Remember the reverb pedal I built recently? Today, we're taking it to the next level with a new build, but I'm warning you: it's going to be "massive destruction." This project is inspired by the legendary sound of Tony Iommi (Black Sabbath), with a circuit adapted to mimic the behavior of lamps using some special transistors.
A big thank you to Pedal Parts and Kits who provided this second kit to allow us to explore the world of DIY. If you want to get started but don't know where to begin, stay with me: we'll break it down simply and effectively.
1. A Short Electronics Lesson: The "Chess Game" of Components
For the first kit, we assembled it "blindly". This time, let's take the time to understand what these small parts are for:
- Resistances (R): They limit the current. They are used to reduce the signal amplitude (volume) or to divide the voltage to bias other components. Their value is measured in Ohms (Ω), often in kilo-ohms (kΩ).
- Trick : Learn the color code (the bands from 0 to 9). The 3rd band indicates the number of zeros to add. Always check with a multimeter as there is a margin of tolerance (gold or silver band).
- Capacitors (C): They store and deliver current. They filter out interference and block direct current (0 Hz) while allowing high frequencies to pass through.
- Usage: In series, they act as "High-Pass" filters (cutting low frequencies); connected to ground, they act as "Low-Pass" filters (cutting high frequencies). They are measured in microfarads (µF), nanofarads (nF), or picofarads (pF).
- Transistors: They act like a valve or a tap. A small variation at the input controls a large variation at the output (amplification).
- Bipolar disorder: They react to the current, but their distortion is often less "nice" for the guitar.
- JFET (Field Effect Transistor): They operate using voltage, like the lamps high-end amplifiers. Their distortion is more harmonious and progressive, although they are more difficult to make commercially stable due to their large tolerance margins.
- Diodes (D): They only allow current to pass in one direction.
- Usage: They are used to rectify the power supply or to "clip" the audio signal to create artificial distortion.
2. Analysis of the "Sabotage" circuit«
The kit Sabotage is an adaptation of the circuit Sabra Cadabra Catalinbread, itself inspired by a Laney Supergroup amp driven by a Dallas Range Master (Treble Booster). This is Tony Iommi's typical rig.
Special feature: There are no diodes to create the distortion. It's the JFET transistors which, when pushed to their limit, naturally generate a dynamic saturation similar to that of a tube amplifier.
- Food Section: Includes a safety diode to prevent damaging the circuit if you connect a power supply backwards.
- Treble Boost: The first stage the signal encounters. The "Range" knob is a variable resistor that allows more or less bass to pass through the booster.
- Preamp: Four cascaded gain stages (transistors working in complementarity).
- Equalization & Output: A 5th gain stage, followed by a volume control and a "Presence" adjustment (high-frequency filter at the output).
3. Tips for flawless welds
Most DIY problems stem from either a careless mistake or a bad solder joint.
- Iron: A model of 40W is a good compromise. A fine (conical) tip helps prevent overheating of neighboring components.
- Interview : Always clean your tip on a damp sponge or steel wool to remove residue.
- Welding: Use an alloy 60/40 (Tin/Lead) or unleaded, but absolutely with a resin core (flux). Absolutely avoid plumbing acid flux paste! A diameter of 0.8 mm is ideal.
- The Technique: Heat the component and the PCB pad, then apply the solder to the hot part (not the soldering iron). A good solder joint should "wet" the metal and form a small, shiny "cone" (like a chocolate). Kiss).
4. The Build: "Destroyed" Look and Assembly
For this project, I chose a raw aluminum case. For the look: cleaning with alcohol, light sanding, and a slightly distressed, "bloody" finish to match the Black Sabbath sound.
The assembly:
- Basic components: Resistors, then capacitors.
- Supports (Sockets): Very important for JFET transistors, in order to be able to test or replace them without desoldering.
- Potentiometers: Solder only the middle tab first so that you can adjust them perfectly in the housing before finalizing.
- Wiring : Unlike the first kit, there is no ribbon cable. Each connection between the main PCB, the 3PDT switch, and the jacks must be wired independently.
5. Troubleshooting: When it doesn't work…
Even with experience, we make mistakes!
- Error #1: I wired the output jack backwards again (no signal). I had to reverse the wires.
- Error #2: I had sound, but it was weak, crackling and without power.
The solution: I went to the forum of GuitarPCB.com (the designers of the circuits sold by Pedal Parts and Kits). The community helped me measure the values with a multimeter. The problem stemmed from a bad solder joint and poor contact between a transistor and its socket. Once that was fixed… BINGO! The heavy, fat sound of Black Sabbath was there.
Conclusion and Perspectives
Moving from assembler to "builder" means understanding the philosophy of the circuit. My next challenge? Assembling a circuit on a... breadboard (prototyping board) to test and modify each component before soldering, in order to create my own custom sound.
This was probably the last video of 2025. Thank you for this wonderful year and see you in 2026 for even more ambitious new projects!
What's stopping you from getting started? Fear of electronics or lack of equipment? Tell me in the comments!
