125B · 3 knobs
DracoAmp Distortion
Based on the Dr. Boogey
- Category
- Distortion· Amp emulation / distortion
- Controls
- Gain · Presence · Volume
- Difficulty
- Intermediate
- Price
- $12.50in stock
From the vendor
A JFET conversion of the Mesa/Boogie Dual Rectifier Solo Head that originated in the DIY community and has become a classic high-gain distortion effect.
The Draco Amp Distortion is based on the Dr. Boogey, which first appeared on the DIYStompboxes forum on January 17, 2005 as an original design by user “electrictabs”.
It uses the basic Fetzer Valve technique pioneered by Runoffgroove to convert the Mega/Boogie Dual Rectifier Solo Head tube stages into JFETs but otherwise keep the tone-shaping as close to the original as possible. Nothing can perfectly emulate tubes, but whatever the case, the result is an excellent high-gain distortion pedal.
It has undergone a few minor community tweaks since the original design, such as scaling the tone stack for lower noise and the addition of Miller capacitors on the JFETs, but for the most part it’s an excellent example of nailing it the first time. We’ve incorporated all of these best-practice changes into our version, as well as greatly improving the power supply filtering.
The Draco includes footprints for both through-hole or surface-mount (SMD) JFETs. Since the J201 is very difficult to find in TO-92 through-hole format, and many DIY hobbyists are intimidated by SMD parts, Aion FX offers J201s in SMD format that have been pre-soldered to adapters so they can be used as through-hole parts.
Important note: Due to the extremely high-gain nature of the pedal, it tends to oscillate on higher gain settings. This is normal, but see the build notes in the documentation for more information as well as suggestions for how to minimize or eliminate this oscillation.
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 72 rows
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 27 | ||||
| R1 | 1M | 1M | Metal film resistor, 1/4W | |
| R2 | 68k | 68k | Metal film resistor, 1/4W | |
| R3 | 1k8 | 1.8k | Metal film resistor, 1/4W | |
| R4 | 15k | 15k | Metal film resistor, 1/4W | |
| R5 | 2M2 | 2.2M | Metal film resistor, 1/4W | |
| R6 | 680k | 680k | Metal film resistor, 1/4W | |
| R7 | 470k | 470k | Metal film resistor, 1/4W | |
| R8 | 1k8 | 1.8k | Metal film resistor, 1/4W | |
| R9 | 15k | 15k | Metal film resistor, 1/4W | |
| R10 | 470k | 470k | Metal film resistor, 1/4W | |
| R11 | 1M | 1M | Metal film resistor, 1/4W | |
| R12 | 3k9 | 3.9k | Metal film resistor, 1/4W | |
| R13 | 15k | 15k | Metal film resistor, 1/4W | |
| R14 | 330k | 330k | Metal film resistor, 1/4W | |
| R15 | 220k | 220k | Metal film resistor, 1/4W | |
| R16 | 1k8 | 1.8k | Metal film resistor, 1/4W | |
| R17 | 15k | 15k | Metal film resistor, 1/4W | |
| R18 | 10k | 10k | Metal film resistor, 1/4W | |
| R19 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R20 | 5k1 | 5.1k | Metal film resistor, 1/4W | |
| R21 | 2k2 | 2.2k | Metal film resistor, 1/4W | |
| R22 | 100R | 100 | Metal film resistor, 1/4W | Power supply filter resistor. |
| R23 | 100R | 100 | Metal film resistor, 1/4W | Power supply filter resistor. |
| R24 | 100R | 100 | Metal film resistor, 1/4W | Power supply filter resistor. |
| R25 | 100R | 100 | Metal film resistor, 1/4W | Power supply filter resistor. |
| RPD | 2M2 | 2.2M | Metal film resistor, 1/4W | Input pull-down resistor. Can be as low as 1M. |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 24 | ||||
| C1 | 100n | 100n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 220pF | 220p | MLCC capacitor, NP0/C0G | |
| C3 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C4 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C5 | 2n2 | 2.2n | Film capacitor, 7.2 x 2.5mm | |
| C6 | 1n | 1n | Film capacitor, 7.2 x 2.5mm | |
| C7 | 22pF | 22p | MLCC capacitor, NP0/C0G | |
| C8 | 220pF | 220p | MLCC capacitor, NP0/C0G | |
| C9 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C10 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C11 | 1n | 1n | Film capacitor, 7.2 x 2.5mm | |
| C12 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C13 | 220pF | 220p | MLCC capacitor, NP0/C0G | |
| C14 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C15 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C16 | 220n | 220n | Film capacitor, 7.2 x 2.5mm | |
| C17 | 220n | 220n | Film capacitor, 7.2 x 2.5mm | |
| C18 | 15n | 15n | Film capacitor, 7.2 x 2.5mm | |
| C19 | 15n | 15n | Film capacitor, 7.2 x 2.5mm | |
| C20 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C21 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C22 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C23 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C24 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| Transistors 5 | ||||
| Q1 | J201 | J201 | JFET, N-channel | See build notes for sourcing info. |
| Q2 | J201 | J201 | JFET, N-channel | See build notes for sourcing info. |
| Q3 | J201 | J201 | JFET, N-channel | See build notes for sourcing info. |
| Q4 | J201 | J201 | JFET, N-channel | See build notes for sourcing info. |
| Q5 | J201 | J201 | JFET, N-channel | See build notes for sourcing info. |
| Potentiometers 5 | ||||
| GAIN | 1MA | A1M | 16mm right-angle PCB mount pot | |
| MID | 5kB | B5k | 16mm right-angle PCB mount pot | |
| BASS | 100kA | A100k | 16mm right-angle PCB mount pot | |
| PRES. | 10kB | B10k | 16mm right-angle PCB mount pot | |
| VOL. | 100kA | A100k | 16mm right-angle PCB mount pot | |
| Trimmers 4 | ||||
| TR1 | 50k | 50k | Trimmer, 10%, 1/4" | Bourns 3362P |
| TR2 | 50k | 50k | Trimmer, 10%, 1/4" | Bourns 3362P |
| TR3 | 50k | 50k | Trimmer, 10%, 1/4" | Bourns 3362P |
| TR4 | 50k | 50k | Trimmer, 10%, 1/4" | Bourns 3362P |
| Switches 1 | ||||
| FSW | 3PDT | 3PDT | Stomp switch, 3PDT | Available from Aion FX. |
| LEDs 1 | ||||
| LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 3 | ||||
| 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 | Lumberg NEB/J 21 C or equivalent. |
| Hardware 1 | ||||
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |