125B · 3 knobs
Tone Bender Mk. IV
Based on the Sola Sound Tone Bender MKIV· 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.
- Category
- Fuzz
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- see vendor
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From the vendor
This is my first build in a while. I tried a few new things with this build, and I'm rather pleased with how it turned out. As with pretty much all of my builds, I couldn't have done this without some of the people on this forum. I'm a longtime fan of @andy-h-h 's blog Vero-P2P blog. It's an amazing repository of information, including this compilation of Tone Bender Mk. III/IV variants and their component values. As with many vintage fuzz pedals, the component values changed frequently from one build or batch to another, sometimes for better, sometimes for worse. Using Andy's table, I played around with a bunch of variants, For this build, I went with the Sola Sound/D*A*M Mk. IV named "Son of the Green Bastard," and aimed for the bias measurements of the late 60's Sola Sound Tone Bender listed on the third tab of the spreadsheet. Outside <a href="https://forum.pedalpcb.com/attachments/img_6108-jpeg.118392/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='1500' height='2000' viewBox%3D'0 0 1500 2000'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/118/118412-59bdbaf2e99947d302b7b3bce0f7a970.jpg?hash=JlHxxJ8cGr" class="bbImage lazyload" style="" alt="IMG_6108.jpeg" title="IMG_6108.jpeg" width="150" height="200" /> <img src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/118/118412-59bdbaf2e99947d302b7b3bce0f7a970.jpg?hash=JlHxxJ8cGr" class="bbImage " style="" alt="IMG_6108.jpeg" title="IMG_6108.jpeg" width="150" height="200" /> Inside <a href="https://forum.pedalpcb.com/attachments/img_6109-jpeg.118393/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='1499' height='2000' viewBox%3D'0 0 1499 2000'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/118/118413-6893f0f5551f8e8f28495602d1202075.jpg?hash=MeZsG8VPIZ" class="bbImage lazyload" style="" alt="IMG_6109.jpeg" title="IMG_6109.jpeg" width="150" height="201" /> <img src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/118/118413-6893f0f5551f8e8f28495602d1202075.jpg?hash=MeZsG8VPIZ" class="bbImage " style="" alt="IMG_6109.jpeg" title="IMG_6109.jpeg" width="150" height="201" /> This one has a couple interesting departures from most of the other Mk. III and IV Tone Benders. First, it uses a 15k collector resistor, rather than an 18k. The smaller Q3 collector resistor increases the prominence of the bass side of the tone control and bumps the output up a little. Second, it uses a 3n3 treble capacitor, which shifts the treble high pass filter down a bit and gives a nice upper midrange response. It's a nice middle ground between the D*A*M-style 220n/4n7 tone control and the 100n/2n2 that was commonly used in vintage units. For transistors, I used a pair of Motorola MA287s for Q1 (hFE 77, leakage 23µA) and Q2 (hFE 97, leakage 43µA). For Q3, I used a
Schematic
The schematic is in the post. Open it at Naegele Audio. No KiCad fragment has been drawn for this circuit yet.
Parts list 28 rows
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Check before you build · 1 value the reader of this schematic was not sure of
- R102: LED resistor drawn as 'CLR' with no value
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 12 | ||||
| R1 | 680k | 680k | read from the schematic by eye | |
| R2 | 100k | 100k | read from the schematic by eye | |
| R3 | 10k | 10k | read from the schematic by eye | |
| R4 | 10k | 10k | read from the schematic by eye | |
| R5 | 3k3 | 3.3k | read from the schematic by eye | |
| R6 | 10k | 10k | read from the schematic by eye | |
| R7 | 10k | 10k | read from the schematic by eye | |
| R8 | 15k | 15k | Q3 collector resistor; read from the schematic by eye | |
| R9 | 10k | 10k | read from the schematic by eye | |
| R10 | 0R | 0 | drawn as JUMPER: a wire link between Tone and Volume; read from the schematic by eye | |
| R101 | 100R | 100 | supply filter; read from the schematic by eye | |
| R102 | ? | ? | LED current limiting resistor, drawn as CLR; read from the schematic by eye | |
| Capacitors 8 | ||||
| C1 | 100n | 100n | read from the schematic by eye | |
| C2 | 220p | 220p | read from the schematic by eye | |
| C3 | 220n | 220n | read from the schematic by eye | |
| C4 | 10µ | 10u | read from the schematic by eye | |
| C5 | 100n | 100n | read from the schematic by eye | |
| C6 | 3n3 | 3.3n | treble cap; read from the schematic by eye | |
| C101 | 100µ | 100u | supply filter; read from the schematic by eye | |
| C102 | 100n | 100n | supply filter; read from the schematic by eye | |
| Diodes 1 | ||||
| D1 | OA1154 | OA1154 | germanium, sets Q3 bias with Q3's leakage; read from the schematic by eye | |
| Transistors 3 | ||||
| Q1 | MA287 | MA287 | Motorola germanium PNP; read from the schematic by eye | |
| Q2 | MA287 | MA287 | Motorola germanium PNP; read from the schematic by eye | |
| Q3 | 2N526 | 2N526 | Motorola germanium PNP; read from the schematic by eye | |
| Potentiometers 3 | ||||
| Fuzz | B100k | B100k | Potentiometer | read from the schematic by eye |
| Tone | B100k | B100k | Potentiometer | read from the schematic by eye |
| Volume | A500k | A500k | Potentiometer | read from the schematic by eye |
| LEDs 1 | ||||
| LED | LED | LED | status LED; read from the schematic by eye | |
Other boards based on the Sola Sound Tone Bender MKIV
- Sola Sound Tone Bender MKIV (1970-72) turretboard.org
- Sola Sound Tone Bender MKIV (1972-76, Batman logo) turretboard.org