Enclosure not stated · 2 knobs
Fallstaff ODVerified
Based on the Fallstaff OD
From the post
Fallstaff OD, or "Fat Mastered" from Jon Patton. It's a modern take on Rangemaster with a few quite cool features. I replaced 8K2 resistor from Q2 base to ground with a 20K trimmer for easier biasing.
From Jon: The Fallstaff overdrive (or "Fat Mastered boost") is a variation on the Rangemaster, but with a buffered input stage and a color knob to fatten the sound in a way that offers a nice change from the usual input cap mods. It can be tweaked to sound a lot like a traditional rangemaster, as a full range boost with sparkly top end, or as a dark mids boost. The extra input stage makes the pedal behave the same whether it's before or after another pedal. It provides a 20db of boost or more depending on the gain of the transistors you use. Unity volume on my prototype was about 10:00.
For Q2, values as low as 35hfe were acceptable with proper biasing, but gain ranges around 50-60 are ideal for the values shown. I got decent results with values as high as 120hfe. NPN Si transistors in that range will work, too. R5 and R6 bias Q2, like a rangemaster, to ~7v on the collector. Use sockets or trim pots or breadboard before building if your transistors aren't pretested! Q1 can also be a JFET. I used 2N2925 instead because it sounded really good and I didn't have to twist the leads to get it in the sockets in my layout.
Schematic
This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Tagboard Effects. No KiCad fragment has been drawn for this circuit yet.
Parts list 19 rows
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Check before you build · 2 values the reader of this layout was not sure of
- 100nF beside the 10M at the left: last letter is hidden under Q1, read as 100nF
- 20K trimmer at lower left: drawn faint/transparent, apparently optional (legend: tweak 220K with trimmer to bias Q2)
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 7 | ||||
| ×1 | 10M | 10M | read from the layout by eye | |
| ×1 | 330K | 330k | read from the layout by eye | |
| ×1 | 8.2K | 8.2k | read from the layout by eye | |
| ×1 | 220K | 220k | 220K*: tweak with trimmer to bias Q2; read from the layout by eye | |
| ×1 | 470K | 470k | read from the layout by eye | |
| ×1 | 22K | 22k | read from the layout by eye | |
| ×1 | 1K | 1k | read from the layout by eye | |
| Capacitors 5 | ||||
| ×2 | 22nF | 22n | read from the layout by eye | |
| ×1 | 100nF | 100n | read from the layout by eye | |
| ×1 | 47nF | 47n | read from the layout by eye | |
| ×1 | 1uF | 1u | read from the layout by eye | |
| ×2 | 47uF | 47u | electrolytic; read from the layout by eye | |
| Diodes 2 | ||||
| D1 | 1N914 | 1N914 | read from the layout by eye | |
| D2 | 1N270 | 1N270 | germanium; read from the layout by eye | |
| Transistors 2 | ||||
| Q1 | 2N2925 | 2N2925 | Q1 is 2N2925 (try 2N3904); read from the layout by eye | |
| Q2 | AC176 | AC176 | Ge NPN hFE 35 and up (AC176..); read from the layout by eye | |
| Potentiometers 2 | ||||
| Boost | A10K | A10k | Potentiometer | read from the layout by eye |
| Color | B500K | B500k | Potentiometer | read from the layout by eye |
| Trimmers 1 | ||||
| ×1 | 20K | 20k | drawn faint, optional bias trimmer for Q2; read from the layout by eye | |