125B · 4 knobs
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
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 14 | ||||
| R1 | 2M2 | 2.2M | Metal film resistor, 1/4W | 1M in original RAT. |
| R2 | 1k | 1k | Metal film resistor, 1/4W | |
| R3 | 680R | 680 | Metal film resistor, 1/4W | 560R in original RAT. |
| R4 | 100R | 100 | Metal film resistor, 1/4W | 47R in original RAT. |
| R5 | 100R | 100 | Metal film resistor, 1/4W | 47R in original RAT. |
| R6 | 1k | 1k | Metal film resistor, 1/4W | |
| R7 | 1k5 | 1.5k | Metal film resistor, 1/4W | |
| R8 | 1M | 1M | Metal film resistor, 1/4W | |
| R9 | 10k | 10k | Metal film resistor, 1/4W | |
| R10 | 100k | 100k | Metal film resistor, 1/4W | |
| R11 | 100k | 100k | Metal film resistor, 1/4W | |
| R12 | 100R | 100 | Metal film resistor, 1/4W | Power supply filter resistor. |
| RPD | 2M2 | 2.2M | Metal film resistor, 1/4W | Input pulldown resistor. Can be as low as 1M. |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | Bypass LED resistor. Adjust value to change LED brightness. |
| Capacitors 12 | ||||
| C1 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 10n | 10n | Film capacitor, 7.2 x 2.5mm | Recommend substituting 100pF MLCC. See build notes. |
| C4 | 4.7uF | 4.7u | Electrolytic capacitor, 4mm | |
| C5 | 2.2uF | 2.2u | Electrolytic capacitor, 4mm | |
| C6 | 22uF | 22u | Electrolytic capacitor, 5mm | |
| C7 | 4.7uF | 4.7u | Electrolytic capacitor, 4mm | |
| C8 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C9 | 3n3 | 3.3n | Film capacitor, 7.2 x 2.5mm | |
| C10 | 10n | 10n | Film capacitor, 7.2 x 2.5mm | 1uF in original RAT. |
| C11 | 47uF | 47u | Electrolytic capacitor, 5mm | Reference voltage filter capacitor. |
| C12 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C13 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 3 | ||||
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D4 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D5 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| Transistors 1 | ||||
| Q1 | 2N5457 | 2N5457 | JFET, N-channel, TO-92 | 2N5458 in original circuit. Any general-purpose JFET will work here. |
| ICs 1 | ||||
| IC1 | OP07 | OP07 | Operational amplifier, single, DIP8 | Original uses LM308. See build notes. |
| Potentiometers 3 | ||||
| DRIVE_1 | 50kA | A50k | 16mm right-angle PCB mount pot | Audio (log) taper. 100kA in original RAT. |
| DRIVE_2 | 50kA | A50k | 16mm right-angle PCB mount pot | Audio (log) taper. 100kA in original RAT. |
| OUTPUT | 100kA | A100k | 16mm right-angle PCB mount pot | Audio (log) taper. |
| Switches 3 | ||||
| CLIP | SPDT cntr. off | SPDT CNTR. OFF | Toggle switch, SPDT on-off-on | |
| BYPASS | 3PDT | 3PDT | Stomp switch, 3PDT | |
| CHANNEL 3PDT | Stomp switch, 3PDT | STOMP SWITCH, 3PDT | ||
| LEDs 7 | ||||
| LED1 | 10k | 10K | Metal film resistor, 1/4W | Channel 1 LED resistor. Adjust value to change LED brightness. |
| LED2 | 10k | 10K | Metal film resistor, 1/4W | Channel 2 LED resistor. Adjust value to change LED brightness. |
| D2 | 3mm red LED | 3MM RED LED | LED, 3mm, red diffused | See build notes about a labeling mistake on the PCB for D2. |
| D3 | 3mm red LED | 3MM RED LED | LED, 3mm, red diffused | |
| CH. 1 LED | 3mm red LED | 3MM RED LED | LED, 3mm, red diffused | |
| CH. 2 LED | 3mm red LED | 3MM RED LED | LED, 3mm, red diffused | |
| BYP. LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 4 | ||||
| IC1-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IN | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| OUT | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| DC | 2.1mm | 2.1MM | DC jack, 2.1mm panel mount | Mouser 163-4302-E or equivalent. |
| Hardware 1 | ||||
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |