aion Heliosphere User manual

HELIOSPHERE DUAL DISTORTION 1
PROJECT NAME
HELIOSPHERE
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Stamps Drive-O-Matic
A boutique two-channel drive based on the RAT Distortion, with selectable gain presets and a diode-
clipping switch.
Dual-channel distortion 1.0.0 (2023-11-24)
BUILD DIFFICULTY
Intermediate
Actual size is 2.3” x 2.14” (main board) and 2.3” x 1.05” (bypass board).

HELIOSPHERE DUAL DISTORTION 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 Heliosphere Dual Distortion is based on the Stamps Amplification Drive-O-Matic, a very rare
distortion pedal built by Robert Stamps of The Amp Shop in Los Angeles in the mid-1990s long before
boutique pedals were mainstream. Despite the relative obscurity, the Drive-O-Matic was used by a few
professional musicians such as Bonnie Raitt and Rick Vito. It was traced by Aion FX in 2023.
The Drive-O-Matic is clearly derived from the RAT Distortion, with a nearly identical circuit topology
but several part value changes for a different voicing. The major feature addition is the channel-
switching, in which a second footswitch engages an alternate drive knob and also switches out a filter
that changes the tone somewhat.
Robert Stamps only made one other pedal under the Stamps Amplification name, a higher-gain variant
called the Drive-O-Matic XL. This version removes the diode switch in favor of an added “Saturation”
control (which may control the diodes directly), and presumably has some circuit tweaks to increase the
gain based on the description. The Drive-O-Matic XL is extremely rare and has not yet been traced, but
if we ever come across one then we’ll open it up and see what’s different about it.
The Heliosphere is an exact clone of the Drive-O-Matic based on our trace. Full details are available in
the tracing journal. We do recommend some small changes to the base circuit to make it more versatile,
which are described in the build notes.
USAGE
The Heliosphere has four knobs, one toggle and one extra stomp switch:
• Drive 1 sets the gain of the first channel.
• Drive 2 sets the gain of the second channel.
• Presence cuts treble after the clipping stage.
• Output sets the overall volume level of the output.
• Clipping (toggle) selects between silicon diodes, LEDs, or no clipping.
• Channel (stomp switch) selects between Drive 1 and Drive 2 settings. An LED shows which knob is
active.

HELIOSPHERE DUAL 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 2M2 Metal film resistor, 1/4W 1M in original RAT.
R2 1k Metal film resistor, 1/4W
R3 680R Metal film resistor, 1/4W 560R in original RAT.
R4 100R Metal film resistor, 1/4W 47R in original RAT.
R5 100R Metal film resistor, 1/4W 47R in original RAT.
R6 1k Metal film resistor, 1/4W
R7 1k5 Metal film resistor, 1/4W
R8 1M Metal film resistor, 1/4W
R9 10k Metal film resistor, 1/4W
R10 100k Metal film resistor, 1/4W
R11 100k Metal film resistor, 1/4W
R12 100R Metal film resistor, 1/4W Power supply filter resistor.
RPD 2M2 Metal film resistor, 1/4W Input pulldown resistor. Can be as low as 1M.
LED1 10k Metal film resistor, 1/4W Channel 1 LED resistor. Adjust value to change LED brightness.
LED2 10k Metal film resistor, 1/4W Channel 2 LED resistor. Adjust value to change LED brightness.
LEDR 10k Metal film resistor, 1/4W Bypass LED resistor. Adjust value to change LED brightness.
C1 22n Film capacitor, 7.2 x 2.5mm
C2 10n Film capacitor, 7.2 x 2.5mm Recommend substituting 100pF MLCC. See build notes.
C3 OMIT Use 27pF or 33pF if using LM308N for IC1.
C4 4.7uF Electrolytic capacitor, 4mm
C5 2.2uF Electrolytic capacitor, 4mm
C6 22uF Electrolytic capacitor, 5mm
C7 4.7uF Electrolytic capacitor, 4mm
C8 22n Film capacitor, 7.2 x 2.5mm
C9 3n3 Film capacitor, 7.2 x 2.5mm
C10 10n Film capacitor, 7.2 x 2.5mm 1uF in original RAT.
C11 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C12 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C13 100n MLCC capacitor, X7R Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 3mm red LED LED, 3mm, red diffused
D3 3mm red LED LED, 3mm, red diffused

HELIOSPHERE DUAL DISTORTION 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
D4 1N914 Fast-switching diode, DO-35
D5 1N914 Fast-switching diode, DO-35
Q1 2N5457 JFET, N-channel, TO-92 2N5458 in original circuit. Any general-purpose JFET will work here.
IC1 OP07 Operational amplifier, single, DIP8 Original uses LM308. See build notes.
IC1-S DIP-8 socket IC socket, DIP-8
DRIVE_1 50kA 16mm right-angle PCB mount pot Audio (log) taper. 100kA in original RAT.
DRIVE_2 50kA 16mm right-angle PCB mount pot Audio (log) taper. 100kA in original RAT.
PRESENCE 100kA 16mm right-angle PCB mount pot Audio (log) taper.
OUTPUT 100kA 16mm right-angle PCB mount pot Audio (log) taper.
CLIP SPDT cntr. off Toggle switch, SPDT on-off-on
CH. 1 LED 3mm red LED LED, 3mm, red diffused
CH. 2 LED 3mm red LED LED, 3mm, red diffused
BYP. 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.
BYPASS 3PDT Stomp switch, 3PDT
CHANNEL 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

HELIOSPHERE DUAL DISTORTION 5
BUILD NOTES
C2 capacitor
In the stock circuit, at higher gain settings, the tone control must be at absolute maximum otherwise the
treble is overly muffled. This is entirely caused by the 10n feedback capacitor which cuts a significant
amount of treble in the first gain stage, with a corner frequency of 318 Hz (!) at max gain. Compare this
to the RAT whose feedback capacitor is 100pF in this position, filtering above 31.8kHz at max gain.
We strongly recommend changing the C2 capacitor to 100pF, which solves this problem entirely and
turns the circuit into a really interesting lower-gain RAT.
RAT modifications
The Drive-O-Matic is essentially a modded RAT, so if you want your build to be a little closer to the
source circuit, you can make any or all of the following changes. Even if you revert back to a standard
RAT, it’s still well worth building due to the footswitchable drive channels.
• C2: 10n →100pF (restores the treble frequencies)
• C10: 10n →1uF (increases bass at output)
• R1: 2M2 →1M (reduces input impedance for lower op-amp noise)
• R3: 680R →560R (increases gain of both channels)
• R4: 100R →47R (increases gain of channel 1)
• R5: 100R →47R (increases gain of channel 2)
• DRIVE 1: 50kA →100kA (increases gain of channel 1)
• DRIVE 2: 50kA →100kA (increases gain of channel 2)
LM308 and OP07
Like the original RAT, the Stamps Drive-O-Matic used the LM308, an early op-amp with a very low slew
rate compared to modern alternatives. The slew rate is critical to the unique sound of the RAT.
In the mid-1990s, the LM308 supply began to dry up, so after some research & experimentation, Pro Co
changed over to the OP07 for their production RATs. Despite insistence from gear enthusiasts that the
LM308 sounds better and the OP07 is inferior, it’s been shown on more than one occasion (both by the
DIY community and more thoroughly by JHS) that the OP07 performs and sounds identical when used
in the same circuit with the same settings.
Because of this, we have specified the OP07 for this build and recommend it over the LM308.
The LM308 has been obsolete for a long time, and most of what’s available today on eBay and
component distributors in Asia are relabeled fakes, so it’s not recommended to risk using one. Let the
article from JHS convince you the LM308 is not special, and use the OP07 with a clear conscience!
C3 compensation capacitor
The OP07 op-amp has an internal slew-rate compensation capacitor while the LM308 does not. C3
(27pF) should be omitted when using the OP07, but it’s required for the LM308 to work properly.

SCHEMATIC
HELIOSPHERE DUAL DISTORTION 6
2M2
1N5817
100uF
50kA
50kA
GND
100kA
100kA
+9V
100n
VA
22n
2M2
VB
1k
LM308N
VA
GND
10n
27pF
100R
680R
4.7uF
GND
100R 100R
2.2uF 22uF
GND GND
1k
4.7uF
1N914
1k5
3n3
1M
2N5458
10k
VA
GND
GND
10n
GND
100k
100k
47uF
GND GND
5MM 5MM
10k 10k
VB +9V
GND
GND
GND
22n
GND
IN
1 2
OUT
RPD
D1
C12
1
2
3
DRIVE 1
1
2
3
DRIVE 2
PRESENCE
1
2
3
OUTPUT
1
2
3
C13
C1
R1
R2 5
1
2
3
6
8
74
IC1
C2
C3
R12
R3
C4
R4 R5
C5 C6
R6
C7
D2
D3 2
3 1
CLIP
D4
D5
R7
C9
R8
Q1
R9
C10
R10
R11
C11
B2
B3
B1 1
2
CH
CH.
CH.
ANNEL B
CHANNEL C
C2
C3
C1
CHANNEL A
A2
A3
A1
CH.1
CH.2
LED1 LED2
C8
GND
C2: 10n → 100pF
C10: 10n → 1uF
R1: 2M2 → 1M
R3: 680R → 560R
R4: 100R → 47R
R5: 100R → 47R
DRIVE 1: 50kA → 100kA
DRIVE 2: 50kA → 100kA
RAT modifications:

HELIOSPHERE DUAL DISTORTION 7
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 sizes assume plain LEDs with no bezel. For the 5mm LED, a 5mm or 13/64” bit is
recommended. 7/32” will work if it’s all you have, but there will be some extra space around the LED.
A 5mm LED bezel will also fit for the bypass LED if you prefer, in which case use a 5/16” drill bit.
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
125B
OUTPUT
DRIVE 1
DRIVE 1 LED DRIVE 2 LED
DRIVE 2
PRESENCE
CLIP
BYP. LED
CHANNEL BYPASS
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”
x: -0.765, y: -1.675
ø15/32”
x: -0.765, y: -1.675
ø15/32”
x: -0.65, y: -0.44
ø1/8”
x: +0.65, y: -0.44
ø1/8”
x: +0.95, y: -1.10
ø5mm”
CENTER (0,0)
x: 0, y: +1.06
ø1/4”
0 1 2
CM
0 1
INCH

HELIOSPHERE DUAL DISTORTION 8
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

HELIOSPHERE DUAL DISTORTION 9
WIRING DIAGRAM
125B
IN +VGND L2 L1 2
PCB
IN
GND +V +V JACK GND JACK
OUTIN
L2 L1 2 CH. 1
OUT
PCB
OUT
CH. 1

HELIOSPHERE DUAL DISTORTION 10
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 (2023-11-24)
Initial release.