aion SOMNUS User manual

SOMNUS AMP DISTORTION 1
PROJECT NAME
SOMNUS
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Sobbat Drive Breaker DB-01
A medium-gain distortion & overdrive with a two-band Baxandall tone stack, most notably used by The
Edge during the All That You Can’t Leave Behind recording sessions.
Distortion / overdrive 1.0.0 (2023-03-24)
BUILD DIFFICULTY
Intermediate
Actual size is 2.3” x 2.42” (main board) and 1.78” x 0.86” (bypass board).

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TABLE OF CONTENTS
1Project Overview 8Drill Template
2Introduction & Usage 9Enclosure Layout
3-5 Parts List 10 Wiring Diagram
6Build Notes 11 Licensing
7Schematic 11 Document Revisions
INTRODUCTION
The Somnus Amp Distortion is an adaptation of the Sobbat DB-01 Drive Breaker, a somewhat obscure
pedal from Japan that was originally released in 1995.
It’s perhaps best known for its association with The Edge, who first started using it during the recording
of All That You Can’t Leave Behind where it featured most prominently on the song “New York”. According
to his guitar tech Dallas Schoo, he also used it on the outro solo for “Until the End of the World” during
the Elevation and Vertigo tours, and it has been spotted in the live rig as of the 360 tour.
Sobbat has released three followup versions of the Drive Breaker called the DB-2, DB-3 and DB-4. None
of these have been traced to our knowledge, but they don’t seem to be drastically different from the
original, which is still by far the most famous and is still produced along with its successors.
The Somnus is based on the first version, and is a direct adaptation except for the addition of a clipping
diode switch. The original unit uses one diode in each direction for clipping, but we’ve added options for
two diodes or LEDs.
USAGE
The Somnus has the following controls:
• Drive controls the amount of gain in the op-amp stage that goes into the clipping diodes.
• Treble forms half of the Baxandall tone control and allows adjustment of the treble frequencies.
• Bass forms the other half and allows adjustment of the bass frequencies.
• Volume controls the overall output of the effect.
• Clipping (toggle switch) selects between stock clipping, 2x diodes, or LED clipping.

SOMNUS AMP DISTORTION 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—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 10k Metal film resistor, 1/4W
R2 1M Metal film resistor, 1/4W
R3 100k Metal film resistor, 1/4W
R4 100k Metal film resistor, 1/4W
R5 220k Metal film resistor, 1/4W
R6 47k Metal film resistor, 1/4W
R7 22k Metal film resistor, 1/4W
R8 10k Metal film resistor, 1/4W
R9 22k Metal film resistor, 1/4W
R10 2k2 Metal film resistor, 1/4W
R11 1k Metal film resistor, 1/4W
R12 10k Metal film resistor, 1/4W
R13 10k Metal film resistor, 1/4W
R14 10k Metal film resistor, 1/4W
R15 47k Metal film resistor, 1/4W
R16 1k Metal film resistor, 1/4W
R17 47k Metal film resistor, 1/4W
R18 1k Metal film resistor, 1/4W
R19 100k Metal film resistor, 1/4W
R20 470R Metal film resistor, 1/4W
R21 8k2 Metal film resistor, 1/4W Power supply filter resistor.
R22 10k Metal film resistor, 1/4W Power supply filter resistor.
R23 8k2 Metal film resistor, 1/4W Power supply filter resistor.
R24 10k Metal film resistor, 1/4W Power supply filter resistor.
RPD 2M2 Metal film resistor, 1/4W Input pull-down resistor. Can be as low as 1M.
LEDR 10k Metal film resistor, 1/4W LED current-limiting resistor. Adjust value to change LED brightness.
C1 22n Film capacitor, 7.2 x 2.5mm
C2 1uF Film capacitor, 7.2 x 3.5mm
C3 1uF Film capacitor, 7.2 x 3.5mm
C4 6n8 Film capacitor, 7.2 x 2.5mm
C5 1uF Film capacitor, 7.2 x 3.5mm
C6 68n Film capacitor, 7.2 x 2.5mm

SOMNUS AMP DISTORTION 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C7 1uF Film capacitor, 7.2 x 2.5mm
C8 1uF MLCC capacitor, NP0/C0G
C9 22n MLCC capacitor, NP0/C0G
C10 1uF Film capacitor, 7.2 x 3.5mm
C11 33n Film capacitor, 7.2 x 2.5mm
C12 100n Film capacitor, 7.2 x 2.5mm
C13 1n Film capacitor, 7.2 x 2.5mm
C14 1uF MLCC capacitor, NP0/C0G
C15 47uF Film capacitor, 7.2 x 3.5mm Reference voltage filter capacitor.
C16 47uF Film capacitor, 7.2 x 2.5mm Reference voltage filter capacitor.
C17 100uF Film capacitor, 7.2 x 2.5mm Power supply filter capacitor.
C18 100n Film capacitor, 7.2 x 2.5mm Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 1N914 Fast-switching diode, DO-35
D3 1N914 Fast-switching diode, DO-35
D4 1N914 Fast-switching diode, DO-35
D5 1N914 Fast-switching diode, DO-35
D6 1N914 Fast-switching diode, DO-35
D7 1N914 Fast-switching diode, DO-35
D8 5mm LED LED, 5mm, red diffused
D9 5mm LED LED, 5mm, red diffused
IC1 JRC4558D Operational amplifier, DIP8
IC1-S DIP-8 socket IC socket, DIP-8
IC2 TL072 Operational amplifier, dual, DIP8 IC2 and IC3 are a single TL074 (quad) in the original.
IC2-S DIP-8 socket IC socket, DIP-8
IC3 TL072 Operational amplifier, dual, DIP8 IC2 and IC3 are a single TL074 (quad) in the original.
IC3-S DIP-8 socket IC socket, DIP-8
DRIVE 1MB 16mm right-angle PCB mount pot
BASS 10kA 16mm right-angle PCB mount pot
TREBLE 10kA 16mm right-angle PCB mount pot
LEVEL 10kA 16mm right-angle PCB mount pot
CLIP SPDT on-off-on 16mm right-angle PCB mount pot

SOMNUS AMP DISTORTION 5
PARTS LIST, CONT.
PART VALUE TYPE NOTES
LED 5mm LED, 5mm, red diffused
IN 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X 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.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

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BUILD NOTES
C9 capacitor
There have been two community traces of the Drive Breaker and the schematics differ slightly.
Most notably, one of them shows 68n for C9 while the other shows 22n. This will make a substantial
difference to the tone, so it’s worth digging in to see if we can determine the real value.
We’ve never opened up one to verify, but we elected to go with 22n for two reasons: first, the schematic
that shows 68n has a couple of other minor yet obvious errors, so it seemed more likely that the 68n
value was another mistake; second, there have been community reports from DIYers who built the 22n
version and said that it sounded just like the original to them.
If anyone has an original unit and could confirm the value of C9 in our schematic (the feedback capacitor
of the output stage) then we will update the documentation accordingly.

SCHEMATIC
SOMNUS AMP DISTORTION 7
GND
2M2
1N5817
100uF
1MB
10kA
GND
10kA
10kA
+9V
100n
VA
10k
22n
1M
JRC4558D
GND
VA
VB
VB
8k210k
47uF
GND GND
1uF
100k
GND
1uF
100k
VB
JRC4558D
220k
47k
VB
22k
6n8
GND
1uF
TL072
10k
VB
VA
GND
22k
68n
2k2
VB
1uF
1k
GND
GND
1uF
TL072
22n
10k
10k
1uF
TL072P
33n
47k
1k
TL072P
VA
GND
100n
1n
47k
1k
1uF
100k
GND
470R
GND
8k210k
47uF
VC
GND GND
VC VC
VC
10k
VC
IN
OUT
RPD
D1
C17
1
2
3
DRIVE
BASS
1
2
3
LEVEL
1
2
3
TREBLE
1
2
3
C18
R1
C1
R2
2
3
1
IC1A
84
R21R22
C15
C2
R3
C3
R4
6
5
7
IC1B
R5
R6
R7
C4
C5
2
3
1
IC2A
R8
84
R9
C6
R10
C7
R11
D2
D3
C8
6
5
7
IC2B
C9
R12
R13
C10
2
3
1
IC3A
C11
R15
R16 6
5
7
IC3B
84
C12
C13
R17
R18
C14
R19
R20
D4D5
D6 D7
CLIP
2
3
1
D8
D9
R23R24
C16
R14
GND

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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.
ø3/8” ø1/2”
0.385”
0.625” 0.625”
x: 0, y: -1.775
ø15/32”
x: -0.775, y: -1.775
ø5/16”
ø3/8”
125B
OUT
FOOTSWITCHLED
DC IN
CENTER (0,0)
LEVEL DRIVE
TREBLE BASS
CLIP
x: 0, y: +1.06
ø1/4”
x: -0.65, y: +1.71 x: 0.65, y: +1.71
ø9/32” ø9/32”
x: -0.65, y: +0.41
ø9/32”
x: 0.65, y: +0.41
ø9/32”
0 1 2
CM
0 1
INCH

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

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WIRING DIAGRAM
125B
IN +VGND NC NC OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT

SOMNUS AMP DISTORTION 11
LICENSE & USAGE
No direct support is offered for these projects beyond the provided documentation. It’s assumed
that you have at least some experience building pedals before starting one of these. Replacements and
refunds cannotbe offered unless it can be shown that the circuit or documentation are in error.
All of these circuits have been tested in good faith in their base configurations. However, not all the
modifications or variations have necessarily been tested. These are offered only as suggestions based
on the experience and opinions of others.
Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
“goop” the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but
please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!)
DOCUMENT REVISIONS
1.0.0 (2023-03-24)
Initial release.