Akashic Guitar effects PCB lookup
SUSTAINGRITTREBLEBLENDVOLUME

125B · 5 knobs

Aion FX

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
RefValueNormalizedTypeNotes
Resistors 21
R110k10kMetal film resistor, 1/4W
R2470k470kMetal film resistor, 1/4W
R38k28.2kMetal film resistor, 1/4W
R42k72.7kMetal film resistor, 1/4W
R510k10kMetal film resistor, 1/4W
R62k72.7kMetal film resistor, 1/4W
R747R47Metal film resistor, 1/4W
R82M22.2MMetal film resistor, 1/4W
R9220k220kMetal film resistor, 1/4W
R10100k100kMetal film resistor, 1/4W
R1127k27kMetal film resistor, 1/4W
R121M81.8MMetal film resistor, 1/4W
R1356k56kMetal film resistor, 1/4W
R142k72.7kMetal film resistor, 1/4W
R15100k100kMetal film resistor, 1/4W
R1668k68kMetal film resistor, 1/4WMistakenly listed as 6k8 in earlier DIY schematics. See build notes.
R1791k91kMetal film resistor, 1/4W
R18100k100kMetal film resistor, 1/4W
R19150R150Metal film resistor, 1/4W
RPD1M1MMetal film resistor, 1/4W
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 17
C122n22nFilm capacitor, 7.2 x 2.5mm
C2680pF680pMLCC capacitor, NP0/C0G
C36n86.8nFilm capacitor, 7.2 x 2.5mm
C42.2uF2.2uFilm capacitor, 7.2 x 5mm
C51uF1uFilm capacitor, 7.2 x 4.5mm560n in earliest versions. See build notes.
C633pF33pMLCC capacitor, NP0/C0G
C91uF1uElectrolytic capacitor, 4mm
C1022pF22pMLCC capacitor, NP0/C0G
C111uF1uElectrolytic capacitor, 4mm
C122n22.2nFilm capacitor, 7.2 x 2.5mm
C14100uF100uElectrolytic capacitor, 6.3mmReference voltage filter capacitor.
C1510uF10uElectrolytic capacitor, 5mmPower supply filter capacitor.
C16470n470nMLCC capacitor, X7RPower supply filter capacitor.
C1710uF10uElectrolytic capacitor, 5mmPower supply filter capacitor.
C18470n470nMLCC capacitor, X7RPower supply filter capacitor.
C19220uF220uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C20100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 18
D11N58171N5817Schottky diode, DO-41
D21N9141N914Fast-switching diode, DO-35
D31N9141N914Fast-switching diode, DO-35
D41N9141N914Fast-switching diode, DO-35
D51N9141N914Fast-switching diode, DO-35
D61N9141N914Fast-switching diode, DO-35
D71N9141N914Fast-switching diode, DO-35
D81N9141N914Fast-switching diode, DO-35
D91N9141N914Fast-switching diode, DO-35
D101N9141N914Fast-switching diode, DO-35
D111N9141N914Fast-switching diode, DO-35
D12GeGEGermanium diode, DO-7Original uses 1N60. Can also use BAT46 Schottky. See build notes.
D141N9141N914Fast-switching diode, DO-35
D151N9141N914Fast-switching diode, DO-35
D161N9141N914Fast-switching diode, DO-35
D171N58171N5817Schottky diode, DO-41
D181N58171N5817Schottky diode, DO-41
Z11N4742A1N4742AZener diode, 12V, DO-41
ICs 5
IC1NE5532PNE5532POperational amplifier, dual, DIP-8
IC2TL072TL072Operational amplifier, dual, DIP-8
IC3RC4558PRC4558POperational amplifier, dual, DIP-8
IC4LM741LM741Operational amplifier, single, DIP-8
IC5LT1054CPLT1054CPCharge pump, DIP-8Can also use TC1044SCPA.
Opto 1
VACT.VTL5C6VTL5C6Vactrol, fast on/fast offAvailable from Aion FX. See build notes for optocoupler information.
Potentiometers 5
BLEND10kBB10k16mm right-angle PCB mount pot
SUSTAIN100kBB100k16mm right-angle PCB mount pot
GRIT100kBB100k16mm right-angle PCB mount pot
TREBLE100kBB100k16mm right-angle PCB mount pot
VOLUME10kAA10k16mm right-angle PCB mount pot
Switches 1
FSW3PDT3PDTStomp switch, 3PDTAvailable from Aion FX.
LEDs 2
D135mm LED5MM LEDLED, 5mm, red diffused
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 8
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC2-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC3-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC4-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC5-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountLumberg NEB/J 21 C or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.