSTROM BASS DRIVE 19
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. Be aware that the bezel is fairly
sharp. Try using a rubber band for grip instead of
just pressing your finger against the bottom.
The LED will just
sit loosely inside
the bezel for now.
POTENTIOMETERS
Drive: 100kC
Era: 100kB
Blend: 100kB
Volume: 100kA
Era is labeled “Tone” on the
enclosure.
125B
100kC 100kA
FOOTSWITCH
BEZEL
& LED
SPDT
on-off-on
SPDT
on-off-on
100kB 100kB

MAELSTROM BASS DRIVE 20
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
100kC 100kA
FOOTSWITCH
BEZEL
& LED
SPDT
on-off-on
SPDT
on-off-on
100kB 100kB