Akashic Guitar effects PCB lookup
DRIVE 1DRIVE 2PRESENCEOUTPUT

125B · 4 knobs

Aion FX

HeliosphereDual Distortion

Based on the Stamps Drive-O-Matic

Category
Distortion· Dual-channel distortion
Controls
Drive 1 · Drive 2 · Presence · Output
Difficulty
Intermediate
Price
$12.50in stock

From the vendor

A boutique two-channel drive based on the RAT Distortion, with selectable gain presets and a diode-clipping switch.

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.

Schematic

The schematic is in the vendor's build document, page 7. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 49 rows

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RefValueNormalizedTypeNotes
Resistors 14
R12M22.2MMetal film resistor, 1/4W1M in original RAT.
R21k1kMetal film resistor, 1/4W
R3680R680Metal film resistor, 1/4W560R in original RAT.
R4100R100Metal film resistor, 1/4W47R in original RAT.
R5100R100Metal film resistor, 1/4W47R in original RAT.
R61k1kMetal film resistor, 1/4W
R71k51.5kMetal film resistor, 1/4W
R81M1MMetal film resistor, 1/4W
R910k10kMetal film resistor, 1/4W
R10100k100kMetal film resistor, 1/4W
R11100k100kMetal film resistor, 1/4W
R12100R100Metal film resistor, 1/4WPower supply filter resistor.
RPD2M22.2MMetal film resistor, 1/4WInput pulldown resistor. Can be as low as 1M.
LEDR10k10kMetal film resistor, 1/4WBypass LED resistor. Adjust value to change LED brightness.
Capacitors 12
C122n22nFilm capacitor, 7.2 x 2.5mm
C210n10nFilm capacitor, 7.2 x 2.5mmRecommend substituting 100pF MLCC. See build notes.
C44.7uF4.7uElectrolytic capacitor, 4mm
C52.2uF2.2uElectrolytic capacitor, 4mm
C622uF22uElectrolytic capacitor, 5mm
C74.7uF4.7uElectrolytic capacitor, 4mm
C822n22nFilm capacitor, 7.2 x 2.5mm
C93n33.3nFilm capacitor, 7.2 x 2.5mm
C1010n10nFilm capacitor, 7.2 x 2.5mm1uF in original RAT.
C1147uF47uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C12100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C13100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 3
D11N58171N5817Schottky diode, DO-41
D41N9141N914Fast-switching diode, DO-35
D51N9141N914Fast-switching diode, DO-35
Transistors 1
Q12N54572N5457JFET, N-channel, TO-922N5458 in original circuit. Any general-purpose JFET will work here.
ICs 1
IC1OP07OP07Operational amplifier, single, DIP8Original uses LM308. See build notes.
Potentiometers 3
DRIVE_150kAA50k16mm right-angle PCB mount potAudio (log) taper. 100kA in original RAT.
DRIVE_250kAA50k16mm right-angle PCB mount potAudio (log) taper. 100kA in original RAT.
OUTPUT100kAA100k16mm right-angle PCB mount potAudio (log) taper.
Switches 3
CLIPSPDT cntr. offSPDT CNTR. OFFToggle switch, SPDT on-off-on
BYPASS3PDT3PDTStomp switch, 3PDT
CHANNEL 3PDTStomp switch, 3PDTSTOMP SWITCH, 3PDT
LEDs 7
LED110k10KMetal film resistor, 1/4WChannel 1 LED resistor. Adjust value to change LED brightness.
LED210k10KMetal film resistor, 1/4WChannel 2 LED resistor. Adjust value to change LED brightness.
D23mm red LED3MM RED LEDLED, 3mm, red diffusedSee build notes about a labeling mistake on the PCB for D2.
D33mm red LED3MM RED LEDLED, 3mm, red diffused
CH. 1 LED3mm red LED3MM RED LEDLED, 3mm, red diffused
CH. 2 LED3mm red LED3MM RED LEDLED, 3mm, red diffused
BYP. LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 4
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountMouser 163-4302-E or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.