Enclosure not stated · 4 knobs
Fred Briggs 'Face MKI
Based on the Briggs' 'Face· 1 other board clones it
- Category
- Overdrive
- Price
- see vendor
- Tags
- freestompboxes.org trace
From the vendor
The author's own Fender-voiced booster/overdrive: two stacked JFETs in an SRPP-style stage, inspired by a 1943 patent, a 1997 microphone preamp and Tim Escobedo's Syrupp Booster, with diode clipping and an onboard charge pump for up to 18V. Lower supply voltage gives less gain and clipping, more gives more.
Supply can be 4.5-18V; the lower the voltage the less gain and clipping. 2N5457 JFETs give more gain and a more compressed sound (tweed); MPF102s give more headroom and less gain (Twin). 2N5458 and J201 also work; the author found J201s too compressed and fuzzy. Use a larger tone cap than 3n3 for a darker tone, a smaller one for more high-end drive. The author's build used MPF102s at 18V with a 4n7 tone cap. Adjust the 4K7 trimmer for the best tone.
Schematic
The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.
Parts list 22 rows
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Check before you build · 1 value the reader of this schematic was not sure of
- Which way round the two series 1N4148s and the single anti-parallel 1N4148 sit is hard to read on the photo of the drawing.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 2 | ||||
| R1 | 10K | 10k | input; read from the schematic by eye | |
| R2 | 1K | 1k | source; read from the schematic by eye | |
| Capacitors 7 | ||||
| C1 | 22n | 22n | input; read from the schematic by eye | |
| C2 | 47p | 47p | bright cap across Vol; read from the schematic by eye | |
| C3 | 3.3n | 3.3n | tone; read from the schematic by eye | |
| C4 | 10u | 10u | source bypass, switched by Bias; read from the schematic by eye | |
| C5 | 100n | 100n | output; read from the schematic by eye | |
| C6 | 10u | 10u | charge pump, electrolytic; read from the schematic by eye | |
| C7 | 10u | 10u | charge pump, electrolytic; read from the schematic by eye | |
| Diodes 5 | ||||
| D1 | 1N4148 | 1N4148 | clipping; read from the schematic by eye | |
| D2 | 1N4148 | 1N4148 | clipping; read from the schematic by eye | |
| D3 | 1N4148 | 1N4148 | clipping; read from the schematic by eye | |
| D4 | ? | ? | low voltage drop silicon; read from the schematic by eye | |
| D5 | ? | ? | low voltage drop silicon; read from the schematic by eye | |
| Transistors 2 | ||||
| Q1 | 2N5457 | 2N5457 | or MPF102; read from the schematic by eye | |
| Q2 | 2N5457 | 2N5457 | or MPF102; read from the schematic by eye | |
| ICs 1 | ||||
| IC1 | MAX1044 | MAX1044 | or ICL7660S; read from the schematic by eye | |
| Potentiometers 4 | ||||
| Trim | 4.7K | 4.7k | Potentiometer | trimmer between the JFETs; read from the schematic by eye |
| Vol | A1M | A1M | Potentiometer | read from the schematic by eye |
| Tone | A100K | A100k | Potentiometer | read from the schematic by eye |
| Master | B100K | B100k | Potentiometer | read from the schematic by eye |
| Switches 1 | ||||
| Bias | SPST | SPST | read from the schematic by eye | |
Other boards based on the Briggs' 'Face
- Briggs' 'Face Tagboard Effects