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EQDISTORTIONVOLUME

125B · 3 knobs

Aion FX

SynapseResonant Drive

Based on the Systech Overdrive· 1 other board clones it

Category
Fuzz· Resonant filter fuzz
Controls
EQ · Distortion · Volume
Difficulty
Beginner
Price
$12.50in stock

From the vendor

A rare fuzz pedal that combines hard-clipping distortion with an extreme resonant filter that lends a vocal “stuck wah” quality.

The Synapse Resonant Drive is based on the Systech Overdrive, a fuzz pedal released in the early 1970s before the idea of “overdrive” had become distinct from “distortion” and “fuzz”.

Today, Systech’s most well-known circuit is the Harmonic Energizer (available from Aion FX as the Parsec), which is similar in its frequency-sweepable filter but lacks any of its own clipping. The Harmonic Energizer was most notably used by Frank Zappa.

It’s not known whether the Overdrive was derived from the Harmonic Energizer or the other way around—but either way, they’re similar in concept, and the Overdrive is very unique among drive pedals. It doesn’t have the Zappa association, but it’s interesting enough that it’s worth your time.

The resonant filter can be tuned from 133 Hz to 900 Hz, but unlike a wah, its Q is very sharp, and it has a definite “tuned” quality that can either complement the notes being played or collide in a dissonant way.

There is no way to disable the filter or reduce its gain, so it’s definitely not an always-on tone stap;e, but very useful as a quirky effect to get some spaced-out filter tones are hard to come by in such a small package.

The Synapse is a straight clone of the Systech Overdrive with no changes except changing Systech’s standard polarity protection for a simple Schottky diode as in other Aion FX projects.

Schematic

The schematic is in the vendor's build document, page 6. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 48 rows

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RefValueNormalizedTypeNotes
Resistors 20
R110k10kMetal film resistor, 1/4W
R210M10MMetal film resistor, 1/4W
R33k33.3kMetal film resistor, 1/4W
R415k15kMetal film resistor, 1/4W
R5300k300kMetal film resistor, 1/4W
R6220R220Metal film resistor, 1/4W
R75k15.1kMetal film resistor, 1/4W
R82M2MMetal film resistor, 1/4W
R9100k100kMetal film resistor, 1/4W
R1022k22kMetal film resistor, 1/4W
R11300k300kMetal film resistor, 1/4W
R12100k100kMetal film resistor, 1/4W
R1310k10kMetal film resistor, 1/4W
R145k15.1kMetal film resistor, 1/4W
R151M1MMetal film resistor, 1/4W
R1610k10kMetal film resistor, 1/4W
R1710k10kMetal film resistor, 1/4W
R18100R100Metal film resistor, 1/4W
RPD2M22.2MMetal film resistor, 1/4W
LEDR4k74.7kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 12
C11n1nFilm capacitor, 7.2 x 2.5mm
C210uF10uElectrolytic capacitor, 5mm
C322n22nFilm capacitor, 7.2 x 2.5mm
C422n22nFilm capacitor, 7.2 x 2.5mm
C510uF10uElectrolytic capacitor, 5mm
C6100n100nFilm capacitor, 7.2 x 2.5mm
C710uF10uElectrolytic capacitor, 5mm
C8100n100nFilm capacitor, 7.2 x 2.5mm
C9100n100nFilm capacitor, 7.2 x 2.5mm
C1047uF47uElectrolytic capacitor, 5mmVoltage reference filter capacitor.
C11100uF100uElectrolytic capacitor, 5mmPower supply filter capacitor.
C12100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 3
D11N58171N5817Schottky diode, DO-41
D21N9141N914Fast-switching diode, DO-35
D31N9141N914Fast-switching diode, DO-35
Transistors 2
Q12N54572N5457JFET, N-channel, TO-92Substitute. Original uses 2N5458.
Q22N50882N5088BJT transistor, NPN, TO-92
ICs 1
IC1LM1458LM1458Operational amplifier, DIP8Consider substituting for a lower-noise IC. See build notes.
Potentiometers 3
DIST.50kCC50k16mm right-angle PCB mount pot
EQ50kCC50k16mm right-angle PCB mount pot
VOL.50kAA50k16mm right-angle PCB mount pot
Switches 1
FSW3PDT3PDTStomp switch, 3PDT
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 4
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" stereo1/4" STEREO1/4" phone jack, closed frameSwitchcraft 112BX or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountMouser 163-4302-E or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

Other boards based on the Systech Overdrive