Akashic Guitar effects PCB lookup
DRIVEVOLUMEFREQUENCY

1590B · 3 knobs

Aion FX

Fractal (Legacy)

Based on the Pearl OD-05

Category
Overdrive· Parametric Overdrive
Controls
Drive · Volume · Frequency
Difficulty
Intermediate
Price
see vendor

From the vendor

The Fractal Overdrive is a clone of the Pearl OD-05 Overdrive, an obscure effect from the early 80’s when Pearl (yes, the drum company) briefly dipped into the effects pedal business. The result was a line of very well-engineered pedals that unfortunately never got the attention they deserved.

The interesting thing is, even almost 40 years later this pedal still is relatively unknown. There are no commercial clones of this pedal and it’s relatively unexplored in the DIY scene (with the exception of BYOC’s Parametric Overdrive project). But those who have played through one universally praise it for its tonal flexibility.

The OD-05 has a standard feedback-diode clipping stage like a Tube Screamer, but the magic is what comes in front of it: a parametric equalizer that allows either a cut or boost of up to 15dB in a range from 100 Hz to 4 KHz. With this flexible preclipping EQ, you can get some incredible sounds out of it. You can crank the mids for a cocked-wah sound, or tune the circuit to enhance the resonant peak of your specific guitar and amp. You can even get a scooped-mids sound if that’s what you’re shooting for, something that’s pretty rare in an overdrive.

The circuit has a lot of familiar things in common with others you’ve seen, but in this implementation they don’t always behave how you expect. This is not quite a Tube Screamer where you can tweak just about any part and get something good out of it! The original designers balanced the stock circuit very well, but if you’re modifying it, you may find that if you change one thing on one end you may need to change something clear over on the other end to make the first thing sound good.

Schematic

The schematic is in the vendor's build document, page 4. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 61 rows

Report a wrong parse
RefValueNormalizedTypeNotes
Resistors 28
R11k1k
R2510k10k
R21M1M
R2610k10k
R310k10k
R2710k10k
R4680k680k
R2810k10k
R5270k270k
R622k22k
R722k22k
R822k22k
R9470R470
R103k33.3k
R112k22.2k
R122k22.2k
R1322k22k
R1422k22k
R1522k22k
R1622k22k
R1710k10k
R1810k10k
R1910k10k
R201M1M
R211k1k
R221k1k
R2310k10k
R241k1k
Capacitors 15
C133n33n
C21uF1u
C310uF10uelec
C447uF47uelec
C51uF1u
C64n74.7n
C768n68n
C8100n100n
C9470pF470p
C10100n100n
C11220n220n
C1215n15n
C131uF1u
C14100uF100uelec
C1547uF47uelec
Diodes 7
D51N9141N914
D61N9141N914
D71N9141N914
D81N9141N914
D31N9141N914
D41N9141N914
D11N40021N4002
Transistors 4
Q12N50882N5088
Q22N50882N5088
Q32N50882N5088
Q42N50882N5088
ICs 1
IC2JRC4558DJRC4558D
Potentiometers 5
DRIVE100KBB100kPotentiometer
VOLUME10KBB10kPotentiometer
EQ Gain10KBB10kPotentiometer
FREQUENCY100KCC100kPotentiometer
RPD1M1MPotentiometer
LEDs 1
LED1intoINTO