1590BB2 · 3 knobs
Trumpet Fuzz
Based on the Paul Trombetta Rotobone· 2 other boards clone it
Want a PCB? Naegele Audio laid out a PCB for this circuit and sells boards, as well as relay bypass and I/O boards: message PedalBuilder on the PedalPCB forum.
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- Fuzz
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From the vendor
Picking a favorite fuzz pedal is like picking your favorite offspring. With that said, the Rotobone is a strong candidate for my favorite fuzz. Enough has been written elsewhere about its trumpet-like tones, the glassy cleans when you roll back the volume knob, and its wide range of more traditional fuzz tones, so I won't reprise that here. At its heart, the circuit is a derivative of the Jordan Bosstone with the PNP transistor installed backwards, with emitter to ground. This softens the distortion and keeps the oscillations that are responsible for the trumpet-like tones from getting too chaotic and unmusical. You could probably use a very low hFE transistor, like certain power transistors, installed with collector to ground to get the same effect, but I haven't tried that myself. Additionally, the Rotobone adds an array of switches: switches to choose between germanium and silicon for both transistors, a low/high gain switch to add/remove an emitter resistor to Q1, and rotary switches for the input and output capacitors. I made a few changes to mine. The original Rotobone used 1P6T rotary switches for the input and output capacitors. I used 1P8T rotary switches, and added C7, C8, C16, and C17. I also added R2 because I am a firm believer that a fuzz pedal should only have one control that mutes it.* For this build, I followed the schematic (at the bottom of the post) more or less exactly, with the exception of the transistor selection: Q1: Central Semiconductor 2N5088, hFE 460 Q2: General Instrument 2N1304, hFE 123, leakage 10µA Q3: ON Semiconductor 2N4403, hFE 186 Q4: Texas Instruments 182505 (2N404A equivalent), hFE 178, leakage 45µA The enclosure is a Tayda Ball Silver 1590BB2, so I am holding my breath and waiting for it to spontaneously cover itself with scratches. I used one in this build because I figured that the inevitable patina would go well with the overall aesthetic of the pedal. I made a small error on the UV print—the Ge/Si switches have Ge and Si backwards, but otherwise everything came out exactly as planned. Inside <a href="https://forum.pedalpcb.com/attachments/img_5110-png.103648/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='1400' height='1867' viewBox%3D'0 0 1400 1867'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/103/103667-6dd64b363aff6d77afcbee377264a1e1.jpg?hash=RXCeoKO_7z" class="bbImage lazyload" style="" alt="IMG_5110.png" title="IMG_5110.png" width="150" height="201" /> <img src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/103/103667-6dd64b363aff6d77afcbee377264a1e1.jpg?hash=RXCeoKO_7z" class="bbImage " style="" alt="IMG_5110.png" title="IMG_5110.png" width="150" height="201" /> Outside <a href="https://forum.pedalpcb.com/attachments/img_5115-png.103647/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='140
Schematic
The schematic is in the post. Open it at Naegele Audio. No KiCad fragment has been drawn for this circuit yet.
Parts list 42 rows
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Check before you build · 2 values the reader of this schematic was not sure of
- R101: LED resistor drawn as 'LEDR' with no value
- Q1 Element, Q2 Element, Low/High Power: switch types are not printed; read from the poles drawn
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 9 | ||||
| R1 | 2k | 2k | read from the schematic by eye | |
| R2 | 1k | 1k | under the Gain pot so it never mutes; read from the schematic by eye | |
| R3 | 560k | 560k | read from the schematic by eye | |
| R4 | 150k | 150k | read from the schematic by eye | |
| R5 | 560k | 560k | read from the schematic by eye | |
| R6 | 1k2 | 1.2k | switched in by Low/High Power; read from the schematic by eye | |
| R7 | 18k | 18k | read from the schematic by eye | |
| R9 | 2k | 2k | in series with Octave; read from the schematic by eye | |
| R101 | ? | ? | LED current limiting resistor, drawn as LEDR; read from the schematic by eye | |
| Capacitors 18 | ||||
| C1 | 8n2 | 8.2n | Y Rotary; read from the schematic by eye | |
| C2 | 15n | 15n | Y Rotary; read from the schematic by eye | |
| C3 | 22n | 22n | Y Rotary; read from the schematic by eye | |
| C4 | 47n | 47n | Y Rotary; read from the schematic by eye | |
| C5 | 68n | 68n | Y Rotary; read from the schematic by eye | |
| C6 | 82n | 82n | Y Rotary; read from the schematic by eye | |
| C7 | 100n | 100n | Y Rotary; read from the schematic by eye | |
| C8 | 120n | 120n | Y Rotary; read from the schematic by eye | |
| C9 | 22n | 22n | read from the schematic by eye | |
| C10 | 47p | 47p | read from the schematic by eye | |
| C11 | 8n2 | 8.2n | X Rotary; read from the schematic by eye | |
| C12 | 22n | 22n | X Rotary; read from the schematic by eye | |
| C13 | 47n | 47n | X Rotary; read from the schematic by eye | |
| C14 | 68n | 68n | X Rotary; read from the schematic by eye | |
| C15 | 82n | 82n | X Rotary; read from the schematic by eye | |
| C16 | 100n | 100n | X Rotary; read from the schematic by eye | |
| C17 | 150n | 150n | X Rotary; read from the schematic by eye | |
| C18 | 220n | 220n | X Rotary; read from the schematic by eye | |
| Diodes 2 | ||||
| D1 | 1N4148 | 1N4148 | read from the schematic by eye | |
| D2 | 1N4148 | 1N4148 | read from the schematic by eye | |
| Transistors 4 | ||||
| Q1 | 2N5088 | 2N5088 | silicon, hFE 424 on the drawing; the post's build used a Central Semiconductor 2N5088, hFE 460; read from the schematic by eye | |
| Q2 | AC130 | AC130 | germanium, hFE 110, leakage 10µA on the drawing; the post's build used a General Instrument 2N1304, hFE 123; read from the schematic by eye | |
| Q3 | P2N2907 | P2N2907 | silicon, hFE 225 on the drawing; the post's build used an ON Semiconductor 2N4403, hFE 186; read from the schematic by eye | |
| Q4 | 2N404 | 2N404 | germanium, hFE 174, leakage 137µA on the drawing; the post's build used a TI 182505 (2N404A equivalent), hFE 178; read from the schematic by eye | |
| Potentiometers 3 | ||||
| Gain | B100k | B100k | Potentiometer | read from the schematic by eye |
| Octave | B100k | B100k | Potentiometer | read from the schematic by eye |
| Volume | A100k | A100k | Potentiometer | read from the schematic by eye |
| Switches 5 | ||||
| Q1 Element | DPDT | DPDT | first stage: Q1 (silicon) or Q2 (germanium); read from the schematic by eye | |
| Q2 Element | DPDT | DPDT | second stage: Q3 (silicon) or Q4 (germanium); read from the schematic by eye | |
| Low/High Power | SPDT | SPDT | adds R6 to the Q1 emitter; read from the schematic by eye | |
| Y Rotary | 1P8T | 1P8T | input capacitor selector (1P8T from the post); read from the schematic by eye | |
| X Rotary | 1P8T | 1P8T | output capacitor selector (1P8T from the post); read from the schematic by eye | |
| LEDs 1 | ||||
| D101 | LED | LED | status LED; read from the schematic by eye | |
Other boards based on the Paul Trombetta Rotobone
- Paul Trombetta Rotobone Dirtbox Layouts
- Event Horizon Naegele Audio · 1590BBS