125B · 5 knobs
PolyphemusOptical Compressor
Based on the Pigtronix Philosopher's Tone
- Category
- Overdrive· Compressor / overdrive
- Controls
- Sustain · Grit · Treble · Blend · Volume
- Difficulty
- Intermediate
- Price
- $12.50in stock
From the vendor
An inventive optical compressor noted for its long sustain and blendable overdrive, designed by Howard Davis, best known as the designer of the EHX Memory Man and Electric Mistress.
The Polyphemus Optical Compressor is based on the Pigtronix Philosopher’s Tone, a vactrol-based compressor & overdrive first released in 2009. It’s known for its incredibly long sustain, and has a unique diode-clipping overdrive that can be blended in with the clean compressed signal.
The Philosopher’s Tone was designed by Howard Davis, the legendary inventor of the Memory Man and Electric Mistress when he worked for Electro-Harmonix in the late 1970s. Since that time, he’s designed several effects on a contract basis, and this is one of a few he did for Pigtronix.
After the original release, the Philosopher’s Tone underwent several revisions and new editions. The first was the “Germanium Gold” edition, which was in a gold enclosure and featured a single germanium diode in place of one of the silicon diodes in the clipping section (in other words, a marketing gimmick).
Later, the circuit was reworked into two new and slightly simplified pedals: the Philosopher’s Rock, which emphasized the overdrive component, and the Philosopher’s Bass, which was tuned for bass frequencies. These replaced the original Philosopher’s Tone.
Most recently, it was redesigned as a miniature pedal, once again using the original Philosopher’s Tone name. This version included an onboard charge pump voltage doubler, so it no longer needed its own 15V or 18V adapter. This is the only one currently manufactured as of this project’s release.
The Polyphemus is an amalgamation of all of these, primarily based on the original Philosopher’s Tone (which had more features than any subsequent versions) but incorporating various modifications and tweaks from some of the later versions, including the charge pump, germanium diode, and improvements to the sustain control.
Note: This project uses a type of capacitor that has been temporarily discontinued by WIMA. Please see our news article about the issue and the substitution spreadsheet for project-specific recommendations. The build document has not yet been updated to reflect this.
Schematic
The schematic is in the vendor's build document, page 8. Open the build document. No KiCad fragment has been drawn for this circuit yet.
Parts list 79 rows
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 21 | ||||
| R1 | 10k | 10k | Metal film resistor, 1/4W | |
| R2 | 470k | 470k | Metal film resistor, 1/4W | |
| R3 | 8k2 | 8.2k | Metal film resistor, 1/4W | |
| R4 | 2k7 | 2.7k | Metal film resistor, 1/4W | |
| R5 | 10k | 10k | Metal film resistor, 1/4W | |
| R6 | 2k7 | 2.7k | Metal film resistor, 1/4W | |
| R7 | 47R | 47 | Metal film resistor, 1/4W | |
| R8 | 2M2 | 2.2M | Metal film resistor, 1/4W | |
| R9 | 220k | 220k | Metal film resistor, 1/4W | |
| R10 | 100k | 100k | Metal film resistor, 1/4W | |
| R11 | 27k | 27k | Metal film resistor, 1/4W | |
| R12 | 1M8 | 1.8M | Metal film resistor, 1/4W | |
| R13 | 56k | 56k | Metal film resistor, 1/4W | |
| R14 | 2k7 | 2.7k | Metal film resistor, 1/4W | |
| R15 | 100k | 100k | Metal film resistor, 1/4W | |
| R16 | 68k | 68k | Metal film resistor, 1/4W | Mistakenly listed as 6k8 in earlier DIY schematics. See build notes. |
| R17 | 91k | 91k | Metal film resistor, 1/4W | |
| R18 | 100k | 100k | Metal film resistor, 1/4W | |
| R19 | 150R | 150 | Metal film resistor, 1/4W | |
| RPD | 1M | 1M | Metal film resistor, 1/4W | |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 17 | ||||
| C1 | 22n | 22n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 680pF | 680p | MLCC capacitor, NP0/C0G | |
| C3 | 6n8 | 6.8n | Film capacitor, 7.2 x 2.5mm | |
| C4 | 2.2uF | 2.2u | Film capacitor, 7.2 x 5mm | |
| C5 | 1uF | 1u | Film capacitor, 7.2 x 4.5mm | 560n in earliest versions. See build notes. |
| C6 | 33pF | 33p | MLCC capacitor, NP0/C0G | |
| C9 | 1uF | 1u | Electrolytic capacitor, 4mm | |
| C10 | 22pF | 22p | MLCC capacitor, NP0/C0G | |
| C11 | 1uF | 1u | Electrolytic capacitor, 4mm | |
| C12 | 2n2 | 2.2n | Film capacitor, 7.2 x 2.5mm | |
| C14 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Reference voltage filter capacitor. |
| C15 | 10uF | 10u | Electrolytic capacitor, 5mm | Power supply filter capacitor. |
| C16 | 470n | 470n | MLCC capacitor, X7R | Power supply filter capacitor. |
| C17 | 10uF | 10u | Electrolytic capacitor, 5mm | Power supply filter capacitor. |
| C18 | 470n | 470n | MLCC capacitor, X7R | Power supply filter capacitor. |
| C19 | 220uF | 220u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C20 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 18 | ||||
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D2 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D3 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D4 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D5 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D6 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D7 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D8 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D9 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D10 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D11 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D12 | Ge | GE | Germanium diode, DO-7 | Original uses 1N60. Can also use BAT46 Schottky. See build notes. |
| D14 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D15 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D16 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D17 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D18 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| Z1 | 1N4742A | 1N4742A | Zener diode, 12V, DO-41 | |
| ICs 5 | ||||
| IC1 | NE5532P | NE5532P | Operational amplifier, dual, DIP-8 | |
| IC2 | TL072 | TL072 | Operational amplifier, dual, DIP-8 | |
| IC3 | RC4558P | RC4558P | Operational amplifier, dual, DIP-8 | |
| IC4 | LM741 | LM741 | Operational amplifier, single, DIP-8 | |
| IC5 | LT1054CP | LT1054CP | Charge pump, DIP-8 | Can also use TC1044SCPA. |
| Opto 1 | ||||
| VACT. | VTL5C6 | VTL5C6 | Vactrol, fast on/fast off | Available from Aion FX. See build notes for optocoupler information. |
| Potentiometers 5 | ||||
| BLEND | 10kB | B10k | 16mm right-angle PCB mount pot | |
| SUSTAIN | 100kB | B100k | 16mm right-angle PCB mount pot | |
| GRIT | 100kB | B100k | 16mm right-angle PCB mount pot | |
| TREBLE | 100kB | B100k | 16mm right-angle PCB mount pot | |
| VOLUME | 10kA | A10k | 16mm right-angle PCB mount pot | |
| Switches 1 | ||||
| FSW | 3PDT | 3PDT | Stomp switch, 3PDT | Available from Aion FX. |
| LEDs 2 | ||||
| D13 | 5mm LED | 5MM LED | LED, 5mm, red diffused | |
| LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 8 | ||||
| IC1-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC2-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC3-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC4-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IC5-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IN | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| OUT | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| DC | 2.1mm | 2.1MM | DC jack, 2.1mm panel mount | Lumberg NEB/J 21 C or equivalent. |
| Hardware 1 | ||||
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |