aion theseus User manual

THESEUS DUAL OVERDRIVE 1
PROJECT NAME
THESEUS
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Analogman King of Tone
One of the earliest boutique “waitlist” pedals, this dual-channel drive is made up of two modified
Marshall Bluesbreaker circuits in series.
Dual-channel overdrive 1.0.0 (2023-02-02)
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

THESEUS DUAL OVERDRIVE 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 Trimmers
14 DIP Switches
15 Capacitors (Non-Polarized)
16 Wire Headers
17 Capacitors (Polarized)
18 Footswitch PCB
19 Input/Output PCB
20 Enclosure Layout: Potentiometers
21 Enclosure Layout: LED Bezels
22 Enclosure Layout: LEDs
23 Enclosure Layout: Footswitches
24 Enclosure Layout: Main & Footswitch PCBs
25 Enclosure Layout: Input/Output PCB
26 Enclosure Layout: Finished Diagram
27 Final Testing & Assembly
28 Schematic
29 Full Parts List
30 Troubleshooting Information
31 Support & Resale Terms
32 Legal Information & Document Revisions

THESEUS DUAL OVERDRIVE 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!

THESEUS DUAL OVERDRIVE 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 29.
If you find that any parts are missing or damaged, please fill out the Missing Parts form.
Film Capacitors
NAME QTY
10n 8
22n 2
100n 2
1uF 2
Electrolytic Capacitors
NAME QTY
1uF 2
100uF 4
MLCC Capacitors
NAME QTY
100pF (marked “101”) 2
100n (marked “104”) 1
ICs
NAME QTY
JRC4580D 2
8-pin socket 2
Other
NAME QTY
Trimmer, 50k 2
DIP switch, 3-pos. 2
Resistors
NAME QTY
47R 2
1k 4
6k8 4
10k 2
22k 2
27k 2
33k 2
47k 4
100k 2
220k 2
1M 6
Diodes
NAME QTY
1N5817 1
1N914 4
BAS33 8

THESEUS DUAL OVERDRIVE 5
PACKING LIST (CONT.)
Potentiometers
NAME QTY
25kB 2
100kA 2
100kB 2
Dust cover 6
Knob 6
Mounting nut, potentiometer, 0.44" 6
Lock washer, potentiometer, 0.5" 6
Outer washer, potentiometer, 0.475" 6
Other
NAME QTY
LED bezel 2
LED, blue 1
LED, red 1
DC jack 1
Input/output jack 2
Mounting nut, I/O jack, 0.54" 4
Outer washer, I/O jack, 0.6" 2
Lock washer, I/O jack, 0.5" (thin) 2
Send/return jack, Neutrik NMJ6 2
Insulation washer, Neutrik NMJ6 2
Ferrule, chrome, Neutrik NMJ6 2
Enclosure 1
Enclosure screws 4
PCB, main circuit 1
PCB, footswitch 1
PCB, input/output/DC 1
Switches
NAME QTY
Stomp switch, 3PDT 2
Mounting nut, stomp switch, 0.6" 4
Lock washer, stomp switch, 0.6" 2
Dress nut, stomp switch, 0.77" 2
Wiring
NAME QTY
4-strand wire assembly, 60mm 2
6-strand wire assembly, 96mm 1
4-pin wire assembly header 2
6-pin wire assembly header 1

THESEUS DUAL OVERDRIVE 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).

THESEUS DUAL OVERDRIVE 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
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.
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.
DIP SWITCH
The number of switch
positions may vary.
ON
1 2
DIP
3

THESEUS DUAL OVERDRIVE 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
SEND/RETURN JACK
POTENTIOMETER
(SINGLE)
FOOTSWITCH
POTENTIOMETER
(DUAL)
MOUNTING NUT
MOUNTING NUT
CHROME FERRULE
MOUNTING NUT
DRESS NUT
OUTER WASHER
INSULATING WASHER
OUTER WASHER KNOB
LOCK WASHER
LOCK WASHER
LOCK WASHER
DIAMETER: 0.54” / 13.7mm
DIAMETER: 0.44” / 11.2mm DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.6” / 15.2mm
DIAMETER: 0.475” / 12mm
DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.63” / 16mmDIAMETER: 0.77” / 19.6mmDIAMETER: 0.63” / 16mm

THESEUS DUAL OVERDRIVE 9
PCB ASSEMBLY OVERVIEW
To begin, snap apart the main PCB and footswitch board and break off the tabs from each using needle-
nose or flat-head pliers. You’ll be left with the three PCBs shown above.
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, we want to populate them in this order:
1. Resistors & diodes
2. IC sockets & DIP switches
3. MLCC capacitors
4. Film capacitors
5. Electrolytic capacitors

THESEUS DUAL OVERDRIVE 10
RESISTORS
PART VALUE
R1 1M
R2 100k
R3 1k
R4 27k
R5 33k
R6 10k
R7 220k
R8 6k8
PART VALUE
R9 1k
R10 6k8
R11 1M
R12 47k
R13 47k
R14 1M
R15 100k
R16 1k
PART VALUE
R17 27k
R18 33k
R19 10k
R20 220k
R21 6k8
R22 1k
R23 6k8
R24 1M
PART VALUE
R25 47k
R26 47k
R27 47R
R28 47R
R29 22k
R30 22k
RPD1 1M
RPD2 1M
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.

THESEUS DUAL OVERDRIVE 11
DIODES
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.
The BAS33 and 1N914 diodes are very similar in appearance. The names are printed on the side, but
if they’re too hard to read, the easiest way of telling them apart is that the glass case of the BAS33 is a
little longer.
PART VALUE
D1 1N5817
D2 BAS33
D3 BAS33
D4 BAS33
PART VALUE
D5 BAS33
D6 1N914
D7 1N914
PART VALUE
D8 BAS33
D9 BAS33
D10 BAS33
PART VALUE
D11 BAS33
D12 1N914
D13 1N914

THESEUS DUAL OVERDRIVE 12
SOCKETS & ICS
Next up are the sockets. You can’t bend the leads of the socket as with the other components, so they
won’t stay in on their own until they’re soldered. Flip the PCB over and use gravity to hold them in place.
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 JRC4580D
IC2 JRC4580D

THESEUS DUAL OVERDRIVE 13
TRIMMERS
Next up are the trimmers. The legs on these can be bent like normal components to hold them in place
while soldering.
Using the trimmers
The original Bluesbreaker circuit has a fixed 2.3kHz treble cut immediately after the tone control. In the
King of Tone, each channel’s Presence trimmer essentially fades this hi-cut capacitor out of the circuit,
reducing the impact of the treble cut as you turn it up. This can also increase the amount of noise or hiss.
The default position is full counter-clockwise for both, which is equivalent to the stock Bluesbreaker.
PART VALUE
PRESENCE A 50k trimmer
PRESENCE B 50k trimmer

THESEUS DUAL OVERDRIVE 14
DIP SWITCHES
Now we’ll do the DIP switches. These are very slightly taller than the IC sockets, so they should be done
after the sockets are soldered, but the process is the same. The legs aren’t long enough to be bent, so
just turn the PCB upside down and let it hold the DIP switch in place while you solder.
Make sure the “ON” text faces up, toward the top of the PCB. If it’s installed backwards, it will still work,
but the switch positions will be inverted compared to the labels on the PCB.
Using the DIP switches
The DIP switch modes modes are labeled on the PCB silkscreen. The available modes are identical
between the two channels. To engage each mode, move the switch toward the dot. If the switch is moved
away from the dot, the mode is disengaged.
The description of each switch mode are as follows.
Hi Gain: This shifts the gain range of the drive knob. The default position is OFF. It’s equivalent to the
Hi Gain mode in the original King of Tone, but instead of being hardwired by customer request, it’s
selectable per channel.
Soft Clip: When engaged, the soft-clipping diodes are active. The default position is ON.
Hard Clip: When engaged, the hard-clipping diodes are active. The default position is OFF.
Note that the hard-clipping diodes essentially override the soft-clipping diodes since they clip at a lower
signal level. If hard-clipping mode is active, you’ll notice little or no change in sound when engaging or
disengaging soft-clipping mode.
Disengage both “Soft Clip” and “Hard Clip” for boost mode. It’s not a perfectly clean boost, and the op-
amp itself will eventually clip at higher gain settings, but it’s much cleaner than the stock mode.
PART VALUE
SW1 3-position DIP switch
SW2 3-position DIP switch

THESEUS DUAL OVERDRIVE 15
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: The red box-film capacitors have the value printed on the side, while the blue box-film capacitors
have the value printed on the top.
C2 and C12 (100pF MLCCs) are always blue and typically come taped to cardboard. C23 (100n MLCC)
is always yellow. They can be identified by color since these are the only two values of MLCC.
PART VALUE
C1 22n film
C2 100pF MLCC
C3 10n film
C4 10n film
C5 100n film
C6 10n film
PART VALUE
C7 10n film
C8 1uF film
C11 22n film
C12 100pF MLCC
C13 10n film
C14 10n film
PART VALUE
C15 100n film
C16 10n film
C17 10n film
C18 1uF film
C23 100n MLCC

THESEUS DUAL OVERDRIVE 16
WIRE HEADERS
Install the two 4-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 6-pin header on the I/O board that we will do in a later step.

THESEUS DUAL OVERDRIVE 17
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
C9 1uF electro
C10 100uF electro
C19 1uF electro
PART VALUE
C20 100uF electro
C21 100uF electro
C22 100uF electro

THESEUS DUAL OVERDRIVE 18
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 6 wires and two shorter ones with 4 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
footswitches and LEDs in a later step.
PARTS
4-strand wire
assembly (2)
6-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 down through the
slot as far as it can go.
BLUE
MARKING

THESEUS DUAL OVERDRIVE 19
INPUT/OUTPUT PCB
Next comes the input/output PCB. Find 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.
Solder each jack, taking care to make them as straight as possible relative to the white outline on the
PCB. It’s recommended to just solder one of the six pins at first, then check it. If it’s out of alignment, the
joint can be reheated to allow the jack to be adjusted. Once the next pin is soldered, it will stay aligned.
After you’ve soldered these, make sure to snip the leads on the jacks as close as possible to the PCB,
particularly the outer input & output jacks. 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 do the send and return jacks, which are shorter and wider than the input/output jacks. These
typically come in individual bags. Open the bags and set aside the included hardware for now.
This type of jack does not snap in like the other components, so you’ll have to set them in the holes and
then flip the board upside down while holding them in place. Ensure the jack is facing forward, the same
way as the input & output jacks, because it will fit in the holes either way.
PARTS
Input & output jacks
Send & return jacks
DC jack
Wire header

THESEUS DUAL OVERDRIVE 20
100kA
25kB 25kB
100kB 100kB 100kA
POTENTIOMETERS
Drive A: 100kB
Tone A: 25kB
Volume A: 100kA
Drive B: 100kB
Tone B: 25kB
Volume B: 100kA
ENCLOSURE LAYOUT: POTENTIOMETERS
Attach the potentiometers to the enclosure as shown. Make sure they’re aligned as straight as possible,
then tighten the outer nut firmly. It can be helpful to use a second set of pliers to hold the potentiometer
in place from the inside while tightening the nut from the outside.
MOUNTING NUT
OUTER WASHER
LOCK WASHER
DUST CAP